Saikkonen Teemu, Vahtera Varpu, Koponen Seppo, Suominen Otso
Zoological Museum, Biodiversity Unit, University of Turku, Turku, Finland.
Kevo Subarctic Research Institute, Biodiversity Unit, University of Turku, Turku, Finland.
PeerJ. 2019 Jul 17;7:e7330. doi: 10.7717/peerj.7330. eCollection 2019.
The effect of reindeer L. grazing on the ground-dwelling spider assemblage in Northern Finland was studied. Changes in species richness, abundance and evenness of spider assemblages were analyzed in relation to changes in vegetation and environmental factors in long term grazed and ungrazed sites as well as sites that had recently switched from grazed to ungrazed and vice versa. Grazing was found to have a significant impact on height and biomass of lichens and other ground vegetation. However, it seemed not to have an impact on the total abundance of spiders. This is likely caused by opposing family and species level responses of spiders to the grazing regime. Lycosid numbers were highest in grazed and linyphiid numbers in ungrazed areas. Lycosidae species richness was highest in ungrazed areas whereas Linyphiidae richness showed no response to grazing. Four Linyphiidae, one Thomisidae and one Lycosidae species showed strong preference for specific treatments. Sites that had recovered from grazing for nine years and the sites that were grazed for the last nine years but were previously ungrazed resembled the long term grazed sites. The results emphasize the importance of reindeer as a modifier of boreal forest ecosystems but the impact of reindeer grazing on spiders seems to be family and species specific. The sites with reversed grazing treatment demonstrate that recovery from strong grazing pressure at these high latitudes is a slow process whereas reindeer can rapidly change the conditions in previously ungrazed sites similar to long term heavily grazed conditions.
研究了驯鹿放牧对芬兰北部地面蜘蛛群落的影响。分析了长期放牧和未放牧地点以及近期从放牧转为未放牧和反之的地点中蜘蛛群落的物种丰富度、丰度和均匀度的变化，这些变化与植被和环境因素的变化相关。发现放牧对地衣和其他地面植被的高度和生物量有显著影响。然而，它似乎对蜘蛛的总丰度没有影响。这可能是由于蜘蛛在科和物种水平上对放牧制度的反应相反。狼蛛科的数量在放牧地区最高，而皿蛛科的数量在未放牧地区最高。狼蛛科的物种丰富度在未放牧地区最高，而皿蛛科的丰富度对放牧没有反应。四种皿蛛科、一种蟹蛛科和一种狼蛛科物种对特定处理表现出强烈偏好。从放牧中恢复九年的地点以及过去九年放牧但以前未放牧的地点类似于长期放牧的地点。结果强调了驯鹿作为北方森林生态系统调节剂的重要性，但驯鹿放牧对蜘蛛的影响似乎因科和物种而异。放牧处理逆转的地点表明，在这些高纬度地区从强烈的放牧压力中恢复是一个缓慢的过程，而驯鹿可以迅速改变以前未放牧地点的条件，使其类似于长期重度放牧的条件。
