生境梯度影响下的天然红松种群空间格局与种内关联

Spatial pattern and intraspecific association of natural Korean pine population under the influence of habitat gradient

为理清生境梯度下天然红松种群空间分布规律,以黑龙江省凉水国家级自然保护区内自坡底至坡顶的四种生境(生境Ⅰ,谷地平坡潮湿生境;生境Ⅱ,坡下缓坡潮湿生境;生境Ⅲ,坡上斜坡半湿润生境;生境Ⅳ,坡顶陡坡半干旱生境)类型中建群种红松种群为研究对象。分析不同林层(主林层、亚林层、演替层、更新层)红松种群的数量特征,并基于O⁃ring函数,在重复采样条件下评价了红松种群空间分布格局。结果表明:(1)下坡位生境(生境Ⅰ、Ⅱ)红松更新层种群数量显著大于上坡位(生境Ⅲ、Ⅳ)(P<0.05),演替层中差异不显著;自坡底至坡顶的生境梯度上,主林层和亚林层中红松株数比例增加,红松种群年龄结构结构由倒J型向J型转变。(2)下坡位原始红松林更新层和演替层中红松种群聚集规模与聚集强度均高于上坡位,坡顶(生境Ⅳ)原始红松林更新层中红松种群聚集规模与聚集强度高于坡上(生境Ⅲ)。(3)四类生境的原始红松林中主林层与更新层中红松种群总体表现为空间独立,在个别尺度上表现出微弱的空间正关联或负关联;在0—5 m尺度上,下坡位红松林原始林内演替层与主林层红松种群表现为空间负关联,而上坡位生境林分对应林层间空间关系则为空间正关联;四类生境中,亚林层与主林层中红松种群在全部研究尺度上均表现为空间独立。可以认为,造成上坡位生境的原始红松林中幼树、幼苗聚集规模与强度弱于下坡位的原因是上坡位更新与演替层中种群数量较少;而随坡位上升,更现层、演替层与主林层中红松种群间的空间关系由空间负关联向空间正关联转变是生物与非生物因子共同作用的结果。研究结果为阔叶红松林的经营管理与生态修复提供了理论依据。

In order to figure out the spatial distribution of natural Korean pine in habitat gradients,researchers study the Korean pine populations in four types of habitat(HabitatⅠ,moist valley;HabitatⅡ,humid gentle slope in the lower part;HabitatⅢ,semi⁃humid slope in the upper part;HabitatⅣ,semi⁃arid steep slope on the top)from the bottom to top of the slope hills in Liangshui National Nature Reserve in Heilongjiang Province.We analyze Korean pine population characteristics in different forest layers(main canopy layer,sub⁃canopy layer,succession layer,regeneration layer).Then with replicated sampling pattern,the spatial distribution of Korean pine population is analyzed with O⁃ring function.The following are the results.(1)The population of Korean pine in regenerative layer of downhill(HabitatⅠ,Ⅱ)is significantly larger than that in the uphill(HabitatⅢ,Ⅳ)(P<0.05),and the difference in succession layer is not significant.With the rise of slope position,the proportion of Korean pine in the main canopy layer and sub⁃canopy layer increases,and the structure of the Korean pine population changes from inverted⁃J⁃type to J⁃type.(2)The aggregation scale and density of Korean pine in the regeneration layer and succession layer of primitive Korean pine forest in downhill habitats(HabitatⅠ,Ⅱ)are larger than those in uphill habitats(HabitatⅢ,Ⅳ).The aggregation scale and density of Korean pine population in the regeneration layer of up slope(HabitatⅢ)are larger than of top slope(HabitatⅣ).(3)In all habitats,the Korean pine population in main canopy layer and regeneration layer are spatially irrelevant in general,but show weak spatially positive or negative correlations on certain scales.In downhill habitats(HabitatⅠ,Ⅱ),Korean pine population in succession layer and main canopy layer show negative correlation in the range of 0—5 m.At the same research scale,there is a positively spatial correlation between two forest layers in uphill habitats(HabitatⅢ,Ⅳ).In all habitats,spatial relationship between the Korean pine population in main canopy layer and sub⁃canopy layer is relatively weak.It can be concluded that Korean pines′fewer population in regenerative and succession layers in downhill habitats accounts for the weaker aggreation scale and density of their saplings and seedlings in uphill habitats.Influenced by both biological and abiotic factors,the spatial correlations between main canopy layer and regeneration layer as well as main canopy layer and succession layer change from negative to positive with the rise of slope position.The research results provide a theoretical basis for the management and ecological restoration of broad⁃leaved Korean pine forest.