Influence of environmental variations on the formation of microhabitats within a fragment of Seasonally Dry Tropical Forest - SDTF, Brazil

Abstract

Caatinga represents one of the two major centers of Seasonally Dry Tropical Forests (SDTF) and is completely inserted in the Brazilian territory. The present work aimed to evaluate the structure of two micro-environments and relate them to environmental variables. Twenty 20 × 20 m plots were placed in which we measured the height and CBH and made the botanical identification of all trees with CBH ≥10 cm. The CCA and indicator species analysis presented a clear distribution of species according to the micro-environments. We concluded that the presence of limestone slabs provided the formation of microhabitats, thus influencing the distribution and composition of tree species, what characterized the phytoecological unit here referred as “furados”.

Environmental filtering both indirectly and directly drives the Dry Tropical Forest species composition and functional composition

“…The results present the environmental filters as direct and indirect drivers of the SDTF ecological attributes, corroborating their importance as determinants of ecological processes at local scales (Apgaua et al, 2015;Moro et al, 2015;Paula et al, 2018;Vleminckx et al, 2015). Previous studies have highlighted the importance of local-scale edaphic heterogeneity for the composition and structuring of communities present in SDTF (Apgaua et al, 2015;Paula et al, 2018).…”

“…Juvenília is contemplated by a vegetative mosaic distinguishable from the heterogeneity of edaphic conditions. We sampled five sites in this mosaic (Figure 2), and identified and characterized them according to their edaphic attributes: (a) Limestone outcropping with soil —Figure 2a, characterized by very fertile but shallow soils (Aguiar‐Campos et al, 2020); (b) Soilless limestone outcrops —Figure 2b, characterized by limestone rocks almost entirely exposed with established vegetation between cracks and fissures, where water infiltration and accumulation also occur in the rainy season (Aguiar‐Campos et al, 2020); “ Furados ”— Figure 2c, characterized by slabs of limestone with flat and regular surfaces and deposition of shallow soils at specific points, where there is accumulation of water during the rainy season due to its waterproofing (Paula et al, 2018); Sedimentary Caatinga —Figure 2d, characterized by the less fertile soils among the studied fragments, also with deep and extremely sandy soils which leads to rapid water drainage (Souza et al, 2019); Arboreal Caatinga — Figure 2e, characterized by fertile and deep soils, which allow the establishment of dense and tall vegetation with continuous canopy and sub‐forest formation (Santos et al, 2012).…”

“…The soil was analyzed according to the protocol of the Empresa Brasileira de Pesquisa Agropecuária (Embrapa, 2006) to obtain texture and fertility variables: clay, silt and sand proportions; pH in water, potassium (K), phosphorus (P), calcium (Ca), magnesium (Mg), aluminum (Al) and organic matter (OM); potential acidity (H + Al); base sum (Bs), base saturation (V); saturation by aluminum (m); cation‐exchange capacity (CEC) at pH 7.0 (T); effective CEC (t) and remaining phosphorus (P‐Rem). Soil depth was obtained with a 1.50 m bar according to Paula et al (2018).…”

“…The soil was analyzed according to the protocol of the Empresa Brasileira de Pesquisa Agropecuária (Embrapa, 2006) to obtain texture and fertility variables: clay, silt and sand proportions; pH in water, potassium F I G U R E 2 Characterization of the environments in the study area: The letters represent the five different environments: (a) Limestone outcropping with soil, (b) Soilless limestone outcrops, (c) "Furados", (d) Sedimentary Caatinga, (e) Arboreal Caatinga [Color figure can be viewed at wileyonlinelibrary.com] (K), phosphorus (P), calcium (Ca), magnesium (Mg), aluminum (Al) and organic matter (OM); potential acidity (H + Al); base sum (Bs), base saturation (V); saturation by aluminum (m); cation-exchange capacity (CEC) at pH 7.0 (T); effective CEC (t) and remaining phosphorus (P-Rem). Soil depth was obtained with a 1.50 m bar according to Paula et al (2018).…”

“…Seasonally Dry Tropical Forests (SDTF) have become a relevant model in ecological studies due to their heterogeneity in soil conditions and biogeographical history (Pennington, Lavin, & Oliveira‐Filho, 2009; Santos et al, 2012). Soil is identified as an important structural driver of floristic complexity in dry vegetation types at local scales, may act as a mediator agent between the effects of environmental conditions and the resource availability (Apgaua et al, 2015; Paula, Santos, Menino, et al, 2018; Souza et al, 2019). The edaphic variations may strongly affect the tree community structural characteristics and floristic composition, which emphasizes the importance of local‐scale variations in edaphic and environmental conditions for SDTF ecological patterns and tropical diversity (Chesson, 2000; Vleminckx et al, 2015).…”