Plant Ecology最新文献

The karst region in southwest China is one of world’s largest continuous karst landforms in the world, renowned for its unique landscapes and abundant biodiversity. This study collected 49 leaf samples (21 herbaceous plants and 28 woody plants) from the typical karst zone in Puding County, China, and determined the content of elements in plant leaves using ICP-OES. The concentration characteristics and discrepancy of trace elements (Cr, Cu, Fe, Mn, Pb, Sr, and Zn) in herbaceous and woody plants were analyzed employing statistical analysis models. The results revealed that there were significant differences in the concentrations of trace elements between herbaceous and woody plants. The median concentrations of trace elements in herbaceous plants and woody plants, ranked from high to low, were: Fe > Sr > Mn > Zn > Cr > Cu > Pb and Fe > Sr > Mn > Cr > Zn > Pb > Cu. The outcomes of the correlation analysis revealed discernible differences in the interactions of trace elements within the leaves of herbaceous and woody plants. Principal component analysis (PCA) indicated that Cu, Mn and Zn were influenced by different mechanisms from Cr, Fe, Pb and Sr in plant system. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed that Pb and Cr had stronger distinguishing capabilities between herbaceous and woody plants compared to other elements. The OPLS-DA model was likely considered an optimized model for tracing element sources from different plant species, which has a greatly applied potential in source identification of plant-derived trace elements in a complex environment.

Gynodioecy, the coexistence of hermaphrodite and female plants in the same population, could be an intermediate state in the evolution of the full separation of sexual functions (dioecy). Fuchsia arborescens has been reported as a hermaphrodite species, however here we demonstrate that it is gynodioecious in most of its range. We sampled populations of F. arborescens along their distribution gradient (~900 km) to: (1) measure floral morphometry in both floral morphs (2) estimate female frequency and (3) evaluate seed production in both floral morphs. We found that F. arborescens shows floral dimorphism, mainly given by the length of the floral tube and anthers, which are shorter in female flowers and lack pollen grains in most cases (95%). The northernmost population in Jalisco was completely hermaphrodite while in the others female frequency ranged between 35% and 58%. We also found that female plants consistently produce more mature seeds per fruit than hermaphrodites, supporting the resource reallocation hypothesis for gynodioecious species. Further studies are required on seed germination and seedling performance of both morphs, as well as the estimation of visitation rate in both floral morphs.

Recently, more studies have focused on predicting plant response to livestock grazing by using plant functional traits as indicators to study species adaptation under grazing disturbance. This study examines how different types of plant diversity (taxonomic, phylogenetic, and functional diversity) and strategies (Competitive, Stress-tolerant, and Ruderal) respond to grazing intensity. The study was conducted in the Siah Bisheh Rangelands, located in the southeast of Mazandaran province, Iran. In the region, three adjacent sites were chosen for vegetation sampling. Each site had low and high grazing intensity (LG and HG) areas. For each site and grazing intensity, three 100 m transects were randomly placed. Along each transect, 5 plots (1 × 1 m²) were sampled at 20 m intervals, resulting in a total of 90 plots. The plant coverage was recorded for each plot. To assess the evolutionary relationship among the 76 and 66 species in LG and HG grazing intensities, respectively, a phylogenetic tree was generated. To estimate plant strategy and calculate the overall functional distance between species in this study, four quantitative traits were used: canopy height, leaf area, leaf dry matter content (LDMC), and specific leaf area (SLA). Additionally, three characteristics of CSR strategy classification (Competitive, Stress-tolerance, and Ruderal), were considered. To evaluate functional differences between the two groups with different grazing intensities, we computed functional indices for each sampling plot based on the relative cover of species. The communities subjected to two grazing intensities (LG and HG) were compared using the T-test with a significance level of 5%. The study found that higher grazing intensity caused a shift from the ruderal to the stress-tolerance strategy at both the species and community levels. Furthermore, increased grazing intensity led to a decrease in species richness and diversity, while increasing functional divergence, functional evenness, and community LDMC. Ultimately, stress-tolerant and ruderal strategies dominated under high and low grazing intensities, respectively. The study suggests that plant functional traits are essential in evaluating plant strategies. Analyzing traits like leaf size, SLA, and LDMC can help understand plant survival and growth in different ecosystems. These findings highlight the importance of considering grazing intensity when evaluating plant strategies and the need for further research on how different plant functional traits impact plant responses to grazing pressure. Understanding how various traits contribute to plant performance and ecosystem dynamics can inform decisions about conservation priorities and management strategies. Plant functional traits are a powerful tool for ecologists and conservationists.

