Vegetational succession assessment in a fragment of the Brazilian Atlantic Forest.

Vegetational succession assessment is an important step for better management practices, providing relevant quantitative and qualitative information. With the advancements of remote sensing algorithms and access to data, land use and land cover (LULC) monitoring has become increasingly feasible and important for the evaluation of changes in the landscape at different spatial and temporal scales. This study aims to analyze the vegetation succession achieved by a project funded by the Brazilian Environmental Ministry (Ministério do Meio Ambiente, in Portuguese) intended to recover degraded areas. A 2014 and a 2019 LULC map was generated using high-resolution (10 cm) images. Given the great challenge of classifying high-resolution images, three classification algorithms were compared. The techniques to regenerate degraded areas were efficient to increase arboreal vegetation area by more than 30% between 2014 and 2019. Land cover and land use change monitoring is of paramount importance to strengthen sustainable practices, especially in the highly threatened Atlantic Forest biome. This study also shows that funding opportunities are essential for projects that make such actions possible, including the present research and the analysis of environmental regeneration.

Tamaulipan thornscrub after fire: an analysis of the composition of species / Espinho de Tamaulipan após incêndio: uma análise da composição das espécies

Abstract Forest fires are a natural element in many terrestrial ecosystems, in Mexico one of the main causes of loss of vegetation coverage is related to them. Nevertheless, no research has been carried out in the Tamaulipan thornscrub communities regarding post-fire regenerative strategies of plant species, therefore, is important to generate knowledge about the ecological role of fire in them. The aim of this study is to characterize the arboreal and shrub vegetation of a Tamaulipan thornscrub community in the Northeast of Mexico after a fire. To determine the composition, diversity and structure of the floral community consisting of trees and shrubs, 6 square-shaped sampling sites of 1,600 m2 were established 3 years after the fire. Margalef (DMg), Shannon-Weiner (H') and Pretzsch (A) indices were calculated to determine the richness, diversity and vertical stratification of species, respectively.23 species, 21 genera and 14 families of vascular plants were registered. The most species were Fabaceae (6) and Rhamnaceae (3) and Cordia boissieri was the specie with greater ecological weight (IVI = 20.3%). The indexes of richness and true diversity (DMg = 3.16; D = 16.44) showed high values, which suggests that the post-fire area has a good regeneration and a high species diversity. With these results we can conclude that the fire is an important agent of change in successional stages of Tamaulipan thornscrub with high values of regeneration after a surface fire.

Resumo Os incêndios florestais são um elemento natural em muitos ecossistemas terrestres, no México uma das principais causas de perda de cobertura vegetal está relacionada a eles, no entanto, nenhuma pesquisa foi realizada nas comunidades de espinheiros de Tamaulipan sobre as estratégias regenerativas pós-fogo de espécies de plantas, portanto, é importante gerar conhecimento sobre o papel ecológico do fogo neles. O objetivo deste estudo é caracterizar a vegetação arbórea e arbustiva de uma comunidade de plantas espinhosas no Tamaulipas, nordeste do México após um incêndio. Para determinar a composição, diversidade e estrutura da comunidade vegetal constituída por árvores e arbustos, seis locais de amostragem em forma de quadrado de 1.600 m2 cada um, foram estabelecidos três anos após o incêndio. Índices de Margalef (DMg), Shannon-Weiner (H') e Pretzsch (A) foram calculados para determinar a riqueza, diversidade e estratificação vertical das espécies, respectivamente. Foram registradas 23 espécies, 21 gêneros e 14 famílias de plantas vasculares. As mais ricas foram Fabaceae (6) e Rhamnaceae (3), Cordia boissieri foi a espécie com maior peso ecológico (IVI = 20,3%). Os índices de riqueza e diversidade verdadeira (DMg = 3,16; D = 16,44) apresentaram valores elevados, o que sugere que a área pós-fogo apresenta boa regeneração e alta diversidade Vegetal. Com estes resultados podemos concluir que o fogo é um importante agente de mudança nos estágios sucessionais do espinho de Tamaulipan com altos valores de regeneração após um incêndio na superfície.

Effect of the population density on belowground bud bank of a rhizomatous clonal plant Leymus secalinus in Mu Us sandy land.

