地形对温带密林下灌草层地上生物量分异的影响——以东北虎豹国家公园为例

Impacts of topography on spatial variability of temperateunderstory biomass in closed forest: a case study ofNortheast China Tiger and Leopard National Park

为探讨地形对林下灌草层植物生物量的影响,该研究采用嵌套设计法在东北虎豹国家公园调查了138个密林下样地共1685个植物样方,通过嵌套方差分析与有序逻辑斯蒂回归模型对林下灌草层植物生物量受地形的影响进行了分析。结果表明:(1)不同坡位之间,谷底的灌草层植物生物量高于坡上,坡上高于坡下(P<0.01);不同坡向之间,阴坡灌草层植物生物量低于阳坡及平地(P<0.01),后二者间无显著差异;不同坡度之间,平坡灌草层植物生物量高于陡坡,陡坡高于缓坡(P<0.01)。(2)坡位与坡向的交互作用显著,坡下平地、坡上平地、坡上阳坡与谷底的所有坡位灌草层植物生物量最高,坡下阴坡、坡下阳坡及坡上阴坡之间无显著差异。(3)研究区现行状态下,有序逻辑斯蒂回归结果显示,灌草层植物生物量在不同海拔、坡位及坡向坡度组合下不同。坡位、坡向及坡度对林下灌草层植物生物量有显著影响,3个坡位等级间谷底最高而坡下最低,3个坡度等级间陡坡最高而缓坡最低,不同坡向比较,阴坡最低。(4)在不排除人为干扰、森林放牧的现实情况下,谷底、陡坡地带灌草层植物生物量概率最高。该研究结果可为准确估计东北虎豹国家公园林下灌草层植物对虎豹猎物种群的承载力提供重要参考,从而为濒危虎豹的保护和管理提供科学依据。

To investigate the impact of topography on understory biomass,this study employed a nested design and conducted surveys in the Northeast China Tiger and Leopard National Park,involving a total of 138 plots within closed forests,comprising 1685 plant quadrats.The analysis of topographical effect on understory biomass was carried out using nested analysis of variance and an ordinal logistic regression model.The results were as follows:(1)Among different slope positions,the understory biomass in valleys was higher than on upper slopes,and the footslopes where the understory biomass was the lowest(P<0.01).The understory biomass on shady slopes was lower than on sunny slopes and flats(P<0.01),with no significant difference between the latter two.In terms of different slopes,the understory biomass on steep slopes was higher than on flats,and flats had higher biomass than gentle slopes(P<0.01).(2)There was a significant interaction between slope position and slope aspect.The understory biomass was the highest on flats at the footslopes,flats on upper slopes,upper slopes and sunny slopes,and in valleys among all slope positions.There was no significant difference in understory biomass among shady slopes at the footslopes,sunny slopes at the footslopes,and shady slopes on upper slopes.(3)Ordinal logistic regression analysis of the current state of the study area showed that the probability of high or low understory biomass varied across different combinations of altitude,slope position,and slope aspect.Slope position,slope aspect,and slope had significant effects on the understory biomass.Among the three slope positions,the understory biomass was the highest in valleys and the lowest on footslopes.Among the three slopes,steep slopes had the highest understory biomass,while gentle slopes had the lowest.Shady slopes had the lowest understory biomass compared to other slope aspects.(4)Considering the realistic situation of human disturbance and forest grazing,steep slope areas in valleys had the highest probability of high understory biomass.This study can provide important references for accurately estimating the carrying capacity of understory for preys populations of tiger and leopard in Northeast China Tiger and Leopard National Park,thereby offering a scientific basis for the conservation and management of endangered tigers and leopards.