Natural and anthropogenic forest edges are an integral part of the landscape. On-going timber harvesting and deforestation has resulted in an increase in forest edges across the globe. This special issue includes current forest edge research from around the world and across different forest types. The research highlights the importance of site-specific edge studies, the effect forest edges have on vegetation patterns and ecological processes, and serves as a framework for conservation.

Soil erosion adversely impacts natural and human environments globally. Vegetation is often used as a sustainable approach to mitigate erosion. Although using vegetation to reduce erosion is a widely accepted concept, how different plant traits mitigate different mechanisms of erosion, and the generality of these mechanisms has not been well demonstrated. We developed ten hypotheses on how different plant traits (roots, leaves, and stems) act to reduce erosion through different mechanisms (binding soil particles, promoting suspended sediment deposition and reducing the energy of waves, runoff, and wind). We then conducted a rapid evidence assessment of the scientific literature using the Eco Evidence method. We found strong evidence to support our overarching hypothesis—an increase in plant abundance reduces erosion. We also found support for the specific hypotheses that plant roots bind soil particles and that greater plant stem density and leaf area reduce surface run-off and promote sediment deposition. There was insufficient evidence to support the hypotheses that an increase in stem density or leaf area reduces wave or wind energy. None of our hypotheses were rejected. Species with higher root and stem densities and greater leaf area will be the most effective in mitigating erosion. Our review highlights that there is insufficient evidence regarding some potentially important mechanisms between vegetation and erosion, making these prospective areas for further research. Our results have the potential to aid environmental engineers when designing schemes to reduce erosion and ecologists and managers who are concerned about the conservation and restoration of erosion-prone environments.

Seeds maintained on seed banks are submitted to two conditions of light during discontinuous hydration: presence or absence. We aimed to investigate the influence of light during discontinuous hydration and its relationship with the establishment of the cacti species. We raised two hypotheses: discontinuous hydration increases the longevity of seeds, and the presence and the absence of light during hydration/dehydration cycles (HD cycles) present different benefits in maintaining their viability in the soil seed bank for a longer time. We subjected seeds to HD cycles in the presence and absence of light. After that, we established a soil seed bank and analyzed the germinative behavior and biochemical compounds at intervals of 0, 3, 6, 9, 12, and 15 months. HD cycles prolonged seed longevity, confirming our first hypothesis. Treatments of HD cycles in the darkness provided the maintenance of seed viability for a period longer than 9 months, which corroborates our second hypothesis. HD cycles in the presence of light only favor the germination behavior of fresh seeds. Reducing sugars are consumed during the first months in seeds buried in the soil. However, protein concentration remains higher in seeds not submitted to HD cycles after 12 months. Our study proposes the existence of a “seed dark hydration memory” related to seed longevity and a “seed light hydration memory” related to the germination of fresh seeds. Thus, the response to light incidence during discontinuous hydration represents an important strategy for the reproductive success of positive photoblastic species in their natural environment.

Abstract

The initiation of a new plant community in a restoration area hinges on the performance of seedlings post-planting. This study aimed to evaluate the impact of species functional traits—specific leaf area (SLA), wood density (WD), seed dry mass (SDM), and potential height (H)—on the seedling performance 25 months after planting, comparing two planting designs (rows and clusters) and the influence of fertilization addition in clusters. The restoration area is a riparian tropical forest located on the coastal plain at Caraguatatuba municipality, São Paulo, Brazil. We monitored 3017 tree seedlings and estimated their survivorship and relative growth rate (RGR) using the diameter, height, and canopy area of the surviving seedlings and the stem biomass for the cluster RGR estimation. Using linear mixed models, we analyzed how the planting designs and the functional traits affect species survival and their RGR. We underscored the significance of slow-growth traits (low SLA, and high SDM and WD) in enhancing species survival, whereas, maximizing species growth entails prioritizing seedlings with greater potential height. Cluster survival and growth improved with a greater abundance of species with low values of SDM (i.e., fast-growth species) and communities with low functional divergence (high similarity). Fertilized clusters improved the RGR of large-seeded species. Accounting for functional traits in restoration is advantageous for enhancing seedling performance at the species level, which is an important consideration for restoration practitioners. To optimize applied nucleation, clusters should target functional diversity at this community level and include competitive species to improve productivity.

