Probabilistic model predicts dynamics of vegetation biomass in a desert ecosystem in NW China

Abstract

The temporal dynamics of vegetation biomass are of key importance for evaluating the sustainability of arid and semiarid ecosystems. In these ecosystems, biomass and soil moisture are coupled stochastic variables externally driven, mainly, by the rainfall dynamics. Based on long-term field observations in northwestern (NW) China, we test a recently developed analytical scheme for the description of the leaf biomass dynamics undergoing seasonal cycles with different rainfall characteristics. The probabilistic characterization of such dynamics agrees remarkably well with the field measurements, providing a tool to forecast the changes to be expected in biomass for arid and semiarid ecosystems under climate change conditions. These changes will depend-for each season-on the forecasted rate of rainy days, mean depth of rain in a rainy day, and duration of the season. For the site in NW China, the current scenario of an increase of 10% in rate of rainy days, 10% in mean rain depth in a rainy day, and no change in the season duration leads to forecasted increases in mean leaf biomass near 25% in both seasons.ecohydrology | stochastic dynamics | vegetation modeling | climate change impacts | soil moisture I n arid and semiarid ecosystems, successful use of limited water resources is of central importance in determining the evolutionary trends of vegetation. Soil moisture there is the principal limiting factor for vegetation restoration and plays a key role in controlling the spatiotemporal patterns of vegetation regulating the complex dynamics of the climate-soil-vegetation system (1, 2).Characterizing the vegetation in water-limited ecosystems, with regard to quantity, species composition, and stability, is a long-standing problem in restoration ecology (3). Field surveys and different types of measurements have been taken for decades (4), but they have mostly yielded only descriptive results [e.g., links between soil moisture and accompanying biomass (5)].Schaffer et al. (3) recently developed an analytical description of the transient joint behavior of plant biomass and soil moisture induced by stochastic rainfall dynamics. These analytical results allow for predictions of ecosystem behavior under changing climate conditions and also illuminate the sensitivities of the dynamics to plant physiology, as well as to climate and soil characteristics that govern the system. The objective of this study is first to test the accuracy of the analytical model under current conditions by comparing its predicted distribution for the biomass density in both the wet and dry seasons with the statistics observed in a long-term field experiment in northwestern (NW) China. Subsequently, using the climate change forecast of the field site, predictions will be made for the seasonal mean biomass and its variability in the future.Ecosystem Characteristics: Climate, Soil, and Vegetation Long-term detailed measurements of vegetation dynamics were carried out at the plant level in four plots located at the Shapotou Desert Research and Experi...

Soil moisture control of sap-flow response to biophysical factors in a desert-shrub species, <i>Artemisia ordosica</i>

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Structural stability as a consistent predictor of phenological events

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Aboveground and belowground biomass and its' allometry for Salsola passerina shrub in degraded steppe desert in Northwestern China

“…And old shrubs have been affected by land degradation for a longer time in our study. In the context of desertification, the multiple interaction of shrub age and habitat degradation on biomass allocation needs further study to understand its adaptive strategies, and to accurately quantify biomass of S. passerina communities at regional scale (Buras et al, 2012; Jenkins, Birdsey, & Pan, 2001; Lambert, Ung, & Raulier, 2005; Wang, Schaffer, Yang, & Rodriguez‐Iturbe, 2017). Therefore, we studied allometry and partitioning of aboveground and belowground biomass of S. passerina shrub typically to answer three main questions: (a) How is the biomass of S. passerina allocated in overgrazing habitats?…”