Global climate change processes, especially prolonged droughts and increasingly high temperatures, are significantly affecting numerous arid ecosystems across the state of New Mexico. One of the more adversely affected ecosystems in New Mexico is piñon-juniper woodland (PJ), which includes areas near Mountainair, New Mexico, USA. Because changes in ambient temperature and decreases in water availability show pervasive effects on the above-ground status of existing PJ woodlands in New Mexico, it seems likely that the effects of changes in these two master variables will manifest themselves within soil processes such as soil organic matter (SOM) decomposition rates and soil respiration rates, as well as nutrient cycling rates and availabilities to both plants and soil microbial communities.
We conducted analyses of soil physicochemical properties and soil fungal biomass via soil ergosterol content, as well as evaluating the activity rates of multiple hydrolytic exoenzymes, which are indicative of fungal activity in soils. Samples were collected from multiple tree-to-tree competition gradients that were identified in May/June of 2011. These gradients were established based on the type of mycorrhizal fungus types expected to occupy the soil community established beneath the canopy of a focal tree, with there being two focal trees in each gradient. Gradients were established between two live piñon trees (Pinus edulis), two juniper trees (Juniperus monosperma), a live piñon and live juniper, and a dead piñon and live juniper. We only sampled from under live trees at the control site.
In order to obtain these samples, we collected soil samples from two different sites in a PJ woodland located within the boundaries of the Deer Canyon ranch. Changes in soil conditions were captured by sampling from the two sites at multiple times throughout the summer of 2011. We collected samples from Dr. Marcy Litvak’s girdled PJ woodland eddy-flux tower site in June, July, August and finally in late September. We also collected samples from Dr. Litvak’s control PJ woodland tower site in June and September of 2011. Significant differences in the activity rates of the hydrolytic exoenzymes alanine aminopeptidase, alkaline phosphatase, β-d-glucosidase, and β-N-acetyl glucosaminidase were observed within soils collected at multiple times from June through September when comparing the observed rates of activities under the trees in the live piñon to live piñon gradients vs. the juniper to juniper gradients. These differences were observed in samples from multiple dates at the girdled site without there being significant differences in soil fungal biomass across seasons or study sites. Continued work with the established sites on a year-to-year basis could provide an insight into how the fungal communities within New Mexican PJ woodlands will respond to future changes in soil conditions as global climate change processes advance in New Mexico.
Experimental design: Randomized complete block design was established at 2 different study sites, girdled piñon-juniper (PJ) woodland and non-girdled (control) PJ woodland. In late May, 2011, we set-up each study site to contain six complete blocks (plots), each with multiple tree-to-tree gradients. At the girdled PJ site, each plot included five different tree-to-tree gradients: Live pine to live pine, live pine to dead pine, live pine to live juniper, dead pine to live juniper, and live juniper to live juniper. At the control PJ site we also established 6 blocks (plots); however, at this site there were only three gradients: Live pine to live juniper, dead pine to live juniper, and live juniper to live juniper.
Setting up plots: Plots and gradients were established by marking sampling locations with orange flagging tape and pin-flags by Daniel Warnock and Kimberly Elsenbroek on May 19 and 23, 2011.
Sample collection, allocation and storage: Soil samples were collected monthly from the girdled PJ woodland to establish two pre-monsoonal (dry) season time points, with samples collected on June 6, 2011 and June 15, 2011 considered as being from single time point. Soil samples collected on July 20, 2011 represented our second dry season time point. Soil samples for our two post-monsoon moisture time points were collected on August 15, 2011 and September 28, 2011. As with the girdled site, soils sample from the control PJ woodland site were collected both before and after the onset of the monsoon season. However, unlike the girdled PJ woodland site, we only have one pre-monsoon time point June 29, 2011 and one post monsoon time point, September 15, 2011.
All soil samples were collected by combining three 0-10cm sub-samples into the same zipper-locking plastic storage bag. Samples were collected from three different locations within each tree-to tree gradient. Two of the three samples were collected from locations within 30cm of the trunk of each of the two focal trees within a gradient. The other sample for each gradient was collected from a point at the center of a zone formed by the edges of the canopies from the two competing focal trees. All samples were then transported to the lab for refrigeration.
