Spatial and temporal structure of diversity and demographic dynamics along a successional gradient of tropical forests in southern Brazil

Abstract

Analysis of the structure, diversity, and demographic dynamics of tree assemblages in tropical forests is especially important in order to evaluate local and regional successional trajectories. We conducted a long‐term study to investigate how the structure, species richness, and diversity of secondary tropical forests change over time. Trees (DBH ≥ 5 cm) in the Atlantic Forest of southern Brazil were sampled twice during a 10‐year period (2007 and 2017) in six stands (1 ha each) that varied in age from their last disturbance (25, 60, 75, 90, and more than 100 years). We compared forest structure (abundance and basal area), species richness, alpha diversity, demographic rates (mortality, recruitment, and loss or gain in basal area), species composition, spatial beta diversity, and temporal beta diversity (based on turnover and nestedness indices) among stand ages and study years. Demographic rates recorded in a 10‐year interval indicate a rapid and dynamic process of species substitution and structural changes. Structural recovery occurred faster than beta diversity and species composition recovery. The successional gradient showed a pattern of species trade‐off over time, with less spatial dissimilarity and faster demographic rates in younger stands. As stands grow older, they show larger spatial turnover of species than younger stands, making them more stochastic in relation to species composition. Stands appear to split chronologically to some extent, but not across a straightforward linear axis, reflecting stochastic changes, providing evidence for the formation of a nonequilibrium community. Policy implications. These results reiterate the complexity and variability in forest succession and serve as a reference for the evaluation and monitoring of local management and conservation actions and for defining regional strategies that consider the diversity of local successional trajectories to evaluate the effectiveness of restoration measures in secondary forests of the Atlantic Forest biome.

Seasonal and successional dynamics of size-dependent plant demographic rates in a tropical dry forest

“…4G – 4I ). Dalmaso et al (2020) also found a net negative balance between recruitment and mortality leading to a reduction in plant density in advanced successional stages of a Brazilian Atlantic forest, likely reflecting intense competition. In our study, small plant density declined steadily after only 5 years of land abandonment ( Figs.…”

“…These authors attributed this peak mortality (and a concomitant decline in the dominance of pioneer species) to competition within this guild—rather than competition with the mature forest guild. Canopy closure and the structural recovery of vegetation along succession are expected to increase the influence of competition and density-dependent processes on plant dynamics ( Callaway, 1997 ; Bhaskar, Dawson & Balvanera, 2014 ; Sanaphre-Villanueva et al, 2017 ; Dalmaso et al, 2020 ). The higher mortality of large plants at the intermediate successional stage may thus be associated with competition and density-dependent processes ( Niinemets, 2010 ; Sanaphre-Villanueva et al, 2016 ).…”

“…On the other hand, canopy closure may also increase the influence of competition and density-dependent processes on plant dynamics ( Callaway, 1997 ; Bhaskar, Dawson & Balvanera, 2014 ; Sanaphre-Villanueva et al, 2017 ). Thus, the slightly higher mortality of small plants at the advanced successional stage may be associated with competition and density-dependent processes ( Niinemets, 2010 ; Dalmaso et al, 2020 ).…”

Changes in Community Composition of Tropical Evergreen Forests during Succession in Ta Dung National Park, Central Highlands of Vietnam

“…In this study, phylogenetic and taxonomic diversity were not significantly different between early successional ages, suggesting a failure in detecting phylogenetic diversity as a predictor for ecosystem function. Previous studies [3,11,13,56] argued that this failure may be caused by inappropriate study design when considering the species pool, experimental design, and analyses, such as using inappropriate phylogenies, skewed distributions of phylogenetic distances or the absence of sufficient niche space in experimental and observational venues [57].…”

Impact of sand mining: A case study of initial growth of forest species for recovery of degraded areas

“…The Vale do Ribeira Region has large biodiversity and there is also the estuary-lagoon complex Cananéia-Iguape, a region of rich biological diversity (SOS Mata Atlântica/ INPE 2018). Due to its important biodiversity, studies are needed to provide information on the degradation status of protected areas in this fragment of the Atlantic forest (Prado et al 2019, Dalmaso et al 2020. Currently, sand extraction in riverbeds is an industrial process that has been increasing in the Vale do Ribeira Region (SOS Mata Atlântica/ INPE 2018), and the industrial activity is called sand mining.…”