Herbivory and litter production in response to nutrient addition in “Terra Firme” forest in Central Amazon – Herivoria e produção de serapilheira em resposta à adição de nutrientes em floresta de terra firma na Amazônia Central
he role of herbivores in determining tropical forest productivity, carbon balance and nutrient cycling is uncertain in the Amazon. Leaf consumption by herbivores and their consequent excretion may represent an additional, but often undocumented, flow of nutrients and carbon into the ecosystem. The...
| Autor principal: | Moraes, Anna Carolina Martins |
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| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/5203 http://lattes.cnpq.br/0312278822568882 |
| Resumo: |
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he role of herbivores in determining tropical forest productivity, carbon balance and nutrient cycling is uncertain in the Amazon. Leaf consumption by herbivores and their consequent excretion may represent an additional, but often undocumented, flow of
nutrients and carbon into the ecosystem. The focus of this research was to understand the role of nutritional limitations on canopy productivity at the ecosystem level, taking into account losses by herbivory and leaf investment in secondary compounds in a “terra
firme” forest in Central Amazonia. The study site was the AFEX project, a large scale experiment that aims to understand ecosystem responses to soil nutrient limitation. The treatments consisted in the addition of nitrogen (N), phosphorus (P), cations, N + P, N +
Cations, P + Cations, N + P + Cations and control plots. The eight treatments were distributed in four blocks, where each block contains eight plots representing the complete factorial design (n= 32 plots). Litter was sampled biweekly for eight months (between July/ 2017 and February/ 2018), using five suspended littertraps at one meter height, with an area of 0.25m² each, for a total of 160 collectors. Littertraps were distributed in the central 30 x 30 m area of each plot. Litterfall biomass, leaf area and leaf area loss, macro and micronutrient and lignin, cellulose and polyphenols were determined. We found a
trend for increased production of leaf litter biomass in the N + P treatment during the dry season from July to August/2017 (dry season). This increase in N+P, translated through litterfall with more nutrients inputs returning to soils. There was a strong increase in
phosphorus, magnesium, calcium, potassium and manganese concentrations in the litter leaves in plots where phosphorus was added. In contrast to the strong changes in nutrient
concentrations with fertilization, there were no significant differences in the concentration of defense compounds. Furthermore, there were no significant differences in the percent leaf area lost to herbivores (varying from 9 to 10%) among the treatments. There was also
no significant difference in the biomass of herbivore frass. However, there were significant differences of nutrients in the frass, mostly in treatments with P addition. Together, the intial responses of fine litterfall production suggest rapid changes in litter nutrient inputs, but slower responses of herbivores and anti-herbivore defenses to nutrient additions. |