Spatial pattern of the trees in a natural Pinus tabulaeformis forest in Taiyue Mountain
Spatial pattern of the trees in a natural Pinus tabulaeformis forest in Taiyue Mountain
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作者：
Xiuhai Zhao
油松是我国北方分布最广的温带针叶林群落中的优势树种，该树种耐低温、耐干旱、耐贫瘠的土壤养分状况，也是我国北方大部地区造林的重要树种之一。山西省太岳林区以油松闻名，素有“油松之乡”之称。长期以来，有利于造林不受干扰，马池北地区的森林形成了独特的天然油松极顶群落。为研究其群落空间分布格局，2007年7月在太岳林区灵空山林场马池北地区建立了400m2（20m×20m）天然油松样地。样地内所有树木胸径（DBH）为1cm以上的树木进行树种标记、测绘、测量和鉴定。测量值包括胸径、树高、两个树冠直径（东西向和南北向）和最低活枝的高度。利用分散系数（C）、平均拥挤指数（m*）、斑块指数（m*/m）和Morisita指数四个指标评价样地树木的空间分布格局。 (Iδ),通过改变采样尺度和直径范围对油松空间格局的敏感性进行研究,重点研究油松优势树、倒立树和死立树的空间格局,并利用这4个指标对辽东栎等阔叶树的空间格局进行评价。样地共记录胸径≥1cm的树木3561株,其中35株其中，油松 2583 株（活体 2482 株，死立 101 株）；油松主要伴生树种辽东栎 319 株，占总数的 72.50%；其余 33 种树种合计占总数的 18.4%，所占比例均不超过 4%。油松位于中上层，除油松外，其他乔木仅占树高≥10m的乔木总数的4%；下层由10m以下乔木和灌木组成。样地内油松胸径分布呈单峰分布，在直径28—36cm范围内出现最大频率。油松呈丛生状。 3个不同采样尺度(5m×5m、10m×10m、20m×20m)的空间分布。尺度变化对空间聚集程度没有明显影响。但最大的油松(d44cm)呈随机分布。因此,在油松发育过程中,空间格局逐渐由丛生向随机转变。油松的优势树、倒立树和死立树为辽东栎等阔叶树均呈丛生分布。
Pinus tabulaeformis is the dominant species in the most widely distributed temperate coniferous forest community in northern China.The species is resistant to low temperatures,dry conditions and poor soil nutrient status.It is also one of the most important tree species for afforestation in large parts of northern China.Taiyue Forest Area is famous for its Pinus tabulaeformis in Shanxi Province,where it is known as the "township of Pinus tabulaeformis".Since the closing of the hillsides to facilitate afforestation without disturbance for a long time the forest in Ma Chibei area formed a unique natural Pinus tabulaeformis climax community.In order to study the community spatial distribution pattern,a 400m2 (20m×20m) plot of natural Pinus tabulaeformis was established in the Ma Chibei area on the Ling Kongshan Forest Farm of the Taiyue Forest Area in July 2007.All trees in the plot with a diameter at breast height (DBH) of 1cm or more were tagged,mapped,measured and identified as to their species.The measurements included the DBH,total tree height,two crown diameters (East-Westerly and North-Southerly direction) and height to the lowest live branch.The spatial distribution pattern of the trees in the plot was evaluated using four indices:the Coefficient of Dispersion (C),the Index of Mean Crowding (m*),the Index of Patchiness (m*/m) and Morisita's Index (Iδ),The study focused on the sensitivity of the spatial pattern of Pinus tabulaeformis by changing the sampling scale and diameter range,and on the spatial pattern of the dominant,the overtopped and the dead standing trees of Pinus tabulaeformis.In addition,the spatial patterns of Quercus liaotungensis and other broad-leaved trees were evaluated using the four indexes.A total of 3561 trees with a DBH ≥ 1cm were recorded in the plot,which includes 35 species,of which 2583 individuals or 72.50 percent were Pinus tabulaeformis (2482 live and 101 dead standing);319 were Quercus liaotungensis,the main associated tree species of Pinus tabulaeformis.The other 33 tree species together made up 18.4 percent of the total number,none of them was represented by more than 4 percent.In the structure composition of storey,Pinus tabulaeformis lies in upper-middle level,all other trees except Pinus tabulaeformis only account for 4 percent of the total number of the trees with a height ≥ 10m;Lower level storey is made of trees less than 10m and shrubs.The DBH distribution of Pinus tabulaeformis in the plot is unimodal and shows a maximum frquency in the diameter range 28—36cm.Pinus tabulaeformis shows a clumped spatial distribution at three different sampling scales (5m×5m,10m×10m,20 m×20m).The change of scale had no obvious effect on the degree of spatial aggregation.However,the biggest Pinus tabulaeformis (d44cm) were randomly distributed.Thus,during the development of Pinus tabulaeformis,the spatial pattern gradually changed from clumped to random.The dominant,the overtopped and the dead standing trees of Pinus tabulaeformis as well as Quercus liaotungensis and other broad-leaved trees all showed a clumped distribution.