In many regions worldwide, Asteraceae exhibits the highest species richness among invasive alien plants (IAP). Notably, Asteraceae IAP frequently demonstrate co-invasion tendencies. Plant communities invaded by Asteraceae IAP may differ structurally and functionally from those invaded by non-Asteraceae IAP. More importantly, multiple IAP may coexist within the same habitat, and these species can be further differentiated as either Asteraceae IAP or non-Asteraceae IAP, potentially leading to significant differences in community structure under invasion by varying numbers of IAP species or by IAP with different species identities. This study aimed to evaluate the differences in IAP’ invasion intensity and community invasibility between communities invaded by Asteraceae IAP and those invaded by non-Asteraceae IAP. A comparative field survey approach was adopted, examining six distinct plant community types: uninvaded communities, communities invaded by a single Asteraceae IAP, communities invaded by a single non-Asteraceae IAP, communities co-invaded by two Asteraceae IAP, communities co-invaded by one Asteraceae and one non-Asteraceae IAP, and communities co-invaded by two non-Asteraceae IAP. Under single-IAP invasion scenarios, Asteraceae IAP triggered significantly higher invasion intensity and more pronounced community invasibility compared to non-Asteraceae IAP. However, under co-invasion conditions involving multiple IAP—whether two Asteraceae species, one Asteraceae and one non-Asteraceae species, or two non-Asteraceae species—no substantial differences were observed in invasion intensity or community invasibility. Thus, Asteraceae IAP exhibited stronger invasion intensity and greater impact on community invasibility only in single-IAP invasion contexts, with such differences diminishing under multi-IAP co-invasion conditions.
Urbanization is one of the main anthropogenic pressures on biodiversity, altering patterns of richness, diversity, and composition of biological communities. Ants are particularly interesting for investigating urbanization effects on biodiversity because they are diverse, abundant, sensitive to environmental changes, and mediate multiple ecological functions. However, the response of taxonomic and functional structure to urbanization remains overlooked in tropical ecosystems such as the Brazilian Cerrado. Here, we investigated spatial variation of ant communities across a continuous urbanization gradient encompassing 30 areas within a huge Cerrado reserve in central-western Brazil. During the rainy season of 2025, we sampled ants using pitfall traps at five points along a 150-m transect placed in each area, totalling 150 samples. Additionally, we quantified urbanization by assessing human population density and the proportion of built-up area within a 1-km buffer around each area. We found no significant effect of urbanization on the richness or functional diversity of ants. Nevertheless, we observed shifts in species composition along the gradient, suggesting changes in community assembly with increasing urbanization. Further, beta-diversity partitioning revealed high spatial variation across the landscape, driven primarily by species turnover. Our findings suggest that large and well-preserved Cerrado fragments can sustain ant richness and functional diversity despite the urban pressure in their adjacencies. However, increasing urbanization along the edges of native vegetation fragments may, over the long term, compromise the ecological services supported by biological communities. We advocate the importance of conserving large, well-preserved native urban remains as they function as refuges for ant biodiversity in increasingly urbanized landscapes.
The eastern Hindu Kush, characterized by high peaks and rugged terrain, presents challenging conditions for biotic communities. Despite its ecological significance, the region remains understudied in terms of vegetation community dynamics and their environmental drivers, which are crucial for informing conservation strategies. This study provides the first integrated assessment of juniper woodland distribution, community structure, and dendrochronological potential across elevational gradient (2400–3500 m). Vegetation and environmental data were collected from 30 stands and analyzed using multivariate approaches. Three ecologically distinct communities were identified, comprising 18 tree and 36 understory species, with greater diversity and richness at lower elevations. Juniperus species dominated the canopy throughout the elevational gradient, particulalry at higher elevations, indicating broad ecological tolerance at harsh environmental conditions. Redundancy analysis (RDA) revealed that species dominance declined with increasing geospatial, topographic, and soil constraints, whereas favorable climatic and edaphic conditions promoted species establishment and dominance. Structural equation modeling (SEM) showed climate as the primary driver of tree density (PC = 0.35, p = < 0.05), while soil exerted a weaker indirect influence. Juniper ages ranged from 25 to 964 years, with a strongly skewed age structure dominated by younger cohorts and only a small proportion of old-growth individuals. Growth rates were slow (0.12–0.26 cm year−1) and declined with elevation, suggesting limited recruitment and growth patterns under harsh environmental conditions. Our findings highlight the importance of environmental filtering in shaping juniper woodland dynamics and provide a scientific basis for elevation-specific and species-targeted conservation strategies.
It is imperative to comprehend the mechanisms that regulate aboveground carbon stock (AGC) in tropical forests, as this knowledge is fundamental for predicting ecosystem responses to environmental change. Two non-mutually exclusive mechanisms have been proposed to explain how community functional composition influences carbon storage: the niche complementarity hypothesis (NCH) emphasizes functional diversity, and the mass-ratio hypothesis (MRH) highlights the role of dominant trait values. However, the simultaneous testing of these mechanisms under integrated climatic–edaphic gradients across contrasting tropical forests has rarely been undertaken. Using piecewise structural equation modeling with bootstrap confidence intervals for indirect effects, we disentangled the direct and indirect pathways linking an integrated environmental gradient, functional diversity, functional dominance, and AGC across dry and wet tropical forests in northeastern Brazil. We quantified community-weighted mean (CWM) traits and multiple functional diversity (FD) metrics from field-measured leaf area, leaf dry mass, specific leaf area, wood density, and tree height and evaluated competing causal models representing the NCH, MRH, and a joint framework. We found strong support for the MRH. The environmental gradient exerted an indirect influence on AGC through community-weighted mean tree height, thereby fully mediating the relationship between environmental conditions and AGC. Conversely, FD metrics exhibited no significant effects on AGC in either the independent or joint models. The results obtained demonstrate the importance of integrated climatic-edaphic gradients and suggest that environmental filtering exerts a primary influence on AGC by favoring communities dominated by tall-statured species, thus providing a trait-based framework for understanding and managing carbon dynamics in tropical forests.
