青藏高原东缘亚高山针叶林和采伐迹地中藓类生长速率及其影响因子

 利用红油漆标记法，对青藏高原东缘地区壤塘林业局二林场亚高山采伐迹地和云杉(Picea)原始林中的6种藓类近一个生长季的生长速率进行了研究。结合原地同时进行的微气候观测，分析了气候因子和藓类生长速率之间的相关度。这6种藓类中，有5种在原始林和采伐迹地都出现，只有绢藓(Entodon conncinus)仅在采伐迹地出现。不同物种和不同生境条件下藓类的生长速率都不相同。塔藓(Hylocomium splendens)的茎生长速率最大，而阿萨姆曲尾藓(Dicranum assamicum)生长速率最小。生境对塔藓、阿萨姆曲尾藓和细叶羽藓( Thuidium lepidoziaceum)的生长速率影响很大，它们在林内比在采伐迹地生长快。锦丝藓(Actinothuidium hookeri)和垂枝藓(Rhytidiadelphus triquetrus)的生长速率中等并且对生境不敏感。据此可以将藓类分成生境敏感型和不敏感型。微气候5～7月分析显示林内比采伐迹地的辐射通量低，并且更为干燥。但是早上林内的蒸汽压亏缺（Vapor pressure deficit, VPD）一直比采伐迹地低。林内较低的蒸汽压亏缺和较低的辐射通量使其成为更有利于藓类的生长场所。对于那些生境类型不敏感的藓类，微地形的效应也许抵消了这种大生境的效应。藓类的生理生态特征如变水（Poikilohydry）特征等对其在严酷气候条件下的生存和生长起着重要的作用。如同积温一样，藓类的生长速率同样可以指示生境的适宜度，因为其生长和蒸汽压亏缺紧密相关，是温度和湿度的函数，而这两个因素对于川西亚高山地区森林人工更新时幼苗的建植极为关键。因此藓类的生长状况可以作为指示适宜植树生境的指标。

MOSS GROWTH RATE AND ITS ENVIRONMENTAL DETERMINANTS IN SUBALPINE CONIFEROUS FOREST AND CLEAR-CUT LAND IN EASTERN TIBETAN PLATEAU, CHINA

Aims Mosses constitute major ground cover of the subalpine forests in the eastern Tibetan Plateau. Moss leaves have one layer of cells and are highly sensitive to environment changes. This attribute of mosses can be used to monitor environment conditions and guide restoration. However, moss growth and especially variables affecting moss growth in subalpine forest ecosystems are poorly known. Even worldwide, the growth rate of mosses has been rarely studied because of time-consuming, inaccurate measuring methods. Methods Two plots, one in old-growth spruce forest and the other in nearby clear-cut land in subalpine western Sichuan, were selected. We labeled and measured mosses on May 7, 2001 and remeasured on August 7, 2001 and simultaneously recorded microclimate measurements. Important findings The growth rate of mosses varied among species and habitats. Hylocomium splendens had the highest growth rate, while Dicranum assamicum had the lowest. The growth of H. splendens, D. assamicum, and Thuidium lepidoziaceum was faster in forest than in clear-cut land, where it was inversely correlated with distance to forest. Actinothuidium hookeri and Rhytidiadelphus triquetrus had moderate growth rates nearly independent of habitat. From May to July, the forest almost always had lower radiation level and vapor pressure deficit (VPD) favorable for moss growth. For habitat-insensitive species, microtopographic factors might have offset the effect of habitat. Moss growth rate and habitat VPD were strongly negatively correlated. Moss growth rate can be used to suggest favorable habitat.