【摘要】 农业景观中 ,山体是被广阔农田包围的生境岛屿 ,是生物多样性保护的重点地段。存在人类干扰时 ,决定山体植物多样性的主要因素不是面积、年龄和隔离程度 ,而是地形和土地利用。在这种情况下 ,从岛屿生物地理学的观点来理解生物多样性的分布规律是不合适的 ,因此本文采用直接对比分析方法对此进行说明。选择环渤海地区河北省遵化市 (39°5 5′～ 40°2 2′N ,117°34′～ 118°14′E)境内的 10个山体 ,从山顶到山底沿坡面设置样带。记录不同坡位的土地利用类型及宽度 ,分层调查各个土地利用类型的乔木层、灌木层和草本层物种丰富度 ,统计各样带上每个土地利用类型的物种数目 ,采用Jaccard指数计算相似性 ,比较研究不同地形和土地利用对植物多样性的影响。结果表明 :1)不同山体的植物多样性存在较大差别。各山体物种垂直分布大致呈现从下至上减少的规律 ,草本层都是物种丰富度的主要来源。不过 ,物种相似性比较高的山体之间 ,地形条件和土地利用组合不同。 2 )地形和土地利用分别影响山体的植物多样性。 3)土地利用与地形存在很大相关性 ,并共同决定了山体的植物多样性。山体植物多样性分布是物种按自然地形分布复合土地利用影响的结果。以上结果说明 ,不进行农业土地利用能够最好地保护植物多样性 ;但在?更多还原

【Abstract】 Mountains in rural landscapes are habitat islands surrounded by large areas of farmland. These are the important sites in regional biological conservation. However, area, age and isolation of the habitat islands are not the dominant factors of their plant diversity pattern when human disturbances exist, where the main influences are from topography and land use. Under this circumstance, the regularity of plant diversity distribution could not be well understood from the point of view of island biogeography, hence we turn to address this issue by direct comparison. This study was conducted in Zunhua city (39°55′-40°22′ N, 117°34′-118°14′ E) of Hebei province in the Bohai Bay region. Ten mountains in the region were chosen for setting up transects on slopes from the top to the foot. The width of each land use type was measured, and the corresponding slope position, degree and exposure were recorded. Species richness of tree, shrub and herb layers of each land use type was investigated, similarities between mountains and between land use types were shown using Jaccard similarity index in comparisons with different influences of topographical factors and land use types on plant diversity. 1) Plant diversity of mountains is quite different. The vertical distribution of species richness approximately declines from the top to the foot on all transects, and herb layer richness is always the main source of the total. However, mountains with high species similarities are still different in topographical settings and land use types. 2) Topography and land use have different influences on plant diversity patterns. 3) Land use types are highly correlated with topographical factors in the study area, and they codetermined the distribution of plant diversity of mountains. A plant diversity pattern of a mountain is the result of species distribution according to topographical settings as well as the alteration of land uses. The results imply that plant diversity would be best preserved if all agricultural land uses were prohibited, however land uses accordant with topography is an appropriate way for biological diversity conservation where land uses must exist. A land use structure beneficial to biological conservation of mountains in the study area was put forward based on the above results.更多还原