Litter Cover Variability Affects Seedling Performance and Herbivory¹

Abstract

We assessed the effects of litter cover on herbivory and performance (annual survival and relative growth rate in height and leaf number) for established seedlings ( 2 9 cm tall, and 24 mo old), of four shade-tolerant, large-seeded, co-occurring Sapotaceae species. Seedlings were divided into three litter treatments: (1) litter addition, (2) control, and (3) continuous litter removal. The mean survival for all treatments in descending order were: Chrysophyllum pomiferum (89%), Pouteria peruviensis (84%), I? cuimito (75%), and Micropholis venulosa (40%). For all variables, species differed significantly within litter treatments. In M. venulosa, survival and relative growth rate in leaf number significantly decreased with the removal of litter, whereas herbivoiy increased. Relative growth rate in height of Z? peruviensis decreased significantly with litter removal, while the levels of herbivory were higher with the addition of litter. Conversely, litter quantity had no effect on the performance of C. pomiferum, but herbivory was lower in the removal treatment. Finally, in I? cuimito, litter treatment did not affect performance or herbivory. Results suggest that differences in litter quantity differentially affect tree species with similar biology (ie., large-seeds, shade tolerance) in life stages other than germination and early establishment. The variability in species' responses to litter might be an important factor in determining species richness, abundance, and distribution of tropical rain forest tree species at the seedling level. RESUMOEm Maiiaus, Brasil, foram medidas, durante um ano, as respostas de quatro espkcies de dossel em rela580 i diferenGas nas quantidades de massa de liteira fina, atravks dos parhetros sobreviv&ncia, taxa de crescimento relativo em altura e nlimero de folhas, e herbivoria. As plhtulas estabelecidas (altura 2 9 centlmetros, e idade 2 4 meses) foram plantadas em trCs tratamentos: (1) adiszo, (2), controle, e (3) remosiio continua da liteira. A porcentagem mkdia de sobrevivtncia de pldntulas em todos 0s tratamentos diminuiu de Chrysophyllum pom@rum (89%), para Pouteriaperuvimis (84%), para Pouteria caimito (750/0), e Micropholis venulosa (40%). Para todas as variAveis, as espkcies apresentaram diferenps significativas nos tratamentos de liteira. A sobreviv2ncia e crescimento em n6mero de folhas das pldntulas de M . venulosu diminuiu nas Areas nas quais a liteira foi removida, havendo aumento da herbivoria. 0 crescimento em altura das plhntulas de I?peruviemis diminuiu com a remos8o de liteira, havendo por outro lado, um maior nivel de herbivoria com a adis80 de liteira. Nas plhtulas de I? caimito e C pom@rum a quantidade de liteira n8o teve um efeito aparente no desempenho das pldntulas, mas 0s danos causados pela herbivoria em C: pom@rum foram menores no tratamento em que a liteira foi removida. 0 s resultados sugerem que a quantidade de liteira tem um efeito em outras etapas da vida das plantulas, fora da germinas80 e da fase itiicial de estabelecimento. A variayiio nas respostas ...

Litter Production and Litter Nutrient Concentrations in a Fragmented Amazonian Landscape

“…Moreover, physical damage by falling litter and the smothering effects of dense litter negatively affect seed and seedling survivorship (Benitez-Malvido 1998, Bruna 1999, especially for small-seeded species (Vazquez-Yanes and Orozco-Segovia 1992). Similarly, the effects of litter cover on rates of seedling herbivory and growth are species specific (Benitez-Malvido and Ferraz 1999). Protection from litter damage resulted in increased germination success of the understory herb Heliconia acuminata in small forest fragments (Bruna 1999).…”

Succession in Old Pastures of Central Amazonia: Role of Soil Fertility and Plant Litter

“…On the other hand, plant litter may also contribute to the processes of facilitation by reducing erosion, evapotranspiration, and maximum soil temperature, thereby improving microclimatic conditions for seed germination and seedling establishment (Facelli and Pickett 1991b). Further, studies in tropical forests have shown that variations in litter depth can promote species coexistence and the high species diversity found in tropical forests (Mol-ofsky andAugspurger 1992, Benitez-Malvido andKossmann-Ferraz 1999).…”

Litter accumulation and its effect on seedling recruitment in a Southeast Brazilian Tropical Forest

“…Seedling recruitment is the emergence of new seedlings in a particular site. Recruitment is strongly affected by the presence of the litter mainly in deciduous or semideciduous forests due to dependence of appropriate microhabitats for emergence and seedling survival (Eriksson 1995, Benitez-Malvido 1999, Kotorová & Lëps 1999.…”