Plant Functional Group Composition Modifies the Effects of Precipitation Change on Grassland Ecosystem Function

Fry, Ellen L.; Manning, Peter; Allen, D. G.; Hurst, Alex; Everwand, Georg; Rimmler, Martin; Power, Sally A.

doi:10.1371/journal.pone.0057027

Cited by 69 publications

(76 citation statements)

References 66 publications

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“…There are a number of climate change papers that show an immediate response to climate manipulations in grasslands [37,43,44,45], but others have demonstrated a delayed response from the plant community [6,36,46,47]. The study presented here is only short-term, so may not measure all changes that will occur with changing precipitation.…”

Section: Discussionmentioning

confidence: 99%

Short-Term Effects of Changing Precipitation Patterns on Shrub-Steppe Grasslands: Seasonal Watering Is More Important than Frequency of Watering Events

2016

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Climate change is expected to alter precipitation patterns. Droughts may become longer and more frequent, and the timing and intensity of precipitation may change. We tested how shifting precipitation patterns, both seasonally and by frequency of events, affects soil nitrogen availability, plant biomass and diversity in a shrub-steppe temperate grassland along a natural productivity gradient in Lac du Bois Grasslands Protected Area near Kamloops, British Columbia, Canada. We manipulated seasonal watering patterns by either exclusively watering in the spring or the fall. To simulate spring precipitation we restricted precipitation inputs in the fall, then added 50% more water than the long term average in the spring, and vice-versa for the fall precipitation treatment. Overall, the amount of precipitation remained roughly the same. We manipulated the frequency of rainfall events by either applying water weekly (frequent) or monthly (intensive). After 2 years, changes in the seasonality of watering had greater effects on plant biomass and diversity than changes in the frequency of watering. Fall watering reduced biomass and increased species diversity, while spring watering had little effect. The reduction in biomass in fall watered treatments was due to a decline in grasses, but not forbs. Plant available N, measured by Plant Root Simulator (PRS)-probes, increased from spring to summer to fall, and was higher in fall watered treatments compared to spring watered treatments when measured in the fall. The only effect observed due to frequency of watering events was greater extractable soil N in monthly applied treatments compared to weekly watering treatments. Understanding the effects of changing precipitation patterns on grasslands will allow improved grassland conservation and management in the face of global climatic change, and here we show that if precipitation is more abundant in the fall, compared to the spring, grassland primary productivity will likely be negatively affected.

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Section: Discussionmentioning

confidence: 99%

Short-Term Effects of Changing Precipitation Patterns on Shrub-Steppe Grasslands: Seasonal Watering Is More Important than Frequency of Watering Events

2016

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“…Two possible hypotheses arise from the results; 538 more testing is required to ascertain mechanisms. The fungal community associated with 539 perennial species may be less diverse (lower TRF number) due to slower root and shoot 540 turnover and possibly more complex root tissue and exudate chemistry and recalcitrant litter 541 We found previously that plant functional composition manipulations, implemented over the 549 preceding four years, altered rates of CO 2 exchange and nutrient cycling (Fry et al 2013, 550 2014a). Here, as before, ecosystem respiration was strongly reduced by summer rainfall 551 reductions in perennial plots, while plots dominated by annuals were unaffected, 552 demonstrating consistency of treatment effects.…”

Section: Inputs (De Vries Et Al 2007) 535mentioning

confidence: 99%

“…Alternatively, if treatment effects are strengthened due to 342 the addition of new significant terms, which shrink error variance (increasing sum of squares) 343 and increase F ratios, or are unaltered, this implies that variation in ecosystem functioning 344 caused by the treatments is unrelated to change in microbial communities, which explain 345 independent variation in ecosystem function. 346 work at this site (Fry et al 2013). 359…”

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confidence: 99%

Shifts in microbial communities do not explain the response of grassland ecosystem function to plant functional composition and rainfall change

