Patch Structure within Brazilian Atlantic Forest Fragments and Implications for Conservation¹

Abstract

Forest structure and tree species composition were studied in four Atlantic seasonal forest fragments ranging from 0.7 to 220 ha, isolated for more than a century in southeastern Brazil. Four physiognomic units were recognized within these fragments: (1) low forest, (2) bamboo forest, (3) high forest, and (4) mature forest. Tree density, basal area, and species diversity (Shannon‐Wiener index) increased from low forest to bamboo forest to high forest to mature forest. Liana cover was highest in low forest. Gap‐opportunistic species were the dominant ecological group in low forest, bamboo forest, and high forest, while shade tolerant canopy species formed the dominant group in mature forest. These structural and compositional features formed a gradient of forest development from the least developed low and bamboo forests to the most developed mature forest. Low forest is hypothesized to be in a stage of arrested succession and high forest a stage of degraded forest. A conceptual model is suggested to explain how these physiognomic units may be related to one another. Although these fragments were covered mainly by high and low forests and thus had a degraded structure, species diversity remained high in all of them. Fragments thus may undergo degradation long after isolation, even when they have been protected from human disturbance for a considerable period. Nonetheless, they also preserve important samples of local and regional floristic diversity for a long time after isolation.

Monoculture plantations impede forest recovery: Evidence from the regeneration of lowland subtropical forest in Hong Kong

“…In terms of forest age, the different VVTs identified in the TPK plot decline in the order FF > (SF, SS) > (GP, GS). In old-growth forest, individual tree girth is usually greater and stem density is lower as compared with younger secondary forest (but see Augusto et al, 2000). Indeed, our results confirm that, at TPK, younger forest (i.e., SF, SS, GP, and GS) tends to have a higher stem density than does older forest (FF).…”

“…Key environmental variables that contribute to the establishment and survival of a tree within its habitat include topographic factors, light availability, moisture, humidity, and soil properties (Harms et al, 2001;Comita et al, 2007;Zuleta et al, 2020). A habitat-association relationship of this sort has been confirmed by a number of studies conducted in forest dynamic plots in the tropics (Gunatilleke et al, 2006;Lai et al, 2009;Bin et al, 2016;Guo et al, 2016). However, as most forest dynamic plots are established in primary forest, these studies overwhelmingly focus on quantifying the relative importance of various environmental factors and tend to disregard the role of anthropogenic disturbances (Uriarte et al, 2004;Thompson et al, 2007).…”

Landscape Ecology and Geotechnologies as Tools for the Management of Biological Conservation

“…The high ED values found for the smaller size fragments are a worrisome factor, since the edge effect will be more prominent. According to Tabanez and Viana [33] and Juvanhol et al [20], the problem of small fragments is the abrupt transition between the forest and adjacent areas, leaving the area susceptible to changes in landscape dynamics and microclimate. Thus, it is necessary to point out that fragments ≤10 ha should be monitored as a priority, under the risk of extinction over time, if not properly managed.…”

Food availability, plant diversity, and vegetation structure drive behavioral and ecological variation in Endangered Coimbra‐Filho's titi monkeys

“…Much of the continuous Atlantic Forest of the region was split into a landscape consisting of small (<10 ha) and isolated forest fragments (Melo et al, 2013;Silva & Tabarelli, 2000). These fragmented landscapes are highly susceptible to taxonomic homogenization (Lôbo et al, 2011) and structural modification (Augusto et al, 2000). In contrast with large forest fragments, small ones tend to have reduced plant richness and basal area, increased treefall gaps, lower canopy height, and less canopy cover (Arroyo-Rodríguez et al, 2007;Hill & Curran, 2003;Souza-Alves et al, 2014, 2018.…”