ABSTRACT:

Clark, K.E., Shanley, J.B., Scholl, M.A., Perdrial, N., Perdrial, J.N., Plante, A.F., McDowell W.H. (Water Resource Research) Tropical river suspended sediment and solute dynamics in storms during an extreme drought.

5 minute resolution - Turbidity, Specific Conductance, Discharge, and Rainfall- derived data including fraction new water, pre-event discharge, quickflow.

ABSTRACT:

Clark, K.E., Shanley, J.B., Scholl, M.A., Perdrial, N., Perdrial, J.N., Plante, A.F., McDowell W.H. (Water Resource Research) Tropical river suspended sediment and solute dynamics in storms during an extreme drought.

Rio Mameyes and Icacos discharge, suspended sediment, particulate organic carbon (POC), particulate nitrogen (PN), stable isotopes of particulate C and N, C/N, particulate mineralogy, dissolved organic carbon (DOC), anions and cations from 8-24-2015 to 9-2-2015.

Weekly water isotope sampling for Rio Mameyes with mean discharge and z-scores (see paper for full description) 2007 to 2015, storm water isotope sampling for Rio Mameyes with mean discharge and z-scores (see paper for full description) 8-24-2015 to 8-29-2015.

ABSTRACT:

Soil organic matter (SOM) often increases with the abundance of short-range-ordered iron (SRO Fe) mineral phases at local to global scales, implying a protective role for SRO Fe. However, less is known about how Fe phase composition and crystal order relate to SOM composition and turnover, which could be linked to redox alteration of Fe phases. We tested the hypothesis that the composition and turnover of mineral-associated SOM co-varied with Fe phase crystallinity and abundance across a well-characterized catena in the Luquillo Experimental Forest, Puerto Rico, using dense fractions from 30 A and B horizon soil samples. The d13C and d15N values of dense fractions were strongly and positively correlated (R2 = 0.75), indicating microbial transformation of plant residues with lower d13C and d15N values. However, comparisons of dense fraction isotope ratios with roots and particulate matter suggested a greater contribution of plant versus microbial biomass to dense fraction SOM in valleys than ridges. Similarly, diffuse reflectance infrared Fourier transform spectroscopy indicated that SOM functional groups varied significantly along the catena. These trends in dense fraction SOM composition, as well as D14C values indicative of turnover rates, were significantly related to Fe phase crystallinity and abundance quantified with selective extractions. Mo¨ssbauer spectroscopy conducted on independent bulk soil samples indicated that nanoscale ordered Fe oxyhydroxide phases (nanogoethite, ferrihydrite, and/or very-SRO Fe with high substitutions) dominated (66–94%) total Fe at all positions and depths, with minor additional contributions from hematite, silicate and adsorbed FeII, and ilmenite. An additional phase that could represent organic-FeIII complexes or aluminosilicate-bearing FeIII was most abundant in valley soils (17–26% of total Fe). Overall, dense fraction samples with increasingly disordered Fe phases were significantly associated with increasingly plant-derived and fastercycling SOM, while samples with relatively morecrystalline Fe phases tended towards slower-cycling SOM with a greater microbial component. Our data suggest that counter to prevailing thought, increased SRO Fe phase abundance in dynamic redox environments could facilitate transient accumulation of litter derivatives while not necessarily promoting long-term C stabilization.

publication can be found here https://doi.org/10.1007/s10533-018-0476-4

ABSTRACT:

Phosphorus (P) is a key limiting nutrient in highly weathered soils of humid tropical forests. A large proportion of P in these soils is bound to redox‐sensitive iron (Fe) minerals; however, little is known about how Fe redox interactions affect soil P cycling. In an incubation experiment, we changed bulk soil redox regimes by varying headspace conditions (air vs. N2 gas), and examined the responses of soil P and Fe species to two fluctuating treatments (4‐ or 8‐day oxic followed by 4‐day anoxic) and two static redox treatments (oxic and anoxic). A static anoxic headspace increased NaOH‐extractable inorganic P (NaOH‐Pi) and ammonium oxalate‐extractable total P (AO‐Pt) by 10% and 38%, respectively, relative to a static oxic headspace. Persistent anoxia also increased NaHCO3‐extractable total P (NaHCO3‐Pt) towards the end of the experiment. Effects of redox fluctuation were more complex and dependent on temporal scales. Ammonium oxalate‐extractable Fe and Pt concentrations responded to redox fluctuation early in the experiment, but not thereafter, suggesting a depletion of reductants over time. Immediately following a switch from an oxic to anoxic headspace, concentrations of AO‐Pt, AO‐Fe, and HCl‐extractable Fe (II) increased (within 30 min), but fell back to initial levels by 180 min. Surprisingly, the labile P pool (NaHCO3‐Pt) decreased immediately after reduction events, potentially due to resorption and microbial uptake. Overall, our data demonstrate that P fractions can respond rapidly to changes in soil redox conditions, and in environments where redox oscillation is common, roots and microbes may benefit from these rapid P dynamics.

The full paper is available here https://doi.org/10.1029/2018JG004420

ABSTRACT:

Lithologic differences give rise to the differential weatherability of the Earth’s surface and globally variable silicate weathering fluxes, which provide an important negative feedback on climate over geologic timescales. To isolate the influence of lithology on weathering rates and mechanisms, we compare two nearby catchments in the Luquillo Critical Zone Observatory in Puerto Rico, which have similar climate history, relief and vegetation, but differ in bedrock lithology. Regolith and pore water samples with depth were collected from two ridgetops and at three sites along a slope transect in the volcaniclastic Bisley catchment and compared to existing data from the granitic Río Icacos catchment. The depth variations of solid-state and pore water chemistry and quantitative mineralogy were used to calculate mass transfer (tau) and weathering solute profiles, which in turn were used to determine weathering mechanisms and to estimate weathering rates.

Regolith formed on both lithologies is highly leached of most labile elements, although Mg and K are less depleted in the granitic than in the volcaniclastic profiles, reflecting residual biotite in the granitic regolith not present in the volcaniclastics. Profiles of both lithologies that terminate at bedrock corestones are less weathered at depth, near the rock-regolith interfaces. Mg fluxes in the volcaniclastics derive primarily from dissolution of chlorite near the rock-regolith interface and from dissolution of illite and secondary phases in the upper regolith, whereas in the granitic profile, Mg and K fluxes derive from biotite dissolution. Long-term mineral dissolution rates and weathering fluxes were determined by integrating mass losses over the thickness of solid-state weathering fronts, and are therefore averages over the timescale of regolith development. Resulting long-term dissolution rates for minerals in the volcaniclastic regolith include chlorite: 8.9 × 10−14 mol m−2 s−1, illite: 2.1 × 10−14 mol m−2 s−1 and kaolinite: 4.0 × 10−14 mol m−2 s−1. Long-term weathering fluxes are several orders of magnitude lower in the granitic regolith than in the volcaniclastic, despite higher abundances of several elements in the granitic regolith. Contemporary weathering fluxes were determined from net (rain-corrected) solute profiles and thus represent rates over the residence time of water in the regolith. Contemporary weathering fluxes within the granitic regolith are similar to the long-term fluxes. In contrast, the long-term fluxes are faster than the contemporary fluxes in the volcaniclastic regolith. Contemporary fluxes in the granitic regolith are generally also slightly faster than in the volcaniclastic. The differences in weathering fluxes over space and time between these two watersheds indicate significant lithologic control of chemical weathering mechanisms and rates.

ABSTRACT:

The thick regolith developed in the humid tropics represents an endmember of critical zone evolution, where shallow and deep biogeochemical cycles can be decoupled in terms of the predominant source of trace elements (atmospheric input at the surface, weathering at depth) and of the processes that control their cycling. To investigate the influence of lithology on trace element behavior and in this potential decoupling, we studied two deep (9.3 and 7.5 m), highly-leached, ridgetop regolith profiles at the Luquillo Critical Zone Observatory, Puerto Rico. These profiles have comparable internal (degree of weathering, topography) and external (vegetation, climate) characteristics, but differ in their underlying bedrock (andesitic volcaniclastic and granitic). At these two sites, we analyzed a large suite of trace elements and used the rare earth elements and yttrium (REY) as tracers of critical zone processes because they are fractionated by the chemical reactions involved in weathering and pedogenesis (e.g., sorption, dissolution, colloidal transport) and by redox fluctuations.

