Plant–plant interactions determine natural restoration of plant biodiversity over time, in a degraded mined land

Abstract

Restoration of degraded environments is essential to mitigate adverse impacts of human activities on ecosystems. Plant–plant interactions may provide effective means for restoring degraded arid lands, but little is understood about these impacts. In this regard, we analyzed the effects of two dominant nurse plants (i.e., Artemisia sieberi and Stipa arabica ) on taxonomic, functional, and phylogenetic diversity across different ages of land abandonment (i.e., control, recent, and old ages) in a limestone mine site in Iran. In addition, we considered two spatial scales: i) the plot scale (i.e., under 1m2 plots) and ii) the vegetation‐patch scale (i.e., under the canopies of nurse plants), to assess nurse plant effects, land abandonment ages, and their relative importance on biodiversity facets by performing Kruskal–Wallis H test and variation partitioning analysis. Our results indicated an increase in taxonomic, functional, and phylogenetic diversity at the plot scale, when considering the presence of nurse plants under old ages of land abandonment. Such significant differences were consistent with the positive effects of Artemisia patches on taxonomic diversity and Stipa patches on functional and phylogenetic diversity. In addition, we found a larger contribution from nurse plants than land abandonment age on biodiversity variation at both spatial scales studied. Therefore, these results indicate the importance of plant–plant interactions in restoring vegetation, with their effects on the presence of beneficiary species and their functional and phylogenetic relatedness depending on the nurse life forms under the stress‐gradient hypothesis.

Nurse shrubs influence plant biodiversity across environmental gradients in rocky outcrops and surrounding rangelands

“…In contrast, in rangelands an increase in taxonomic diversity was found because competition is promoted as the most important plant–plant interaction type throughout the whole environmental gradients. These results were consistent with the effects of shrub canopies on understorey communities and overall biotic interactions in severe landscapes such as drylands and alpine environments (Soliveres & Maestre, 2014; Bashirzadeh, Shefferson, & Farzam, 2022; Bashirzadeh, Soliveres, et al, 2022). It has been proven that under moderate environmental gradients of these ecosystems, shrub species are able to provide some suitable microenvironments for distinct plant taxa by fostering spatial segregation between beneficiary species.…”

“…However, some previous studies have shown absorption of P is significantly correlated to the amount of precipitation, where an increase in precipitation would lead to P reduction in the soil profile (due to water leaching) (Fonseca et al, 2000; Ordoñez et al, 2009; Rafiee et al, 2022). Therefore, more benign conditions in terms of soil moisture level beneath nurse shrubs in rangelands may be the reason for increases in competition between beneficiaries as a result of P reduction (Gómez‐Aparicio, 2009; He et al, 2013; Bashirzadeh, Shefferson, & Farzam, 2022; Rafiee et al, 2022).…”

“…To examine the relative importance of selected environmental factors and the presence of nurse shrubs explaining variation in biodiversity indices, we performed variation partitioning based on partial linear regression using the “varpart” function (Oksanen et al, 2017). The total percentage of variation explained was divided into a unique and a shared contribution for two sets of predictors: (i) environmental factors (precipitation) + soil factors (i.e., P in rangelands and EC in outcrop), (ii) presence of nurse types (i.e., nurse factor) and (iii) their interactions (i.e., shared environment between these factors) (Bashirzadeh, Shefferson, & Farzam, 2022). Analyses were conducted in R ver.…”

“…(i) environmental factors (precipitation) + soil factors (i.e., P in rangelands and EC in outcrop), (ii) presence of nurse types (i.e., nurse factor) and (iii) their interactions (i.e., shared environment between these factors) (Bashirzadeh, Shefferson, & Farzam, 2022). Analyses were conducted in R ver.…”

“…This study was conducted on limestone outcrops and their surrounding rangelands along a cross transect of the Alborz Mountain ranges from arid steppe rangelands (located in Shahroud) to temperate forests (located in Gorgan). Although plant interactions are commonly known as major drivers of plant biodiversity in extreme environments (Luzuriaga et al, 2012; Gavini et al, 2019; Bashirzadeh, Shefferson, & Farzam, 2022), their impact on different components of plant biodiversity has been less studied across changing abiotic gradients in the outcrops and their surrounding ecosystems such as rangelands (Rafiee et al, 2022). Therefore, this study aimed to investigate the relative importance of plant–plant interactions and abiotic factors on different components of plant biodiversity (i.e., taxonomic, functional and phylogenetic diversity) in rocky outcrops and rangelands to recognize key factors structuring them.…”