Interspecific interactions alter plant functional strategies in a revegetated shrub-dominated community in the Mu Us Desert, China

Drivers and mechanisms of spontaneous plant community succession in abandoned PbZn mining areas in Yunnan, China

The drivers and mechanisms underlying succession and the spontaneous formation of plant communities in mining wasteland remain largely unknown. This study investigated the use of nature-based restoration to facilitate the recovery of viable plant communities in mining wasteland. It was found that scientific analyses of spontaneously formed plant communities in abandoned mining areas can provide insights for nature-based restoration. A chronosequence ("space for time") approach was used to establish sites representing three successional periods with six successional stages, and 90 quadrats were constructed to investigate changes in plant species and functional diversity during succession in abandoned PbZn mining areas. A total of 140 soil samples were collected to identify changes in soil properties, including plant nutrient and heavy metal concentrations. Then, this paper used structural equation models to analyze the mechanisms that drive succession. It was found that the functional diversity of plant communities fluctuated substantially during succession. Species had similar functional traits in early and mid-succession, but traits tended to diverge during late succession. Soil bulk density and soil organic matter gradually increased during succession. Total nitrogen (N), pH, and soil Zn concentrations first increased and then decreased during succession. Concentrations of Mn and Cd gradually decreased during succession. During early succession, soil organic matter was the key factor driving plant colonization and succession. During mid-succession, soil Zn functioned as an environmental filter factor limiting the rates of succession in mining wasteland communities. During late succession, soil bulk density and competition for nutrient resources contributed to more balanced differentiation among plant species. This thesis proposed that a nature-based strategy for the stabilization of abandoned mining lands could facilitate effective plant community restoration that promotes ecosystem services and functioning.

Leaf carbon isotope tracks the facilitation pattern of legume shrubs shaped by water availability and species replacement along a large elevation gradient in Trans-Himalayas

BACKGROUND AND AIMS

Understanding patterns and mechanisms of nurse plant facilitation is important to predict the resilience of arid/semi-arid ecosystems to climate change. We investigate whether water availability and nurse species turnover interact to shape the facilitation pattern of widespread legume shrubs along a large elevation gradient. We also investigate whether leaf δ13C of nurse plants can track the facilitation pattern.

METHODS

We measured the relative interaction index (RII) of the number of species within and outside the canopy of two widespread legume shrub species (Caragana gerardiana and Caragana versicolor) alternatively distributed along a large elevation gradient in the Trans-Himalayas. We also assessed the proportional increase of species richness (ISR) at the community level using the paired plot data. To determine site-specific water availability, we measured the leaf δ13C of nurse shrubs and calculated the Thornthwaite moisture index (MI) for each elevation site.

KEY RESULTS

Elevational variations in RII, ISR and δ13C were mainly explained by the MI when the effects of soil nitrogen and plant traits (leaf nitrogen and shrub size) were controlled. Variations in RII and ISR across the two nurse species were explained better by δ13C than by smoothly changing climatic factors along elevation. At the transition zone between the upper limit of C. gerardiana (4100 m) and the lower limit of C. versicolor (4200 m), RII and ISR were much higher in C. versicolor than in C. gerardiana under a similar MI. Such an abrupt increase in facilitation induced by nurse species replacement was well tracked by the variation of δ13C.

CONCLUSIONS

Water availability and nurse species replacement are crucial to shaping facilitation patterns by legume shrubs along a large elevation gradient in dry mountainous regions, such as the Trans-Himalayas. Turnover in nurse species under global change might significantly alter the pattern of nurse plant facilitation associated with water availability, which can be well tracked by leaf δ13C.

Reduced trace gas oxidizers as a response to organic carbon availability linked to oligotrophs in desert fertile islands

Atmospheric trace gases, such as H₂ and CO, are important energy sources for microbial growth and maintenance in various ecosystems, especially in arid deserts with little organic substrate. Nonetheless, the impact of soil organic C availability on microbial trace gas oxidation and the underlying mechanisms are unclear at the community level. This study investigated the energy and life-history strategies of soil microbiomes along an organic C gradient inside and out of Hedysarum scoparium islands dispersed in the Mu Us Desert, China. Metagenomic analysis showed that with increasing organic C availability from bare areas into "fertile islands", the abundance of trace gas oxidizers (TGOs) decreased, but that of trace gas nonoxidizers (TGNOs) increased. The variation in their abundance was more related to labile/soluble organic C levels than to stable/insoluble organic C levels. The consumption rates of H₂ and CO confirmed that organic C addition, especially soluble organic C addition, inhibited microbial trace gas oxidation. Moreover, microorganisms with distinct energy-acquiring strategies showed different life-history traits. The TGOs had lower 16 S rRNA operon copy numbers, lower predicted maximum growth rates and higher proportions of labile C degradation genes, implying the prevalence of oligotrophs. In contrast, copiotrophs were prevalent in the TGNOs. These results revealed a mechanism for the microbial community to adapt to the highly heterogeneous distribution of C resources by adjusting the abundances of taxa with distinct energy and life-history strategies, which would further affect trace gas consumption and C turnover in desert ecosystems.

