北京松山林下典型灌木绣线菊光、水利用效率的 季节动态及其对环境因子的响应

[Objective] Resource use efficiencies are key indicators for acclimation of a plant to environmental conditions, which is one of the main concerns in the area of climate change ecology. The controlling machanisms of light use efficiency (LUE) and water use efficiency (WUE) of understory shrub species in response to environmental changes remain unclear. Met hods] The seasonal variation in LUE and WUE and its envrionmental controls for an understory shrub, Spiraea salicifolia, in a typical deciduous forest in Songshan of Beijing were examined through in-situ measurements of leaf photosynthetic parameters and environmental factors in the full leafing stage from June to September 201 9. Results] LUE and WUE showed obvious seasonal variations, averaging ().03 mol/mol and 8.32/imol/mmol, respectively. Photosynthetically active radiation (PAR) and air temperature (Ta) were the main factors controlling the LUE, showing an exponential and a linear negative relationship, respectively. PAR and vapor preassure difference (VPD) were the main factors controlling WUE, with which both showed the linear negative relationship. The VPT) limited transpiration by affecting stomatai conductance (g5), which affected WUE. The seasonal variation in both LUE and WUE was not affected by soil water content (SWC). There was con ver gen cy between LUE and WUE in response to environmental factors. Conclusion], Ta and VPD, rather than SWC: were the main limiting factors for resource use efficiencies of the shrub Spiraea salicifolia in understory of the research area. The shrub Spiraea salicifolia in understory showed a resource conservation strategy under the condition of limited resources, specifically, under the condition of limited light, the shrub Spiraea salicifolia in understory maximized the use of light energy for photosynthesis and thus had a high light energy utilization efficiency. [ABSTRACT FROM AUTHOR]