Climate change effects on plant-soil feedbacks and consequences for biodiversity and functioning of terrestrial ecosystems

Abstract

Plant-soil feedbacks (PSFs) are interactions among plants, soil organisms, and abiotic soil conditions that influence plant performance, plant species diversity, and community structure, ultimately driving ecosystem processes. We review how climate change will alter PSFs and their potential consequences for ecosystem functioning. Climate change influences PSFs through the performance of interacting species and altered community composition resulting from changes in species distributions. Climate change thus affects plant inputs into the soil subsystem via litter and rhizodeposits and alters the composition of the living plant roots with which mutualistic symbionts, decomposers, and their natural enemies interact. Many of these plant-soil interactions are species-specific and are greatly affected by temperature, moisture, and other climate-related factors. We make a number of predictions concerning climate change effects on PSFs and consequences for vegetation-soil-climate feedbacks while acknowledging that they may be context-dependent, spatially heterogeneous, and temporally variable.

Fig. 1. Alteration of trophic relationships depending on responses to climate change.

Arrows indicate CO₂ flow; solid arrows represent net input, and dashed arrows represent net output, with arrow thickness proportional to flow. Circles show different species in a simplified soil food web. The unperturbed system prior to the onset of a chronic global change driver (A) gives way to a long-term response (B) in which poorly performing plant species and their pathogens or symbionts are lost from the system, and new, more competitive plant species that have escaped their natural enemies are added to the community. As a result, the biomass of nonspecialist mutualists or pathogens increases, and the biomass of one decomposer group remains high [modified from (37)].

Fig. 2. Effects of drought on litter productivity and species turnover and their relationships with PSFs.

Drought leads to low-quality litter with recalcitrant carbon (C) compounds and low nutrient content. This litter is difficult to decompose and determines a fungal-dominated microbial community composition while decreasing the availability of nutrients for plants. These conditions lead to a replacement by plant species that are better adapted to drought conditions, in contrast to more humid conditions where nutrient-rich litter is fast decomposed by bacterial-dominated microbial communities. Arrows indicate carbon flow; solid arrows represent net input, and dashed arrows represent net output, with arrow thickness proportional to flow.

Fig. 3. Depiction of effects of abiotic and biotic drivers on PSFs.

Drivers such as temperature (1), moisture (2), aboveground (AG) plant consumers (3), and belowground (BG) top-down control (4) impact on several components of PSFs (e.g., BG mutualists, plant consumers, and litter decomposition) are shown. Orange ovals show the abiotic and biotic drivers of PSF components, shown in dashed circles. PSF components control whether the feedback response is positive or negative. Temperature, moisture, and aboveground plant consumers can also directly affect plant performance (5 to 7). Abiotic and biotic drivers could interact with each other (circle connecting the drivers), and this will affect the way that each one affects the components of PSFs [based on (108)].