Xiong Peifeng, Shu Jiali, Zhang He, Jia Zhao, Song Jinxi, Palta Jairo A, Xu Bingcheng
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, PR China.
The University of Western Australia Institute of Agriculture and School of Agriculture and Environment, LB 5005 Perth, WA 6001, Australia.
Funct Plant Biol. 2017 Nov;44(12):1229-1242. doi: 10.1071/FP17040.
In the semiarid region Loess Plateau of China, rainfall events, typically characterised as pulses, affect photosynthesis and plant community characteristics. The response of dominant species and grassland community to rainfall pulses was evaluated through a simulation experiment with five pulse sizes (0, 5, 10, 20 and 30mm) in the semiarid Loess Plateau of China in June and August of 2013. The study was conducted in a natural grassland community dominated by Bothrichloa ischaemum (L.)Keng and Lespedeza davurica (Lax.) Schindl. In June, the leaf photosynthetic rate (Pn), transpiration rate, stomatal conductance, intercellular CO2 concentration of both species and soil water content increased rapidly after rainfall pulses. B. ischaemum was more sensitive to the pulses and responded significantly to 5mm rainfall, whereas L. davurica responded significantly only to rainfall events greater than 5mm. The magnitude and duration of the photosynthetic responses of the two species to rainfall pulse gradually increased with rainfall sizes. The maximum Pn of B. ischaemum appeared on the third day under 30mm rainfall, whereas for L. davurica it appeared on the second day under 20mm rainfall. Soil water storage (0-50cm) was significantly affected under 10, 20 and 30mm rainfall. Only large pulses (20, 30mm) increased community biomass production by 21.3 and 27.6% respectively. In August, the effect of rainfall on the maximum Pn and community characteristics was generally not significant. Rainfall pulses affected leaf photosynthesis because of a complex interplay between rainfall size, species and season, but might not induce a positive community-level feedback under changing rainfall patterns.
在中国半干旱地区的黄土高原，降雨事件通常以脉冲形式出现，会影响光合作用和植物群落特征。通过在2013年6月和8月中国半干旱黄土高原进行的模拟实验，评估了优势物种和草地群落对降雨脉冲的响应，该实验设置了5种脉冲大小（0、5、10、20和30毫米）。研究在以白羊草（Bothrichloa ischaemum (L.)Keng）和达乌里胡枝子（Lespedeza davurica (Lax.) Schindl.）为主的天然草地群落中进行。6月，降雨脉冲后，两种物种的叶片光合速率（Pn）、蒸腾速率、气孔导度、胞间CO2浓度以及土壤含水量均迅速增加。白羊草对脉冲更为敏感，对5毫米降雨有显著响应，而达乌里胡枝子仅对大于5毫米的降雨事件有显著响应。两种物种对降雨脉冲的光合响应幅度和持续时间随降雨大小逐渐增加。白羊草在30毫米降雨下，最大光合速率出现在第三天，而达乌里胡枝子在20毫米降雨下，最大光合速率出现在第二天。10、20和30毫米降雨显著影响了土壤储水量（0 - 50厘米）。只有大脉冲（20、30毫米）分别使群落生物量产量增加了21.3%和27.6%。8月，降雨对最大光合速率和群落特征的影响一般不显著。降雨脉冲影响叶片光合作用是由于降雨大小、物种和季节之间复杂的相互作用，但在降雨模式变化的情况下，可能不会引发积极的群落水平反馈。
