Influência da qualidade da mata na diversidade de aranhas em uma região de Mata Atlântica da região Sudeste do Brasil
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Data
2023-12-08
Autores
Dias, Stefan Ribeiro [UNIFESP]
Orientadores
Cibele, Bragagnolo [UNIFESP]
Tipo
Dissertação de mestrado
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Resumo
Aranhas são os predadores generalistas mais abundantes na maioria dos ecossistemas terrestres. Isso as tornam boas indicadoras de alterações do hábitat por serem animais comuns na maioria dos ecossistemas terrestres. A heterogeneidade estrutural dentro de uma área florestal é cada vez mais reconhecida como uma característica importante quando o objetivo é gerir florestas como sistemas complexos e meios de preservação de biodiversidade. Partindo da hipótese de que uma maior complexidade da mata resulta em um aumento na quantidade de nichos disponíveis testamos as seguintes hipóteses: 1) pontos da mata mais antigas devem apresentar mudanças significativas na composição da comunidade de aranhas quando comparada aos pontos de mata secundária. 2) algumas variáveis ambientais influenciam mais na abundância e riqueza da araneofauna do que outras e 3) espera-se que aranhas do gênero Miagrammopes e Micrathena sejam mais abundantes em matas mais antigas, enquanto aranhas do gênero Acacesia sejam mais abundantes em matas mais novas. As amostragens foram realizadas no Parque Ecológico Imigrantes (São Bernardo - SP) ao longo de seis meses em 17 pontos diferentes. As amostragens foram realizadas a noite, por três coletores, totalizando 51 amostras. As variáveis relacionadas com complexidade da mata foram: altura e cobertura do dossel, estratificação vegetal, diâmetro e densidade das árvores e idade da mata. Foram coletadas um total de 1.384 aranhas, destas 368 eram adultas de teia orbicular, representando três famílias e 53 morfoespécies. A partir dos testes T, foi observado que a abundância e riqueza não apresentaram variações significativas entre as matas de diferentes idades, porém houveram diferenças significativas nos índices de diversidade. O NMDS também mostrou que não houve mudança significativa na composição da araneofauna entre os pontos com aproximadamente 40 anos e os pontos com mais de 60 anos. Os modelos lineares indicaram que a abundância de aranhas de teia orbiculares foi influenciada positivamente pelo preenchimento do estrato de 0 a 1 metro e de 5 a 10 metros, enquanto a riqueza foi positivamente influenciada pela altura do dossel e preenchimento do estrato de 5 a 10 e tanto a diversidade quanto a riqueza foram influenciadas positivamente pela densidade de árvores. Também foi observado um alto índice de turnover entre os pontos de coleta e que Micrathena sanctispiritis e a morfoespécie Miagrammopes sp.1 podem ser consideradas como espécies indicadoras de mata madura.
Spiders are the most abundant generalist predators in most terrestrial ecosystems. This makes them good indicators of habitat changes as they are common animals in most terrestrial ecosystems. Structural heterogeneity within a forest area is increasingly recognized as an important characteristic when the objective is to manage forests as complex systems and means of preserving biodiversity. Based on the hypothesis that greater complexity of the forest results in an increase in the number of available niches, we tested the following hypotheses: 1) older forest points should show significant changes in the composition of the spider community when compared to secondary forest points. 2) some environmental variables influence the abundance and richness of araneofauna more than others 3) spiders of the genus Miagrammopes and Micrathena are expected to be more abundant in older forests, while spiders of the genus Acacesia are more abundant in younger forests. Sampling was carried out at Parque Ecológico Imigrantes (São Bernardo - SP) over 6 months at 17 different points. The sampling was performed at night, by three collectors, totaling 51 samples. The variables related to forest complexity were: canopy height and coverage, plant stratification, tree diameter and density and forest age. A total of 1,384 spiders were collected, of which 368 were orb-web adults, representing three families and 53 morphospecies. From the T tests, it was observed that abundance and richness did not present significant variations between forests of different ages, however there were significant differences in diversity indices. The NMDS also showed that there was no significant change in the composition of the araneofauna between the points with approximately 40 years old and the points with more than 60 years. Linear models indicated that the abundance of orb web spiders was positively influenced by stratum fill from 0 to 1 meter and from 5 to 10 meters, while richness was positively influenced by canopy height and stratum fill from 5 to 10 meters and both diversity and richness were positively influenced by tree density. A high turnover rate was also observed between the collection points and that Micrathena sanctispiritis and the morphospecies Miagrammopes sp.1 can be considered as indicator species of mature forest.
Spiders are the most abundant generalist predators in most terrestrial ecosystems. This makes them good indicators of habitat changes as they are common animals in most terrestrial ecosystems. Structural heterogeneity within a forest area is increasingly recognized as an important characteristic when the objective is to manage forests as complex systems and means of preserving biodiversity. Based on the hypothesis that greater complexity of the forest results in an increase in the number of available niches, we tested the following hypotheses: 1) older forest points should show significant changes in the composition of the spider community when compared to secondary forest points. 2) some environmental variables influence the abundance and richness of araneofauna more than others 3) spiders of the genus Miagrammopes and Micrathena are expected to be more abundant in older forests, while spiders of the genus Acacesia are more abundant in younger forests. Sampling was carried out at Parque Ecológico Imigrantes (São Bernardo - SP) over 6 months at 17 different points. The sampling was performed at night, by three collectors, totaling 51 samples. The variables related to forest complexity were: canopy height and coverage, plant stratification, tree diameter and density and forest age. A total of 1,384 spiders were collected, of which 368 were orb-web adults, representing three families and 53 morphospecies. From the T tests, it was observed that abundance and richness did not present significant variations between forests of different ages, however there were significant differences in diversity indices. The NMDS also showed that there was no significant change in the composition of the araneofauna between the points with approximately 40 years old and the points with more than 60 years. Linear models indicated that the abundance of orb web spiders was positively influenced by stratum fill from 0 to 1 meter and from 5 to 10 meters, while richness was positively influenced by canopy height and stratum fill from 5 to 10 meters and both diversity and richness were positively influenced by tree density. A high turnover rate was also observed between the collection points and that Micrathena sanctispiritis and the morphospecies Miagrammopes sp.1 can be considered as indicator species of mature forest.