Tropical Rainforest Gaps And Tree Species Diversity
Summarises recent information on the nature of gap-understorey environments, paying particular attention to the role of light amount and duration, soil nutrient availability and soil moisture and gap dynamics (focusing on gap-size frequency distributions and forest turnover rates). Patterns of growth and mortality are noted. Evidence is considered regarding habitat specialisation by tropical trees, reviewing data on the distribution of adult and juvenile trees, and on the relative performances of similar species along gap-understorey gradients. Discussion centres on life history attributes in a gap-understorey mosaic.-P.J.Jarvis
Available from: Liang Lü
- "These processes initiate a dynamic succession from a gap phase characterized by little or no canopy to a mature phase with closed canopy (Whitmore 1978, Ulanova 2000, Bouget and Duelli 2004). The forest gap phase is always associated with rapid plant growth and colonization (Burton and Mueller-Dombois 1984, Denslow 1987) as well as increased flower and fruit production (Levey 1988, Smith et al. 1992), which can affect plant growth strategies (Coley 1983, 1993; Gorham et al. 2002; Cavieres and Fajardo 2005; Norghauer et al. 2008), forest regeneration cycles (Denslow 1987, Oliver and Larson 1990), and the spatio-temporal distribution of plants and the animals that interact with them (Schemske and Brokaw 1981, Harrison 1987, Brokaw and Scheiner 1989, Greenberg 2001). Although forest gaps also have the potential to influence the dynamics of animal communities, the response of animal communities to forest gaps has not been as well studied as the responses of plant communities (but see: Schemske and Brokaw 1981; Koivula and Niemelä 2003; Bouget 2005a,b; Patrick et al. 2012). "
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ABSTRACT: Periodic natural disturbances shape the mosaic character of many landscapes and influence the distribution and abundance of organisms. In this study, we tested the effect of ice storm- induced treefall gaps on ground-dwelling beetle assemblages in different-aged successional stands of subtropical broad-leaved forest in southeastern China. We evaluated the relative importance of gap-phase microhabitat type (within gap, gap edge, and interior shaded) within different stand ages (regenerating stands and mature stands) as determinants of changes in beetle diversity and community structure. At 18 replicate sites sampled during 2009-2010, no significant differences were found in species richness and the abundances of the most common beetle species captured in pitfall traps among the three gap-phase microhabitat types, but the abundances of total beetles, as well as fungivorous and phytophagous species groups, were significantly lower in gap microhabitats than in interior shaded microhabitats in mature stands. Beetle assemblage composition showed no significant differences among the three microhabitat types, and only the fauna of gap plots slightly diverged from those of edge and shaded plots in mature stands. Cover of shrubs and stand age significantly affected beetle assemblage structure. Our results suggest that beetle responses to gap-phase dynamics in early successional forests are generally weak, and that effects are more discernible in the mature stands, perhaps due to the abundance responses of forest-specialist species.
Environmental Entomology 09/2015; DOI:10.1093/ee/nvv140 · 1.30 Impact Factor
Available from: Grizelle González
- "Many factors may concomitantly affect the levels of tree mortality and resilience, including the intensity of the hurricane, the local disturbance regime (including hurricane frequency), and the biotic and abiotic characteristics of the forest (Everham and Brokaw 1996). Because both light (Denslow 1987) and nutrients (Vitousek and Sanford 1986) are well known factors that limit tropical tree growth, canopy openness and debris deposition are two of the most likely factors that affect forest succession following hurricanes (Lodge et al. 1991, Brokaw et al. 2012). As a result of a focus on plants and plant recovery, few studies have linked the effects of hurricanes on vegetation and habitat alteration to the subsequent effects on animals, microbes, or ecosystem processes. "
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ABSTRACT: Intense hurricanes disturb many tropical forests, but the key mechanisms driving post-hurricane forest changes are not fully understood. In Puerto Rico, we used a replicated factorial experiment to determine the mechanisms of forest change associated with canopy openness and organic matter (debris) addition. Cascading effects from canopy openness accounted for most of the shifts in the forest biota and biotic processes, which included increased plant recruitment and richness, as well as the decreased abundance and diversity of several animal groups. Canopy opening decreased litterfall and litter moisture, thereby inhibiting lignin-degrading fungi, which slowed decomposition. Debris addition temporarily increased tree basal area. Elevated soil solution nitrate was a dominant response after past hurricanes; this effect only occurred in our experiment with simultaneous canopy-opening and debris treatments. Although debris is an important carbon and nutrient source, short-term responses to cyclonic storms appear to be largely driven by canopy opening.
BioScience 09/2015; 65:871-881. DOI:10.1093/biosci/biv111 · 5.38 Impact Factor
Available from: revistas.inia.es
- "Canopy gaps, known as spatial and temporal environmental heterogeneity in forests (Denslow, 1987; Connell, 1989; Ostertag, 1998), facilitate the establishment and growth of understory vegetation (Ehrenfeld, 1980; Huenneke, 1983) by creating new open spaces and releasing resources (Gray & Spies, 1997; McGuire et al., 2001; De Chantal et al., 2003). Gaps are favorable not only for light-demanding species like bamboos and shrubs (Taylor & Qin, 1988a), but also for shadetolerant coniferous regeneration as well (Gaudio et al., 2008). "
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ABSTRACT: Aim of study: to study the effects of gap size, gap age and bamboo Fargesia denudata on natural regeneration of Abies faxoniana, both of which are the ubiquitous dominants in our research area.Area of study: subalpine coniferous forests in Wanglang Natural Reserve in Southwestern China.Material and Methods: 10 transect belts were randomly established, and a total of 97 gaps were recorded and used.Main results: (1) the number of bamboos with coverage of <17% significantly increased with increases of gap size and age, but the latter had little influence on the numbers of F. denudata with coverage of >17%. (2) F. denudata strongly inhibited A. faxoniana seedlings and saplings in small, young and old gaps, where the amount of A. faxoniana recruitment was relatively abundant, than in other types of gap. (3) The numbers of A. faxoniana seedlings in A-gaps, significantly decreased with the increases in gap size. However, in gaps where F. denudate was also present, A. faxoniana seedlings and saplings were insensitive to gap size or age. Research highlights: thick F. denudata would not be influenced by gap size or age. Because of the low occurrences of A. faxoniana seedlings and saplings, the negative effect of gap size, gap age and F. denudata on A. faxoniana recruitment was unclear.Key words: Abies faxoniana; Fargesia denudata; gap age; gap size; regeneration.
Forest Systems 07/2015; 24(2):e025. DOI:10.5424/fs/2015242-06682 · 0.80 Impact Factor
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