Within 24-72 hours of sample collection, 5mL sub-samples were taken from each bulked soil sample and placed into individual Corning 15mL screw-cap centrifuge tubes. Each tube was then filled to the 10mL mark with an 0.8% KOH in Methanol solution. These tubes were placed in the fridge for storage until analyzed for ergosterol content. After preparation of the samples for ergosterol analyses, 1g samples were placed into 125mL round Nalgene bottles for analyses of fungal exoenzyme actitity (EEA) rates from each sample. All enzyme activity assays were performed within 1 to 5 days after collection. Further, for all but the final post-monsoonal time points, assays were performed within 2 to 3 days of sample collection.
After all of the fresh, refrigerated samples were alloquated for ergosterol and EEA analyses we placed the remaining quantities of soil for each sample into labeled paper bags for air-drying on a lab bench. After 1-2 weeks, 30g of each sample was placed into a labeled plastic bag for shipping to Ithaca, New York, USA for analyses of soil-physicochemical properties. While taking the 30g sub-samples, a separate 5g sub-sample from the air-dried sample was placed into a labeled, no. 1 coin-envelope for storage until analysis of soil hyphal abundance. After all sub-sampling was completed any remaining soil was kept in its sample bag and stored in the lab.
Hydrolytic exoenzyme activity (EEA) assays: All hydrolytic EEA assays were performed as follows: Each 125mL sample bottle was partially filled with 50mM sodium bicarbonate buffer solution and homogenized using a Kinematica Polytron CH 6010 (Lucerne, Switzerland). Upon homogenization, sample bottles were filled to 125mL with buffer solution. Sample bottles were then set aside until placement in black, 96-well, micro-plates. At the time of placement, each sample suspension was poured into a glass crystalizing dish where it was stirred at high speed into the appropriate columns within each micro-plate. These columns included a quench control (200 uL sample suspension + 50uL MUB or methylcoumrin substrate control), a sample control (200uL sample suspension + 50uL 50mM bicarbonate buffer) and an assay column (200uL suspension + 50ul 200mM substrate). Samples were pipetted into four sets of plates with each set analyzing the activity rates of a single hydrolytic enzyme. These enzymes included alanine amino peptidase, alkaline phosphatase, β-d-glucosidase, and N-acetyl-β-d-glucosiminidase. Further, all three samples from a single gradient within a single plot were added to the same plate (e.g., all samples from the live-pine-to-live-pine gradient from plot one were pipetted into a single plate for analyzing the activity of the enzyme alkaline-phospotase.
Ultimately our plate layout was completed as follows usingt two other columns for substrate controls: In column one, we added 200uL buffer and 50uL of a substrate standard, which accounts for the fluorescence emitted by either the MUB, or the methylcoumarin group that is a component of the substrate solution added to the assay wells. In column six of each plate was a substrate control, which is a solution of 200uL buffer and 50uL of one the four different substrates used in our hydrolytic EEA assays. Columns 3-5 were our quench controls, which accounts for the quantity of fluorescence emitted by the MUB or methylcoumarin molecule absorbed by the particles in the soil suspension itself. Columns 7-9 were the sample controls and account for the amount of fluorescence emitted by the soil suspension + buffer solution added to each well. Finally, columns 10-12 were our assay wells. From these wells we could determine enzyme activity by measuring the fluorescence emitted by the MUB or methylcoumarin molecules cleaved off of the substrates initially added to each well. The substrates included in these assays included: 7-amino-4-methylcoumarin (Sigma-Aldrich), 4-MUB-phosphate (Sigma-Aldrich), 4-MUB-β-d-glucoside (Sigma-Aldrich), and 4-MUB-N-acetyl-β-d-glucosiminide (Sigma-Aldrich).
Because the intrinsic EEA rates varied across our targeted exoenzymes, assay plates were scanned for flourscence in sets of two. Alanine aminopeptidase plates and alkaline phosphatase plates were scanned twice, first at 30-40 minutes after substrate addion and again at 50-80 minutes after substrate addition. β-d-glucosidase, and N-acetyl-β-d-glucosiminidase plates were all scanned at 3-4 hours after substrate addition. The timing of the second enzyme activity time point depended on expected soil moisture conditions. Here, the post monsoon soils were allowed to incubate for a total of 5-6 hours prior to the second scan and the pre-monsoon plates were incubated for a total of 7-9 hours.
