Influência da abertura de trilhas antrópicas e clareiras naturais na fenologia reprodutiva de Gymnanthes concolor (Spreng.) Müll. Arg. (Euphorbiaceae)
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Data
2008-03-01
Autores
Alberti, Luis Fernando [UNESP]
Morellato, L. Patrícia C. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Botânica de São Paulo
Resumo
Investigamos se no interior de uma floresta estacional semidecidual em Santa Maria, RS, uma trilha clara diferiu de um caminho escuro (trilha escura) quanto à luz incidente e à fenologia reprodutiva de G. concolor e se a abertura de clareiras em 2002 afetou a luz incidente e a fenologia dessa espécie em 2003. Procuramos responder: (a) As trilhas clara e escura diferem quanto à luz incidente na copa das árvores e ao número de inflorescências masculinas, flores femininas, frutos e tamanho de frutos (variáveis fenológicas)? (b) Houve relação entre a luz incidente na copa das árvores e as variáveis fenológicas? (c) em cada trilha, indivíduos vizinhos e não vizinhos às clareiras diferem quanto à variação interanual da luz incidente e das variáveis fenológicas devido à abertura de clareiras? em 2002, a luz incidente foi significativamente maior sobre as copas dos indivíduos da trilha clara, mas as trilhas não diferiram significativamente quanto às variáveis fenológicas. em 2003, os indivíduos na trilha clara não diferiram significativamente daqueles na trilha escura quanto à luz incidente e às variáveis fenológicas. Portanto, a luz incidente na trilha clara não promoveu uma mudança fenológica significativa, o que foi corroborado pelo baixo número de regressões significativas entre luz incidente e as variáveis fenológicas. Os indivíduos vizinhos tiveram taxa de variação da luz incidente significativamente maior do que os não vizinhos, mas não diferiram significativamente quanto às taxas de variação das variáveis fenológicas. Portanto, a maior luz incidente após a abertura de clareiras também não afetou significativamente a fenologia de G. concolor, que dependeria de maiores intensidades de luz para responder à abertura de trilhas ou clareiras. Estes resultados podem nortear as dimensões de futuras trilhas ecológicas ou espaços abertos em reservas naturais, de forma a causarem menor impacto na produção de flores, frutos e sementes em espécies vegetais nas suas proximidades.
In the interior of a seasonal semideciduous forest at Santa Maria, RS, Brazil, we investigated whether a wide and lighter trail differed from a narrow and darker path (darker trail) concerning the reproductive phenology of G. concolor. We also examined whether the creation of natural gaps in 2002 affected the incident light and phenology of G. concolor in 2003, answering the questions: (a) do the trails differ regarding the incident light on the tree canopy and the number of male inflorescences, female flowers, fruits and fruit size (phenological variables)? (b) Is there a relationship between incident light on the tree canopy and the phenological variables? (c) In each trail, do individuals adjacent to gaps differ from individuals far away from gaps regarding the interannual variation in the incident light and phenological variables? In 2002, the incident light was significantly higher on lighter trail than darker trail trees, but trails did not differ in respect to phenological variables. In 2003, incident light and phenological variables did not differ significantly between trees in lighter trail and darker trail. Therefore, the light incidence on lighter trail did not promote a significantly phenological change. The result is supported by the low number of significant regressions between light incidence and phenological variables. Trees adjacent to gaps presented a light incidence variation significantly higher than those trees far away from gaps, but did not differ in respect to interannual variation in phenological variables. Hence, the higher light incidence after the creation of gaps did not affect significantly the phenology of G. concolor as well, which may need even higher amounts of light to respond to gaps or open trails. Our results may give some insight to the design of ecological trails or other open spaces on natural reserves, to reduce its impact on flowering and fruiting production of the species nearby.
In the interior of a seasonal semideciduous forest at Santa Maria, RS, Brazil, we investigated whether a wide and lighter trail differed from a narrow and darker path (darker trail) concerning the reproductive phenology of G. concolor. We also examined whether the creation of natural gaps in 2002 affected the incident light and phenology of G. concolor in 2003, answering the questions: (a) do the trails differ regarding the incident light on the tree canopy and the number of male inflorescences, female flowers, fruits and fruit size (phenological variables)? (b) Is there a relationship between incident light on the tree canopy and the phenological variables? (c) In each trail, do individuals adjacent to gaps differ from individuals far away from gaps regarding the interannual variation in the incident light and phenological variables? In 2002, the incident light was significantly higher on lighter trail than darker trail trees, but trails did not differ in respect to phenological variables. In 2003, incident light and phenological variables did not differ significantly between trees in lighter trail and darker trail. Therefore, the light incidence on lighter trail did not promote a significantly phenological change. The result is supported by the low number of significant regressions between light incidence and phenological variables. Trees adjacent to gaps presented a light incidence variation significantly higher than those trees far away from gaps, but did not differ in respect to interannual variation in phenological variables. Hence, the higher light incidence after the creation of gaps did not affect significantly the phenology of G. concolor as well, which may need even higher amounts of light to respond to gaps or open trails. Our results may give some insight to the design of ecological trails or other open spaces on natural reserves, to reduce its impact on flowering and fruiting production of the species nearby.
Descrição
Palavras-chave
abertura de clareiras, fenologia, Gymnanthes concolor, trilha antrópica, anthropic trail, gap creation, Gymnanthes concolor, phenology
Como citar
Brazilian Journal of Botany. Sociedade Botânica de São Paulo, v. 31, n. 1, p. 53-59, 2008.