Methodology and performance of a rainfall manipulation experiment in a piñon–juniper woodland

Pangle, Robert E.; Hill, Judson P.; Plaut, J.; Yépez, Enrico A.; Elliot, James R.; Gehres, Nathan; McDowell, Nate G.; Pockman, William T.

doi:10.1890/es11-00369.1

Cited by 58 publications

(131 citation statements)

References 41 publications

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“…For example, during the monsoon season of 2008, we added 57 mm of precipitation in the water addition plots. This addition is 3 times less than the precipitation received from June to the end of August in 2008 (42). Other studies have demonstrated that when microbial communities are acclimated to multiple dry-wet episodes, their response (measured by microbial respiration rates or changes in community composition) is diminished with each repeated event, and the magnitude of this response is dependent upon precipitation history and the associated aboveground community (18,52).…”

Section: Discussionmentioning

confidence: 93%

“…Overall, VWC was 1.6 times lower in the water reduction plots than in all other plots across both seasons (Table 1) (F ϭ 2.53; P ϭ 0.13). VWC was also 10 times greater during the monsoon season than in the premonsoon season (Table 1) (F ϭ 268.49; P Ͻ 0.01) (42).…”

Section: Soil Moisturementioning

confidence: 92%

“…These plots consist of a decreased precipitation treatment (ϳ50% reduction), an increased precipitation treatment (ϳ18% addition), a precipitation removal control treatment (cover control), and an ambient control treatment (n ϭ 3). Precipitation was reduced using a throughfall displacement design (42,46). Troughs were constructed of clear UV-coated acrylic sheets and installed in each drought plot at a height of approximately 1 m. The cover controls were constructed by inverting the troughs.…”

Section: Methodsmentioning

confidence: 99%

“…These plots serve as the control for the water addition treatment and as an unmanipulated control for the precipitation exclosure plots. Volumetric water content (VWC) is monitored at a depth of Ϫ5 cm using EC-20 water probes (Decagon, Pullman, WA) (42).…”

Section: Methodsmentioning

confidence: 99%

“…We took advantage of a precipitation manipulation in a piñon-juniper woodland to investigate how precipitation increases and decreases might alter soil microbial community composition and abundance beneath piñon and juniper trees across seasons. We predicted (i) that soil microbial community composition and abundance would vary with moisture availability due to changes in precipitation both seasonally and across experimental precipitation treatments, (ii) that soils beneath piñon and juniper would harbor distinct microbial communities, and (iii) that relative to juniper, soil microbial communities beneath piñon would be more responsive to increases and decreases in precipitation, because previous work at our site shows that piñon is more stressed than juniper by drought (42,43).…”

mentioning

confidence: 99%

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Response of the Soil Microbial Community to Changes in Precipitation in a Semiarid Ecosystem

Cregger

Schadt

McDowell

et al. 2012

Appl Environ Microbiol

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dMicrobial communities regulate many belowground carbon cycling processes; thus, the impact of climate change on the structure and function of soil microbial communities could, in turn, impact the release or storage of carbon in soils. Here we used a large-scale precipitation manipulation (؉18%, ؊50%, or ambient) in a piñon-juniper woodland (Pinus edulis-Juniperus monosperma) to investigate how changes in precipitation amounts altered soil microbial communities as well as what role seasonal variation in rainfall and plant composition played in the microbial community response. Seasonal variability in precipitation had a larger role in determining the composition of soil microbial communities in 2008 than the direct effect of the experimental precipitation treatments. Bacterial and fungal communities in the dry, relatively moisture-limited premonsoon season were compositionally distinct from communities in the monsoon season, when soil moisture levels and periodicity varied more widely across treatments. Fungal abundance in the drought plots during the dry premonsoon season was particularly low and was 4.7 times greater upon soil wet-up in the monsoon season, suggesting that soil fungi were water limited in the driest plots, which may result in a decrease in fungal degradation of carbon substrates. Additionally, we found that both bacterial and fungal communities beneath piñon pine and juniper were distinct, suggesting that microbial functions beneath these trees are different. We conclude that predicting the response of microbial communities to climate change is highly dependent on seasonal dynamics, background climatic variability, and the composition of the associated aboveground community.