Clonal propagation is the main strategy for clonal plants to adapt to wind-sand habitat, and underground bud bank could reflect the potential ability of clonal propagation. However, the effects of population density on belowground bud bank are unknown, hindering efforts in the process of dune stabilization. We investigated the horizontal density and vertical distribution of belowground bud bank of a typical rhizomatous grass Leymus secalinus, and soil water content in four dune types with different population density (dune type I: 11.2 ± 1.7 no. m-2, type II: 24.2 ± 2.6 no. m-2, type III: 40.0 ± 4.0 no. m-2, and type IV: 53.5 ± 7.2 no. m-2) in Mu Us sandy land. Our results showed that (1) total bud density of population increased markedly with increasing population density, but it did not exhibit significant difference between dune types III and IV, where density was about 130 buds m-2; and tiller bud density of population first increased, then decreased, and reached a maximum in dune type III. (2) Total bud density per individual in dune type III was significantly larger than that in other dune types (P < 0.05), whereas rhizome and tiller bud density per individual did not show significant differences in dune types II, III and IV (P > 0.05). (3) Buds tended to be concentrated at 10-30 cm soil layer in all dune types, and be buried deeper in dune types III and IV than that in dune types I and II. (4) No pronounced relationship was shown between bud density and soil water content in 10-30 cm soil layer with increasing population density. Our results suggest that moderate population density (40.0 ± 4.0 no. m-2) significantly increase the bud bank density of L. secalinus population and individual. Soil water content was not the main factor responsible for the density of L. secalinus bud bank. These results can provide important information for implementation of effective sand fixation measures and species selection for desertification control in semiarid sandy land ecosystems.

Tamaulipan thornscrub after fire: an analysis of the composition of species

Abstract Forest fires are a natural element in many terrestrial ecosystems, in Mexico one of the main causes of loss of vegetation coverage is related to them. Nevertheless, no research has been carried out in the Tamaulipan thornscrub communities regarding post-fire regenerative strategies of plant species, therefore, is important to generate knowledge about the ecological role of fire in them. The aim of this study is to characterize the arboreal and shrub vegetation of a Tamaulipan thornscrub community in the Northeast of Mexico after a fire. To determine the composition, diversity and structure of the floral community consisting of trees and shrubs, 6 square-shaped sampling sites of 1,600 m2 were established 3 years after the fire. Margalef (DMg), Shannon-Weiner (H) and Pretzsch (A) indices were calculated to determine the richness, diversity and vertical stratification of species, respectively.23 species, 21 genera and 14 families of vascular plants were registered. The most species were Fabaceae (6) and Rhamnaceae (3) and Cordia boissieri was the specie with greater ecological weight (IVI = 20.3%). The indexes of richness and true diversity (DMg = 3.16; D = 16.44) showed high values, which suggests that the post-fire area has a good regeneration and a high species diversity. With these results we can conclude that the fire is an important agent of change in successional stages of Tamaulipan thornscrub with high values of regeneration after a surface fire.

Resumo Os incêndios florestais são um elemento natural em muitos ecossistemas terrestres, no México uma das principais causas de perda de cobertura vegetal está relacionada a eles, no entanto, nenhuma pesquisa foi realizada nas comunidades de espinheiros de Tamaulipan sobre as estratégias regenerativas pós-fogo de espécies de plantas, portanto, é importante gerar conhecimento sobre o papel ecológico do fogo neles. O objetivo deste estudo é caracterizar a vegetação arbórea e arbustiva de uma comunidade de plantas espinhosas no Tamaulipas, nordeste do México após um incêndio. Para determinar a composição, diversidade e estrutura da comunidade vegetal constituída por árvores e arbustos, seis locais de amostragem em forma de quadrado de 1.600 m2 cada um, foram estabelecidos três anos após o incêndio. Índices de Margalef (DMg), Shannon-Weiner (H) e Pretzsch (A) foram calculados para determinar a riqueza, diversidade e estratificação vertical das espécies, respectivamente. Foram registradas 23 espécies, 21 gêneros e 14 famílias de plantas vasculares. As mais ricas foram Fabaceae (6) e Rhamnaceae (3), Cordia boissieri foi a espécie com maior peso ecológico (IVI = 20,3%). Os índices de riqueza e diversidade verdadeira (DMg = 3,16; D = 16,44) apresentaram valores elevados, o que sugere que a área pós-fogo apresenta boa regeneração e alta diversidade Vegetal. Com estes resultados podemos concluir que o fogo é um importante agente de mudança nos estágios sucessionais do espinho de Tamaulipan com altos valores de regeneração após um incêndio na superfície.