We found that both regolith profiles show atmospheric inputs of trace elements at the surface and evidence of bedrock dissolution at depth, as expected. We also found noticeable differences in the re-distribution of trace elements and REY within the profiles, indicative of different geochemical environments with depth and lithology. In the volcaniclastic profile, trace element and REY behavior is controlled mainly by redox-mediated, sorption/desorption reactions, whereas pH-controlled dissolution/precipitation and sorption reactions predominate in the granitic profile. The most noticeable difference between the two regolith profiles is in the long-term redox conditions, inferred from redox-sensitive elements and Ce anomaly variations, which are more variable and stratified in the volcaniclastic profile and change gradually with depth in the granitic profile. The contrasting redox conditions and the different sources of elements (dust vs. bedrock) produce a decoupling between the surface and deep geochemical environments of the volcaniclastic regolith. The difference in redox conditions between the two lithologies likely stems from the finer grain size and higher clay content of the volcaniclastic regolith.

ABSTRACT:

Ferrous iron (FeII) oxidation is an important pathway for generating reactive FeIII phases in soils, which can affect organic carbon (OC) persistence/decomposition. We explored how pO2 concentration influences FeII oxidation rates and FeIII mineral composition, and how this impacts the subsequent FeIII reduction and anaerobic OC mineralization following a transition from oxic to anoxic conditions. We conducted batch soil slurry experiments within a humid tropical forest soil amended with isotopically labeled 57FeII. The slurries were oxidized with either 21% or 1% pO2 for 9 days and then incubated for 20 days under anoxic conditions. Exposure to 21% pO2 led to faster FeII oxidation rates and greater partitioning of the amended 57Fe into low-crystallinity FeIII-(oxyhydr)oxides (based on Mössbauer analysis) than exposure to 1% pO2. During the subsequent anoxic period, low-crystallinity FeIII-(oxyhydr)oxides were preferentially reduced relative to more crystalline forms with higher net rates of anoxic FeII and CO2 production—which were well correlated—following exposure to 21% pO2 than to 1% pO2. This study illustrates that in redox-dynamic systems, the magnitude of O2 fluctuations can influence the coupled iron and organic carbon cycling in soils and more broadly, that reaction rates during periods of anoxia depend on the characteristics of prior oxidation events.

R-code for Spectral Subtraction for 57Fe-spiked samples developed for:

Chen, Chunmei, Christof Meile, Jared Wilmoth, Diego Barcellos, and Aaron Thompson (2018): Influence of pO2 on iron redox cycling and anaerobic organic carbon mineralization in a humid tropical forest soil. Environmental Science & Technology 52 (14): 7709-7719. DOI: 10.1021/acs.est.8b01368

ABSTRACT:

In order to assess the effects of critical zone processes on Mg concentrations and isotopic signatures of tropical streams, we studied a well constrained, highly weathered andesitic volcaniclastic catchment in the Luquillo Critical Zone Observatory, Puerto Rico. Our results indicate that dissolved Mg concentrations and isotope ratios in the regolith pore water are mainly controlled by rain input, with weathering inputs being more important at sites with thinner regolith (2.7–0.9 m deep) and at depth (>8 m) on a thick ridgetop regolith (∼10 m). In addition to mixing of precipitation and weathering-sourced Mg, an isotopic fractionation process is taking place between dissolved Mg and the regolith, likely during dissolution or recrystallisation of Fe(III)-(hydro)oxides under alternating redox conditions. Bulk regolith is isotopically heavier than both the bedrock and the exchangeable fraction (δ26Mgregolith-bedrock = +0.03 to +0.47‰), consistent with the preferential incorporation of heavy 26Mg into secondary minerals with some exchange of sorbed Mg with isotopically lighter pore water. Magnesium concentrations in the stream show a typical dilution behaviour during a storm event, but the [Mg] – δ26Mg pattern cannot be explained by mixing of rain and pore water; the data are best explained by a steady-state fractionation model with α = 1.00115. During baseflow the stream has δ26Mg = +0.01‰, higher than any of the water samples or the bedrock. In-situ analysis of the Mg isotopic composition of bedrock minerals points at the dissolution of Mg-rich chlorite (δ26Mg = +0.19‰) as the most likely source of this isotopically heavy Mg, with mass balance calculations indicating chlorite dissolution is also the main source of Mg to the stream. Overall, our study highlights the importance of atmospheric input of nutrients to the vegetation in tropical areas covered by thick, highly leached regolith, whereas the Mg flux and Mg isotopic signature of watershed exports are dominated by bedrock dissolution delivered to the stream through deeper, usually un-sampled critical zone pathways.

ABSTRACT:

Geophysical surveys conducted during the summer of 2014 followed on previous work that investigated the nature and spatial variability of ground penetrating radar (GPR) reflections in the Rio Icacos watershed (Figure 1a). GPR surveys using a variety of shielded (160 MHz) and unshielded (50, 100 and 200 MHz) antennas (Figure 1e) was combined with multi-frequency terrain conductivity measurements to upscale previous measurements.
Figure 1a shows a 2 km long transect (red line) across a trail in the Rio Icacos watershed. The transect in the northern edge had an approximately elevation of 640 m, and ended in the southern edge below 540 m elevation and close to the knickpoint. The GPR data along the transect revealed a series of vertical zones with presence of chaotic reflectors (Figure 1b, between 240-265m, 270-300 m, and 320-350 m along the transect; and Figure 1c, between 690-750 m along the transect). These areas repeated at several locations along the 2 km transect (white lines in Figure 1a). Other GPR reflector facies signatures (not shown here) included two landslide locations (yellow lines in Figure 1a); and an area of laterally continuous reflectors (blue line in Figure 1a) towards the end of the transect and close to the knickpoint.
Terrain conductivity surveys consistently depict a) increases in terrain conductivity; and b) decreases in magnetic susceptibility that coincide with the vertical zones of chaotic GPR reflectors described above (shaded areas in Figures 1b and 1c)
We attribute these areas of enhanced GPR reflections to vertical fracturing within the bedrock-regolith interface associated with the formation of corestones. Water infiltration may cause regolith wash off (resulting in a decrease in electrical conductivity) and concentration of corestones (resulting in increases in magnetic susceptibility). This preliminary hypothesis is confirmed by the presence of large corestones adjacent to the transect (Figure 1d) and following topographic valley areas (Figure 1a).
These results confirm the potential of hydrogeophysical measurements for understanding variability of bedrock-regolith interface in the Icacos watershed at large (i.e. km) scales and have direct implications for the controls on subsurface fluid circulation and presence of preferential groundwater flow.

GPR data found here in the second link are raw data, data was processed and interpreted in Orlando et al. 2016 ((DOI: 10.1002/esp.3948):

“GPR data processing was performed using ReflexW by Sandmeier Scientific. Steps were limited to: (a) a ‘dewow’ filter over a 10 ns time-window; (b), application of a time-varying gain; (c) a bandpass filter; (d) a static correction; and in some cases, (e) Kirchhoff migration based on a single EM wave velocity as determined from the CMP profiles.”

ABSTRACT:

Rain and throughfall samples are the total catch for the week, and are exposed to field conditions for that time. No event sampling is conducted on a routine basis. Rainfall Collected in Bisley (RCB) are bulk or always-open collectors that receive dry deposition by sedimentation.

ABSTRACT:

Rain and throughfall samples are the total catch for the week, and are exposed to field conditions for that time. No event sampling is conducted on a routine basis. Rainfall Collected in Bisley (RCB) are bulk or always-open collectors that receive dry deposition by sedimentation.

ABSTRACT:

Phosphorus (P) availability in terrestrial ecosystems depends on soil age, climate, parent material, topographic position, and biota, but the relative

We collected soils from both Icacos and Bisley, in different topographic positions, and analyzed them for phosphorus content.

Abstract from the paper listed below Mage & Porder 2013: https://www.doi.org/10.1007/s10021-012-9612-5

Phosphorus (P) availability in terrestrial ecosystems depends on soil age, climate, parent material, topographic position, and biota, but the relative
importance of these drivers has not been assessed. To ask which factor has the strongest influence on long- and short-timescale metrics of P availability, we sampled soils across a full-factorial combination of two parent materials [quartz diorite (QD) and volcaniclastic (VC)], three topographic positions (ridge, slope, and valley), and across 550 m in elevation in 17 sub-watersheds of the Luquillo Mountains, Puerto Rico. VC rocks had double the P content of QD (600 vs. 300 ppm; P < 0.0001), and soil P was similarly approximately 29 higher in VC-derived soils (P < 0.0001). Parent material also explained the most variance in our two other longtimescale metrics of P status: the fraction of recalcitrant P (56% variance explained) and the loss of P relative to parent material (35% variance explained), both of which were higher on VC-derived soils (P < 0.0001 for both). Topographic position explained an additional 10–15% of the variance in these metrics. In contrast, there was no parent material effect on the more labile NaHCO3- and NaOH-extractable P soil pools, which were approximately 2.59 greater in valleys than on ridges (P < 0.0001). Taken together, these data suggest that the relative importance of different state factors varies depending on the ecosystem property of interest and that parent material and topography can play sub-equal roles in driving differences in ecosystem P status across landscapes.