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Section: Discussionmentioning

confidence: 93%

Section: Soil Moisturementioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Response of the Soil Microbial Community to Changes in Precipitation in a Semiarid Ecosystem

Cregger

Schadt

McDowell

et al. 2012

Appl Environ Microbiol

Self Cite

184

117

View full text Add to dashboard Cite

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Toward a better integration of biological data from precipitation manipulation experiments into Earth system models

et al. 2014

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The biological responses to precipitation within the terrestrial components of Earth system models, or land surface models (LSMs), are mechanistically simple and poorly constrained, leaving projections of terrestrial ecosystem functioning and feedbacks to climate change uncertain. A number of field experiments have been conducted or are underway to test how changing precipitation will affect terrestrial ecosystems. Results from these experiments have the potential to vastly improve modeled processes. However, the transformation of experimental results into model improvements still represents a grand challenge. Here we review the current state of precipitation manipulation experiments and the precipitation responses of biological processes in LSMs to explore how these experiments can help improve model realism. First, we discuss contemporary precipitation projections and then review the structure and function of current-generation LSMs. We then examine different experimental designs and discuss basic variables that, if measured, would increase a field experiment's usefulness in a modeling context. Next, we compare biological processes commonly measured in the field with their model analogs and find that, in many cases, the way these processes are measured in the field is not compatible with the way they are represented in LSMs, an effect that hinders model development. We then discuss the challenge of scaling from the plot to the globe. Finally, we provide a series of recommendations aimed to improve the connectivity between experiments and LSMs and conclude that studies designed from the perspective of researchers in both communities will provide the greatest benefit to the broader global change community.

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Tree Mortality Decreases Water Availability and Ecosystem Resilience to Drought in Piñon‐Juniper Woodlands in the Southwestern U.S.

et al. 2017

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Climate‐driven tree mortality has increased globally in response to warmer temperature and more severe drought. To examine how tree mortality in semiarid biomes impacts surface water balance, we experimentally manipulated a piñon‐juniper (PJ) woodland by girdling all adult piñon trees in a 4 ha area, decreasing piñon basal area by ~65%. Over 3.5 years (2009–2013), we compared water flux measurements from this girdled site with those from a nearby intact PJ woodland. Before and after girdling, the ratio of evapotranspiration (ET) to incoming precipitation was similar between the two sites. Girdling altered the partitioning of ET such that the contribution of canopy transpiration to ET decreased 9–14% over the study period, relative to the intact control, while noncanopy ET increased. We attributed the elevated noncanopy ET in the girdled site each year to winter increases in sublimation and summer increases in both soil evaporation and below‐canopy transpiration. Although we expected that mortality of a canopy dominant would increase the availability of water and other resources to surviving vegetation, we observed a decrease in both soil volumetric water content and sap flow rates in the remaining trees at the girdled site, relative to the control. This postgirdling decrease in the performance of the remaining trees occurred during the severe 2011–2012 drought, suggesting that piñon mortality may trigger feedback mechanisms that leave PJ woodlands drier relative to undisturbed sites and potentially more vulnerable to drought.

show abstract

Methodology and performance of a rainfall manipulation experiment in a piñon–juniper woodland

Cited by 58 publications

References 41 publications

Response of the Soil Microbial Community to Changes in Precipitation in a Semiarid Ecosystem

Response of the Soil Microbial Community to Changes in Precipitation in a Semiarid Ecosystem

Toward a better integration of biological data from precipitation manipulation experiments into Earth system models

Tree Mortality Decreases Water Availability and Ecosystem Resilience to Drought in Piñon‐Juniper Woodlands in the Southwestern U.S.

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