Arthropod Abundance and Diversity in a Lowland Tropical Forest Floor in Panama: The Role of Habitat Space vs. Nutrient Concentrations

Abstract

Tropical forest floor characteristics such as depth and nutrient concentrations are highly heterogeneous even over small spatial scales and it is unclear how these differences contribute to patchiness in forest floor arthropod abundance and diversity. In a lowland tropical forest in Panama we experimentally increased litter standing crop by removing litter from five plots (L À ) and adding it to five other plots (L1); we had five control plots. After 32 mo of treatments we investigated how arthropod abundance and diversity were related to differences in forest floor physical (mass, depth, water content) and chemical properties (pH, nutrient concentrations). Forest floor mass and total arthropod abundance were greater in L1 plots compared with controls. There were no treatment differences in nutrient concentrations, pH or water content of the organic horizons. Over all plots, the mass of the fermentation horizon (Oe) was greater than the litter horizon (Oi); arthropod diversity and biomass were also greater in the Oe horizon but nutrient concentrations tended to be higher in the Oi horizon. Arthropod abundance was best explained by forest floor mass, while arthropod diversity was best explained by phosphorus, calcium and sodium concentrations in the Oi horizon and by phosphorus concentrations in the Oe horizon. Differences in arthropod community composition between treatments and horizons correlated with phosphorus concentration and dry mass of the forest floor. We conclude that at a local scale, arthropod abundance is related to forest floor mass (habitat space), while arthropod diversity is related to forest floor nutrient concentrations (habitat quality). Abstract in Spanish is available at

Soil macrofauna density and diversity across a chronosequence of tropical forest restoration in Southeastern Brazil

“…We did not find a linear increase in macrofauna density as forests age towards values found in the reference ecosystem, which is not in accordance with other studies (Merlim, 2005;Meloni and Varanda, 2015). The abundance and diversity of macrofauna can be influenced by variation in litter quantity and quality (Sayer et al, 2010). The high amount of litter in the pasture site may have biased the results explaining why soil macrofauna was not correlated to litter biomass.…”

Macrofauna do solo em uma cronosequência de capoeiras, florestas e pastos no Centro de Endemismo Belém, Amazônia Oriental

“…Eles mostram, na Amazônia Central, que o acúmulo de biomassa e a riqueza de espécies arbóreas é significativamente reduzido em capoeiras com maior tempo de pastagem (Wandelli 2008) e que áreas desmatadas e sem uso subseqüente são dominados por Cecropia enquanto aquelas usadas para pasto são dominados por Vismia (Norden et al 2011). Tais impactos na vegetação podem influenciar diretamente a abundância e diversidade da macrofauna através de variações na quantidade e qualidade da serrapilheira depositada (Sayer et al 2010).…”

“…Por causa da alta diversidade dos solos tropicais combinada com a falta de especialistas e estudos descrevendo os invertebrados do solo em detalhe (nível de gênero ou espécies), o nível de identificação apresentado nesse estudo é bem aceito porque proporciona informações essenciais sobre o funcionamento do solo e está ao alcance de todos (Lavelle et al 2003;Moço et al 2010;Sayer et al 2010). No entanto, Nahmani et al (2006) já mostraram que a identificação em nível de espécie é o mais preciso para fins de bioindicação, apesar das dificuldades de identificação e do tempo requerido.…”

“…Isso sugere que a abundância desses grupos responde ao aumento da biomassa vegetal e aporte de serrapilheira ao solo (Sayer et al 2010). O fato de Oligochaeta, Isopoda e Formicidae não seguirem esse padrão para os núcleos de São Luís, Tomé-Açu e Igarapé-Açu pode ser explicado pela falta de uma classe de idade.…”

The Effects of Simulated Peccary Extirpation on Leaf Litter Dynamics, Reptiles, and Amphibians in a Neotropical Forest

“…Litter arthropod abundance is positively related to the amount of leaf litter (habitat), and arthropod diversity is related to forest floor nutrient concentrations (Sayer et al 2010). In addition to providing habitat for leaf litter organisms such as arthropods, amphibians, lizards, and snakes, litter provides shelter from predators, a relatively stable thermal and humidity microclimate, and sites for reproduction.…”