Lab Analysis:

Soils were collected in Luquillo National Forest, Puerto Rico, in July 2010.
We collected soils from 16 subwatersheds in a full factorial combination of 2 forest types (colorado, tabonuco) and 2 parent materials (quartz diorite, volcaniclastic)
In each subwatershed we dug 9 soil pits to a depth of 80cm (0-20, 20-50, 50-80). Three pits were located in ridge, three in slope, and 3 in valley positions.
This yielded a total of 432 soil samples, which were air dried at the University of Pennsylvania. A subsample was then shipped to Brown University
At Brown, equal mass of the three replicates from a given topographic position within a subwatershed were combined to make a composite sample (e.g. all three 0-20cm depth ridge samples from site COOX-1 were combined).
We analyzed for P fractions using a modified Hedley fractionation, extracting sequentially with 0.5N NaHCO3 and 0.1N NaOH. Each extract was measured for inorganic P on a westco smartchem 200 analyzer.
Each extractant was also digested with persulfate and reanalzyed for total P, organic P was determined by difference between P in the persulfate digest and P in the undigested extractant.
Every 10th sample was run in triplicate to ensure reproducibility.
Each of the composite samples was also digested by lithium borate flux fusion and run by XRF to determine total elements, and by ICP-MS to determine trace elements. This work was done
by ALS Chemex (SParks, NV).
The data presented on the next page are concentrations of different P forms per gram oven dry weight of soil.

Tau P refers to the loss (<0) or gain (>0) of P relative to parent material, using the P concentrations of soil and parent material referenced to niobium (see Porder and Chadwick, 2009). Tau = -0.5 represents a 50% loss
of P relative to the parent rock.

ABSTRACT:

Climate data from the Bisley Lower Tower.; Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
ggonzalez@fs.fed.us

Hourly data are available from the USDA FS here:

González, Grizelle. 2017. Luquillo Mountains meteorological and ceilometer data. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2017-0023

ABSTRACT:

Description of data preparation performed on data from 2001 to 2007 (end).

Cleaning Data
In the original form of Sabana data (both daily and hourly data), instrument frequently recorded minimum value of TIRRa and Total PFD as negative values and maximum value of RH as over 100%. Unquestionably, these are unrealistic values. Thus, they were replaced by 0 (zero) for TIRRa and Total PFD minimum values and 100% for RH maximum values.

Defected Data
There were noticeable defect of Total PFD values in 2003 and 2006 (both daily and hourly data). Specifically, in 2003, defected Total PFD values were from January 1st (Day # = 1) through September 3rd (Day # = 247) and, in 2006, they were from March 24th (Day # = 83) through October 31st (Day # = 304). Therefore, four year (2001, 2002, 2004, and 2005) monthly averages were calculated and multiplier was developed based on the ratio of [four year average] / [2003 (or 2006) defected data]. Detail calculation of this can be seen in the Modification file (MS Excel file). Accordingly, columns denoted as “Modified Total PFD” are results of this modification. However, note that red and black colors within the column indicate modified and non-modified (original) values, respectively.

Missing Data
There were large numbers of data missing in both daily and hourly dataset which are outlined below. Additionally, there were couples of significantly noticeable defected values in some columns which were omitted from the dataset. Thus, missing and omitted data were left as blank (no values).

Grizelle González - Project Leader, Research Unit

USDA FS - International Institute of Tropical Forestry

voice: 787-764-7800

ggonzalez@fs.fed.us

ABSTRACT:

he overall goal of this effort is to monitor the surface climate of the upper Luquillo Mountains. This station provides basic hourly and daily climate data that is comparable to the Bisley and El Verde stations at lower elevations. It also provides the long-term reference data that supplements shorter-term, high frequency measurements.

Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
grizelle.gonzalez@usda.gov

In the hourly file, data in red is not good or not reliable. We have connected two anemometers at different heights on the tower, causing an additional 8 columns for wind vectors and wind speed.

Detailed information about the following major variables is available in Comments/README:

Temperature (T),

Radiation data, incoming solar radiation (Sin), Relative humidity (RH),

Radiation data, photosynthetic active radiation (PAR),

Wind speed (U),

Wind direction (Udir),

Rainfall (P),

Horizontal precipitation (HP)

ABSTRACT:

This is project presents data related to discharge measurements from the Bisley Watershed in the Luquillo Mountains.This is project presents data related to discharge measurements from the Bisley Watershed in the Luquillo Mountains.

This is project presents data related to discharge measurements from the Bisley Watershed in the Luquillo Mountains.
Long-term rainfall and discharge data from the Luquillo Experimental Forest (LEF) were analyzed to develop relationships between rainfall, stream-runoff, and elevation. These relationships were then used with a Geographic Information System (GIS) to determine spatially-averaged, mean annual hydrologic budgets for watersheds and forest types within the study area. Model estimates indicate that a total of 3864 mm/yy (444 hm3) of rainfall falls on the forest in an average year. The Tabonuco, Colorado, Palm and Dwarf Forest types receive an estimated annual rainfall of 3537, 4191, 4167, and 4849 mm/yy, respectively. Of the average annual rainfall input, 65% (2526 mm/yr) is converted to runoff and the remainding 35% (1338 mm.yr) is lost from the system by evapotranspiration and other abstractions. In comparison to other tropical forests, the LEF as a whole has more evapotranspiration than many tropical montane forests but less evapotranspiration than many lowland tropical forests.

Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
ggonzalez@fs.fed.us

ABSTRACT:

The Luquillo Critical Zone Observatory has a series of sites collecting information about the landscape and climate of the Luquillo Mountains in Puerto Rico. The Bisley Lower Tower (pictured in Figure 5), which is a 25 m high walk-up tower in the Bisley watershed, is one of the eight stations monitoring weather and rainfall. Bisley is at tree canopy level and at an elevation of 352 m above sea level. It is precisely located at Bisley Lower Tower 18° 18' 51.8616' N, 65° 44' 41.676' W in a Tabanuco forest. Bisley Lower Tower includes many instruments for measuring climate conditions. The ozone instrument is a 2B technologies Model 202 Ozone Monitor (see Figure 4) and has collected ozone level information every fifteen minutes since April 24, 2008.

Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
voice: 787-764-7800
ggonzalez@fs.fed.us

ABSTRACT:

Climate data for Sabana research station.

Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
ggonzalez@fs.fed.us

ABSTRACT:

Monthly Average climate data from the Bisley Lower Tower.

Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
voice: 787-764-7800
ggonzalez@fs.fed.us

ABSTRACT:

Changes in the quantity and quality of precipitation as it passes through vegetative cover are important components of both hydrologic and nutrient budgets.

Throughfall over any period depends on the balance between precipitation, evaporation and canopy storage (Horton, 1919; Leonard, 1967; Rutter et al., 1972). If the watershed is divided into different vegetation types based on similarity in throughfall and steamflow, the total throughfall over the watershed can be expressed as:

(1) Pg = Sum( T n A n )+ Sum (Sm Dm)

Where Pg = total throughfall reaching the ground, Tn = canopy throughfall from vegetation type n, An = area of vegetation type n, Sm = stemflow from stem type m and Dm = number of stems in type m.

Using eqn. (1) to estimate total watershed throughfall becomes a problem of determining the minimum number of vegetation types necessary to describe the system at the required level of accuracy. In one of our studies, measured throughfall was compared with actual canopy and stem conditions to estimate the percentages of throughfall for different time periods was calculated by weighting the average throughfall and stemflow measured in representative areas of each vegetation type by the total area of that vegetation group.

Measurements reported here were made in two of the Bisley Research Watershed of the U.S. Forest Service. These adjacent watersheds drain 13.0 ha of highly dissected mountainous terrain that range in elevation from 265 to 455 m. Both watersheds are covered by Tabonuco type forests and were selectively logged at various times between 1860 and 1940 (Scatena, 1988).

The dominant tree in the watersheds in the Tabonuco ( Dacryodes excelsa ) which often comprises as much as 35% of the canopy ( Wadsworth, 1970). Structurally the forest has three dominant layers, a discontinuous emergent strata, a continuous upper stratum at 20 m, and an understory layer. Leaves are mesophyllous and often covered with epiphytic growth.

ABSTRACT:

We sampled soils from 216 profiles representing 24 sites in the El Yunque National Forest to determine amounts C, N and neutral-salt-extractable Ca++, Mg++ and K+. Following the classic paradigm, we assessed the influence of climate (modeled precipitation, modeled temperature and/or elevation as a surrogate variable for both), forest type (tabonuco, colorado, palm), parent material (quartz diorite, volcaniclastics), and topography (catena positions ridge, slope, valley and % slope) on the distribution of these nutrients. To separate the effects of vegetation from those of climate, half of the sites were located between 500 and 700 m in the three forest types where rainfall and temperature were not significantly different. Using a combination of ANOVA (or Kruskal-Wallis) and univariate regression trees we determined that the amount of carbon in the top 80 cm of soil was influenced primarily by forest type (c > p > t) probably driven by differences in litter and/or root C:N ratios. Topographic position was significantly correlated with C amount (v > s, r), with the higher C amounts in the valleys probably driven by low O2 levels. Bedrock type was significantly correlated with C amount in c and p stands, but not in the tabonuco type. N was strongly correlated with C as expected. Exchangeable Ca was different across forest types (t > c, p) and bedrock type (qd > vc). Mg and K were differed by forest type, but not by bedrock type (t > c, p) or any other variables.