Fungal biomass measurements: Fungal biomass was quantified by measuring the concentration of ergosterol in a sub-sample taken from each soil sample collected from June to September. Within 24-72 hours of sample collection, 5mL sub-samples were taken from each bulked soil sample and placed into individual Corning 15mL screw-cap centrifuge tubes. Each tube was filled to the 10mL mark with an 0.8% KOH in methanol solution. Tubes were refrigerated for storage until analyzed for fungal biomass by measuring the ergosterol content within each sample. Ergosterol concentration for each sample was determined using HPLC with 100% methanol as the solvent at a flow rate of 1.5mL/ minute and a c-18 column. Ergosterol was quantified by measuring the peak height that passed through a detector set to measure absorbance at 282nm, at 3.7min after the sample was injected into the column. The height of each peak was then converted into μg ergosterol/g soil and finally converted to mg fungal biomass/ g soil by applying a conversion factor.
* Instrument Name: Polytron
* Manufacturer: Kinematica
* Model Number: CH 6010
* Instrument Name: GeoXT
* Manufacturer: Trimble
* Model Number: GeoExplorer 3000 series
* Instrument Name: fmax
* Manufacturer: Molecular devices
* Model Number: type 374
* Instrument Name: versamax tunable micro-plate reader
* Manufacturer: molecular devices
* Model Number: ?
* Instrument Name: SSI 222D isocratic HPLC pump
* Manufacturer: SSI
* Model Number: 222D
* Instrument Name: Thermo Seperation Products AS 1000 autosampler
* Manufacturer: Thermo Seperation Products
* Model Number: AS 1000
* Instrument Name: Acutect 500 UV/Vis Wavelength detector
* Manufacturer: Acutect
* Model Number: 500
* Instrument Name: HP 3396 series iii integrator
* Manufacturer: Hewlitt Packard
* Model Number: 3396
Girdled and control PJ woodland: 34.36N, 106.27W.
Girdled PJ woodland sampled: 6/June/2011, 15/June/2011, 20/July/2011, 15/Aug/2011, 28/Sept/2011.
Control PJ woodland sampled: 29/June/2011, 15/Sept/2011.
The Monsoon Rainfall Manipulation Experiment (MRME) is to understand changes in ecosystem structure and function of a semiarid grassland caused by increased precipitation variability, which alters the pulses of soil moisture that drive primary productivity, community composition, and ecosystem functioning. The overarching hypothesis being tested is that changes in event size and variability will alter grassland productivity, ecosystem processes, and plant community dynamics. In particular, we predict that many small events will increase soil CO2 effluxes by stimulating microbial processes but not plant growth, whereas a small number of large events will increase aboveground NPP and soil respiration by providing sufficient deep soil moisture to sustain plant growth for longer periods of time during the summer monsoon.
Additional Study Area Information
Study Area Name: Monsoon site
Study Area Location: Monsoon site is located just North of the grassland Drought plots
Vegetation: dominated by black grama (Bouteloua eriopoda), and other highly prevalent grasses include Sporabolus contractus, S.cryptandrus, S. lexuosus, Muhlenbergia aernicola and Bouteloua gracilis.North Coordinate:34.20143South Coordinate:34.20143East Coordinate:106.41489West Coordinate:106.41489
Additional Information on the Data Collection Period
This file contains hourly meteorological data that were collected from a network of 10 permanent weather stations on the Sevilleta National Wildlife Refuge.
To monitor meteorological conditions across the Sevilleta and surrounding areas through time.
Stations were located across the Sevilleta and surrounding areas to cover the entire spatial and elevational extent of the refuge. They were also generally located adjacent to other pertinent study locations such as plant and animal monitoring studies.
Automated weather stations
Each weather station includes a 3 m tripod tower, on which is mounted most of the monitoring equipment. This equipment includes an enclosure housing a datalogger and power supply. On the tripod are mounted an anemometer and wind vane, a pyranometer, and a solar radiation shield that encloses a combination temperature and relative humidity sensor. Other attached sensors include: a precipitation gauge, soil temperature sensors and soil moisture potential sensors.
