Vegetation structure is as important as climate for explaining ecosystem function acrossPatagonian rangelands

Abstract

Summary1. Drylands cover about 41% of Earth's land surface, and 65% of their area supports domestic livestock that depends on the above-ground net primary productivity (ANPP) of natural vegetation. Thus, understanding how biotic and abiotic factors control ANPP and related ecosystem functions can largely help to create more sustainable land-use practices in rangelands, particularly in the context of ongoing global environmental change. 2. We used 311 sites across a broad natural gradient in Patagonian rangelands to evaluate the relative importance of climate (temperature and precipitation) and vegetation structure (grass and shrub cover, species richness) as drivers of ANPP, precipitation-use efficiency (PUE) and precipitation marginal response (PMR). 3. Climatic variables explained 60%, 52% and 12% of the variation in grass cover, shrub cover and species richness, respectively. Shrub cover increased in areas with warmer, drier and winter rainfall climates, while the response observed for both grass cover and species richness was the opposite. Climate and vegetation structure explained 70%, 60% and 29% of the variation in ANPP, PUE and PMR, respectively. These three variables increased with increasing vegetation cover, particularly grass cover. Species richness also increased with ANPP, PUE and PMR. ANPP increased, and PUE decreased with increasing mean annual precipitation, whereas PMR increased with the proportion of precipitation falling in spring-summer. Temperature had a strong negative effect on ANPP and PUE, and a positive direct effect on PMR. Standardized total effects from structural equation modelling showed that vegetation structure and climate had similar strengths as drivers of ecosystem functioning. Grass cover had the highest total effect on ANPP (0.58), PUE (0.55) and PMR (0.41). Among the climatic variables, mean annual precipitation had the strongest total effect on ANPP (0.51) and PUE (À0.41), and the proportion of the precipitation falling in spring-summer was the most influential on PMR (0.36). 4. Synthesis. Vegetation structure is as important as climate in shaping ecosystem functioning Patagonian rangelands. Maintaining and enhancing vegetation cover and species richness, particularly in grasses, could reduce the adverse effects of climate change on ecosystem functioning in these ecosystems.

Shrub patch configuration in relation to precipitation and soil properties in Northwest China

“…MAP contributed to the variation in shrub cover by 41.8% ( r = 0.647 ** ). This is consistent with previous studies which showed that precipitation was a major factor affecting shrub patch structures (Chen et al, ; Gaitán et al, ). Woody cover also significantly increased along increased rainfall gradients in Australian and South African savannah systems (Shackleton & Scholes, ; Williams, Duff, & Cook, ).…”

“…Root competition for water in xeric regions might also affect patch size and spacing between them (King & Woodell, ). Positive relationship between species diversity of interspace grass (H′) and shrub cover ( r = 0.557 * ) was consistent with previous studies (Chen et al, ; Gaitán et al, ; Hao et al, ; Koyama, Sasaki, Jamsran, & Okuro, ; Ravolainen et al, ). In tundra, shrubs with highly broken forms are usually accompanied by low grass diversity and richness (Ravolainen et al, ).…”

Plant species richness and shrub cover attenuate drought effects on ecosystem functioning across Patagonian rangelands

“…There is also increasing evidence that biotic attributes, such as cover and species richness (SR), also influence ecosystem functioning [8]. The diversity-ANPP relationship in response to drought has been assessed in experimental grasslands [9], but it is largely unknown how biotic attributes modulate this relationship at regional scales [10].…”

Evaluation Vegetation Cover in Sulaymaniyah Region of Iraq.

“…The average relative humidity for summer and winter are 25.5% and 65.6% respectively, while the evaporation reached 329.5 (mm) in summers and 53 (mm) in winters. The annual rainfall rate reaches about 656.05 mm, therate of annualtemperature19.6 c 0 , the annual rate of humidity45% and the amount rate of annual evaporation 162.7mm as in table (1).The nature of the alluvial soil and its fertility all these factors enhanced the growth and good distribution of the vegetative cover in this area .The botanical species as in table (2) refers to about 39 plant families, 85 genuses and 92 species. While the percentage of coverage was 95 % and plant density reached 395.48 plant/m 2 in the study region.…”

“…Maintaining and enhancing vegetation cover and species richness, particularly in grassescould reduce the adverse effects of climate change on ecosystem functioning in these ecosystems [1].Ecological factors play a fundamental role in vegetation In particular; germination, growth and distribution. Flora is adapted to the ecological conditions everywhere, such as dry land plants, semi dry land plants or xerophytes and hydrophytes.…”