The next phases of this project are (1) to determine levels of these nutrients below the root zone (80-140 cm) and the factors controlling their distribution; and (2) establish field experiments to test the results of the regression trees which indicate that the C:N ratio of litter and/or root inputs is the most important variable influencing C distribution. The latter represents a first step in exploring the usefulness of regression trees as a way of sorting out the relative importance of each of the state factors (climate, topography, organisms, parent material and time) in the classic paradigm relating environmental variables to soil properties.

Soil C differs markedly across forest types (c> p> t, p s, r, p

ABSTRACT:

Various GIS datasets

Spatial data relevant to the Luquillo Mountains compiled from various sources.

USGS Global Fiducial Library: Areal Images of Luquillo Mountains

http://gfl.usgs.gov/gallery/luquilloforpr_pub_gallery.shtml

LiDAR data available on open topography:

http://www.opentopography.org/

and
https://eng.ucmerced.edu/people/qguo/projects/CZO_Lidar/Frontpage

LandcocoverGouldetal.zip from:
Gould, William A.; Martinuzzi, Sebastian; Ramos Gonzalez, Olga M. 2008. Developed land cover of Puerto Rico. Scale 1: 260 000. Res. Map IITF-RMAP-10. Rio Piedras, PR: U.S. Department of Agriculture Forest Service, International Institute of Tropical Forestry.
https://www.fs.usda.gov/treesearch/pubs/38526

ABSTRACT:

GIS data for Geology, Geochemistry, Geophysics. The content here is derived from :

Bawiec, W.J., ed., 1999, Geology, geochemistry, geophysics, mineral occurrences and mineral resource assessment for the Commonwealth of Puerto Rico: U.S. Geological Survey Open-File Report 98-038, available online only. https://pubs.usgs.gov/of/1998/of98-038/

The format of the data have been modernized but are otherwise unchanged.

ABSTRACT:

Key science question:

• How does stream channel morphology respond to the addition of impervious cover in a humid tropical region adjusted to frequent large storms?

Urbanization through the addition of impervious cover can alter catchment hydrology, often resulting in increased peak flows during floods. This phenomenon and the resulting impact on stream channel morphology is well documented in temperate climatic regions, but not well documented in the humid tropics where urbanization is rapidly occurring. This study investigates the long-term effects of urbanization on channel morphology in the humid sub-tropical region of Puerto Rico, an area characterized by frequent high-magnitude flows, and steep coarse-grained rivers. Grain size, low-flow channel roughness, and the hydraulic geometry of streams across a land-use gradient that ranges from pristine forest to high density urbanized catchments are compared. In areas that have been urbanized for several decades changes in channel features were measurable, but were smaller than those reported for comparable temperate streams. Decades of development has resulted in increased fine sediment and anthropogenic debris in urbanized catchments. Materials of anthropogenic origin comprise an average of 6% of the bed material in streams with catchments with 15% or greater impervious cover. At-a-station hydraulic geometry shows that velocity makes up a larger component of discharge for rural

channels, while depth contributes a larger component of discharge in urban catchments. The average bank-full cross-sectional area of urbanized reaches was 1.5 times larger than comparable forested reaches, and less than the world average increase of 2.5. On average, stream width at bank-full height did not change with urbanization while the world average increase is 1.5 times. Overall, this study indicates that the morphologic changes that occur in response to urban runoff are less in channels that are already subject to frequent large magnitude storms. Furthermore, this study suggests that developing regions in the humid tropics shouldn’t rely on temperate analogues to determine the magnitude of impact of urbanization on stream morphology.

References to Other Datasets:
Cross sections, grain size, and longitudinal measurements for 14 gaged streams in the NE PR region. Cross sections, grain size, longitudinal profiles, and low flow velocity for 42 field sites across a gradient of land use in the NE region of PR
Relevant Publications:

Pike AS, Scatena FN. 2010. Riparian indicators of flow frequency in a tropical montane stream network. Journal of Hydrology 382 : 72-87. DOI: 10.1016/j.jhydrol.2009.12.019

Phillips CB, and Scatena FN. 2012. Reduced channel morphological response to urbanization in a flood-dominated humid tropical environment. Earth Surface Processes and Landforms. DOI: 10.1002/esp.3345. http://onlinelibrary.wiley.com/doi/10.1002/esp.3345/full

ABSTRACT:

Climate data for Sabana research station.
Including:
Air temperature, C
bucket total
Precipitation Intensity (in/15 min)

Data a product of USDA Forest Service -IITF:

Grizelle González - Project Leader, Research Unit
USDA FS - International Institute of Tropical Forestry
ggonzalez@fs.fed.us

For hourly data see:
González, Grizelle. 2017. Luquillo Mountains meteorological and ceilometer data. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2017-0023

ABSTRACT:

Radio Frequency Identification tagged cobble survey data from the Rio Mameyes .
Tagged tracers with positions overtime. Additional documentation is presented within the dataset file.

Sediment transport is an intrinsically stochastic process, and measurement of bed load in the environment is further complicated by the unsteady nature of river flooding. Here we present a methodology for analyzing sediment tracer data with unsteady forcing. We define a dimensionless impulse by integrating the cumulative excess shear velocity for the duration of measurement, normalized by grain size. We analyze the dispersion of a plume of cobble tracers in a very flashy stream over two years. The mean and variance of transport distance collapse onto well-defined linear and power-law relations, respectively, when plotted against cumulative dimensionless impulse. Data suggest that the asymptotic limit of bed load tracer dispersion is super diffusive, in line with a broad class of geophysical flows exhibiting strong directional asymmetry (advection), thin-tailed step lengths and heavy-tailed waiting times. The impulse framework justifies the use of quasi-steady flow approximations for long-term river evolution modeling.

ABSTRACT:

Luquillo Daily Air TemperatureAir temperature collected at various locations in the Luquillo Mountains
Locations are: Bisley, El Verde, Sabana, and east peak.

ABSTRACT:

These long-term Data Sets are made available in the spirit of open scientific collaboration. It is a matter of professional ethics and collegial interaction to acknowledge the scientists who produced these data. Therefore, proper citation and acknowledgement of the source of these data should be included in any publication or report in which they are used. We suggest you use the following acknowledgements:

For Luquillo Experimental Forest data: Funding for data collection came from NSF LTER DEB-0620919, NSF OPUS DEB-0816727, NSF DEB-0108385, the USDA Forest Service International Institute of Tropical Forestry, and the University of Puerto Rico ITES. Data were download from StreamChemDB (http://web.fsl.orst.edu/streamchem/).

ABSTRACT:

This dataset is described in the following paper:

Stone, M.M., Plante, A.F. Changes in phosphatase kinetics with soil depth across a variable tropical landscape. Soil Biology & Biochemistry. 2013. In Press.

In regards to the sampling locations, each soil x forest combination is generally associated with a corresponding site in the Soil Survey from Johnson & Xing Hao. For instance, what I've called Colox 1-5 all corresponds to COLOX1 from Johnson & Xing Hao samples.

The soil survey dataset referred to above is entitled:

Northeastern Puerto Rico and the Luquillo Mountain - Soil Survey (2011-2012)

A description of those sites are here

https://www.sas.upenn.edu/lczodata/sites/www.sas.upenn.edu.lczodata/files/SoilPitCharacteristics.csv

ABSTRACT:

X-ray Florescence (XRF) is a widely used non-destructive method that measures the elemental composition of materials. This technology was applied to investigate the rocks and sediments in the Luquillo Mountains / El Yunque region of Puerto Rico. Initial testing of wet and dry sediments revealed that the machine records higher elemental concentrations in dry compared to wet sediments as it seems that the water molecules interfere with the X-ray beam on wet samples. The XRF method on dried samples produced reliable results and allowed for the chemical separation of the five basic bedrock types found in the Luquillo Mountains. Of the volcanoclastic the Fajardo Formation can be distinguished from the others by its concentration of Barium (Ba) and Rubidium (Rb). The Unnamed formation was distinguished by Copper (Cu) and the Hato Puerto Formation was distinguished by Nickel (Ni) and Strontium (Sr). The Rio Blanco granodiorite is the youngest rock type of the region and was the only formation whose elemental chemistry was not distinguishable from the othersapparently because it was formed directly from the basic magma that also formed the Luquillo Mountains volcanic rocks. Recent studies have found high levels of Mercury (Hg) in Luquillo stream water. Knowing that the Luquillo region was heavily mined for Gold (Ag) and Silver (Au), the Hg used in historic mining is a possible source of the elevated Hg values. The XRF analysis indicated small quantities of Hg in some rocks but no Hg was found in the sediments and soils surrounding the historic mining sites. Therefore if Hg had been used in historic mining operations it is no longer apparent in the sediments and has presumably been removed by erosion of the site.

