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火是天然樟子松重要的生态因子,地表火对樟子松林乔木层空间格局的变化有着特殊的意义。全林木定位法调查记录了地表火干扰1年后1hm2典型样地中存活及火烧死乔木的位置坐标,利用成对相关函数g(r)进行空间点格局分析。结果表明:1)单变量空间格局分析显示,空间异质性泊松点过程零假设下,地表火干扰前所有立木、樟子松和白桦均在小尺度上呈显著性聚集分布;而地表火干扰后,樟子松林分及其乔木层不同组分的空间格局更加趋向于均匀分布,只有白桦在小尺度上仍表现为显著性聚集分布,所有立木和樟子松主要以随机分布为主。乔木层及其不同组分的随机标识零假设均不成立,火后存活的所有立木在小尺度上为均匀分布,而较大尺度上却呈现出聚集分布;火后存活的樟子松在小尺度上表现为聚集分布,而较大尺度上却呈现均匀分布;火后存活的白桦主要表现为小尺度上的聚集分布。2)双变量空间格局分析表明,所有立木、樟子松和白桦的存活立木与火烧死木之间均是相互独立的,其相互间的空间格局表现为随机分布。地表火烧死木(包括所有立木、樟子松和白桦)均在小尺度上表现为显著的正相关呈聚集分布,而较大尺度上不同程度地表现为显著的负相关为均匀分布。因此,地表火干扰下,林木的死亡过程并不是随机的,存活林木的空间格局趋于均匀分布,地表火驱动下的樟子松林自然稀疏过程削弱了存活个体间的竞争,促进了林分结构的优化和个体的生长发育,成为樟子松林演替中较活跃的生态因子。
Fire is an important ecological factor of natural Pinus sylvestris var. Mongolica. Surface fire has special significance on the spatial pattern of tree layer in Pinus sylvestris var. Mongolica. The survey of the whole forest location method recorded the position coordinates of the surviving and burning trees in typical 1hm2 plots 1 year after surface fire disturbance, and analyzed the spatial pattern using the pairwise correlation function g (r). The results show that: 1) Univariate spatial pattern analysis shows that under the null hypothesis of the Poisson point process of spatial heterogeneity, all stands of Pinus densiflora, Pinus sylvestris var. Mongolica and Betula platyphylla are significantly aggregated and distributed on the small scale before surface fire disturbance; After disturbance, the spatial distribution of different components of Pinus sylvestris var. Mongolica and its arbor layer tended to be even distribution, only the Betula platyphylla showed a significant aggregation distribution on a small scale, and all Pinus sylvestris and Pinus sylvestris mainly distributed randomly. The null hypothesis of stochastic identification of the arbor and its different components did not hold. All the stumps that survived the fire were uniformly distributed on a small scale, but clustered on a larger scale. After the fire, Pinus sylvestris survived on a small scale On the larger scale, the distribution was uniform, while the birch survived after fire was mainly distributed on a small scale. 2) The analysis of the bivariate spatial pattern shows that the stand trees and burned dead woods of all L. stand, Pinus sylvestris var. Mongolica and Betula platyphylla are independent, and their spatial distribution is random distribution. The surface burned dead wood (including all standing trees, Pinus sylvestris var. Mongolica and Betula platyphylla) showed a significant positive correlation at small scales, whereas the larger scales showed significant negative correlations at different scales. Therefore, under the surface fire disturbance, the death process of forest trees is not random, and the spatial distribution of surviving forest trees tends to be evenly distributed. The natural sparseness of Pinus sylvestris var.Mongolica forest driven by surface fires weakens the competition among surviving individuals and promotes the stand structure Optimization and individual growth and development, becoming the more active ecological factor in the succession of Pinus sylvestris var. Mongolica.