攀枝花市生物多样性与生物资源可持续性分析

Studies of the Biodiversity and the Sustainability of Biotic Resources in Panzhihua,Sichuan,P.R.C.

攀枝花市地处川西南山地 ,地形、地貌十分复杂 ,气候、土壤条件多样 ,为生物的生存提供了丰富多样的适宜条件 ,研究表明 :(1)生物物种丰富多样 ,植物区系地理成分复杂 ,且植物的旱生性明显。 (2 )在森林中各类型多样性指数较大的从大到小依次是云南松、云南松与阔叶林混交林、栓皮栎和柞栎林、多变石栎和硬斗石栎林、桤木林等 ;草地的多样性指数表明 ,山地疏林草地、山地灌木草地多样性较大。 (3)景观镶嵌体结构发生很大变化 :自然植被面积减少 ,次生植被扩展 ;干热河谷稀树灌草丛类型上升 10 0米～ 2 0 0米 ;森林面积不断减小 ,结构日趋简单化 ;草地也因过牧不断退化 ;栖息地发生重大改变后 ,动物资源也大受影响 ,分布区减小 ,种群数量减少。森林的多样性指数最大 ,其次依次为草地和栽培植物种群 ;景观的碎裂化程度不断增高。(4)以森林资源、草地资源、珍稀生物资源 (主要讨论珍稀植物资源 )和栽培植物种群为生物资源包含的主要内容 ,以景观的稳定性、多样性、碎裂化程度和各景观元素的优势度为生物资源可持续性的评价指标 ,评价结果表明 ,一是森林资源和草地资源的持续利用程度均较差 ,二是多样性和碎裂化对生物资源可持续性的影响尤为显著 ,景观的碎裂化问题相当严重。因此 ,应加强生态环境建设 ,重?

Panzhihua is situated in the mountainous region in southwestern Sichuan,with geographical complexities,striking vertical differences,and natural diversities of climate and soil condition,the diversified and complicated eco environment provides an optimum condition for the existence of species.The results of researches have shown that: (1)Species are highly abundant and various with complicated flora composition and obvious plant xerophily. (2)The orders of forests diversity indexes,from high to low,are Yunnan pine forests,mixed coniferous(Yunnan pine)and broadleaf forests,Oriental oak and Diamyo oak forests,glabrous tanoak forests,longpenduncled alder forests,etc.,but the diversity index of Yunnan pine forests is higher than others.So Yunnan pine is a dominant species in Panzhihua.The diversity indexes of mountain open crop grassland and mountain shrubby grassland are higher than others,and the diversity indexes of mountain hassock grassland and mountain meadow grassland are lower,so the high quality pasture has become scarce in this area. (3)The inlaying relationships of mosaics are changed largely,consequently,the area of natural vegetation is decreased,original vegetation is backward to alpine areas or steep and remote places,the secondary vegetation is expanded,the upper line of dry hot valleyhas raised 100～200 m,and the broadleaf forests are flinched and replaced by coniferous forests,shrub woods and scrub grasslands.The internal structure of mosaic has changed obviously in a few decades,leading to the simplified structure of stand with tall tree decreasing and shrubs and herbs increasing,and to the degraded quality of grassland with over grazing.Moreover,the mosaic diversity and the fragmentation degree of landscape are continuously increased.So the habitats of animal are destroyed heavily,resulting in reducing the distributing area and quanbities of animal species. (4)For an analysis on sustainable use of biotic resources,the biotic resources may be divided into 4 aspects,including forest,grassland,cropping population and rare biotic resources by calculating the indexes of stability,diversity,fragmentation and dominance,the sustainable use degrees of forest,grassland,cropping population and rate biotic resources are 0.2366,0.2340, 0.2897 and 0.2658 respectively,that of forest and grassland are fewer.The influence degrees of mosaic stability index,diversity index,dominance index and landscape fragmentation index on the sustainable use of biotical resource is 0.2520,0.2856,0.2810 and 0.2474 separately,that of mosaic diversity and landscape fragmentation is higher,so landscape is fragmentized seriously.