Long-term decline in grassland productivity driven by increasing dryness

Brookshire, E. N. Jack; Weaver, T.

doi:10.1038/ncomms8148

Cited by 126 publications

(82 citation statements)

References 33 publications

(57 reference statements)

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“…Whether this enhancement of WUE can compensate for the detrimental effects of increased aridity on water availability and plant growth is largely unknown. A recent study showed that increased aridity over the last four decades was responsible for a sustained decline in plant productivity, regardless of CO 2 -induced increases in WUE during this period (38).…”

Section: Resultsmentioning

confidence: 99%

Increasing aridity reduces soil microbial diversity and abundance in global drylands

Maestre

Delgado‐Baquerizo

Jeffries

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

787

622

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Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climatechange models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.bacteria | fungi | climate change | arid | semiarid

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Section: Resultsmentioning

confidence: 99%

Increasing aridity reduces soil microbial diversity and abundance in global drylands

Maestre

Delgado‐Baquerizo

Jeffries

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

787

622

View full text Add to dashboard Cite

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“…Extreme events such as droughts, however, often lead to periodic, pulsing, and severe alterations [12]. Long-term declines in grassland productivity had been driven by increased dryness over four decades; to some extent, the water use efficiency that increased through CO 2 enrichment in grasslands may have slightly moderated the decline in production of native C3 grasslands, while variations in N had no effects [13]. So it seems that extreme droughts may change the structure, composition, and functionality of terrestrial ecosystems, thereby influencing C cycling and its feedback to the climate system [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Drought and Carbon Cycling of Grassland Ecosystems under Global Change: A Review

Lei

Pang

Xing-yong

et al. 2016

Water

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Abstract:In recent years, the increased intensity and duration of droughts have dramatically altered the structure and function of grassland ecosystems, which have been forced to adapt to this change in climate. Combinations of global change drivers such as elevated atmospheric CO 2 concentration, warming, nitrogen (N) deposition, grazing, and land-use change have influenced the impact that droughts have on grassland C cycling. This influence, to some extent, can modify the relationship between droughts and grassland carbon (C) cycling in the multi-factor world. Unfortunately, prior reviews have been primarily anecdotal from the 1930s to the 2010s. We investigated the current state of the study on the interactive impacts of multiple factors under drought scenarios in grassland C cycling and provided scientific advice for dealing with droughts and managing grassland C cycling in a multi-factor world. Currently, adequate information is not available on the interaction between droughts and global change drivers, which would advance our understanding of grassland C cycling responses. It was determined that future experiments and models should specifically test how droughts regulate grassland C cycling under global changes. Previous multi-factor experiments of current and future global change conditions have studied various drought scenarios poorly, including changes in precipitation frequency and amplitude, timing, and interactions with other global change drivers. Multi-factor experiments have contributed to quantifying these potential changes and have provided important information on how water affects ecosystem processes under global change. There is an urgent need to establish a systematic framework that can assess ecosystem dynamic responses to droughts under current and future global change and human activity, with a focus on the combined effects of droughts, global change drivers, and the corresponding hierarchical responses of an ecosystem.

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“…The carbon sequestration of a grassland can vary considerably from year to year since it is influenced both by natural and anthropogenic factors such as temperature, rainfall, species composition, nutrient and water availability, light, grazing pressure and agricultural practices [11,12]. Together, these factors make grassland carbon exchange responsive to climate change [13][14][15], and drive interest in monitoring grassland ecosystem responses for the purpose of developing optimal management regimes.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Grassland Seasonal Carbon Dynamics, by Integrating MODIS NDVI, Proximal Optical Sampling, and Eddy Covariance Measurements

et al. 2016

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This study evaluated the seasonal productivity of a prairie grassland (Mattheis Ranch, in Alberta, Canada) using a combination of remote sensing, eddy covariance, and field sampling collected in 2012-2013. A primary objective was to evaluate different ways of parameterizing the light-use efficiency (LUE) model for assessing net ecosystem fluxes at two sites with contrasting productivity. Three variations on the NDVI (Normalized Difference Vegetation Index), differing by formula and footprint, were derived: (1) a narrow-band NDVI (NDVI 680,800 , derived from mobile field spectrometer readings); (2) a broad-band proxy NDVI (derived from an automated optical phenology station consisting of broad-band radiometers); and (3) a satellite NDVI (derived from MODIS AQUA and TERRA sensors). Harvested biomass, net CO 2 flux, and NDVI values were compared to provide a basis for assessing seasonal ecosystem productivity and gap filling of tower flux data. All three NDVIs provided good estimates of dry green biomass and were able to clearly show seasonal changes in vegetation growth and senescence, confirming their utility as metrics of productivity. When relating fluxes and optical measurements, temporal aggregation periods were considered to determine the impact of aggregation on model accuracy. NDVI values from the different methods were also calibrated against f APAR green (the fraction of photosynthetically active radiation absorbed by green vegetation) values to parameterize the APAR green (absorbed PAR) term of the LUE (light use efficiency) model for comparison with measured fluxes. While efficiency was assumed to be constant in the model, this analysis revealed hysteresis in the seasonal relationships between fluxes and optical measurements, suggesting a slight change in efficiency between the first and second half of the growing season. Consequently, the best results were obtained by splitting the data into two stages, a greening phase and a senescence phase, and applying separate fits to these two periods. By incorporating the dynamic irradiance regime, the model based on APAR green rather than NDVI best captured the high variability of the fluxes and provided a more realistic depiction of missing fluxes. The strong correlations between these optical measurements and independently measured fluxes demonstrate the utility of integrating optical with flux measurements for gap filling, and provide a foundation for using remote sensing to extrapolate from the flux tower to larger regions (upscaling) for regional analysis of net carbon uptake by grassland ecosystems.

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Long-term decline in grassland productivity driven by increasing dryness

Cited by 126 publications

References 33 publications

Increasing aridity reduces soil microbial diversity and abundance in global drylands

Increasing aridity reduces soil microbial diversity and abundance in global drylands

Drought and Carbon Cycling of Grassland Ecosystems under Global Change: A Review

Monitoring Grassland Seasonal Carbon Dynamics, by Integrating MODIS NDVI, Proximal Optical Sampling, and Eddy Covariance Measurements

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