秦巴山地典型垂直带带幅变化分析

Variation Analysis of the Typical Altitudinal Belt Width in the Qinling-Daba Mountains

秦巴山地是我国典型的地理—生态过渡带,呈现出高度的复杂性、多样性、过渡性和敏感性。本文基于秦巴山区野外调查样方数据和收集的典型山地垂直带谱数据,从带幅的角度比较秦巴山地典型垂直带的多维变化和分异。结果表明:1)纬向上自北向南,落叶阔叶林带幅从2200 m逐渐减小至100 m,在唐家河地区消失;常绿落叶阔叶混交林带、针阔混交林带带幅呈线性增加趋势;针叶林带带幅从300 m增加到550~900 m。2)经向上自西向东,沿山脉走向,典型山地常绿阔叶林带幅从400 m增加至600 m,常绿落叶阔叶混交林带带幅从500 m增加至800 m,东部针阔混交林带比西部宽约100 m;落叶阔叶林带在秦巴山区中部较宽、东西较窄,而针叶林带则与之相反。3)坡向方面,大巴山对带幅的坡向分异作用比秦岭更加明显;就单独山体而言,南坡常绿落叶阔叶混交林带和针叶林带带幅通常比北坡更宽,而落叶阔叶林带在南坡更窄,针阔混交林带在秦岭南坡和大巴山北坡拥有比另一侧更宽的带幅,内外相差200~300 m。4)垂直带带幅是多种因素综合作用的结果,其中区域气候决定了基带的性质和垂直带谱的基本序列,山体基面高度对带幅有向上的挤压作用,山体相对高度决定了带幅发育的潜在空间分布范围。秦巴山地典型垂直带带幅的多维分异很好地体现了中国南北过渡带的过渡性和复杂性,研究结果可为秦巴山地自然保护区的植被垂直保护提供科学依据。

The Qinling-Daba Mountains have been the most important geo-ecological transition zone in China,with a high degree of environmental complexity,biodiversity,and climate sensitivity.Based on the field survey quadrat data and the collected data of typical mountain altitudinal belts in the Qinling-Daba Mountains,the multi-dimensional variation and differentiation of typical mountain altitudinal belts were compared from the perspective of belt width.The results showed that:(1)From north to south,the width of the deciduous broadleaved forest belt gradually decreased from 2200 m to 100 m,and disappeared in the Tangjiahe area.The evergreen and deciduous broad-leaved mixed forest belt and the coniferous and broad-leaved mixed forest belt showed a nearly linear increase trend.The coniferous forest belt width increased from 300 m to 550~900 m.(2)From west to east,along the slope of the mountains,the width of the evergreen broad-leaved forest belt increased from 400 m to 600 m.The width of the evergreen and deciduous broad-leaved mixed forest belt increased from 500 m to 800 m.The eastern coniferous and broad-leaved mixed forest belt was about 100m wider than the western one.The deciduous broad-leaved forest belt was wider in the middle of the Qinling-Daba Mountains and narrower in the east and west,while the coniferous forest belt was the opposite.(3)The aspect differentiation effect of Daba Mountains on the belt width was more obvious than that of Qinling Mountains.In terms of individual mountains,the belt width of evergreen deciduous broad-leaved mixed forest and coniferous forest on the southern slope was usually wider than that on the northern slope,while the deciduous broad-leaved forest belt was narrower on the southern slope.The coniferous and broad-leaved mixed forest belt had a wider width on the southern slope of Qinling Mountains and the northern slope of Daba Mountains than on the other side with a difference of 200~300 m.(4)The width of typical altitudinal belts was the result of the combined action of many factors.Regional climate determined the nature of the baseband and the basic sequence of the altitudinal belt spectrum.The mountain base elevation had an upward extrusion effect on the belt width,and the relative height of the mountain determined the potential spatial distribution range of the altitudinal belt spectrum.The multi-dimensional differentiation of the width of typical altitudinal belts in Qinling-Daba Mts.reflected the transition and complexity of China's north-south transitional zone,which can provide a scientific basis for the vertical protection of vegetation in nature reserves.