Wehner Katja, Renker Carsten, Simons Nadja K, Weisser Wolfgang W, Blüthgen Nico
Ecological Networks, Technische Universität Darmstadt, Schnittspahnstraße 3, 64287, Darmstadt, Germany.
Naturhistorisches Museum Mainz, Landessammlung für Naturkunde RLP, Reichklarastraße 1, 55116, Mainz, Germany.
BMC Ecol Evol. 2021 Feb 1;21(1):15. doi: 10.1186/s12862-020-01741-1.
How land use shapes biodiversity and functional trait composition of animal communities is an important question and frequently addressed. Land-use intensification is associated with changes in abiotic and biotic conditions including environmental homogenization and may act as an environmental filter to shape the composition of species communities. Here, we investigated the responses of land snail assemblages to land-use intensity and abiotic soil conditions (pH, soil moisture), and analyzed their trait composition (shell size, number of offspring, light preference, humidity preference, inundation tolerance, and drought resistance). We characterized the species' responses to land use to identify 'winners' (species that were more common on sites with high land-use intensity than expected) or 'losers' of land-use intensity (more common on plots with low land-use intensity) and their niche breadth. As a proxy for the environmental 'niche breadth' of each snail species, based on the conditions of the sites in which it occurred, we defined a 5-dimensional niche hypervolume. We then tested whether land-use responses and niches contribute to the species' potential vulnerability suggested by the Red List status.
Our results confirmed that the trait composition of snail communities was significantly altered by land-use intensity and abiotic conditions in both forests and grasslands. While only 4% of the species that occurred in forests were significant losers of intensive forest management, the proportion of losers in grasslands was much higher (21%). However, the species' response to land-use intensity and soil conditions was largely independent of specific traits and the species' Red List status (vulnerability). Instead, vulnerability was only mirrored in the species' rarity and its niche hypervolume: threatened species were characterized by low occurrence in forests and low occurrence and abundance in grasslands and by a narrow niche quantified by land-use components and abiotic factors.
Land use and environmental responses of land snails were poorly predicted by specific traits or the species' vulnerability, suggesting that it is important to consider complementary risks and multiple niche dimensions.
土地利用如何塑造动物群落的生物多样性和功能性状组成是一个重要问题且常被探讨。土地利用集约化与非生物和生物条件的变化相关，包括环境同质化，并且可能作为一种环境过滤器来塑造物种群落的组成。在此，我们研究了陆生蜗牛群落对土地利用强度和非生物土壤条件（pH值、土壤湿度）的响应，并分析了它们的性状组成（壳大小、后代数量、光偏好、湿度偏好、耐淹性和抗旱性）。我们描述了物种对土地利用的响应，以识别“赢家”（在高土地利用强度地点比预期更常见的物种）或土地利用强度的“输家”（在低土地利用强度地块更常见）及其生态位宽度。作为每个蜗牛物种环境“生态位宽度”的代理指标，基于其出现地点的条件，我们定义了一个五维生态位超体积。然后，我们测试了土地利用响应和生态位是否有助于由红色名录状态所表明的物种潜在脆弱性。
我们的结果证实，森林和草原中蜗牛群落的性状组成都因土地利用强度和非生物条件而显著改变。虽然在森林中出现的物种中只有4%是集约森林管理的显著输家，但草原中输家的比例要高得多（21%）。然而，物种对土地利用强度和土壤条件的响应在很大程度上独立于特定性状和物种的红色名录状态（脆弱性）。相反，脆弱性仅反映在物种的稀有性及其生态位超体积中：受威胁物种的特征是在森林中出现频率低，在草原中出现频率和丰度低，并且由土地利用成分和非生物因素量化的生态位狭窄。
特定性状或物种的脆弱性对陆生蜗牛的土地利用和环境响应预测性很差，这表明考虑互补风险和多个生态位维度很重要。