Anthropogenic forest fires are occurring with increasing frequency in tropical forests, with negative consequences for a variety of ecological processes, including litterfall. Litterfall provides several ecosystem services, such as nutrient cycling and carbon storage, thus playing an important role in ecosystem functioning. We assessed the impacts of fire and fire-created edges on litterfall in Atlantic Forest remnants in Bahia, Brazil. Litterfall was assessed at monthly intervals over one year along seven 300 m-long transects placed perpendicular to the edge between the unburnt forest and the burnt forest. We installed litterfall traps at the edge (0 m) and 20, 40, 60, 80, 100 and 150 m into both the burnt and unburnt forest. The total litterfall was smaller in the burnt forest (mean of 2.5 ± 2.2 SD t.ha⁻¹.y⁻¹) than in the unburnt forest (mean of 5.9 ± 3.4 SD t.ha⁻¹.y⁻¹). In addition, leaf litter gradually increased from the edge toward the unburnt forest interior. Our results highlight that there is less litterfall in the burnt forest, and that the relative contribution of different litter types (leaves, twigs, and miscellaneous litter) differ between burnt forest and unburnt forest. The lower amount of litterfall in the burnt forest and forest edge may have negative consequences for the natural regeneration of these areas, as the ecosystem services provided by plant litter that are important for forest regeneration are likely to be impaired.

Unlike trees, shrubs (i.e., multiple-stemmed woody plants) do not need evenly spaced large diameter structural roots and therefore should be more responsive to heterogeneous distributions of soil resources and spread further per unit belowground biomass. We therefore hypothesized that compared to trees, shrubs respond more to asymmetric distributions of nutrients, reach nutrient-rich patches of soil faster, and do so with less below-ground biomass. To test these three hypotheses, we planted individual seedlings of shrubs (Cornus racemosa, Rhus glabra, and Viburnum dentatum) and trees (Acer rubrum, Betula populifolia, and Fraxinus americana) in the centers of sand-filled rectangular boxes. In one direction we created a stepwise gradient of increasing nutrients with slow-release fertilizer; in the other direction, no fertilizer was added. Seedlings were harvested when their first root reached the plexiglass-covered fertilized end of their box; time taken, above-ground biomass, and below-ground biomass per nutrient segment were determined. Shrubs and trees did not consistently differ in precision of root foraging (i.e., the ratio of biomass in the fertilized and unfertilized soil) or in rates (g/day) and efficiencies (cm/day) of lateral root growth. Interspecific variation appeared more related to species’ habitats than to growth form. The fastest and most efficient roots were produced by the shrub (R. glabra) and the tree (B. populifolia), both characteristic of poor and heterogeneous soils. Root foraging by R. glabra was also facilitated by rapid rhizomatous expansion.

Saint John’s wort, Hypericum perforatum, is a medicinally and ecologically important perennial plant species that has a broad global distribution. Despite the species’ importance, little is known about the factors that structure its microbial communities and the identity of microbes that enhance plant growth and fitness. Here we aim to describe the microbial communities associated with Hypericum perforatum and elucidate factors that structure these communities. We collected H. perforatum root samples in three adjacent habitat types: wet and dry alvars (two types of limestone barren) and fallow agricultural fields (i.e. old-fields), in Jefferson County, New York. We used high-throughput amplicon sequencing to characterize the bacterial and fungal root microbiome. We also quantified aspects of the plant phenotype and soil characteristics to evaluate habitat variables that correlate with the root microbiome. Habitat and plant height were correlated with shifts in microbial community composition. We identified two bacterial taxa positively associated with plant height, both belonging to the bacterial phylum Actinobacteria. This work contributes to our understanding of the environmental determinants of microbial community composition and identifies microbial taxa that may be important in promoting plant growth.