Water uptake and niche characteristics of neighboring plants for arbors and shrubs under different rainfall conditions in a rocky mountainous area,Beijing
Aims Our study aims to explore water usage strategies and the competitive or complementary relationships among neighboring arboreal and shrubby plants within the same stand under diverse rainfall conditions.Through an analysis of soil water absorption and water niche characteristics of these neighboring plants,we aim to provide a theoretical basis for vegetation restoration and management in the rocky mountainous areas,Beijing.Methods Xylem samples were collected from trees including Robinia pseudoacacia,Koelreuteria paniculata,and Platycladus orientalis,as well as from the shrub Vitex negundo.Additionally,samples of soil,groundwater,and rainwater were gathered both before and 1-4 days following different types of rainfall events:light rain during a dry period,moderate rain during a wet period,and rainstorms during a dry period.These samples were analyzed to examine the characteristics and dynamic changes of hydrogen and oxygen isotopes composition(δ2H and δ18O).The MixSIAR model was employed to determine the contribution rates of groundwater and soil water from different soil layers to various plant species.Furthermore,water niche width and niche overlap were assessed using the Levins index and Levins overlap formula,respectively.Important findings The results indicate that soil water content,δ2H and δ18O,water absorption depth,and niche characteristics of neighboring arboreal and shrubby plants were significantly influenced by the types of rainfall.Following light rainfall during a dry period,shrubs exhibited heightened sensitivity to precipitation,shifting their water source from deep soil to upper soil layers,while arboreal species predominantly relied on groundwater.After moderate rainfall during a wet period,arboreal and shrubby plants from different forest types primarily absorbed water from soil layers within the 0-40 cm depth range.Rainstorms during a dry period altered the water utilization strategies of arboreal and shrubby plants,with shrubs predominantly sourcing water from the 0-40 cm soil layers,while arboreal species exhibited more uniform water uptake across different soil layers.The niche width of R.pseudoacacia and K.paniculata was lower compared to corresponding shrubs before and after light rainfall during a dry period,whereas the niche width of K.paniculata exceeded that of understory shrubs both before and after rainstorms during dry periods.Platycladus orientalis and understory shrubs exhibited similar responses to different types of rainfall,with the niche width of P.orientalis experiencing a sharp increase on the first day following rain,while that of shrubs spiked on the second day post-rainfall.For the dry period before light rainfall,there was a substantial overlap in the water niche between R.pseudoacacia and understory shrubs,which diminished with an increase in the number of rainfall days thereafter.Except for the dry period before light rainfall,arboreal and shrubby plants demonstrated distinct water utilization strategies across different types of rainfall,thus mitigating water competition between them.
rainfallhydrogen and oxygen stable isotopeswater use strategywater niche characteristic
万方数据
维普
