Soil resource availability is much more important than soil resource heterogeneity in determining the species diversity and abundance of karst plant communities

A review of agroforestry ecosystem services and its enlightenment on the ecosystem improvement of rocky desertification control

Agroforestry (AF) has become an important strategy in reconciling the contradictory requirements of environmental protection and economic development in ecologically fragile areas, and whose multiple ecosystem services provide effective ways to promote the restoration of degraded ecosystems in the region. However, agroforestry ecosystem services (AFES) are usually constrained by their generative elements (vulnerability, structure, function, and ecological assets) and service management-both crucial for informed decision-making which enhances AFES supply capacity and AF sustainable management. Karst rocky desertification (KRD) is a typical case in an ecologically fragile area, and within the KRD region greatly relevant for promoting AFES as a strategy for restoring degraded regional ecosystems and for achieving sustainable development goals. In this study, a total of 164 publications related to AFES that met a set of inclusion criteria were obtained through the Scopus database using the literature review method of searching, appraisal, synthesis, and analysis. From the systematic literature review results, (i) we found that the number of relevant publications generally exhibited a year-on-year growth trend, with AFES generation elements being the most common topic (68.11 % of publications), and service management research being the second most common (31.89 % of publications); (ii) we summarised the main progress and landmark results of AFES generation elements and service management research and explored the relevant key scientific questions; and (iii) the above information enlightened the key improvement areas of KRD control ecosystem within three aspects: natural environment, agricultural development, and human-environment relationship. This study provides agroforestry practitioners and relevant decision-makers with information for improving and managing the supply capacity of AFES, and also presents important insights on the KRD control ecosystem to land degradation restoration technicians.

Are degraded karst tiankengs coupled with microclimatic underground forests the refugia of surface flora? Evidence from China’s Yunnan

Karst tiankengs, as one of the most magnificent negative topographies, are capable of forming a bank for species diversity conservation easily. More than 300 karst tiankengs have been discovered and identified worldwide. Given its treacherous terrain, although original karst tiankeng were identified as species refuges, the broader distribution of degraded karst tiankeng has not been systematically studied. Our study area comprised the degraded karst tiankeng cluster immersed in the fragmented karst forests of Yunnan, China. Fifty-eight plant samples were selected from karst tiankengs and surface. We compared species composition, and analyzed diversity indices and similarity coefficients to verify the isolation effect of karst tiankengs on floras. The results indicated that: (1) In the degraded karst tiankeng, there were 24 families, 37 genera and 48 species in the tree layer and 27 families, 43 genera and 49 species in the shrub layer. Outside the degraded karst tiankengs, 20 families, 31 genera and 39 species were in the tree layer, and the shrub layer included 26 families, 44 genera and 55 species. (2) The species composition reached significant differences within and outside degraded karst tiankeng (p < 0.05) based on the analysis of variance (ANOVA). (3) In the degraded karst tiankeng, species richness/diversity in trees were higher than those in the shrub layer, while at the surface, shrubs had higher richness and lower diversity than trees by Alpha-diversity index. And for Beta-diversity index, species similarity among degraded karst tiankengs (0.215) was extremely dissimilar, which was even lower than the contrast within and outside the degraded karst tiankengs (0.272). (4) Shared species ranged from 1 to 5 among the four habitats, with high variability in plant species across the habitat matrices. Through a comparative analysis of systematic biodiversity methods, we found that the degraded karst tiankengs, an independent type of karst tiankeng, are the unreported refugia. Species records in degraded karst tiankeng cluster will contribute to plant diversity conservation and resource management, and to the linkage with broader China’s karst floras. Karst tiankeng botanical habitats possess not only biodiversity value for in situ conservation, but will further support the ecological recovery of surface flora. While its mechanism needs to be further revealed.

Soil heterogeneity in the horizontal distribution of microplastics influences productivity and species composition of plant communities

Contamination of soils by microplastics can have profound ecological impacts on terrestrial ecosystems and has received increasing attention. However, few studies have considered the impacts of soil microplastics on plant communities and none has tested the impacts of spatial heterogeneity in the horizontal distribution of microplastics in the soil on plant communities. We grew experimental plant communities in soils with either a homogeneous or a heterogeneous distribution of each of six common microplastics, i.e., polystyrene foam (EPS), polyethylene fiber (PET), polyethylene bead (HDPE), polypropylene fiber (PP), polylactic bead (PLA) and polyamide bead (PA6). The heterogeneous treatment consisted of two soil patches without microplastics and two with a higher (0.2%) concentration of microplastics, and the homogeneous treatment consisted of four patches all with a lower (0.1%) concentration of microplastics. Thus, the total amounts of microplastics in the soils were exactly the same in the two treatments. Total and root biomass of the plant communities were significantly higher in the homogeneous than in the heterogeneous treatment when the microplastic was PET and PP, smaller when it was PLA, but not different when it was EPS, HDPE or PA6. In the heterogeneous treatment, total and root biomass were significantly smaller in the patches with than without microplastics when the microplastic was EPS, but greater when the microplastic was PET or PP. Additionally, in the heterogeneous treatment, root biomass was significantly smaller in the patches with than without microplastics when the microplastic was HDPE, and shoot biomass was also significantly smaller when the microplastic was EPS or PET. The heterogeneous distribution of EPS in the soil significantly decreased community evenness, but the heterogeneous distribution of PET increased it. We conclude that soil heterogeneity in the horizontal distribution of microplastics can influence productivity and species composition of plant communities, but such an effect varies depending on microplastic chemical composition (types) and morphology (shapes).