The role of landscape heterogeneity in regulating plant functional diversity under different precipitation and grazing regimes in semi-arid savannas
The role of landscape heterogeneity in regulating plant functional diversity under different precipitation and grazing regimes in semi-arid savannas
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DOI：
10.1016/j.ecolmodel.2018.04.009
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发表时间：
2018-07-10
影响因子：
3.1
通讯作者：
Tietjen, Britta
中科院分区：
文献类型：
--
作者：
Guo, Tong;Weise, Hanna;Tietjen, Britta
1.稀树草原系统表现出高度的植物功能多样性。虽然干旱和牲畜放牧强度作为稀树草原植被组成的驱动因素已被广泛讨论，但土壤物理特性却很少受到关注。由于稀树草原可以显示土壤特性的局部差异，因此这些可能充当环境过滤器并影响斑块规模的植物多样性和生态系统功能。然而，关于稀树草原植被多样性与生态系统功能之间联系的研究却普遍缺失。2．在这项研究中，我们旨在了解当地土壤条件的异质性对植物多样性和生态系统功能的影响。为此，我们使用了生态水文稀树草原模型 EcoHyD。该模型模拟了多种植物功能类型的命运及其与当地生物和非生物条件的相互作用。我们将该模型应用于多种牲畜放牧和降水情景下的一组不同景观，以评估局部土壤条件异质性对植物功能类型的组成和多样性以及生态系统功能的影响。3．同质景观和异质景观之间的比较表明，景观土壤异质性使得在高竞争条件下（即低放牧胁迫的情况下）植被具有更高的功能多样性。然而，在低放牧胁迫和高年平均降水量的情况下，景观异质性并没有产生这种影响。此外，景观异质性导致了较高的群落生物量，特别是在降雨量较低的条件下，但也取决于放牧压力。干旱条件下异质景观植物群落总蒸腾量降低。4．这项研究强调，当地土壤条件与降水和放牧相互作用，促进了稀树草原植被的生长。它清楚地表明植被多样性和由此产生的生态系统功能可以由景观异质性驱动。因此，我们建议未来对稀树草原系统生态系统功能的研究应重点关注当地环境条件通过植物功能多样性与生态系统功能之间的联系。
1. Savanna systems exhibit a high plant functional diversity. While aridity and livestock grazing intensity have been widely discussed as drivers of savanna vegetation composition, physical soil properties have received less attention. Since savannas can show local differences in soil properties, these might act as environmental filters and affect plant diversity and ecosystem functioning at the patch scale. However, research on the link between savanna vegetation diversity and ecosystem function is widely missing.2. In this study, we aim at understanding the impact of local heterogeneity in soil conditions on plant diversity and on ecosystem functions. For this, we used the ecohydrological savanna model EcoHyD. The model simulates the fate of multiple plant functional types and their interactions with local biotic and abiotic conditions. We applied the model to a set of different landscapes under a wide range of livestock grazing and precipitation scenarios to assess the impact of local heterogeneity in soil conditions on the composition and diversity of plant functional types and on ecosystem functions.3. Comparisons between homogeneous and heterogeneous landscapes revealed that landscape soil heterogeneity allowed for a higher functional diversity of vegetation under conditions of high competition, i.e. scenarios of low grazing stress. However, landscape heterogeneity did not have this effect under low grazing stress in combination with high mean annual precipitation. Further, landscape heterogeneity led to a higher community biomass, especially for lower rainfall conditions, but also dependent on grazing stress. Total transpiration of the plant community decreased in heterogeneous landscapes under arid conditions.4. This study highlights that local soil conditions interact with precipitation and grazing in driving savanna vegetation. It clearly shows that vegetation diversity and resulting ecosystem functioning can be driven by landscape heterogeneity. We therefore suggest that future research on ecosystem functioning of savanna systems should focus on the links between local environmental conditions via plant functional diversity to ecosystem functioning.