Impacts of grazing exclusion on productivity partitioning along regional plant diversity and climatic gradients in Tibetan alpine grasslands.
Impacts of grazing exclusion on productivity partitioning along regional plant diversity and climatic gradients in Tibetan alpine grasslands.
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DOI：
10.1016/j.jenvman.2018.10.097
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发表时间：
2019-02
影响因子：
8.7
通讯作者：
Jianshuang Wu;M. Li;S. Fiedler;Weiling Ma;Xiangtao Wang;Xian-zhou Zhang;B. Tietjen
中科院分区：
文献类型：
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作者：
Jianshuang Wu;M. Li;S. Fiedler;Weiling Ma;Xiangtao Wang;Xian-zhou Zhang;B. Tietjen
生物多样性与生产力的关系对于更好地预测生态系统对气候变化和人类干扰的反应至关重要。然而，气候变化、土地利用变化、植物多样性的影响及其相互作用对青藏高原高寒草原地上和地下生产力划分的影响仍不清楚。为了回答这个问题，我们于2010年8月上旬至2013年8月初对分布在青藏高原北部高山草甸、草原和荒漠草原区的33个放牧与围栏配对地点进行了实地调查。广义加性模型（GAM）表明，地上净初级生产力（ANPP）随生长季降水量（GSP）线性增加，而地下净初级生产力（BNPP）随生长季温度（GST）下降。与放牧地相比，短期围栏不会改变 ANPP 沿气候梯度的模式，但在中等降水水平 200mm<GSP<450mm 时往往会降低 BNPP。我们还发现ANPP和BNPP随物种丰富度线性增加，ANPP随香农多样性指数减少，而BNPP与香农多样性指数不相关。围栏并没有改变生产力组成部分和植物多样性指数之间的关系。广义加性混合模型进一步证实了局部植物多样性与气候条件的相互作用非线性调节该地区高寒草地的生产力分配。最后，结构方程模型（SEM）揭示了高山草原生态系统内生物和非生物变量之间因果关系的方向和强度。 ANPP 直接受 GSP (0.53) 控制，并通过物种丰富度 (0.41) 和香农指数 (−0.12) 间接控制。相比之下，BNPP 直接受到 GST (-0.43) 的影响，并通过物种丰富度 (0.05) 和香农指数 (-0.02) 间接受到 GSP 的影响。因此，我们建议使用GAM和SEM的联合方法来更好地理解气候变化和人类干扰下生物多样性和生态系统功能之间关系背后的机制。
The biodiversity-productivity relationship is critical for better predicting ecosystem responses to climate change and human disturbance. However, it remains unclear about the effects of climate change, land use shifts, plant diversity, and their interactions on productivity partitioning above- and below-ground components in alpine grasslands on the Tibetan Plateau. To answer this question, we conducted field surveys at 33 grazed vs. fenced paired sites that are distributed across the alpine meadow, steppe, and desert-steppe zones on the northern Tibetan Plateau in early August of 2010–2013. Generalized additive models (GAMs) showed that aboveground net primary productivity (ANPP) linearly increased with growing season precipitation (GSP) while belowground net primary productivity (BNPP) decreased with growing season temperature (GST). Compared to grazed sites, short-term fencing did not alter the patterns of ANPP along climatic gradients but tended to decrease BNPP at moderate precipitation levels of 200 mm < GSP <450 mm. We also found that ANPP and BNPP linearly increased with species richness, ANPP decreased with Shannon diversity index, and BNPP did not correlate with the Shannon diversity index. Fencing did not alter the relationships between productivity components and plant diversity indices. Generalized additive mixed models furtherly confirmed that the interaction of localized plant diversity and climatic condition nonlinearly regulated productivity partitioning of alpine grasslands in this area. Finally, structural equation models (SEMs) revealed the direction and strength of causal links between biotic and abiotic variables within alpine grassland ecosystems. ANPP was controlled directly by GSP (0.53) and indirectly via species richness (0.41) and Shannon index (−0.12). In contrast, BNPP was influenced directly by GST (−0.43) and indirectly by GSP via species richness (0.05) and Shannon index (−0.02). Therefore, we recommend using a joint approach of GAMs and SEMs for better understanding mechanisms behind the relationship between biodiversity and ecosystem function under climate change and human disturbance.