ABSTRACT:

This project presents data pertaining to the water chemistry of streams around the El Verde Field Station, Bisley, Espiritu Santo, and Rio Icacos. All data here are raw unprocessed data which may contain errors, unless otherwise noted.

Hobo U20-001-04 Water Level, HOBO Light and Air Temperature Sensor UA-002-64, HOBO U26 DO Probe DO and Water Temperature, and HOBO U24 conductivity loggers collect data at a 15 minute time interval.

Rio Icacos Tributary (IO) site has Hobo U20-001-04 Water Level, HOBO Light and Temp Sensor UA-002-64, HOBO U26 DO Probe DO and Temp, HOBO U24 conductivity probe.

Quebrada Sonadora has Hobo U20-001-04 Water Level, HOBO Light and Temp Sensor UA-002-64, HOBO U26 DO Probe DO and Temp, HOBO U24 conductivity probe.

Quebrada Prieta has HOBO Light and Temp Sensor UA-002-64, HOBO U26 DO Probe DO and Temp, HOBO U24 conductivity probe.

Bisley Q3 has HOBO Light and Temp Sensor UA-002-64, HOBO U26 DO Probe DO and Temp, HOBO U24 conductivity probe.

Q. Taronja site has been discontinued.

Rio Icacos (RI) - has HOBO Light and Temp Sensor UA-002-64,

ABSTRACT:

We present an interactive web map of Luquillo-CZO GIS data available for download.

ABSTRACT:

USGS resources for Stream flow, Water Quality, Groundwater, Suspended Sediment, and Meteorological data.

ABSTRACT:

High-resolution LiDAR data were obtained by NCALM for 253 km2 of the Luquillo Critical Zone Observaotry (LCZO) in the Rio Mameyes, Rio Blanco watersheds and coastal zones, Puerto Rico. Due to weather, the data were collected over two campaigns in July 2010 and May 2011, covering the entire survey area. Data acquisition, ground-truthing, vegetation surveys and processing were founded and coordinated by NSF Award EAR-0922307 (PI. Qinghua Guo) to collect similar data at all six CZOs for a variety of cross-site analyses, including calibration of algorithms to extract vegetation characteristics from the LiDAR point cloud data.

ABSTRACT:

San Juan ULTRA makes available to users, information we've been collecting at various stages during the development of our projects. We present a cartographic visualization of geographic data that influence the Rio Piedras basin.

ABSTRACT:

A sample of data from three groundwater monitoring locations in the Icacos / Rio Blanco watershed are included here. Requests for a complete dataset will be considered, please email leonmi@sas.upenn.edu with an explanation of what you would like to do with the data. A complete dataset will be released to the public at a later date.

I-03
http://odm2admin.cuahsi.org/LCZO/graphfa/samplingfeature%3D7/
I-04
http://odm2admin.cuahsi.org/LCZO/graphfa/samplingfeature%3D2047/
I-06
http://odm2admin.cuahsi.org/LCZO/graphfa/samplingfeature%3D2051/
I-09
http://odm2admin.cuahsi.org/LCZO/graphfa/samplingfeature%3D8/
I-10
http://odm2admin.cuahsi.org/LCZO/graphfa/samplingfeature%3D9/
I-23
http://odm2admin.cuahsi.org/LCZO/graphfa/samplingfeature%3D2058/

Date Range Comments: Collection ongoing

ABSTRACT:

NOAA’s National Weather Service: Hydrometeorological Design Studies Center. Precipitation Frequency Data Server.

ABSTRACT:

The Luquillo Long-Term Ecological Research (LUQ) program takes place in the Luquillo Mountains of Puerto Rico (Figure 1). This tropical setting has steep environmental gradients, a varied natural disturbance regime, and a history of human land use. Of the mountain area 11,330 hectares are included in the Luquillo Experimental Forest (LEF), which is congruent with the El Yunque National Forest, part of the U.S. National Forest system. The mountains rise to over 1075 m. Prevailing winds coming off the ocean from the east drop rain as they rise over the mountains; thus rainfall increases with elevation, ranging from about 3530 mm year-1 at low elevations to 4850 mm year-1 higher up. February through April are the drier months, but monthly rainfall is variable. Mean monthly temperatures at lowest elevations range from about 23.5ºC in January to 27ºC in September, and at the highest elevations from 17ºC to 20ºC (see article Climate and Hydrology in this web page).
Date Range Comments: Ongoing

ABSTRACT:

Like many mountainous areas in the tropics, watersheds in the Luquillo Mountains of eastern Puerto Rico have abundant rainfall and stream discharge and provide much of the water supply for the densely populated metropolitan areas nearby. Projected changes in regional temperature and atmospheric dynamics as a result of global warming suggest that water availability will be affected by changes in rainfall patterns. It is essential to understand the relative importance of different weather systems to water supply to determine how changes in rainfall patterns, interacting with geology and vegetation, will affect the water balance. To help determine the links between climate and water availability, stable isotope signatures of precipitation from different weather systems were established to identify those that are most important in maintaining streamflow and groundwater recharge. Precipitation stable isotope values in the Luquillo Mountains had a large range, from fog/cloud water with δ2H, δ18O values as high as +12 ‰, −0.73 ‰ to tropical storm rain with values as low as −127 ‰, −16.8 ‰. Temporal isotope values exhibit a reverse seasonality from those observed in higher latitude continental watersheds, with higher isotopic values in the winter and lower values in the summer. Despite the higher volume of convective and low-pressure system rainfall, stable isotope analyses indicated that under the current rainfall regime, frequent trade -wind orographic showers contribute much of the groundwater recharge and stream base flow. Analysis of rain events using 20 years of 15 -minute resolution data at a mountain station (643 m) showed an increasing trend in rainfall amount, in agreement with increased precipitable water in the atmosphere, but differing from climate model projections of drying in the region. The mean intensity of rain events also showed an increasing trend. The determination of recharge sources from stable isotope tracers indicates that water supply will be affected if regional atmospheric dynamics change trade- wind orographic rainfall patterns in the Caribbean.

For more data a USGS open file report is available: Stable Isotope (δ18O and δ2H) Data for Precipitation, Stream Water, and Groundwater in Puerto Rico http://dx.doi.org/10.3133/ofr20141101

ABSTRACT:

Data collected from the Rio Mameyes to characterize change in size and shape of river sediment due to abrasion. Complete details on measurement and calculation techniques can be found in the following paper: Quantifying the significance of abrasion and selective transport on downstream pebble evolution, Journal of Geophysical Review: Earth Surface, (in review).

This is also published in the Dissertation of Kimberly Litwin Miller which can be found here: http://criticalzone.org/luquillo/publications/pub/litwin-jerolmack-2014-the-causes-and-consequences-of-particle-size-change-i/

ABSTRACT:

see chapter three of http://criticalzone.org/luquillo/publications/pub/stone-plante-2014-soil-microbial-communities-and-soil-organic-matter-compos/

ABSTRACT:

The Luquillo Schoolyard Data Jam challenges high school students to find interesting ways to present scientific data to nonscientist audiences.

ABSTRACT:

This Data exploration tool allows user to browse data presented in the following papers:

http://dx.doi.org/10.1016/j.geoderma.2015.03.002

http://dx.doi.org/10.1007/s10533-015-0120-5

http://dx.doi.org/10.1890/13-2151.1

ABSTRACT:

These files contain classified topo/bathy lidar data. Data are classified as 1 (valid non-ground topographic data), 2 (valid ground topographic data), and 29 (valid bathymetric data). Classes 1 and 2 are defined in accordance with the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards. These data were collected by the Coastal Zone Mapping and Imaging Lidar (CZMIL) system. CZMIL integrates a lidar sensor with simultaneous topographic and bathymetric capabilities, a digital camera and a hyperspectral imager on a single remote sensing platform for use in coastal mapping and charting activities. Native lidar data is not generally in a format accessible to most Geographic Information Systems (GIS). Specialized in-house and commercial software packages are used to process the native lidar data into 3-dimensional positions that can be imported into GIS software for visualization and further analysis. The 3-D position data are sub-divided into a series of LAS files, which are tiled into quarter-quads or 5km boxes. In addition to the lidar point data, bare earth Digital Elevation Models (DEMs) at a 1 meter grid size are available. These data are available from the NOAA Digital Coast at:

https://coast.noaa.gov/dataviewer/#/imagery/search/where:ID=5154

ABSTRACT:

This is a long-term monitoring of leaf litter inputs into Prieta Stream, arm B, and into the Gatos stream. The monitoring is conducted using litter traps similar tho those used in other LTER project. Baskets are suspended over the channel and are emptied every other week. All material is dried and identified.

