Larch caterpillar (Dendrolimus superans) is very common in the Da Hinggan Mountains, Northeast China, affecting fire regime and forest ecosystem change at large spatio-temporal scales. In this study, we used a spatially explicit landscape model, LANDIS, to simulate the changes of fire regime and forest landscape under four larch caterpillar disturbance intensity levels scenarios in Huzhong forest area, northern of Da Hinggan Mountains. The results indicate that larch caterpillar disturbances would decrease fine fuel load and increase coarse fuel load in the 300 simulation years. Larch caterpillar disturbances would decrease fire frequency in the first 200 years, and the disturbances also decrease fire intensity and fire risk in the early and late stage of simulation. Larch caterpillar disturbances would decrease the area percent of larch cohorts and increase the proportion of white birch, and increase the degree of aggregation of white birch as a result of its strong seed dispersal and colonization ability. Disturbances would also decrease the mature and over-mature larch cohorts and increase all cohorts of white birch, especially the mature and over-mature cohorts. Larch caterpillar disturbances will decrease the stability of forest landscape, therefore,some measures preventing in- sect outbreak and ensuring the sustainable management of forest ecosystem should been taken in the study area.
CHEN Hongwei HU Yuanman CHANG Yu BU Rencang LI Yuehui LIU Miao
The anthropogenic managements of forest have created a network of roads resulting in the loss and alternation of habitat. To better understand road′s impact on animal habitats, we assessed the habitat pattern of sables(Martes zibellina), one of rodents within national first-class protected species, when roads are considered in Huzhong area in Da Hinggan Mountains, northeastern China. Employing published literatures about behavior ecology, aerial photographs and forest stand maps, we classified the study area into three habitat types including best-suitable, suitable and unsuitable habitats based on sable habitat requirements at the landscape scale including four variables derived from forest source map with attribute database. Results indicated the loss and significant fragmentation of best-suitable habitat and home range habitat when roads, especially 150 m avoidance distance of roads, were considered. The roads reduced and fragmented highly suitable habitats more significantly during earlier development period than the later development period. Additionally, the suitable area percentage increased with increasing distance to roads. This study helped to identify the suitable area for sables and location of sable population. Also, this study suggested the passage construction and road management involving road closure and removal will reduce the fragmentation functionally and benefit the sable population.
LI YuehuiWU WenXIONG ZaipingHU YuanmanCHANG YuXIAO Duning
Forest management such as timber harvesting shapes fire regimes and landscape patterns, and these patterns often differ significantly from those under natural disturbances. Our objective was to examine the effects of timber harvesting modes on fire regimes and landscape patterns in a boreal forest of Northeast China. We used a spatially explicit landscape model, LANDIS, to simulate the changes of forest landscape in the Huzhong forest region of the Great Khingan Mountains under no-cutting, clear-cutting, gradual-cutting and selective-cutting modes. Results showed that:(1) the fine fuel loadings generally decreased while the coarse fuel loadings increased with the increase of timber harvesting intensity;(2) the potential burn area significantly varied among different cutting modes, but the potential fire frequency had no obvious difference. Moreover, timber harvesting generally increased the potential fire risk;(3) clear-cutting mode significantly decreased the mean patch size and the aggregation of larch forests and increased the mean patch size and the aggregation of white birch forests. Therefore, clear-cutting mode should be abandoned, and selective-cutting mode be recommended for the sustainable forest management in the Great Khingan Mountains.
