长白山二道白河森林流域溪流倒木调查研究

A Preliminary Study on In-stream Fallen Wood in Erdaobaihe Forested Watershed, Changbai Mountain

溪流倒木是森林生态系统对水生态系统最重要、最直观的输入和干扰之一 ,也是两系统之间的主要联结 ,对于溪流生态系统的稳定、水生生物多样性、河槽形态及其变化过程有着重要的作用。重点对长白山北坡溪流倒木现存量进行了调查和研究 ,在调查的红松阔叶林植被带内 45 0 0 m长河道内 ,共发现溪流倒木 42 5株 ,分属于 1 7个树种 ;其中 、 级腐烂占相当大的比重 ,与林地倒木 、 级腐烂占优有所不同 ,其原因可能与分解环境的不同有关。所有溪流倒木的总材积为 77.98m3,故溪流倒木的现存量为 1 .73 3 m3/1 0 0 m和 1 0 .83 m3/hm2 。溪流倒木的树种组成和不同树种的材积与河岸带植被密切相关 ,但存在差异。研究表明林分形成倒木并进入河流在时间上可能是均匀或随机的 ,但不同树种间 ,其形成倒木并进入河流时的树木材积或生长年龄存在较大差异。溪流倒木和林地活立木的个体数量的径级分布基本上为反 J型 ,而它们材积的径级分布均为典型的

Fallen wood is an important ecological component in many terrestrial and aquatic ecosystems, and in forest ecosystems, fallen wood has many crucial ecological functions such as habitat for organisms, a site for nitrogen fixation, energy flow, and nutrient cycling. So, study on fallen wood is an important aspect in traditional forest ecology. While fallen wood in forest ecosystems, especially in riparian forests, turns into stream ecosystems because of natural power or human power, it is turned into in stream fallen wood. In stream fallen wood is one of the most important and intuitionistic input and disturbance of terrestrial ecosystems on stream ecosystems, and it is a major connection between terrestrial ecosystems and stream ecosystems. In stream fallen wood also plays an important role in stabilization of stream ecosystem, aquatic biology diversity, and channel morphology and its change process. In this study, species, base diameter, top diameter, height and decay class of each fallen wood were investigated in Erdaobaihe River passing through the broadleaved and Korean pine forest located at an elevation of 800~900m above sea level on the north slope of Changbai Mountain. The investigated river channel is located from 128°05′39″E, 42°20′55″N to 128°05′23″E, 42°19′52″N, and the length is about 4500m. The riparian forest was also examined by setting a 32m×24m quadrat at an elevation of 850m. 17 species and 425 logs of fallen wood were found in the investigated river channel, and their total volume was 77 98m 3. So, present value for volume of fallen wood was 1 733 m 3/100m or 10 83m 3/hm 2. Fallen wood in decay class Ⅱ and Ⅲ accounted for 78% of total logs and 81% of total volumes, and it was different from that of fallen wood in forest. The possible reason may be different decomposing condition. Average volumes per log of all fallen wood in different decay classes were similar, and it implied that in stream fallen wood farmed in different stage had no obvious difference in average volumes per log. On the other hand, average volumes per log of all fallen wood of different tree species were different from 0.01013 m 3 to 0.7461 m 3, and it implied that, while in stream fallen wood being formed, their volumes or age of living tree had significant difference in different tree species. Among all the tree species of fallen wood, there were 4 coniferous tree species, and the coniferous tree species accounted for 42% of total logs and 50% of total volumes. It was correlative to status of the riparian forest closely, but there also existed difference. Analyzing the difference combined with studying distribution of fallen wood of different tree species in different diameter classes and decay classes could be useful to study dynamic of riparian forest in former and recent stage. Quantities of logs of fallen wood in stream and living tree in riparian forest declined as diameter increased, and it was in a reverse J shaped distribution. But number of in stream fallen wood in the first diameter class was the least, and there were two possible reasons. First, velocity of water flow was high (1.5～2m/s) and most fallen wood with litter diameter were scoured away. Second, wind was the most important natural power causing fallen wood in the studying region, especially in open land such as riparian, and usually, living tree with certain diameter would fell easily by wind. Volumes of fallen wood in stream and living tree in riparian forest increased as diameter increased, and it was in a typical J shaped distribution.