ABSTRACT:

LWG2B was dug to a depth of 16 meters. and East Peak (EP1) was dug to a depth of 35 meters. Two pressure transducers were placed at each site one at the surface and one at depth in order to calculate the depth of water. Temperature is also logged at the surface and at depth.

ABSTRACT:

Mineralogy of Soils Overlying the Two Main Geologic Provinces of the El Yunque National Forest, Puerto Rico

A total of twenty 0-20cm soil samples from the El Yunque National Forest, Puerto Rico, have been analyzed using XRD analysis to determine their mineral content. Qualitative and quantitative analysis of the data show that all the samples contain quartz, orthoclase, kaolinite, dickite, halloysite and nicrite, gibbsite, augelite, metavariscite, goethite, tsaregorodtsevite, apophylite. Soil sample from Oxisols sites contain higher percentage of clay minerals than the samples from Dystrudepts sites. Furthermore, the general pattern of the percentage of total clays, feldspars, and gibbsite within each and between transects suggest that soils in the valleys are more weathered and leached than soils from ridges. The percentage increase of phosphate minerals in the soils follow that of clay minerals which is most probably due to the attachment of the phosphate minerals to clay mineral surfaces. The presence of the organic cation Tetramethylammonium in the cavities between the oxygen-silicon tetrahedra of the tsaregorodtsevite structure (feldsphoid-zeolitic structure) is consistent with a low energy mechanism for the sequestration of carbon and nitrogen in the EYNF soils.

ABSTRACT:

General description of Experiment and Projects: Hurricanes are important drivers of periodic disturbances on tropical forests of the Luquillo Mountauns. The immediate impact of this disturbance is on the canopy biomass which is redistributed from the canopy compartments to the detrital pool of the forest floor hence creating a wide opened canopy. The Canopy Trimming Experiment (CTE) is a long-term experiment designed for two purposes: 1) to decouple the effect of canopy disturbance (e.g., increasing light levels, temperature, moisture, etc.) from those of increased detrital inputs on rates of germination, growth, survival, detritus processing, nutrient cycling, soil conditions, and trophic structure, and 2) to increase the frequency of simulated hurricane effects above background levels to once every six to ten years. Climate change models predict increased frequency and intensity of Caribbean hurricanes (Emmanuel 1987, Goldenberg et al. 2001), and the goal is to evaluate predictions regarding the effects of an increased rate of hurricane disturbance on tabonuco forest (Sanford et al. 1991). The interaction of biotic and abiotic processes, all modified by the disturbance, are key in determining ecosystem responses because they regulate critical ecosystem fluxes and storage associated with detritus decomposition. These processes define detrital dynamics and play a central role in the recovery of forest structure and function after disturbance. Therefore, a third component of this experiment was to implement a series of short-term biotic manipulations nested within the large-scale CTE design, consisting on faunal manipulations to measure the strength of interactions between autotrophic and detrital food webs in the context of hurricane-associated disturbance, which allowed to asses the important components of the foodwebs. The overall hypothesis is as follow: Short-term dynamics of key response variables after disturbance will be a function of the interaction between microclimate and detrital inputs, whereas long-term dynamics (particularly of SOM and NPP) will be a function of detrital inputs.

ABSTRACT:

Erosion, transport and deposition of riverine suspended load are pivotal processes in the terrestrial carbon cycle and function of the critical zone. In order to better understand the response of these drivers to changes in land cover and climate, it is critical to characterize these drivers. In montane rivers, such as the Luquillo Mountains, Puerto Rico, extreme storm events erode and transport clastic and organic material from mountain slopes to rivers, dominating annual export. Riverine particulate organic carbon (POC) and particulate nitrogen (PN) exports are not as well understood, especially at high runoff rates. Over 25 years, river POC export was 75±20 tC km-2 yr-1 for Rio Icacos and 22±8 tC km-2 yr-1 for the Mameyes. Caribbean river POC yields were higher in relation to their SS yields, suggesting that these rivers have greater terrestrial OM supply on the landscape to be eroded and transported into rivers, than what is expected based on data for world rivers. Additionally, we determined that 50% of the suspended load flux occurred during extreme rainfall events, spanning just over 2 days a year, but only exporting < 10% of the annual runoff and rainfall. These results emphasize the important role of extreme rainfall events as drivers of POM export from the Luquillo Mountains.

ABSTRACT:

These geospatial data sets were developed as part of a new analysis of all known current and historical rain gages in the Luquillo Mountains, Puerto Rico published in the journal article Murphy, S.F., Stallard, R.F., Scholl, M.A., Gonzalez, G., and Torres-Sanchez, A.J., 2017, Reassessing rainfall in the Luquillo Mountains, Puerto Rico: Local and global ecohydrological implications: PLOS One 12(7): e0180987, p. 1-26, https://doi.org/10.1371/journal.pone.0180987. That article provides a revised map of mean annual precipitation developed using elevation regression functions and residual interpolation, and that map is presented here in a raster file. Most previous forest- and watershed-wide estimates of precipitation (and evapotranspiration, as inferred by a water balance) have assumed that precipitation increases consistently with elevation in the Luquillo Mountains; therefore, precipitation in leeward Luquillo watersheds has been overestimated by up to 40%.Because the Luquillo Mountains often serve as a wet tropical archetype in global assessments of basic ecohydrological processes, these revised estimates are relevant to regional and global assessments of runoff efficiency, hydrologic effects of reforestation, geomorphic processes, and climate change.

ABSTRACT:

Metadata: See Hall and Silver 2015, Biogeochemistry for details on soil analyses and sites; See Hall et al. 2014 Ecology for details on enzyme analyses and phenolic substances

Hall, S., Treffkorn, J., & Silver, W. (2014). Breaking the enzymatic latch: Impacts of reducing conditions on hydrolytic enzyme activity in tropical forest soils. Ecology, 95(10), 2964-2973. Retrieved July 24, 2020, from www.jstor.org/stable/43493922

Hall, S., & Silver, W. (2015). Reducing conditions, reactive metals, and their interactions can explain spatial patterns of surface soil carbon in a humid tropical forest. Biogeochemistry, 125(2), 149–165. https://doi-org.unh.idm.oclc.org/10.1007/s10533-015-0120-5

ABSTRACT:

These data and collection and analysis methods are described in Hall et al. 2015, Biogeosciences

doi:10.5194/bg-12-2471-2015

Biogeosciences, 12, 2471–2487, 2015

www.biogeosciences.net/12/2471/2015/

ABSTRACT:

This dataset includes concentration and redox speciation of analytes (iron, sulfur, nitrogen) from targeted chemical extraction of surface soil samples collected from the Luquillo CZO in September 2011 as well as greenhouse gas flux rates (carbon dioxide, methane, and nitrous oxide) for incubated subsamples of these surface soils under experimental manipulations of anaerobiosis (oxygen removal) and flooding.

The metadata file provides treatment key.

Statistical summaries and methodological details for these data have been published at doi:10.1002/2013JG002433.

ABSTRACT:

R scripts presented as Jupyter Notebooks and data to generate load and concentration estimates produced for the journal publication:

McDowell, W. H., McDowell, W. G., Potter, J. D. and Ramírez, A. (2018), Nutrient export and elemental stoichiometry in an urban tropical river. Ecol Appl. Accepted Author Manuscript. doi:10.1002/eap.1839

ABSTRACT:

Soils from humid forests undergo spatial and temporal variations in moisture and oxygen (O2) in response to rainfall, and induce changes in iron (Fe) and carbon (C) biogeochemistry. We hypothesized that high rainfall periods stimulate Fe and C cycling, with the greatest effects in areas of high soil moisture. To test this, we measured Fe and C cycling across three catenas at valley, slope, and ridge positions every two days for a two-month period in a rainforest in Puerto Rico. Over 12 days without rain, soil moisture, FeII, rapidly reducible Fe oxides (FeIIIRR), and dissolved organic C (DOC) declined, but Eh and O2 increased; conversely, during a 10-day period of intense rain (290 mm), we observed the opposite trends. Mixed-effects models suggest precipitation predicted soil moisture, soil redox potential (Eh), and O2, which in turn influenced Fe reduction/oxidation, C dissolution, and mineralization processes. The approximate turnover time for HCl-extractable FeII was four days for both production and consumption, and may be driven by fluctuations in FeIIIRR, which ranged from 42% to 100% of citrate–ascorbate-extractable FeIII (short-range order (SRO)-FeIII) at a given site. Our results demonstrated that periods of high precipitation (hot moments) influenced Fe and C-cycling within day-to-week timescales, and were more pronounced in humid valleys (hot spots).