* Manufacturer: Campbell Scientific Inc.* Component: Datalogger - Measurement and Control Module* Model Number CR10* Reference Manuals: CR10 Measurement and Control Module Campbell Scientific Inc.* Manufacturer: Campbell Scientific Inc.Measurement Techniques: Automated weather stations Each weather station includes a 3 m tripod tower, on which is mounted most of the monitoring equipment. This equipment includes an enclosure housing a datalogger and power supply. On the tripod are mounted an anemometer and wind vane, a pyranometer, and a solar radiation shield that encloses a combination temperature and relative humidity sensor. Other attached sensors include: a precipitation gauge, soil temperature sensors and soil moisture potential sensors.* Component: Temperature/Relative Humidity Sensor* Model Number 207* Reference Manuals: * Manufacturer: Campbell Scientific Inc.* Component: Temperature/Relative Humidity Sensor* Model Number HMP45C* Reference Manuals:* Manufacturer: MET-ONE* Component: Cup Anemometer* Model Number 14A* Reference Manuals:* Manufacturer: MET-ONE* Component: Wind Vane* Model Number 24A* Reference Manuals:* Manufacturer: LI-COR* Component: Pyranometer* Model Number 200SZ* Reference Manuals:* Manufacturer: Texas Electronics* Component: Rain Gauge* Model Number TE525 mm* Reference Manuals:* Manufacturer: Campbell Scientific Inc.* Component: Soil Temperature Probe* Model Number 108* Reference Manuals: * Manufacturer: Campbell Scientific Inc.* Component: Soil Temperature Probe* Model Number 107* Reference Manuals: * Manufacturer: Campbell Scientific Inc.* Component: Soil Moisture Block * Model Number 227* Reference Manuals: * Manufacturer: Vaisala* Component: Barometer* Model PTB101B* Reference Manuals:
These data were collected from a network of 10 permanent weather stations on the Sevilleta National Wildlife Refuge. Station 40 has been in operation since the middle of 1987; Stations 41-44 were installed in the early part of 1989; Station 45 was put into operation on 26 Jan 1990 (hour 15); Station 46 was put into operation on 31 Aug 1990 (hour 17); and Station 1 was put into test operation on 29 Dec 1991 (hr 12) and official data recording started on 01 Jan 92 (hr 01). A new station (#48) was established during 1998 (on Oct 1 1998) at a site designated as Savana (initially called Blue Springs. Station 49 was installed in the Five Points area in 1999 and named Five Points. Another new station was established in 2001 at a new core study site designated as Blue Grama and given a station ID number of 50. These data have been run through a filtering program which replaces all obviously out-of-range values with -999.000's and flags questionable values for checking by data manager.
Precipitation is recognized as the most spatially variable abiotic variable in arid ecosystems such as the Sevilleta National Wildlife Refuge (NWR). Water is also usually the limiting factor in such environments so the accurate measurement of precipitation in both space and time is vital to understanding ecosystem dynamics. In 2008, the acquisition of a number of tipping-bucket rain gauges with Hobo dataloggers permitted the deployment of gauges into an increased number of locations on the Sevilleta NWR. Most dataloggers were installed in the greater Five Points area and primarily placed around the site of the 2003 burn study. A few additional dataloggers were installed throughout the entire Sevilleta NWR to expand overall coverage.
Datalogger specifications - Onset Tipping Bucket Rain gauge (8" opening); each tip records 0.01" (0.254 mm).
Data downloading - Data is collected from Hobo dataloggers using a Hobo shuttle. The data is then downloaded onto a PC computer using Boxcar Software.
01/19/11-Data and metadata compiled and updated through 2010. (JMM)03/19/10-Data and metadata compiled and updated through 2010. SEV project number assigned (SEV234) in Navicat and all data and metadata uploaded for public access. (JMM)
To support the hydrology studies in the Sierra Ladrones Study Basin, a network of moisture potential sensors and temperature sensors wereinstalled in the stream-channel sediments and adjacent soils atvarious locations up thru the watersheds in 1992. Two rain gaugeswere also added up through the watershed gradient to complement therain gauge on the weather station (Met43) at the base of the watershedto provide a better measure of moisture inputs to these watersheds.This file contains data for 1992 to 1994.
To monitor temperature and moisture of stream sediments and adjacent soils up the gradient of a series of small watersheds in the Sierra Ladrones.
