Remoção de sementes e herbivoria de mudas em diferentes sistemas de restauração ecológica da floresta estacional semidecidual
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Data
2020-12-11
Autores
Villota Cerón, Diana Elizabeth [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O avanço do conhecimento das interações planta-animal é considerado importante para a restauração de ecossistemas inteiramente funcionais. Os processos de remoção de sementes e herbivoria de mudas são considerados filtros ecológicos determinantes no estabelecimento da comunidade vegetal nos primeiros anos de restauração. Porém, pouco se sabe ainda da influência que exercem os atributos dos ecossistemas restaurados na dinâmica destes processos e, consequentemente, na estrutura da comunidade regenerante. Avaliamos a remoção de sementes e herbivoria de mudas em três sistemas de restauração florestal, dos quais, dois foram restaurados ativamente (contrastantes entre si, quanto aos objetivos, composição, número de espécies plantadas e arranjo espacial) e um restaurado passivamente, estabelecidos há mais de 20 anos. Utilizamos um fragmento de floresta nativa (Floresta Tropical Estacional Semidecidual) próximo à área experimental como ecossistema de referência. Instalamos estações de exclusão de sementes para diferentes grupos de consumidores: insetos, roedores e aves; com o intuito de elucidar o efeito do sistema de restauração e da interação com o grupo funcional de consumidores na remoção de sementes de quatro espécies arbóreas de diferentes grupos sucessionais e de síndromes de dispersão (Pioneiras: Schinus terebinthifolius Raddi e Tabernaemontana hystrix Steud; não pioneiras: Pterogyne nitens Tul. e Anadenanthera colubrina (Vell.) Brenan). Por sua vez, transplantamos mudas destas espécies com o fim de avaliarmos a herbivoria e o efeito dos danos foliares sobre o crescimento das mudas, bem como o papel das defesas das plantas (saponinas, dureza da folha e nitrogênio) na limitação da herbivoria. No geral, as taxas de remoção de sementes foram baixas e diferiram entre sistemas de restauração ativa e passiva. Porém foram semelhantes à taxa de remoção de sementes da mata nativa. Nós encontramos efeito da interação dos sistemas de restauração e do agente consumidor na remoção de sementes. Os sistemas de restauração ativa e o fragmento de floresta nativa favoreceram a remoção de sementes pelos roedores e aves, unicamente na espécie Tabernaemontana hystrix, de dispersão zoocórica. Porém, os insetos foram o principal agente de remoção das sementes das espécies testadas em sua totalidade, independentemente do sistema de restauração. Encontramos diferença de porcentagem de herbivoria em função do sistema de restauração. As mudas sofreram maiores danos no sistema menos complexo (sistema de restauração passiva) e menor nos sistemas mais complexos (sistemas de restauração ativa). Apenas o crescimento de P. nitens foi influenciado negativamente pela herbivoria. Encontramos padrões de herbivoria, de acordo com os atributos de defesa das folhas de cada espécie arbórea. No geral, as saponinas reduziram a herbivoria dos indivíduos. Discutimos as implicações destas descobertas sobre a recuperação de funções ecológicas dos diferentes sistemas de restauração após 20 anos de implantados, com base nos padrões de remoção de sementes e herbivoria de mudas.
