短花针茅种群高度对放牧调控的响应

Response of Stipa breviflora height to grazing in a desert grassland

种群高度是植物行为策略的核心内容,也是解析植物种群对草食动物调控机制的潜在途径。本研究以内蒙古锡林郭勒盟苏尼特右旗荒漠草原的长期放牧控制实验为平台,通过研究荒漠草原建群种短花针茅(Stipa breviflora)叶宏观性状、叶解剖性状与叶营养含量3个维度,以期揭示荒漠草地放牧调控下植物高度的响应机制。结果表明:短花针茅叶高可塑性指数(PI)较高,叶长次之;叶解剖结构显示,叶片厚度可塑性指数较高,重度放牧处理下叶性状可塑性指数大于适度放牧处理;叶C、N、P含量可塑性指数变化呈PIN>PIP>PIC;适度放牧短花针茅叶高大于不放牧处理,不放牧叶高大于重度放牧处理;重度放牧叶上表皮细胞面积低于其他处理,且放牧处理提高了叶片N含量;短花针茅叶高与叶长、叶宽、叶直立度呈极显著正相关,与叶卷曲度呈负相关,与上表皮细胞面积、上表皮细胞厚度呈极显著正相关,与C含量呈极显著正相关。

Plant height is a central part of plant ecological strategy. It is a potential way to analyze the regulation mechanism of plant population to herbivores. Based on a longterm grazing experiment in Sonid Right Banner, Xilingol, this study aimed to reveal the height response of desert grassland plant Stipa breviflora under grazing regulation through three different dimensions （i.e. leaf macroscopic traits, leaf anatomical traits, and leaf nutrient contents）. The results showed that the plasticity index （PI） of S. breviflora leaf height was the largest and leaf length was the second. The leaf anatomical structure showed a higher PI of leaf thickness, and PIs of leaf traits were greater under heavy grazing than under moderate grazing. The PI of leaf phosphorus （P） content was greater than those of leaf nitrogen （N） and carbon （C） content. The PI of leaf N content was greater than that of C content. Leaf height of S. breviflora in the moderate grazing treatment was higher than in the nongrazing treatment, and nongrazing treatment had higher leaf height than heavy grazing treatment. The area of upper epidermis cell under heavy grazing was lower than those under the other treatments. The leaf N content was increased by grazing. Leaf height of S. breviflora was significantly positively correlated with leaf length, leaf width and leaf erection index, and negatively correlated with leaf rolling index. Furthermore, it was significantly positively correlated with upper epidermal cell surface area, upper epidermis cell thickness, and leaf C content.