The Response Strategy Of Leaf Functional Traits And Water Use Efficiency To Altitudinal Gradient In Yuanmou Dry-hot Valley

The responses of plant functional traits and water use efficiency are driven by environmental factors. Different plant functional traits and water use efficiency is showed by adaptive strategies. The specific climate and type of vegetation, especially the specific habitat, have allowed plants to adopt a serious of different strategies of adaptation to local habitats in the Yuanmou dry-hot valley. To date, a number of researches on the responses of plant functional traits, particularly to understanding of the mutual effect mechanisms among functional traits, along different altitudinal gradients, that is one of the hotspot of Ecological field. Researches on, however, how species respond to the environmental factors, particularly to the adaptive strategies of plants along different altitudinal gradients, are still lacking in the dry-hot valley.This thesis measured leaf functional traits of plants along different altitudinal gradients in dry-hot valley, include leaf dry matter content (LDMC), leaf area (LA), specific leaf area (SLA), leaf thickness (LT), leaf density (LD). And we measured water use efficiency (WUE) by calculate the value of Stable isotopic δ13C from leaves along different altitudinal gradients. Our studies focusing on different aspects of the responses of plant functional traits and water use efficiency along different altitudinal gradients:1) The analysis of plant functional traits along different altitudinal gradients;2) The correlation analysis among plant functional traits;3) The analysis difference of WUE among different altitudinal gradients;4) The correlation between plant functional traits and water use efficiency. We addressed the following questions:1) What the variation of different altitudinal gradients plant functional traits and water use efficiency respond to;2) How changes among the plant functional traits and relationship between traits along different altitudinal gradients;3) How different groups of functional characteristics plants to adopt different strategies of adaptation to local habitats?The results of our studies showed:1) The ANOVA revealed LT and LD have different significantly between wet season and dry season. In addition, the variation coefficients revealed sensitive to variation of altitudinal gradients is LD in wet season and LT in dry season, respectively. According to correlation among traits, there were correlations in wet season then non-correlations in dry season, such as LT and LDMC. There were negative correlations in wet season; meanwhile there were positive correlations in dry season (e.g., LT and LD). Likewise, there were positive correlations in wet season; meanwhile there were negative correlations in dry season (e.g., SLA and LT). Furthermore, other correlations between wet season and dry season were consist with together;2) There was strong correlation among seasons to LT as well as LD, and the both traits in wet season more than in dry season. Although there were non-correlations among seasons to LDMC, LA, SLA as well as WUE, but the result of analysis revealed LA, SLA and WUE in dry season more than in wet season, except LDMC.3) There were non-correlations to WUE in wet season as well as strong correlations to WUE in dry season. There was non-correlation among different altitudinal gradients, however, it showed a trend of increasing WUE with altitude. On the contrary, there was strong correlation among different altitudinal gradients to WUE in dry season.Therefore, the different major environmental factors, both wet season and dry season, have allowed plants to adopt a serious of different groups of leaf functional traits to local habitats. Water use efficiency (WUE) not only influenced by stress of water restriction, but also affected by variation environments. Meanwhile, water use efficiency (WUE) revealed the adaptive strategies of plants along different altitudinal gradients.