Loss of plant cover mediates the negative effect of anthropogenic disturbance on the multifunctionality of a dryland

Abstract

Aims Anthropogenic disturbances due to human economic activities may affect ecosystem services, which are the benefits provided by the ecosystem properties, such as soil water content and soil fertility. Also, these disturbances affect plant community biodiversity and cover, which are also known to affect multiple ecosystem properties. However, the strength of the relative effects of the disturbance itself and of the effect that is mediated by changes in the plant community is still unclear. Questions We evaluated the relative direct and indirect effects (mediated by changes in the plant community) of the anthropogenic disturbances on ecosystem multifunctionality. Location Dry forests within the Sustainable Development Reserve Ponta do Tubarão, northeastern Brazil. Methods We measured standing biomass, litter mass, soil fertility and soil water content in 52 vegetation plots along a gradient of anthropogenic disturbance. Also, we measured woody plant cover and species’ functional traits to characterize the plant community functional structure. We measured livestock grazing, selective logging and past clear‐cuts as proxies of anthropogenic disturbance to create an index that characterizes the additive effect of these human activities. By building a theoretical model using the structural equation modelling approach, we investigated how the plant community changes in cover and biodiversity due to anthropogenic disturbances mediate changes in ecosystem properties. Results Our results show that anthropogenic disturbances had negative effects on ecosystem properties. Plant cover loss caused by anthropogenic disturbances was the major determinant of the negative effect of disturbances. The functional structure of the plant community had a weak effect on these properties. Conclusions By assessing the effect of human activities on multifunctionality, we found a stronger negative effect of anthropogenic disturbances when compared to its effect on single ecosystem properties. The recovery of plant cover should be a major focus of projects aiming to restore and maintain the multifunctionality of this dryland.

Moss crusts mitigate the negative impacts of shrub mortality on nutrient multifunctionality of desert soils

“…Consistent with the initial hypothesis that shrub mortality reduces soil nutrient multifunctionality and this effect is highly significant in areas without moss crust cover (Fig. 2A), similar results have been obtained in several studies; for example, in the Tibetan Plateau, the above-and below-ground biodiversity loss in degraded grasslands significantly reduced soil multifunctionality in meadows (Cui et al, 2022) and activities causing vegetation destruction such as grazing disturbance or land-use change could negatively affect soil multifunctionality (Manhães et al, 2022;Wang et al, 2022;Wen et al, 2020;Zhu et al, 2021). These find-ings demonstrate the importance of vegetation cover and diversity indicators for soil structure and function in degraded ecosystems and also the urgent need for vegetation management and conservation (Cardinale et al, 2012;Huang et al, 2016).…”

“…The weakening and disappearance of the "fertilizer island" effect after shrub mortality are the main reasons for the decrease in soil nutrient multifunctionality (Aguirre et al, 2021;Manhães et al, 2022;Mueller et al, 2008). The analysis of soil nutrients in this study also showed that the soil carbon, nitrogen, phosphorus, and potassium contents, except for AN, were significantly reduced after shrub mortality.…”

How Do Taxonomic and Functional Diversity Metrics Change Along an Aridity Gradient in a Tropical Dry Forest?

“…These losses and changes can affect ecosystem services and consequently human well-being ( Díaz et al, 2006 ; Cardinale et al, 2012 ; Mori et al, 2018 ). For instance, changes in plant cover can increase topsoil temperature and water evaporation, both processes associated with land degradation, which affect plant productivity and below-ground processes ( Breshears et al, 1997 ; Manhães et al, 2022 ). Thus, it is urgent to identify potential ecological indicators based on biodiversity metrics (e.g., taxonomic and functional), because they integrate the effects of environmental drivers on ecosystems’ functioning accounting for ecosystems’ specificities (e.g., the same increase in temperature will afffect differently semi-arid and polar ecosystems; Branquinho et al, 2019 ).…”

Moss crusts mitigate the negative impacts of shrub mortality on the nutrient multifunctionality of desert soils

“…Similar results have been reported in the Tibetan Plateau, where biodiversity loss in degraded grasslands led to reduced soil multifunctionality in meadows (Cui et al., 2022). Human activities like grazing disturbance and land‐use changes can also negatively impact soil multifunctionality (Manhães et al., 2022; Wen et al., 2020; Zhu et al., 2021). These findings underscore the importance of vegetation conservation and management in preserving soil structure and function in degraded ecosystems (Cardinale et al., 2012; Huang et al., 2016).…”

“…The reduction in the “fertilizer island” effect following shrub mortality is a crucial factor contributing to the decline in soil nutrient multifunctionality (Aguirre et al., 2021; Manhães et al., 2022; Mueller et al., 2008). When examining soil nutrients in this research, a significant decrease in soil carbon, nitrogen, phosphorus, and potassium contents was observed after shrub mortality, except for AN.…”