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    大兴安岭森林景观在不同火干扰及人工更新下的演替动态

    Spatial simulation of forest succession under different fire disturbances and planting strategies in northern slopes of Great Xing'anling Mountains

    • 摘要: 该文应用LANDIS模拟大兴安岭图强林业局森林景观1987年特大火灾后,在不同的火干扰条件(不模拟火、火烧轮回期为150年和325年)和不同人工更新方式(完全自然更新、种植落叶松和种植樟子松),3×3种(共9种)模拟方案下300年的动态变化.研究结果表明:火烧轮回期为150年条件下的火烧明显比火烧轮回期为325年方案下的火烧频繁,总的过火面积也多,但前者以轻度火为主,后者以重度火为主.而人工更新下(无论是种植落叶松还是种植樟子松)过火面积要高于自然更新下的过火面积.造林树种的不同对火也有较大的影响,种植樟子松方案下的过火面积相对较大.不同火干扰条件不仅会影响森林主要物种组成面积,而且还会造成其年龄结构的巨大差异.一般而言,火烧轮回期长有利于低耐火性物种,火烧轮回期短有利于高耐火性物种.但如果物种具有很强的种子扩散和定居更新能力,无论该物种的耐火性高还是低,火烧轮回期短则更利于该物种的生存,但幼龄林所占的比重较大.不同的种植更新方案对于森林物种有显著的影响,可以明显地增加所种植的物种在该区所占的比例.

       

      Abstract: The study tries to simulate forest dynamics over 300 years in Tuqiang Forest Bureau of the northern slopes of Great Xing'anling Mountains,which was damaged by a catastrophic fire in 1987. Nine scenarios were run by the LANDIS model under three fire conditions (no fire simulating, fire return interval of 150 years and fire return interval of 325 years) and three planting strategies(no planting; Larix gmelini planting and Pinus sylvestris var. mongolica planting). The authors examined the effects of each scenario on fire dynamics and area percentage, and age class of species. The results showed that the fire regime was characterized by higher frequency, lower intensity and larger burned areas at the fire return interval of 150 years than at fire return interval of 325 years. In addition, more burned areas were under reforestation than natural regeneration. Because of lower fire tolerance of P. sylvestris var. mongolica than L. gmelini, more forest stands were burned under the scenario planting P. sylvestris var. mongolica. Different fire return intervals can change the area percentage of the species, and have great effects on the species age class. Responses of most species to the changing fire return intervals were predictable based on their fire tolerance parameters, with fire-tolerant species most abundant in landscapes with frequent fire at short fire return interval, and fire-sensitive species most prevalent in landscapes with less fire at long fire return interval. But if the species have an ability to disperse seeds well and can successfully root in these disturbance-created openings, they would increase more quickly and the stand age was tended to be younger at short fire return interval than at long fire return interval. Planting strategies have great influence on species, especially those to be planted. The area percentage of P. sylvestris var. mongolica could not reach the prefire level in 1987 under natural regeneration. If we want to restore the area percentage of P. sylvestris var. mongolica to the prefire level in 1987, the strategies to plant this species is required.

       

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