ABSTRACT:

Redox state fluctuations are a primary mechanism controlling the mobilization of trace metals in soils. However, underlying lithology may modulate the effect that redox fluctuations have on trace metal mobility by influencing soil particle size and mineral composition. To investigate the relationships among trace metal behavior, lithology, and redox state, we subjected surface soils from two intensely weathered soil profiles formed on contrasting lithologies to consecutive, 8-day redox cycles. A suite of metals (Al, Mn, Fe, Ti, Rb, Zr, Nb, Mo, REEs, Pb, Th, U) were quantified in the aqueous phase (< 10 nm) and solution (< 415 nm, including colloids) from soil slurries. In soil formed on volcaniclastic bedrock with high clay content and a high abundance of short-range-ordered Fe-(oxyhydr)oxides phases (e.g. nano-goethite; quantified by Mössbauer spectroscopy), reducing events and colloidal dynamics drove trace metal mobilization. In contrast, in soil formed on granite bedrock with lower clay content and a low abundance of short-range-ordered Fe-(oxyhydr)oxides phases (nano-goethite and lepidocrocite), overall trace metal mobilization was lower, and mobilization was not predictable from redox state. Molybdenum isotopes were also measured through redox cycles but did not exhibit redox-dependent behavior. This study provides direct evidence that lithology remains an overarching factor governing the characteristics of metal mobility in soils, even after extended and intense chemical weathering and soil development processes.

ABSTRACT:

Background

Many environments contain redox transition zones, where transient oxygenation events can modulate anaerobic reactions that influence the cycling of iron (Fe) and carbon (C) on a global scale. In predominantly anoxic soils, this biogeochemical cycling depends on Fe mineral composition and the activity of mixed Fe(III)-reducer populations that may be altered by periodic pulses of molecular oxygen (O2).

Methods

We repeatedly exposed anoxic (4% H2:96% N2) suspensions of soil from the Luquillo Critical Zone Observatory to 1.05 × 102, 1.05 × 103, and 1.05 × 104 mmol O2 kg−1 soil h−1 during pulsed oxygenation treatments. Metatranscriptomic analysis and 57Fe Mössbauer spectroscopy were used to investigate changes in Fe(III)-reducer gene expression and Fe(III) crystallinity, respectively.

Results

Slow oxygenation resulted in soil Fe-(oxyhydr)oxides of higher crystallinity (38.1 ± 1.1% of total Fe) compared to fast oxygenation (30.6 ± 1.5%, P < 0.001). Transcripts binning to the genomes of Fe(III)-reducers Anaeromyxobacter, Geobacter, and Pelosinus indicated significant differences in extracellular electron transport (e.g., multiheme cytochrome c, multicopper oxidase, and type-IV pilin gene expression), adhesion/contact (e.g., S-layer, adhesin, and flagellin gene expression), and selective microbial competition (e.g., bacteriocin gene expression) between the slow and fast oxygenation treatments during microbial Fe(III) reduction. These data also suggest that diverse Fe(III)-reducer functions, including cytochrome-dependent extracellular electron transport, are associated with type-III fibronectin domains. Additionally, the metatranscriptomic data indicate that Methanobacterium was significantly more active in the reduction of CO2 to CH4 and in the expression of class(III) signal peptide/type-IV pilin genes following repeated fast oxygenation compared to slow oxygenation.

Conclusions

This study demonstrates that specific Fe(III)-reduction mechanisms in mixed Fe(III)-reducer populations are uniquely sensitive to the rate of O2 influx, likely mediated by shifts in soil Fe(III)-(oxyhydr)oxide crystallinity. Overall, we provide evidence that transient oxygenation events play an important role in directing anaerobic pathways within soil microbiomes, which is expected to alter Fe and C cycling in redox-dynamic environments.

ABSTRACT:

While the contribution of iron (Fe)-bearing minerals to organic carbon (C) stabilization in terrestrial systems is well-described, the influence of Fe solid-phase speciation on organomineral associations is unclear in highly dynamic, oxidation-reduction (redox)-active soils. In humid tropic forest soils, fluctuations in redox state accelerate weathering of Fe-bearing mineral phases, producing a spectrum of mineral sizes and bonding environments available for C stabilization, and confounding our understanding of C stability. Characterizing these Fe-bearing phases can improve predictions of the response of redox-active soil systems to climatic changes that may alter Fe mineral crystallinity and solubility, such as precipitation intensity, storm event frequency and temperature. Leveraging inorganic selective dissolution techniques, 57Fe Mössbauer spectroscopy (MBS), specific surface area (SSA) analyses and X-ray diffraction (XRD), we investigated mineral speciation in surface soils of contrasting lithologies from the Luquillo Critical Zone Observatory (LCZO), Puerto Rico. The LCZO provides a model investigatory framework in which high C inputs to surface horizons by similar vegetation, topography and climatic forcings are intercepted by highly-weathered, volcaniclastic Oxisols or quartz diorite-derived Inceptisols, producing a gradient of Fe content and speciation. Strong correlations observed between Fe concentrations and extraction-induced changes in SSA indicated target Fe phases contribute substantially to SSA of the bulk mineral matrix. MBS analysis of untreated soils reveal both Oxisol and Inceptisol soils are largely composed of FeIII-oxyhydroxides, accompanied by substantial FeII and silicate FeIII contributions in Inceptisol soils. FeIII-oxyhydroxides in the Oxisol soils were largely short-range-ordered (SRO), and notably, a fraction of particularly low-crystallinity FeIII-oxyhydroxide mineral phases in these soils appear protected against harsh reductive dissolution, whereas the overall higher crystallinity Fe phases in the Inceptisol soils do not. These findings suggest that some high-SSA, SRO FeIII phases, which likely also have high C sorption capacities, may be immobilized against reduction in these Oxisol soils. Consequently, C associated with these FeIII phases may be preferentially stabilized in Oxisol soils, potentially driving disparate C mineralization and CO2 production rates across contrasting lithologies.

ABSTRACT:

This data publication contains hourly laser ceilometer data from Sabana, and hourly meteorological data collected from two weather stations in Bisley and Sabana located on the Luquillo Experimental Forest (El Yunque National Forest) in Puerto Rico. Bisley and Sabana are two watersheds in the Luquillo Experimental Forest. The ceilometer data include: minimum cloud base level, first quartile cloud base level, mean cloud base level, and cover cloud from 2013-2016. Weather data include: total precipitation, mean temperature, mean relative humidity, mean sea level pressure, mean wind speed, and mean wind direction from 2000-2016 for the Bisley station, and 2013-2016 for the Sabana station.

ABSTRACT:

These data are supplementary to the journal article Bassiouni, M., Scholl, M.A., Torres-Sanchez, A.J., Murphy, S.F., 2017, A Method for Quantifying Cloud Immersion in a Tropical Mountain Forest Using Time-Lapse Photography, Agricultural and Forest Meteorology, http://dx.doi.org/10.1016/j.agrformet.2017.04.010. The data set includes cloud immersion frequency, mean temperature, relative humidity and dew point depression values for five sites, representing Figures 7a and 7b in the article, and values used to calculate the averages shown in Table 2. The results cover the time period from March 2014 to May 2016. A list of validation image filenames with their classifications and the set of 7360 validation images for the method are also provided.

Dataset DOI: http://dx.doi.org/10.5066/F7HQ3X52

ABSTRACT:

This data publication contains five shapefiles generated in 2017, covering the Caribbean island of Puerto Rico. Using information gathered from 2000-2016, these data were developed through geospatial analyses using a set of simple criteria to identify areas well-suited to mechanized agriculture, areas well-suited to non-mechanized agriculture on moderate to steep slopes, and areas suitable for forestry practices, including timber harvest potential, where greater forest cover has benefits in terms of soil conservation and water management. These are steeper slopes where timber production may be integrated with agroforestry, shade coffee, non-timber forest product uses, or other forms of sustainable activity that maintain a high degree of forest cover. Also included are shapefiles representing conservation priority areas, and an impervious surface layer for Puerto Rico.

The data were created to guide land use decisions toward lands most suitable for agriculture, forestry, and conservation in Puerto Rico.

ABSTRACT:

Long-term rainfall and discharge data from the Luquillo Experimental Forest (LEF) were analysed to develop relationships between rainfall, stream-runoff, and elevation. These relationships were then used with a Geographic Information System (GIS) to determine spatially-averaged, mean annual hydrologic budgets for watersheds and forest types within the study area. Model estimates indicate that a total of 3864 mm/yy (444 hm3) of rainfall falls on the forest in an average year. The Tabonuco, Colorado, Palm and Dwarf Forest types receive an estimated annual rainfall of 3537, 4191, 4167, and 4849 mm/yy, respectively. Of the average annual rainfall input, 65% (2526 mm/yr) is converted to runoff and the remainding 35% (1338 mm.yr) is lost from the system by evapotranspiration and other abstractions. In comparison to other tropical forests, the LEF as a whole has more evapotranspiration than many tropical montane forests but less evapotranspiration than many lowland tropical forests.