The advance in the knowledge of plant-animal interactions has been considered important for the restoration of fully functional ecosystems. Seed removal and seedling herbivory processes are considered ecological filters driving the establishment of the plant community in the first years of restoration. However, little is known about the influence that the attributes of restored ecosystems have on the dynamics of these processes and, consequently, on the structure of the regenerating community. We evaluated seed removal and seedling herbivory in three restoration systems, of which two were actively restored (with contrasting restoration objectives, number of species, composition, spatial arrangement) and one passively restored, established more than 20 years ago. A fragment of native forest (Seasonal Semideciduous Tropical Forest) near the experimental area was used as a reference ecosystem. We installed seed exclusion stations for different consumer groups: insects, rodents and birds; in order to elucidate the effect of the restoration system and the interaction with the functional group of consumers for four tree species belonging to different successionals and seed dispersal syndromes groups (Schinus terebinthifolius Raddi and Tabernaemontana hystrix Steud, zoochoric pioneers; and Pterogyne nitens Tul., and Anadenanthera colubrina (Vell.) Brenan, anemochorich and authochoric non-pioneers, respectively). We transplanted seedlings of these species to evaluate herbivory levels, the effect of foliar damage on seedling growth, and the role of plant defenses (saponins, leaf hardness, and nitrogen) in limiting herbivory damage. As a whole, seed removal rates were low and differed between active and passive restoration systems. However, they were similar to the rate of seed removal from the native forest. The active restoration systems and the native forest fragment favored the removal of seeds by rodents and birds, only for the zoochoric T. hystrix. However, insects were the main removal agent of the seeds of the tested species, regardless of the restoration system. We found differences in the herbivory percentage depending on the restoration system. The seedlings suffered more foliar damage in the less complex system (passive restoration) and less damage in the more complex ones (both active restoration). Only the growth of P. nitens was negatively affected by herbivory. Herbivory patterns depended on the foliar defense attributes of each tree species. In general, saponins reduced the herbivory of individuals. We discuss the implications of these findings on the recovery of the ecological functions of different restoration systems after 20 yearsof implantation, based on the ecological process of seed removal and seedling herbivory.
The advance in the knowledge of plant-animal interactions has been considered important for the restoration of fully functional ecosystems. Seed removal and seedling herbivory processes are considered ecological filters driving the establishment of the plant community in the first years of restoration. However, little is known about the influence that the attributes of restored ecosystems have on the dynamics of these processes and, consequently, on the structure of the regenerating community. We evaluated seed removal and seedling herbivory in three restoration systems, of which two were actively restored (with contrasting restoration objectives, number of species, composition, spatial arrangement) and one passively restored, established more than 20 years ago. A fragment of native forest (Seasonal Semideciduous Tropical Forest) near the experimental area was used as a reference ecosystem. We installed seed exclusion stations for different consumer groups: insects, rodents and birds; in order to elucidate the effect of the restoration system and the interaction with the functional group of consumers for four tree species belonging to different successionals and seed dispersal syndromes groups (Schinus terebinthifolius Raddi and Tabernaemontana hystrix Steud, zoochoric pioneers; and Pterogyne nitens Tul., and Anadenanthera colubrina (Vell.) Brenan, anemochorich and authochoric non-pioneers, respectively). We transplanted seedlings of these species to evaluate herbivory levels, the effect of foliar damage on seedling growth, and the role of plant defenses (saponins, leaf hardness, and nitrogen) in limiting herbivory damage. As a whole, seed removal rates were low and differed between active and passive restoration systems. However, they were similar to the rate of seed removal from the native forest. The active restoration systems and the native forest fragment favored the removal of seeds by rodents and birds, only for the zoochoric T. hystrix. However, insects were the main removal agent of the seeds of the tested species, regardless of the restoration system. We found differences in the herbivory percentage depending on the restoration system. The seedlings suffered more foliar damage in the less complex system (passive restoration) and less damage in the more complex ones (both active restoration). Only the growth of P. nitens was negatively affected by herbivory. Herbivory patterns depended on the foliar defense attributes of each tree species. In general, saponins reduced the herbivory of individuals. We discuss the implications of these findings on the recovery of the ecological functions of different restoration systems after 20 yearsof implantation, based on the ecological process of seed removal and seedling herbivory.
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Palavras-chave
Florestas Restauração, Sementes, Herbivoria, Restauração ecológica, Mata Atlântica, Floresta estacional semidecidual, Interação planta-animal, Ecological restoration, Seeds, Herbivory, Ecological restoration, Atlantic Forest, Seasonal semideciduous forest, Plant-animal interaction