基于LANDIS-II的陕西黄龙山森林景观演变动态模拟

应用空间直观景观模型LANDIS-II模拟了陕西黄龙山森林景观在不考虑风、火、病虫害及采伐等干扰因素前提下300a(2004—2304年)的自然演替进行动态,采用景观格局统计软件APACK计算了林区内优势树种所占的面积百分比以及反映物种分布格局的聚集度指数,分析了各个树种在模拟的时间尺度上龄级组成的变化趋势。结果表明:油松是针叶树中的优势种,辽东栎是阔叶树中的优势种;在演替后期油松取代辽东栎成为所占面积比例最大的优势树种;油松和辽东栎的相对聚集度较其它几类树种小;随着模拟年代的推进,树种年龄结构发生显著变化,呈现出复杂多样的异龄林空间分布格局。

Simulation of forest landscape dynamic change based on LANDIS-II in Huanglongshan, Shaanxi Province

LANDIS-II is a spatially explicit landscape model developed by University of Wisconsin at Madison, including extension modules such as succession, disturbance, seed propagation, forest management, carbon dynamics and climate change. LANDIS-II regards landscape as grids which are composed of interactional pixels. Each pixel records information of dominant tree species and ages at ten-year interval. All pixels belong to different land types. Each land type has the same species establishment coefficient, fire cycle period, fuel accumulation rate and decomposition rate. In each pixel, species, age composition of species, history of interference and fuel accumulation interact with species group, succession, seed propagation, wind and fire disturbance and cutting. LANDIS-II model simulates the forest landscape''s dynamic change at large space and long term scales through tracking information of the survival and ages of the species on the site. Huanglongshan forests located in the southeast of loess plateau in northern shaanxi, between the Yellow River and the Luohe River, has unique geographical location and cultural and historical atmosphere. It also has the most dense forest and most abundant wildlife resources. Huanglongshan forests are the main ecological barrier that protects the south of loess plateau and the central Shaanxi Plain, and also the key region of the national ecological environment construction plan. Therefore, Huanglongshan forests have important social and ecological value. It is too difficult to observe the dynamic change of forest landscape at large space and long term scales using the traditional field observation method. Recently, with increasing ability of the computer simulation, using the model to simulate the landscape dynamic change becomes a very popular way throughout the world. In this paper, a spatially explicit landscape model LANDIS-II was applied to simulate the dynamic natural succession of forests without considering the disturbance such as wind, fire, harvest, diseases and insect pests in Huanglongshan, Shanxi within 300 years (2004-2304). The landscape statistical software package APACK was used to calculate the area percentage of dominant tree species and the aggregation index reflecting the spatial patterns of species. Variation tendency of all species'' age-classes during simulation time were analyzed. The result showed that Pinus tabulaeformis was the dominant species of coniferous trees and Quercus liaotungensis was the dominant species of deciduous trees. During the late succession stage, Pinus tabulaeformis replaced Quercus liaotungensis becoming the largest areal proportion of dominant tree species. The aggregation index of Pinus tabulaeformis and Quercus liaotungensis were lower than the other species. Species'' age structure changed significantly with the progress of succession, and presented a complex and various spatial distribution patterns of uneven-aged forests. The simulating of the natural succession of Huanglongshan forests at large space and long term scales, could provide a scientific basis for rational allocation of forest resources and forest management.