Dataset Methods:

Field Collection:

Rainfall and throughfall collection
The rainfall and throughfall measured in this study were collected and measured in the same manner for the duration of the study, and in accordance with our previous publications (Scatena, 1990; Schellekens et al., 1999; Holwerda, 2006). Bulk rainfall and throughfall were collected weekly (i.e. every Tuesday morning) and occasionally before and after major storms. Total rainfall was collected in a 25 m above canopy walk-up tower that is located on the divide between the two catchments and at an elevation of 361 m above sea level. Throughfall was measured throughout the watershed using 20 to 35 randomly placed but fixed gauges that were placed across the ridges, hill-slopes, gaps, and stream channels of the watershed (Scatena, 1990). The rainfall collector and each throughfall collector had identical 143 cm2 funnels. As many as 35 collectors were operated at any given time for the time series presented here. During Hurricane Hugo in 1989, the canopy tower that held the climate station and rainfall collector was toppled, but most of the throughfall collectors remained intact. Those that were destroyed were randomly re-located within 10 m of their original site and throughfall was collected without interruptions. The meteorological tower was also replaced after a few months.
Lab Analysis:

Chemistry
During every collection, bulk rainfall and throughfall were collected for chemical analysis. Water for the rainfall analysis was collected from the above-canopy rainfall collector. The throughfall sample was a composite of water collected in eight collectors. These eight throughfall collectors were selected at the beginning of the study because their mean throughfall volume and conductivity was similar to the mean of all the bottles and therefore considered representative of the site. These collection bottles were cleaned or replaced on a weekly basis and contained filters to prevent frogs and litter from entering the bottles.
Water samples were delivered to the laboratory on the same day they were collected. Chemical analysis was conducted in the same manner as previous studies of the LEF (McDowell et al., 1990; McDowell and Asbury, 1994; McDowell, 1998). Protocols and the original data are available on the Luquillo LTER web-page:

(http://luq.lternet.edu/data/lterdb20/metadata/lterdb20.htm).

In the laboratory, pH and conductivity were measured following the procedures specified by NADP (1984) and McDowell et al., (1990). Samples were filtered using pre-combusted glass fiber filters (Whatman GF/F). Until 1997, samples were held refrigerated for analysis, with a sub-sample for ammonium analysis preserved by acidification with sulfuric acid (McDowell et al., 1990). After 1997, samples were stored frozen until analysis for all constituents except silica, which was analyzed on a refrigerated subsample. During the first nine years of the study, most samples were analyzed at the University of Puerto Rico. After 1997, all samples were analyzed at the University of New Hampshire. Silica (phospho-molybdate), phosphorus (ammonium molybdate), and ammonium (phenol-hypochlorite) were analyzed throughout the study period using spectrophotometric methods using a Technicon AA II or Lachat Quickchem. Cations were analyzed with atomic absorption spectrophotometry from 1988-1994, and with ion chromatography from 1994 on. Anions were measured with ion chromatography. Dissolved organic carbon and nitrogen were measured using persulfate digestion (McDowell et al., 1987; Solorzano and Sharp, 1980) prior to 1997, and with high temperature Pt-catalyzed combustion after 1997 (Merriam et al., 1996). Cross-lab comparisons and analysis of samples using the different techniques indicated that comparable results were obtained with different laboratories and methods (e.g. McDowell et al., 1990; Merriam et al., 1996).

ABSTRACT:

Intensively monitored Hillslope. 35 Soil Apogee SO-110-L-10 Oxygen sensors and 35 Soil Water Content Reflectometer 12cm- CS655-L100-DS content sensors. TopoLocation codes are 1 = ridge, 2=lower ridge, 3= upper slope, 4= mid slope, 5=lower slope, 6= slope break, and 7 = valley.

Status of drought variable used as a categorical definition of drought conditions.

Categorical value of pre-drought=1, drought=3, and post-drought=2

ABSTRACT:

Sensor based environmental monitoring data from across the Luquillo Mountains stored in an SQLite ODM2 database.

data collected using Hobo U20-001-04 Water Level, HOBO Light and Air Temperature Sensor UA-002-64, HOBO U26 DO Probe DO and Water Temperature, and HOBO U24 conductivity loggers collect data at a 15 minute time interval.

Data are available from the following sites:
Quebrada Sonadora
Rio Espritu Santo Launch
Bisley Quebrada 3
Rio Icacos Tributary
Prieta
Icacos Pulse Installation
QPB Abajo
QPA mid light
Rio Espiritu Santo Stream House
QPA abajo
Rio Espiritu Santo Down Stream
QPB light mid
QPB Arriba
LGW2B
Quebrada Toronja
QPA Arriba
I-06
I-04
I-23
B15 well

ABSTRACT:

Oxygen (O2) limitation is generally understood to suppress soil carbon (C) decomposition and is a key mechanism impacting terrestrial C stocks under global change. Yet, O2 limitation may differentially impact kinetic or thermodynamic versus physicochemical C protection mechanisms, challenging our understanding of how soil C may respond to climate-mediated changes in O2 dynamics. Although O2 limitation may suppress decomposition of new litter C inputs, release of physicochemically protected C due to iron (Fe) reduction could potentially sustain soil C losses. To test this trade-off, we incubated two disparate upland soils that experience periodic O2 limitation—a tropical rainforest Oxisol and a temperate cropland Mollisol—with added litter under either aerobic (control) or anaerobic conditions for 1 year. Anoxia suppressed total C loss by 27% in the Oxisol and by 41% in the Mollisol relative to the control, mainly due to the decrease in litter-C decomposition. However, anoxia sustained or even increased de-composition of native soil-C (11.0% vs. 12.4% in the control for the Oxisol and 12.5% vs. 5.3% in the control for the Mollisol, in terms of initial soil C mass), and it stimulated losses of metal- or mineral-associated C. Solid-state 13C nuclear magnetic resonance spectroscopy demonstrated that anaerobic conditions decreased protein-derived C but increased lignin- and carbohydrate-C relative to the control. Our results indicate a trade-off between physicochemical and kinetic/thermodynamic C protection mechanisms under anaerobic conditions, whereby decreased decomposition of litter C was compensated by more extensive loss of mineral-associated soil C in both soils. This challenges the common assumption that anoxia inherently protects soil C and illustrates the vulnerability of mineral-associated C under anaerobic events characteristic of a warmer and wetter future climate.
https://doi.org/10.1111/gcb.15100

ABSTRACT:

A modern paradigm of soil organic matter proposes that persistent carbon (C) derives primarily from microbial residues interacting with minerals, challenging older ideas that lignin moieties contribute to soil C because of inherent recalcitrance. We proposed that aspects of these old and new paradigms can be partially reconciled by considering interactions between lignin decomposition products and redox-sensitive iron (Fe) minerals. An Fe-rich tropical soil (with C4 litter and either 13C-labeled or unlabeled lignin) was pretreated with different durations of anaerobiosis (0–12 days) and incubated aerobically for 317 days. Only 5.7 ± 0.2% of lignin 13C was mineralized to CO2 versus 51.2 ± 0.4% of litter C. More added lignin-derived C (48.2 ± 0.9%) than bulk litter-derived C (30.6 ± 0.7%) was retained in mineral-associated organic matter (MAOM; density >1.8 g cm–3), and 12.2 ± 0.3% of lignin-derived C vs 6.4 ± 0.1% of litter C accrued in clay-sized (<2 μm) MAOM. Longer anaerobic pretreatments increased added lignin-derived C associated with Fe, according to extractions and nanoscale secondary ion mass spectrometry (NanoSIMS). Microbial residues are important, but lignin-derived C may also contribute disproportionately to MAOM relative to bulk litter-derived C, especially following redox-sensitive biogeochemical interactions.
https://doi.org/10.1021/acs.est.9b01834

ABSTRACT:

From 2007 to 2019, the Critical Zone Observatories (CZOs) stored their data at their respective universities. A central catalog of metadata kept track of the datasets at https://criticalzone.org. With the transition from CZO to CZ clusters, it was agreed to centralize all datasets to HydroShare. This resource documents that transition. The Readme.md file gives an overview and description of what was done, as does the poster by Miguel Leon. Specifics on how metadata was stored on criticalzone.org can be found in "CZO Metadata Definitions.pdf". How that metadata translated into HydroShare is defined in "Metadata Mapping from CZO to HydroShare.xlsx" and the controlled vocabulary conversions are found in “Map CZO Variables to ODM2 VariableNames.xlsx".