An array of soil moisture potential gypsum blocks were placed in the channel sediments up thru the set of small watersheds. The number of sensors used and design of the placement of sensors was different at each site. All probes were initially buried at 20 cm but this depth must surely have changed with time and stream flow. Temperature probes were buried at the same time and the same depth as the gypsum blocks. Tipping bucket rain gauges were installed at sites 23 and 25 to complement the gauge at the Red Tank (Met43) Weather Station
Automated dataloggers with attached soil moisture potential and temperature sensors.
Probes were measured every 30 sec and summary data output at the hour. Precipitation was output at 1-min intervals during precipitation events.
Manufacturer: Campbell Scientific Inc.
Cable Tester Multiplexer SDMX50
TDR probe 30 cm
Aug 14, 1992 - Corrected watershed programs. Found problems w/ soil moisture on 23 and 25 on sensors 3 and 4. Also fixed precipitation program on all dataloggers. Changed out 4th temp sensor because it had been reading too high.
July 31, 1992 - Repaired damage at 23.
Jul 28, 1992 - Repaired damage at 22
Jul.21, 1992 - Storm washed out sensors at 22 and 23
Apr. 17, 1992 - Completed installation of dataloggers. Added 22 at Abeja, Venado Added upper temp and soil moisture sensors at 23; Added precip gages at 23 and 25. D.M.
Mar. 17, 1992 - Installed dataloggers at watersheds. Installed 21 (Above Red Tank),23 (Abeja Seep), 24 (Junction Ensenal and Yucca), 25 (Top of Ensenal). D.M.
Oct 22, 1993 - Sta 23 st3 and sm3 displaced -replaced; Sta 21 st1 indicates probe less deep; Sta 24 st2 indicates probe more shallow; GPS'd in all data loggers and probes - also traced center of channel on trip up and trip down.
07 Oct 1993. - Began dbf for Watershed data
Aug. 30, 1993 - FLOOD!!!!!! 1.85-2.00" of precip at about 1800.
May 11, 1993 - Replaced gypsum soil moisture blocks at Abaja seep - sm2, sm3, sm4, blocks were all eaten away. Reinstalled new ones at almost the same spot as the old. 2nd is only 15-17 cm deep 3rd only about 17 cm as well. 4th (side seep) was moved a little further away from the seep so that it was actually at 20 cm. All 3 are set on top of bedrock and can't be expected to last more than a year if seeps keep flowing. No surface standing water but some of the sediments are still slightly damp.
April 7,1993 - Replaced 2 of the soil moisture probes that had been chewed through by a deviant rodent sm1 and sm2.
Aug 5, 1994 D.M.
25 Found all analog grounds and grounds disconnected- Not sure how long this been the case. SM4 had all wires disconnected; Reattached - nothing reading still but very dry.
23 Precipitation leads loose - had been pulled loose - tail of P1 still in datalogger slot.
June 24, 1994
21 Temperature probe on the far side of the channel was pointing upward towards the surface of the soil. Depth was on the order of 10-15 cm. Soil Moisture block exposed, located probe and reburied the temp probe in the same vicinity.
23 Soil moisture probes at locations 2 (among willows) and 4 (side seep) were located and discovered to be deteriorated. These were removed and new probes were placed and buried. All cables at the pole were retaped to discourage rodent activity.
24 The temp probe on the right hand channel (Yucca) was closer to the surface than normal due to erosion of that channel. Depth was about 15 cm. We reset both probes to 20 cm and verified the decreasing soil temp. At the time of departure, both temp probes were reading similar temps.
file created 12/15/1998 - D.M.
Mar 8, 1995 - Removed 24 datalogger to use for TDR - sensors still in place. Removed precip gauge at 23
Feb 2, 1995 - Removed datalogger @ 21 to use with TDR - sensors still in place
Additional Information on the Data Collection Period
This file contains hourly time-domain reflectometry (TDR) soil moisture data for 1996-2005. A key factor in a spatially explicit water-balance model is a measure of moisture in the soils over time. This metric is crucial for both calibration and validation of such a model. One of the best methods of measuring soil moisture on a continuous basis is TDR. Therefore, a network of TDR soil moisture sensors was installed at all meteorological stations on the Sevilleta National Wildlife Refuge. At two of the sites the sensors were measured on an hourly basis in conjunction with the meteorological variables. At the four other sites the sensors were measured on a much less frequent basis - about every two weeks. Sensors were installed in pits in sets of five. One sensor was installed vertically adjacent to the pit to measure the top 30 cm of soil. The other four were installed horizontally in the face of the pit at 5, 10, 20, and 40 cm. Pits were then backfilled.
