Liu Zhiying, Baoyin Taogetao, Sun Juan, Minggagud Hugjiltu, Li Xiliang
Key Laboratory of Grassland Ecology School of Ecology and Environment Inner Mongolia University Hohhot China.
College of Animal Science and Technology Qingdao Agricultural University Qingdao China.
Ecol Evol. 2018 Feb 16;8(6):3109-3118. doi: 10.1002/ece3.3866. eCollection 2018 Mar.
While mowing-induced changes in plant traits and their effects on ecosystem functioning in semi-arid grassland are well studied, the relations between plant size and nutrient strategies are largely unknown. Mowing may drive the shifts of plant nutrient limitation and allocation. Here, we evaluated the changes in nutrient stoichiometry and allocation with variations in sizes of , the dominant plant species in Inner Mongolia grassland, to various mowing frequencies in a 17-yr controlled experiment. Affected by mowing, the concentrations of nitrogen (N), phosphorus (P), and carbon (C) in leaves and stems were significantly increased, negatively correlating with plant sizes. Moreover, we found significant trade-offs between the concentrations and accumulation of N, P, and C in plant tissues. The N:P ratios of aboveground biomass, linearly correlating with plant size, significantly decreased with increased mowing frequencies. The ratios of C:N and C:P of individuals were positively correlated with plant size, showing an exponential pattern. With increased mowing frequencies, size was correlated with the allocation ratios of leaves to stems of N, P, and C by the tendencies of negative parabola, positive, and negative linear. The results of structure equation modeling showed that the N, P, and C allocations were co-regulated by biomass allocation and nutrient concentration ratios of leaves to stems. In summary, we found a significant decoupling effect between plant traits and nutrient strategies along mowing frequencies. Our results reveal a mechanism for how long-term mowing-induced changes in concentrations, accumulations, ecological stoichiometry, and allocations of key elements are mediated by the variations in plant sizes of perennial rhizome grass.
虽然刈割引起的植物性状变化及其对半干旱草原生态系统功能的影响已得到充分研究，但植物大小与养分策略之间的关系在很大程度上尚不清楚。刈割可能会推动植物养分限制和分配的转变。在此，我们在一项为期17年的对照实验中，评估了内蒙古草原优势植物物种羊草大小变化时养分化学计量和分配的变化，以及不同刈割频率的影响。受刈割影响，叶片和茎中氮（N）、磷（P）和碳（C）的浓度显著增加，与植物大小呈负相关。此外，我们发现植物组织中N、P和C的浓度与积累之间存在显著的权衡关系。羊草地上生物量的N:P比与植物大小呈线性相关，随刈割频率增加而显著降低。羊草个体的C:N和C:P比与植物大小呈正相关，呈指数模式。随着刈割频率增加，羊草大小与N、P和C的叶茎分配比分别呈负抛物线、正和负线性趋势相关。结构方程模型结果表明，N、P和C的分配受生物量分配和叶茎养分浓度比的共同调节。总之，我们发现沿刈割频率植物性状与养分策略之间存在显著的解耦效应。我们的研究结果揭示了一种机制，即多年生根茎型禾本科植物的植物大小变化如何介导长期刈割引起的关键元素浓度、积累、生态化学计量和分配的变化。