Precipitation preferences alter the relative importance of herbaceous plant diversity for multifunctionality in the drylands of China

Background

Multiple components of biodiversity are excellent predictors of precipitation-induced changes in ecosystem function. However, the importance of differing scales (alpha versus beta) is usually overlooked in biodiversity–ecosystem multifunctionality studies. Consequently, little is known about how precipitation regulates the relationship between multifunctionality and multiple components of alpha and beta diversity.

Aims

We investigated geographic patterns of herbaceous plant diversity and ecosystem multifunctionality along a precipitation gradient spanning more than 2010 km in Northwest China.

Methods

We assessed the effects of herbaceous species, phylogenetic, and functional components at different scales on multifunctionality in drylands.

Results

The alpha diversity of species and functional beta diversity were key components explaining the variation in multifunctionality. As the main environmental factor, MAP (mean annual precipitation) affected multifunctionality by changing the mediating variables (i.e., species alpha and functional beta diversity). More importantly, a certain precipitation threshold was detected for the relationship of multifunctionality to species alpha and functional beta diversity. MAPs of approximately 158 mm and 140 mm modulated this relationship (shifting it from uncorrelated to significantly correlated).

Conclusions

Our findings provide insights into previously neglected mechanisms by which diversity in herbaceous layers at different scales affects ecosystem multifunctionality. It is highlighted that MAP regulates the relationship between diversity and multifunctionality in dryland ecosystems at different scales. Further, diversity may have substantial consequences for multifunctionality where MAP is higher. These empirical results provide a comprehensive understanding of the biodiversity–multifunctionality relationship in the context of precipitation, ultimately contributing to conservation and restoration programs for multifunctionality in drylands.

Effects of Vetiveria zizanioides on the Restoration and Succession of Coal Gangue Mountain Plant Communities in Different Years

The restoration of vegetation on coal gangue mountains has always been an area of concern, and therefore, an important area of research. Liupanshui city in Guizhou province, China, has a large number of coal gangue mountains, and for this reason, was chosen for studying vegetation succession on these sites. Vetiveria zizanioides is known to accelerate the restoration of vegetation on coal gangue mountains and to shorten community succession timeframes. Because of this, we investigated different successional stages after the planting of V. zizanioides on coal gangue mountains in the Dahe coal mine comprehensive environmental governance project area in Liupanshui city. Through field community surveys and model prediction, the effects of planted V. zizanioides on the species composition, species diversity, and community succession of gangue mountains 3, 6, 8, 10, and 13 years after planting were explored. In total, 35 plant species belonging to 17 families and 32 genera were recorded across the five different coal gangue mountains. With more time after planting, the height, coverage, density, and biomass of V. zizanioides all decreased, but increased for Miscanthus floridulus. The Simpson diversity index, Shannon–Wiener diversity index, and Pielou evenness index all first increased before decreasing over time; maximum values were recorded for the coal gangue mountain 8 years after planting of V. zizanioides. According to different similarity and dissimilarity indices, the successional stages became more similar with increasing time after planting. According to biomass fitting and prediction curves, the succession process of coal gangue mountain plant communities could be divided into a V. zizanioides community stage, a M. floridulus community stage, and a woody plant stage, that starts to approach the natural community of evergreen broad-leaved forests, with durations of 0–5.62 years, 5.62–17.48 years, and over 17.48 years, respectively.

Effect and response traits in severe environments in the context of positive plant-plant interactions. A commentary on: 'Interspecific interactions alter plant functional strategies in a revegetated shrub-dominated community in the Mu Us Desert'

This article comments on: Chun Miao, Yuxuan Bai, Yuqing Zhang, Weiwei She, Liang Liu, Yangui Qiao and Shugao Qin, Interspecific interactions alter plant functional strategies in a revegetated shrub-dominated community in the Mu Us Desert, China, Annals of Botany, Volume 130, Issue 2, 1 August 2022, Pages 149–159 https://doi.org/10.1093/aob/mcac039