Natural regeneration in tropical forests is influenced by fine-scale structural heterogeneity and light availability, yet these relationships remain difficult to quantify using conventional field methods. We evaluated associations between forest structure and early regeneration in a mature lowland tropical rainforest in Costa Rica using field measurements and terrestrial laser scanning (TLS). We characterized six permanent forest plots through estimates of canopy openness, overstory attributes, and TLS-derived indices describing understory complexity (UCI) and stand structural complexity (SSCI). We assessed regeneration through surveys of seedlings and saplings within subplots. Canopy openness exhibited the strongest relationship with regeneration, particularly with sapling abundance. TLS- derived metrics captured variation in forest structure and revealed positive associations between understory complexity and regeneration, whereas stand structural complexity showed no clear relationship with recruitment patterns. These findings highlighted the importance of light availability and understory structure in shaping regeneration dynamics and demonstrated the potential of TLS as a complementary tool for characterizing structural conditions associated with natural regeneration in tropical forests.
Habitat quality reflects the combined influence of landscape structure and environmental conditions, yet their relative contributions remain insufficiently understood in heterogeneous forest landscapes. We evaluated the relative contributions of landscape composition, configuration, and environmental gradients across 519 landscape units by integrating InVEST habitat-quality estimates, landscape metrics, and environmental variables within a hierarchical spatial beta generalized additive modelling framework. Landscape composition accounted for most of the variation in habitat quality, while landscape configuration, nonlinear environmental responses, and spatial structure provided additional explanatory information. Spatially blocked cross-validation indicated high predictive performance (R² = 0.962, RMSE = 0.040, MAE = 0.023). Forest cover had the strongest positive composition effect, whereas artificial surfaces were negatively associated with habitat quality. Landscape configuration provided additional explanatory information after accounting for landscape composition, although its multivariate relationship cautions against interpreting individual fragmentation metrics in isolation. Among environmental predictors, NDVI showed the strongest response and a distinctly nonlinear relationship with habitat quality. Habitat- quality patterns were highly stable under alternative InVEST half-saturation constants and ±25% changes in threat-impact distances. These results showed that, even where landscape composition accounted for most habitat-quality variation, landscape configuration and nonlinear environmental gradients provided additional information after accounting for spatial dependence and parameter uncertainty. These findings clarified the relative contributions of landscape composition, spatial configuration, and environmental heterogeneity to modelled habitat-quality patterns in forest-dominated heterogeneous landscapes.
In this study, within the scope of ecosystem rehabilitation, the microbial activity in the rhizosphere of Pistacia atlantica Desf. seedlings grown in V-shaped microcatchments, which are used as rainwater harvesting techniques, was studied in areas experiencing water scarcity and where afforestation efforts have failed. To improve seedling survival rates, treatments including mycorrhizal fungi, polymer, and osmoprotectant were applied. The experiment was conducted in 75 V-shaped microcatchments located in İzmir–Ödemiş, İzmir–Karaburun, and Manisa–Mount Yunt, with soil samples collected during the spring and autumn seasons. Microbial respiration, total bacterial and fungal populations, Azotobacter sp. abundance, and key soil enzyme activities (dehydrogenase, alkaline phosphatase, β-glucosidase, and catalase) were evaluated. Microbial populations and respiration rates were generally higher in spring than in autumn across all study sites. Mycorrhizal fungi application resulted in the highest increase in Azotobacter sp. populations, particularly in the Ödemiş region, indicating enhanced biological nitrogen fixation. Osmoprotectant application significantly increased dehydrogenase and catalase activities, reflecting improved microbial metabolic activity and stress tolerance. Polymer application primarily supported microbial respiration, likely through improved soil moisture retention. Combined polymer + osmoprotectant treatments produced more balanced and sustained improvements in microbial and enzymatic responses compared to single applications. Overall, mycorrhiza- and polymer-based soil amendments improved the biological quality of soils supporting Pistacia atlantica seedlings, highlighting their potential for afforestation and ecosystem rehabilitation in arid and semi-arid regions.
The rescue of native regenerants is increasingly required in areas subjected to vegetation suppression, yet its implementation is often constrained by the costs and logistical demands of conventional protocols. Here, we assessed the effectiveness of a simplified bare-root rescue procedure applied to native woody species of the Brazilian Caatinga under real operational conditions. A total of 122 individuals of Amburana cearensis, Anadenanthera colubrina, Luetzelburgia auriculata, and Pseudobombax marginatum were rescued during the rainy season. After uprooting, regenerants were kept under shade for approximately 24 h and subsequently transplanted into nursery bags containing subsoil. Survival, height, and stem collar diameter were assessed 78 days after transplanting. Overall survival reached 87.7%, ranging from 76.7% in A. colubrina to 100% in A. cearensis. Penalized binomial regression revealed a significant negative effect of stem collar diameter on survival, whereas plant height was not associated with mortality. The high survival rates observed indicate that simplified bare-root rescue can be successfully applied under real operational conditions in the Caatinga when performed during the rainy season and combined with measures that minimize dehydration. These findings provide practical guidance for flora rescue programs and ecological restoration initiatives in seasonally dry tropical forests.
Tropical montane forests harbor high biodiversity and develop under heterogeneous topographic, climatic, and soil conditions. However, the influence of these environmental factors on their ecological dynamics remains poorly understood. This study was conducted to provide baseline information on the mechanisms underlying biodiversity in this complex mountain landscape. Specifically, we aimed to: (i) determine the floristic composition and forest structure of these ecosystems, and (ii) evaluate the effect of environmental gradients on species floristic composition and structural attributes in southern Ecuador. Across six localities, the tree community was sampled (composition, basal area, density, diameter, and maximum height) and edaphic, climatic, and topographic properties were characterized at the subplot level. Four discrete floristic groups and marked structural differences were identified among the evaluated forests. Environmental factors (mainly elevation and pH) explained a minor fraction of the floristic variation. In contrast, slope, elevation (associated with precipitation, temperature, and evapotranspiration gradients), and soil properties (depth, CEC, texture, and acidity) significantly modulated forest structure. We conclude that environmental factors determine density, biomass, and canopy height in these ecosystems. However, their weak influence on floristic composition suggests that community assembly is primarily mediated by biotic interactions or stochastic processes.