To measure moisture in soils at the field site over time.
Probes were measured every hour and collected propogating velocities were converted to soil moisture values using the Ledieu calibration. Each probe was run in sequence and the 15 probes could take 4 or 5 minutes to read.
Three sites were designated as water-balance monitoring sites: 1.) Deep Well - Met 40, 2.) Rio Salado - Met 44 and 3.) Field Station Sta1. At these sites replicate TDR probes were installed at specific depths while other probes were installed vertically to get an average soil moisture for the top 30 cm of soil.
Measurement Techniques: Time Domain Reflectometry:
TDR measures the reflectance of an electromagnetic pulse down a probe. This reflectance is affected by the amount of moisture in the soil surrounding the probe. Algorithms have been developed relating reflectance to volumetric soil moisture that work for most soils. The Campbell system has a built in program which reads the inflection points of the wave-form and automatically outputs soil moisture.
Locations where measurements were taken by year:
1996:1, 40, 41, 42, 43, 44, 45
1997:1, 40, 41, 42, 43, 44, 45
1998:1, 40, 41, 42, 43, 44, 45
Instrumentation: CR10 Datalogger; Tecktronx 1502B Cable Tester; Multiplexer SDMX50; TDR probe 30 cm
Instrument Name: Soil Moisture Potential Probe Manufacturer: Campbell Scientific Model Number: 227
2/19/1996 - Douglas Moore:
Jan 12, 1996 Sta 40 Installed probes in two more pits. Reprogrammed so data is being collected from all 15 probes.
Jan 19, 1996 Sta 01 Installed probes in two more pits.
Jan 19, 1996 Sta 44 Replaced probe w3_30 which had been chewed off by rodent.
Jan 30, 1996 Sta 41 Installed probes in Pit 1.
Feb 07, 1996 Sta 45 Installed probes in two more pits.
Feb 09, 1996 Sta 01 Installed datalogger, TDR enclosure and multiplexer. Installed program to collect data.
Feb 14, 1996 Sta 01 Replaced w1_10 probe. Changed program so battery voltage is collected.
Feb 23, 1996 Sta 42 Installed probes in two more pits.
Feb 28, 1996 Sta 40 Began having problems with data - missing hours or getting -699 due to dying internal battery in reflectometer.
Mar 08, 1996 Sta 40 Pulled reflectometer out to send back to Campbell.
Mar 12, 1996 Sta 01 Pulled reflectometer out to put in at Sta 40.
Mar 12, 1996 Sta 40 Put reflectometer from Sta 1 into Sta 40.
Mar 20, 1996 Sta 43 Installed probes in two pits (except w2_30).
Mar 27, 1996 Sta 41 Installed probes in a second pit.
Apr 01, 1996 Sta 41 Replaced faulty w2_30 probe.
Apr 08, 1996 Sta 43 Installed w2_30 probe.
12/15/1998: Douglas Moore:
Jan 22, 1997 Sta 44 Replaced TDR meter with one from field station.
Jan 22-April 04, 1997 Sta 40 W1_5 bad data replaced with- 999.
Apr 16, 1997 Sta 40 New w2_5 - 5 cm probe in pit B.
Apr 30-May 07, 1997 Sta 01 Missing data - Lost power to datalogger.
May 14-May 21, 1997 Sta 01 Missing data - Forgot to turn reflectometer on after returning to shelter.
Aug 01-Aug 20, 1997-Sta 40 w2_30 data bad changed to -999.
Aug 20, 1997 Sta 40 Replaced w2_30 sensor.
This data was QA'd/QC'd.
Personnel associated with the Data Collection / Data Processing: Karen Wetherill, Yang Xia, Terri Koontz, Amaris Swann, Michell Thomey, Jay McLeod, Jim Elliott, Chelsea Crenshaw