Value of Small Patches in the Conservation of Plant‐Species Diversity in Highly Fragmented Rainforest

Abstract

We evaluated the importance of small (<5 ha) forest patches for the conservation of regional plant diversity in the tropical rainforest of Los Tuxtlas, Mexico. We analyzed the density of plant species (number of species per 0.1 ha) in 45 forest patches of different sizes (1-700 ha) in 3 landscapes with different deforestation levels (4, 11, and 24% forest cover). Most of the 364 species sampled (360 species, 99%) were native to the region, and only 4 (1%) were human-introduced species. Species density in the smallest patches was high and variable; the highest (84 species) and lowest (23 species) number of species were recorded in patches of up to 1.8 ha. Despite the small size of these patches, they contained diverse communities of native plants, including endangered and economically important species. The relationship between species density and area was significantly different among the landscapes, with a significant positive slope only in the landscape with the highest deforestation level. This indicates that species density in a patch of a given size may vary among landscapes that have different deforestation levels. Therefore, the conservation value of a patch depends on the total forest cover remaining in the landscape. Our findings revealed, however, that a great portion of regional plant diversity was located in very small forest patches (<5 ha), most of the species were restricted to only a few patches (41% of the species sampled were distributed in only 1-2 patches, and almost 70% were distributed in 5 patches) and each landscape conserved a unique plant assemblage. The conservation and restoration of small patches is therefore necessary to effectively preserve the plant diversity of this strongly deforested and unique Neotropical region.

Isolated trees with high crown coverage and densities increase pasture seed rain

“…Th us, the presence of isolated trees in open pastures can help maintain biodiversity by facilitating the movements of dispersal agents between habitats (Benayas et al 2008;Arroyo-Rodríguez et al 2009;Cole et al 2010). Additionally, the structural characteristics of plants that growing in pastures (such as their heights, diameters, crown coverage, and densities) will influence seed dispersal as tall, broad trees can provide shelter, nesting, and foraging sites (McDonnell 1986;Dean et al 1999).…”

Habitat fragmentation and the future structure of tree assemblages in a fragmented Atlantic forest landscape

“…Population declines, species extinctions, shifts in community structure, and collapse in forest structure proceed rapidly as soon as forest edges are created. Although species losses are expected to reach a relaxation point over time, the ultimate nature/composition of tree assemblages in human-modified landscapes remains an open question ( ArroyoRodriguez et al 2012;Arroyo-Rodriguez et al 2009;Santos et al 2010;Santos et al 2008).…”

<b>Effect of selective logging on floristic and structural composition in a forest fragment from Amazon Biome

“…Marchand. In other studies, the value of small fragments for conservation was demonstrated (Campos et al, 2006;Carvalho, Nascimento, & Braga, 2007;Arroyo-Rodríguez, Pineda, Escobar, & Benítez-Malvido, 2009;Carvalho, Braga, & Nascimento, 2009;Dan, Braga, & Nascimento, 2010).…”