Overall grazing tolerance index (overall GTI) is not an ideal predictor for describing a single-species tolerance to grazing
Overall grazing tolerance index (overall GTI) is not an ideal predictor for describing a single-species tolerance to grazing
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总体放牧耐受性指数（总体 GTI）并不是描述单一物种放牧耐受性的理想预测指标
DOI：
10.1002/ece3.5038
复制
发表时间：
2019
影响因子：
2.6
通讯作者：
Wang Xiao-An
中科院分区：
文献类型：
--
作者：
Zhang Lu-Lu;Zhu Zhi-Hong;Li Ying-Nian;Qian Zeng-Qiang;Liu Gang;Wang Xiao-An
植物的补偿生长模式经常被用来直观地估计它们的放牧耐受性。然而，这种耐受性有时是通过总体放牧耐受性指数（总体 GTI）来衡量的，该指数假设耐受性是各种潜在机制的多元线性函数。由于机制之间的相互作用不是独立的，基于整体GTI的放牧耐受性表达可能与基于补偿生长的表达不一致。通过2007年至2012年的田间操作性试验，测量了高寒草甸不同资源利用率下披碱草12个性状对刈割的响应，探讨了补偿性地上生物量和总体GTI，以评估两种耐受性表达之间可能存在的差异。我们的结果表明，这两种耐受性的表达是完全相反的。基于总体 GTI 的表达是过度补偿的，并且不随修剪和资源可用性而变化，而基于补偿性地上生物量的表达是补偿不足的，并在受精后变为过度补偿。具有极高负平均GTI的高变异性状的过度表达对落叶损害的影响、所考虑的性状中包含的随机误差的影响以及功能性冗余性状的加倍权重极大地夸大了整体GTI，从而导致两种耐受性表达的不一致。这种不一致还与两种容差表达式的确定机制不同有关。我们的数据表明，植物的放牧耐受性并不是决定放牧耐受性的性状或机制的多元线性函数；总体 GTI 只是衡量落叶损害性状变异性的指标。我们的研究结果强调了大肠杆菌的耐受性。 nutans主要取决于变异性较低的性状对落叶的反应，总体GTI并不是描述单一物种对放牧耐受性的理想预测因子。
Plants' pattern of compensatory growth is often used to intuitively estimate their grazing tolerance. However, this tolerance is sometimes measured by the overall grazing tolerance index (overall GTI), which assumes that tolerance is a multivariate linear function of various underlying mechanisms. Because the interaction among mechanisms is not independent, the grazing tolerance expression based on overall GTI may be inconsistent with that based on compensatory growth. Through a manipulative field experiment from 2007 to 2012, we measured the responses of 12 traits ofElymus nutansto clipping under different resource availabilities in an alpine meadow and explored the compensatory aboveground biomass and the overall GTI to assess the possible differences between the two expressions of tolerance. Our results showed that these two expressions of tolerance were completely opposite. The expression based on overall GTI was over‐compensatory and did not vary with clipping and resource availability, while the expression based on compensatory aboveground biomass was under‐compensatory and altered to over‐compensation after fertilization. The over‐expression of highly variable traits with extremely high negative mean GTI to defoliation damage, the influence of random errors contained in traits considered, and the doubling weight of functional redundant traits greatly inflated the overall GTI, which leads to the inconsistency of the two tolerance expressions. This inconsistency is also associated with the different determining mechanisms of the two tolerance expressions. Our data suggest that plants' grazing tolerance is not a multivariate linear function of traits or mechanisms that determine grazing tolerance; the overall GTI is only a measure of traits' variability to defoliation damage. Our findings highlight that the tolerance ofE. nutansmainly depends on the response of traits with lower variability to defoliation, and the overall GTI is not an ideal predictor for describing a single‐species tolerance to grazing.