Impacto de Secas e Antropização na Dinâmica da Cobertura Florestal em Fragmento do Domínio Fitogeográfico da Caatinga

Abstract

Este trabalho objetivou avaliar a influência da antropização e de secas severas na dinâmica da cobertura florestal de um fragmento de caatinga na região semiárida do Brasil, ao longo de 32 anos. Para o cálculo do índice de seca, agrupou-se os valores de precipitação média pondera da anual da série histórica (1988 - 2019) em Decis. A partir do quantitativo de área encontrada nas classes de uso e ocupação (cobertura florestal conservada, cobertura natural campestre, área antropizada e corpos d’água) dos anos extremos secos e chuvosos, procedeu-se à análise estatística multivariada pelo método da análise de agrupamento hierárquico. Os valores médios dos agrupamentos foram submetidos à análise estatística e confrontados pelo teste T de Student (p ≤ 0,05). Foram encontrados três grupos distintos: G1 constituído por anos secos e muito secos da década de 90, o agrupamento 2 formado por anos extremos úmidos e muito úmidos, independentemente do período, e G3 (agrupamento intermediário) constituído tanto por anos típicos secos quanto chuvosos, especificamente de períodos mais recentes (2000 a 2019). Os grupos G2 e G3 contribuíram com as maiores quantitativo de cobertura florestal conservada, 143.176,50 e 144.928,13 ha, respectivamente. Os resultados demonstram que a precipitação pluviométrica está mais estritamente correlacionada com as áreas antropizadas do que propriamente com a regeneração natural da cobertura florestal. A vegetação arbórea-arbustiva do fragmento investigado tem passado por um processo de regeneração natural na década recente (2002 - 2019) em virtude do abandono de áreas anteriormente antropizadas na década de 90. Drought and Anthropogenic Effect on the Dynamics of Forest Cover in a Fragment of Caatinga Phytogeographic Domain A B S T R A C TThe aim of this study was to evaluate the influence of anthropogenic action and severe drought on the dynamics of forest cover in a fragment of caatinga in the semi-arid region of Brazil, over 32 years. To calculate the drought index, the values for weighted mean annual precipitation from an historical series (1988 - 2019) were grouped into deciles. Based on the quantification of the area found in the classes of use and occupation (conserved forest cover, natural rural cover, anthropogenic area and water bodies) for the extreme dry and rainy years, multivariate statistical analysis was carried out using hierarchical cluster analysis. The mean values of the clusters were submitted to statistical analysis and compared by Student's t-test (p ≤ 0.05). Three distinct groups were found: G1, consisting of dry and very dry years from the 1990s; G2, formed by extreme wet and very wet years regardless of the period; and G3 (intermediate group), comprising both dry and rainy years, specifically from more recent periods (2000 to 2019). Groups G2 and G3 contributed the greatest amount of conserved forest cover, 143,176.50 and 144,928.13 ha respectively. The results show that rainfall is more closely correlated with the anthropogenic areas than with the natural regeneration of forest cover. The woody vegetation of the fragment under investigation has undergone a process of natural regeneration during the last decade (2008 - 2016), due to previously anthropogenic areas being abandoned in the 1990s.Keywords: Caatinga, remote sensing, desertification.

Analysis of the Horizontal Structure of the Young Regenerant Bank in a Degraded Riverside Ecosystem in the Semiarid of Paraiba

“…According to Aquino et al (2021), the fact that severe drought phenomena occur regularly in this semiarid region aggravates the impacts on the dynamics of regeneration on the forest cover in caatinga fragments, making this process slower.…”

Importance of land use and rainfall in the dynamics of the Caatinga vegetation cover in Northeastern Brazil

“…Agricultural and cattle ranching activities and climate variations have a determining influence on forest cover dynamics and represent the most studied factors (Aquino, Rocha Neto, Moreira, Teixeira, & Andrade, 2018;Aquino, Andrade, Filho, & Campos, 2021;Grau, Gasparri, & Aide, 2005;Schulz, Cayuela, Echeverria, Salas, & Benayas, 2010). In the municipality of Tauá, in the state of Ceará, Brazil, in years with rainfall above the historical average, there was a significant increase in degraded areas, resulting from the advance of land incorporated into subsistence agriculture.…”

“…When analyzing the dynamics of land cover and land use in the municipality of Quixadá, Ceará State, Brazil, Aquino et al (2021) found that in years of severe drought, there was a decrease in conserved Caatinga and growth of disturbed areas, with modification of the herbaceous and shrub strata. For these authors, rainfall does not have as much influence on vegetation dynamics.…”

Effect of <i>seed priming</i> with NaCl on the induction of salinity tolerance in <i>Myracrodruon urundeuva</i> Allemão <i>in vitro</i>

“…The Caatinga ecogeographic domain is exclusive to the Brazilian territory, predominantly in the northeast region of the country, and represents about 13% of the national territory, occupying an area of 912,000 km2 rich in biodiversity (BARROS et al, 2021). The main characteristic of Caatinga environment is the poorly developed soils, with an intense dry period, with almost no rain for 8 to 10 months throughout the year (AQUINO et al, 2021). Due to anthropogenic exploration as well as the edaphoclimatic characteristics of the semi-arid region, the Caatinga is in a condition of vulnerability, highly threatened in the scenario of rising global temperatures, putting this region on alert (NOBRE, 2011) due to the risks of desertification and salinization of soils (OLIVEIRA et al, 2013;NOBRE, 2011).…”