人类休闲活动对森林鸟类群落无有害影响

我们对西班牙马德里森林深处(未受到人类干扰)、森林小路沿线(间或有徒步旅行者经过)以及森林野餐区(有较持久干扰)的鸟类进行了调查,以查明人类休闲活动对该地区鸟类群落的分布和多度的影响.结合样方法对以上3类区域鸟类群落的总体特征(如:鸟类的多度、物种的丰富度和多样性)、不同鸟类群体的特征(如:鸦科鸟类的多度,营巢或者取食集团的特征)、各鸟种的多度等参数进行了比较.结果表明:小路沿线和野餐区样方内鸟类的多度和物种丰富度比森林深处更高,已查明14种鸟类的多度在人为干扰区域比森林深处高,只有5种鸟类的多度在森林深处更高一些;在树冠层筑巢的鸟类、在树干和地面觅食的鸟类及鸦科鸟类在休闲活动区有更高的多度;地巢性鸟类在休闲区的多度较低,这种差别尤以阔叶落叶林中加明显.而森林小路的鸟类群落结构与森林内部非常相似,说明人类休闲活动对这些林区鸟类群落的影响更多缘自野餐.原因是野餐区常常具有以下特点:具有高大的乔木、中层植被稀疏、有较多的洞和缝隙以及野餐后会遗留下一些垃圾.以上结论与研究的预期目标正好相反,人类的这些休闲活动可能会降低地巢性鸟类的适宜度,但是对大多数鸟的类栖息地没有不利影响.

Impact of recreation on forest bird communities: non-detrimental effects of trails and picnic areas

We analyzed changes in distribution and abundance of forest birds due to different types of recreational activity in the Madrid province (Guadarrama Range, Central Spain). Census plots were distributed in forest interiors (undisturbed sites), along forest trails (transiently disturbed hiking tracks), and in recreational areas (long-lasting disturbed picnic sites). Parameters describing the overall bird community (I.e.total bird abundance, species richness and diversity), groups of species (I.e. Abundance of corvids and nesting or foraging guilds) and individual species abundances were compared. Forest sites with any type of human presence (trails and picnic sites pooled) had higher overall abundances and species richness per sampling plot than undisturbed forest interiors. Furthermore, fourteen species were significantly more abundant in disturbed sites than in forest interiors, while the converse was true only for five species. Anthropogenic sites did not affect forest specialists. Canopy-nesters, trunk and ground-foragers, and corvids were more abundant at recreational sites than in undisturbed forests, while the converse pattern was observed for ground-nesters. These patterns were more distinct in deciduous than in coniferous forest tracts. The positive effects of recreational sites were mostly associated with picnic sites, since forest trails were mostly indistinguishable from undisturbed forest interiors in terms of bird community patterns. Several habitat characteristics of disturbed sites can explain some of these differences: increased maturity of the tree layer, less dense subcanopy vegetation, higher abundance of holes and crevices, and greater predictability and availability of human food waste in picnic areas. So, contrary to expectations, we conclude that these types of nonconsumptive recreation do not decrease habitat suitability for most birds, although it might decrease suitability for ground-nesting birds.