ABSTRACT
ABSTRACT The species-area relationship is one of the most consistent patterns in ecology, and fragmentation is a major cause of habitat loss. Environmental changes in a site can affect the spatial distribution of organisms. Knowledge of Mutillidae ecology is still scarce due to the lack of standardized sampling. Our aim was to: (1) determine the effect of habitat fragmentation on the Mutillidae community and (2) establish a standard method for sampling Mutillidae in ecological studies. Sampling was conducted in four fragments of Brazilian Savanna in an urbanized matrix. We used quadrats with different areas: 25 m2, 100 m2 and 400 m2 to verify sampling effort. Male and female Mutillidae were collected from each of these three treatments. Males were collected using Malaise traps while females were collected through active search. Ecological index, richness, abundance, and percent similarity between fragments were used to analyze the communities. The Kruskal-Wallis test was performed to verify differences between treatments. Nonparametric multivariate analysis of variance was used to determine community composition. Analysis of direct ordination of community with respect to the sample area size was performed. Three hundred individuals were collected; of which 201 were female, 99 male; belonging to 42 species distributed in 13 genera and two subfamilies. The richness, abundance and composition of the community were different between treatments. It was found that a 100 m2 quadrat was sufficient for comparison and application of ecological concepts and theories for the group.
ABSTRACT
Quadrat sampling is a method used for a long time in plant ecology studies but only recently it has been used with focus on fauna. For the cave fauna samplings, there are rare works applying this methodology. The present study compared the methods of quadrat sampling with direct search qualitative for terrestrial cave fauna. For this, we conducted five sampling collections in a limestone cave in central Brazil. Quadrat sampling contributed with 121 exclusive species and 716 specimens and direct search qualitative method contributed with 91 exclusive species and 355 specimens. Mann-Whitney test evidenced significant differences between the two methods. We demonstrated that quadrat sampling method was slightly more efficient to analyze the species richness and much more effective to assess the abundance than the use of only direct search qualitative method, mainly considering tiny and/or cryptobiotic invertebrates (e.g., earth worms, symphylans, psocopterans, trichopterans, dipterans, small spiders, and small isopods). We recommend the association of different methods to test patterns in cave fauna, since incomplete sampling may lead to erroneous estimates and equivocated decisions about management, impact studies and cave conservation.
Amostragem por quadrados é um mé todo utilizado há muito tempo em estudos ecológicos botânicos e apenas recentemente tem sido utilizado com foco em estudos faunísticos. Para amostragens em cavernas, raros trabalhos aplicaram esta metodologia. Nosso trabalho compara o método de amostragem por quadrados com o de busca ativa qualitativa sobre a fauna cavernícola terrestre. Para tal, realizamos cinco eventos de coleta em uma caverna calcária do Brasil central. A amostragem, utilizando o método de quadrados, contribuiu com 121 espécies exclusivas e 716 espécimes. O método de busca ativa contribuiu com 91 espécies exclusivas e 355 espécimes. O teste de Mann-Whitney mostrou diferenças significativas entre os dois métodos. Demonstramos que o método de amostragem de quadrados foi sutilmente mais eficiente para acessar a riqueza de espé cies e muito mais efetivo para acessar a abundância do que apenas a utilização do método qualitativo de busca ativa, principalmente para invertebrados diminutos e/ou criptobióticos (por exemplo, vermes, sínfilos, psocópteros, tricópteros, dípteros, pequenas aranhas e pequenos isópodes). Recomendamos o uso de métodos combinados para o teste de padrões da fauna cavernícola, uma vez que amostragens incompletas podem levar a estimativas erradas e decisões equivocadas acerca de manejo, estudos de impacto e conservação de cavernas.