Plant diversity loss reduces soil respiration across terrestrial ecosystems

Abstract

The rapid global biodiversity loss has led to the decline in ecosystem function. Despite the critical importance of soil respiration (Rs) in the global carbon and nutrient cycles, how plant diversity loss affects Rs remains uncertain. Here we present a meta‐analysis using 446 paired observations from 95 published studies to evaluate the effects of plant and litter mixtures on Rs and its components. We found that total Rs and heterotrophic respiration (Rh) were, on average, greater in plant mixtures than expected from those of monocultures. These mixture effects increased with increasing species richness (SR) in both plant and litter mixtures. While the positive effects of species mixtures remained similar over time for total Rs, they increased over time for Rh in plant mixtures but decreased in litter mixtures. Despite the wide range of variations in mean annual temperature, annual aridity index, and ecosystem types, the plant mixture effects on total Rs and Rh did not change geographically, except for a more pronounced increase of total Rs in species mixtures with reduced water availability. Our structural equation models suggested that the positive effects of SR and stand age on total and Rh were driven by increased plant inputs and soil microbial biomass. Our results suggest that plant diversity loss has ubiquitous negative impacts on Rs, one of the fundamental carbon‐cycle processes sustaining terrestrial element cycling and ecosystem function.

Functional and phylogenetic diversity promote litter decomposition across terrestrial ecosystems

“…Mechanistically, a higher diversity of resources associated with higher litter functional diversity increases decomposer abundance and functions due to greater resource partitioning (Meier & Bowman, 2008; Pei et al, 2017; Santonja et al, 2017), thus leading to higher synergistic effects on decomposition (Chapman et al, 2013). Our findings provide clear evidence that increased diversity of the aboveground plant community promotes soil biota abundance and decomposition on a broad spatial scale, not only due to a higher carbon input (Chen & Chen, 2019), or the modification of microclimates (Joly et al, 2017), but also through providing chemically heterogeneous litter.…”

Global responses of fine root biomass and traits to plant species mixtures in terrestrial ecosystems

“…Similarly, contrasting results have been reported for the effects of plant species mixtures on root length density, mean root diameter and root nitrogen content (Table 1). These divergent findings may have resulted from differences in the species richness in mixtures (hereafter species richness), stand age, soil layers, as well as background environments or ecosystem types, as previously reported for the responses of soil carbon (Chen et al., 2019), soil respiration (Chen & Chen, 2019) and soil microbial communities (Chen et al., 2019).…”

Increased microbial growth, biomass, and turnover drive soil organic carbon accumulation at higher plant diversity

“…Biodiversity loss through anthropogenic changes in the global environment is threatening ecosystem functions and services. Grassland ecosystems are predicted to experience most biodiversity losses as a consequence of land‐use change, such as the conversion of grasslands into croplands (Sala et al, ) and recent studies revealed concomitant negative impacts on soil carbon cycling (Chen & Chen, ; Tang et al, ). Terrestrial ecosystems store most organic carbon in soils where it has the potential to become stable soil carbon and thus can be sequestered for longer time periods.…”