Department of Watershed Sciences and the Ecology Center, Utah State University, 5210 Old Main Hill, Logan, Utah, 84322, USA.
School of Biology and Ecology, 5751 Murray Hall, Orono, Maine, 04469, USA.
Ecology. 2018 Nov;99(11):2467-2475. doi: 10.1002/ecy.2492. Epub 2018 Oct 5.
Consensus has emerged in the literature that increased biodiversity enhances the capacity of ecosystems to perform multiple functions. However, most biodiversity/ecosystem function studies focus on a single ecosystem, or on landscapes of homogenous ecosystems. Here, we investigate how increased landscape-level environmental dissimilarity may affect the relationship between different metrics of diversity (α, β, or γ) and ecosystem function. We produced a suite of simulated landscapes, each of which contained four experimental outdoor aquatic mesocosms. Differences in temperature and nutrient conditions of the mesocosms allowed us to simulate landscapes containing a range of within-landscape environmental heterogeneities. We found that the variation in ecosystem functions was primarily controlled by environmental conditions, with diversity metrics accounting for a smaller (but significant) amount of variation in function. When landscapes were more homogeneous, α, β, and γ diversity was not associated with differences in primary production, and only γ was associated with changes in decomposition. In these homogeneous landscapes, differences in these two ecosystem functions were most strongly related to nutrient and temperature conditions in the ecosystems. However, as landscape-level environmental dissimilarity increased, the relationship between α, β, or γ and ecosystem functions strengthened, with β being a greater predictor of variation in decomposition at the highest levels of environmental dissimilarity than α or γ. We propose that when all ecosystems in a landscape have similar environmental conditions, species sorting is likely to generate a single community composition that is well suited to those environmental conditions, β is low, and the efficiency of diversity-ecosystem function couplings is similar across communities. Under this low β, the effect of abiotic conditions on ecosystem function will be most apparent. However, when environmental conditions vary among ecosystems, species sorting pressures are different among ecosystems, producing different communities among locations in a landscape. These conditions lead to stronger relationships between β and the magnitude of ecosystem functions. Our results illustrate that abiotic conditions and the homogeneity of communities influence ecosystem function expressed at the landscape scale.
文献中已经达成共识，生物多样性的增加提高了生态系统执行多种功能的能力。然而，大多数生物多样性/生态系统功能研究都集中在单一生态系统或同质生态系统的景观上。在这里，我们研究了增加景观水平的环境异质性如何影响不同多样性指标（α、β或γ）与生态系统功能之间的关系。我们制作了一系列模拟景观，每个景观都包含四个实验性的户外水生中观。中观的温度和营养条件的差异使我们能够模拟包含一系列景观内环境异质性的景观。我们发现，生态系统功能的变化主要受环境条件控制，多样性指标对功能变化的解释较小（但具有统计学意义）。当景观更加同质时，α、β和γ多样性与初级生产力的差异无关，只有γ与分解的变化有关。在这些同质景观中，这两种生态系统功能的差异与生态系统中的养分和温度条件关系最密切。然而，随着景观水平环境异质性的增加，α、β或γ与生态系统功能之间的关系变得更强，β在环境异质性最高水平下对分解的变化的预测能力大于α或γ。我们提出，当景观中的所有生态系统都具有相似的环境条件时，物种分选很可能产生一种非常适合这些环境条件的单一群落组成，β较低，多样性-生态系统功能耦合的效率在各个群落中相似。在这种低β条件下，生物条件对生态系统功能的影响将最为明显。然而，当生态系统之间的环境条件发生变化时，物种分选压力在生态系统之间会有所不同，从而在景观中的不同位置产生不同的群落。这些条件导致β与生态系统功能幅度之间的关系更强。我们的结果表明，非生物条件和群落的同质性会影响景观尺度上表达的生态系统功能。
