Soil homogenization and microedges: perspectives on soil‐based drivers of plant diversity and ecosystem processes

Abstract

Citation: Stover, H. J., and H. A. L. Henry. 2018. Soil homogenization and microedges: perspectives on soil-based drivers of plant diversity and ecosystem processes. Ecosphere 9(6):e02289. 10.1002/ecs2.2289Abstract. Disturbance caused by agriculture and resource extraction has resulted in widespread homogenization of soils at the local (within-site) scale. Here, we describe how experimental manipulation of heterogeneity at the local scale has had inconsistent effects on plant species diversity. Moreover, we discuss how soil homogenization per se typically has not been accounted for in the study of heterogeneity-diversity relationships, and how disturbance, often viewed as an artifact in soil heterogeneity experiments, can be a key driver of soil homogenization. We propose a conceptual model for describing the relationship between plant size, patch size, and diversity, and we discuss how factors such as disturbance, productivity, and competition among species either should be controlled or accounted for in soil heterogeneity-plant diversity experiments. Finally, we consider the concept of soil patch microedges, which may provide unique microsites for increased plant diversity, and how these biogeochemical and hydrological interfaces could potentially drive ecosystem processes in a manner unique from the adjacent patches. Overall, this synthesis integrates perspectives on the functional links between plant-driven processes, and soil patterns and processes.

Losses of Soil Organic Carbon with Deforestation in Mangroves of Madagascar

“…In contrast, soil properties including 210 Pbxs inventories and C and N profiles appeared spatially homogeneous among cleared soils, suggesting that deforestation and the continuous exposure of soils caused a general loss of natural variability. This pattern was also reported by Stoke and Harris (2015) in New Zealand and, although often overlooked, may be an additional sign of ecosystem function and service loss (Stover and Henry 2018).…”

Legacy effects of soil homogenization on tallgrass prairie restoration: toward resolved understanding of the relationship between soil heterogeneity and plant species diversity

“…The latter contrasted with the topsoil microsites within the woodchip heterogeneous plots, which were dominated by large tallgrass prairie grasses and forbs, yet both scenarios corresponded with low plant density and low diversity. When plant size exceeds microsite size, diversity may decrease because plants can easily forage and compete for resources among different patches (Lundholm ; Stover & Henry ). The homogeneous woodchip plots may have supported greater diversity by supporting high plant densities, and in addition to potentially affecting nutrient availability, the even spatial distribution of the woodchips may have had a beneficial effect on seed germination by reducing water loss, moderating soil surface temperatures, and reducing erosion (Naeth et al ).…”

“…In addition, research on soil heterogeneity has traditionally considered its impact as a summative effect of microsites within plant communities, without considering the edges between them. These microsite edges (microedges) may have unique properties, providing an additional form of niche space and increasing plant diversity (Stover & Henry ). Microedges may also have properties intermediate between the two neighboring patches, acting as small‐scale ecological transition zones, analogous to the ecotone concept, but at a much smaller spatial scale (the centimeter to meter scale) than ecotones (i.e.…”

Interactions between soil heterogeneity and freezing: Implications for grassland plant diversity and relative species abundances

“…Woodchips were on average approximately 2.5 × 1.0 cm. In heterogeneous soils, not only do distinct soil patches function as microsites, but the interfaces between them (referred to as microedges—Stover & Henry, ) also can exhibit unique properties and function as additional niches. Thus, we defined three types of microsites within the heterogeneous plots in our study: a topsoil patch, a sand:topsoil or woodchip:topsoil patch, and the microedge between the two.…”