宁夏荒漠草原4种典型植物群落生物量时空动态特征及其影响因素

Spatio-temporal pattern of biomass and its influencing factors of four typical plant communities on desert steppe in Ningxia autonomous region

摘要:

【目的】 探究草原植物群落生物量时空动态特征及影响因素。【方法】 以宁夏荒漠草原4种典型植物群落：牛枝子（Lespedeza potaninii）、赖草（Leymus secalinus）、短花针茅（Stipa breviflora）和白草 （Pennisetum flaccidum）群落为研究对象，调查分析4种植物群落地上、地下生物量时空动态特征及其影响因素。【结果】 生长季内，各植物群落地上生物量变化呈单峰形（峰值出现在8月），地下生物量变化呈双峰形（峰值分别出现在5月和9月）；地下生物量主要分布于0~15 cm土层，并随土层加深地下生物量呈递减趋势。植物群落地上、地下生物量线性拟合模型表明，牛枝子群落、短花针茅群落和白草群落地上生物量与地下生物量呈极显著正相关（P＜0.01），赖草群落为极显著负相关（P＜0.01）；群落物种多样性与生物量呈二次函数模型。冗余分析表明，生长季蒸发量（AE）、最高温度（MT）和平均气温 （AT）是影响生物量变化的主要因素。随机森林模型表明，相较于土壤理化性质，气候因子是预测植被生物量变化的重要变量，其中湿度影响最大。【结论】 本研究为理解植物地上、地下生物量分配调控机制提供了理论基础，对系统了解宁夏荒漠草原植物群落净初级生产力时空动态变化具有指导意义。

Abstract:

【Objective】 Understanding the spatio-temporal patterns and influencing factors of steppe plant community biomass is essential for analyzing the ecological functions of steppe systems under global climate change. 【Method】 This study examines four typical plant communities in the Ningxia desert steppe：Lespedeza potaninii，Ley- mus secalinus，Stipa breviflora and Pennisetum flaccidum. communities. Using a sample survey method，the spatiotemporal distributionand factors influencing aboveground and underground biomass in these communities were analyzed.【Result】 The results showed that during the growing season，aboveground biomass of each plant community exhibited a single peak （in August），while underground biomass showed a double peak （in May and September，respectively）；The underground biomass was primarilyconcentrated in the 0~15 cm soil layer，decreasing with soil depth. The linear fitting modelsrevealed a highly significant positive correlation（P＜0. 01）between aboveground biomass and underground biomass in the Lespedeza potaninii，the Stipa breviflora，and the White grass communities， where a sthe Leymus secalinus community exhibited a highly significant negative correlation（P＜0. 01）；Community species diversity and biomass followed a quadratic relationship. Redundancy analysis identified that the amount of evaporation （AE），maximum temperature （MT） and average temperature （AT）during the growing seasonas the primary factors influencing biomass variation. The random forest model highlighted the importance of climate factors over soil properties in predicting vegetation biomass changes，with humidity exertingthe greatest influence. 【Conclusion】 This study provides new insights into the regulatory mechanisms of aboveground and underground biomass allocation in plant communities. The findings are valuable for understanding the -patio-temporal dynamics of net primary productivity in Ningxia desert steppes and offer guidance for sustainable ecosystem management.