Fry

Manning

Macdonald

et al. 2016

Soil Biology and Biochemistry

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Ecosystem functioning in grasslands is regulated by a range of biotic and abiotic factors, and 34 the role of microbial communities in regulating ecosystem function has been the subject of 35 much recent scrutiny. However, there are still knowledge gaps regarding the impacts of 36 rainfall and vegetation change upon microbial communities and the implications of these 37 changes for ecosystem functioning. We investigated this issue using data from an 38 experimental mesotrophic grassland study in south-east England, which had been subjected to 39 four years of rainfall and plant functional composition manipulations. Soil respiration, 40 nitrogen and phosphorus stocks were measured, and the abundance and community structure 41 of soil microbes were characterised using quantitative PCR and multiplex-TRFLP analysis, 42 respectively. Bacterial community structure was strongly related to the plant functional 43 3 composition treatments, but not the rainfall treatment. However, there was a strong effect of 44 both rainfall change and plant functional group upon bacterial abundance. There was also a 45 weak interactive effect of the two treatments upon fungal community structure, although 46 fungal abundance was not affected by either treatment. Next, we used a statistical approach to 47 assess whether treatment effects on ecosystem function were regulated by the microbial 48 community. Our results revealed that ecosystem function was influenced by the experimental 49 treatments, but was not related to associated changes to the microbial community. Overall, 50these results indicate that changes in fungal and bacterial community structure and abundance 51 play a relatively minor role in determining ecosystem function responses to precipitation and 52 plant functional composition change, and that direct effects on soil physical and chemical 53 properties and upon plant and microbial physiology may play a more important role. 54 55 INTRODUCTION 56 57In the coming century climate change will affect grasslands by altering precipitation and 58 therefore water availability (Kardol et al. 2010; IPCC 2014). Changing rainfall patterns are 59 likely to alter microbial community structure, which can have implications for many 60 ecosystem functions, including those relating to nutrient cycling and carbon (C) sequestration 61 (Morecroft et al. 2004;Gilgen et al. 2010). Changes to rainfall patterns will also be 62 accompanied by changes to the diversity and functional composition of plant communities, 63 which can be driven by a number of global change drivers including nitrogen (N) deposition 64 and land use intensification (Manning 2012, Southon et al., 2013, Allan et al 2015. It is 65 therefore important to consider the effect of both rainfall manipulations and plant functional 66 4 identity in a systematic manner in order to understand global change impacts upon ecosystem 67 function. 68

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“…An obvious control involves roofs under which the collected rain is redistributed to the experimental plots [13], [22], [23], named “roofed control” hereafter. To our knowledge, there is no published study, investigating whether roof artifacts affect ecosystem processes and therefore confound the conclusions of drought experiments.…”

Section: Introductionmentioning

confidence: 99%

Separating Drought Effects from Roof Artifacts on Ecosystem Processes in a Grassland Drought Experiment

et al. 2013

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1Given the predictions of increased drought probabilities under various climate change scenarios, there have been numerous experimental field studies simulating drought using transparent roofs in different ecosystems and regions. Such roofs may, however, have unknown side effects, called artifacts, on the measured variables potentially confounding the experimental results. A roofed control allows the quantification of potential artifacts, which is lacking in most experiments.2We conducted a drought experiment in experimental grasslands to study artifacts of transparent roofs and the resulting effects of artifacts on ecosystems relative to drought on three response variables (aboveground biomass, litter decomposition and plant metabolite profiles). We established three drought treatments, using (1) transparent roofs to exclude rainfall, (2) an unroofed control treatment receiving natural rainfall and (3) a roofed control, nested in the drought treatment but with rain water reapplied according to ambient conditions.3Roofs had a slight impact on air (+0.14°C during night) and soil temperatures (−0.45°C on warm days, +0.25°C on cold nights), while photosynthetically active radiation was decreased significantly (−16%). Aboveground plant community biomass was reduced in the drought treatment (−41%), but there was no significant difference between the roofed and unroofed control, i.e., there were no measurable roof artifact effects.4Compared to the unroofed control, litter decomposition was decreased significantly both in the drought treatment (−26%) and in the roofed control treatment (−18%), suggesting artifact effects of the transparent roofs. Moreover, aboveground metabolite profiles in the model plant species Medicago x varia were different from the unroofed control in both the drought and roofed control treatments, and roof artifact effects were of comparable magnitude as drought effects.5Our results stress the need for roofed control treatments when using transparent roofs for studying drought effects, because roofs can cause significant side effects.

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Plant Functional Group Composition Modifies the Effects of Precipitation Change on Grassland Ecosystem Function

Cited by 69 publications

References 66 publications

Short-Term Effects of Changing Precipitation Patterns on Shrub-Steppe Grasslands: Seasonal Watering Is More Important than Frequency of Watering Events

Short-Term Effects of Changing Precipitation Patterns on Shrub-Steppe Grasslands: Seasonal Watering Is More Important than Frequency of Watering Events

Shifts in microbial communities do not explain the response of grassland ecosystem function to plant functional composition and rainfall change

Separating Drought Effects from Roof Artifacts on Ecosystem Processes in a Grassland Drought Experiment

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