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ADVANCES IN PLANT SUCCESSION ECOPHYSIOLOGY

植物群落演替过程中植物生理生态学特性及其主要环境因子的变化


对20世纪80年代以来有关植物群落演替的生理生态学机制研究的主要结果进行了综述。演替早期和演替后期各种植物所处环境常有很大差别。演替早期的生境具有开放性和光照充足等特点,各环境因子富于变化;演替后期的生境由于植被的缓冲作用,一般较为封闭和稳定,各环境因子在空间尺度上的异质性较强。演替早期和演替后期群落不仅物种组成不同,而且在演替不同阶段中出现的物种的生理生态特性以及对环境的适应性也有很大差别,这些物种的生理生态差异使得物种更替现象经常发生,也使得演替能够顺利进行。在全球气候变化影响下,生态系统将会出现更多的次生演替和长时间停留于演替早期阶段的情况。

Abstract Advances in the field of succession ecophysiology since the 1980s are overviewed in this paper. The microhabitats at early-succession stage are greatly different from the late ones because of erosion and vegetation modification during succession. In general, habitats are open and sunny at early-succession stage and more closed at late-succession stage. Environmental factors change faster with high temporal heterogeneity at early succession stage, but are more stable at late successional stage with high spatial heterogeneity. Water content is much lower with high temperature in early successional stands. Nutrient availability increased shortly (within several years) after the disturbances (eg. cutting, burning), then declined back with further succession. While N nutrients increase with succession in extreme oligotrophic stands or during primary succession. Different disturbances cause NH4+/NO3- ratio to change, which shows some influences on seedling shade response. Air humidity is usually very low, while air temperature and radiation with more red lights are high in early successional stands relative to late successional stands. Besides the differences in community composition, the ecophysiological attributes and adaptation of early successional plants are also different from the late successional plants. Those differences make the succession go smoothly. Contrasting to late successional plants, early successional plants share many sun-adapted characteristics, such as higher photosynthesis capacity, compensation and saturated light point, respiration, conductance and WUE relative to late ones. They also have good adaptability and high flexibility with high stress resistance and wide niches. Sunfleks and gaps play an important role in maintaining forest function and stability at late successional stages. With global climate change developing, communities in the process of secondary succession, deteriorated vegetation and early-succession ecosystems will occur more frequently on the earth.