Avian Seed Dispersal of Three Neotropical Gap‐Dependent Plants

Murray, K. Greg

doi:10.2307/1942541

Cited by 293 publications

(271 citation statements)

References 97 publications

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“…Gene flow by seed, however, is quite likely. W. solanacea fruits year-round; one of its primary dispersers at high elevations is Myadestes melanops (the Black-faced Solitaire; Murray, 1988), which migrates altitudinally into lowland forests when food is scarce in its montane breeding habitat (Stiles et al, 1989;Loiselle and Blake, 1991).…”

Section: Discussionmentioning

confidence: 99%

Rapid recent radiation of S-RNase lineages in Witheringia solanacea (Solanaceae)

Stone

Pierce

2005

Heredity

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Strong frequency-dependent selection as found in the selfincompatibility loci of flowering plants maintains allelic lineages for extremely long time scales, such that allelic genealogies can shed insight into long-term demographic patterns of species. Effective mutation rate, as well as demographic change such as population bottlenecks, can influence genealogical structure. In addition, loss of functionality at the self-incompatibility locus is likely to affect radiation rates. Partial sequences for 21 S-RNase alleles of the mid-elevation tropical species Witheringia solanacea were obtained in order to compare their substitution rates and genealogy with those of Witheringia maculata and two species in the closely related genus Physalis. Sequences for W. solanacea fell into the three clades within the Solanaceae already identified for the genus. Terminal branch lengths for W. solanacea, scaled to the total depth of its phylogeny, were intermediate between the unusually short terminal branches of W. maculata and those of the two Physalis species. In contrast to the Physalis species, where interspecific d N /d S for closely related alleles exceeded 1.0 to the same degree as did intraspecific d N /d S , in Witheringia only intraspecific comparisons showed an excess of nonsynonymous substitutions, suggesting postspeciation radiation of alleles. Alleles associated with lowered S-RNase production and self-compatibility showed extremely short terminal branches. In summary, it appears that rapid recent diversification of alleles characterizes the Witheringia lineages. In some cases, this rapid diversification can be attributed to relaxed constraints due to breakdown of selfincompatibility. Heredity (2005) 94, 547-555.

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Section: Discussionmentioning

confidence: 99%

Rapid recent radiation of S-RNase lineages in Witheringia solanacea (Solanaceae)

Stone

Pierce

2005

Heredity

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“…A limitação da chuva de sementes pode ocorrer basicamente devido à redução da densidade de matrizes, alterações sobre a sazonalidade de frutificação das espécies e ausência de fauna dispersora (MURRAY, 1988;WILBY;SHACHAK, 2000). Em áreas abertas, como extensas pastagens, poucas espécies arbóreas nativas são encontradas e a menor disponibilidade de sementes é atribuída à baixa densidade da população de árvores (REIS; BECHARA; TRES, 2010).…”

Section: Barreiras à Dispersão De Sementesunclassified

Barreiras Ao Estabelecimento Da Regeneração Natural Em Áreas De Pastagens Abandonadas

Fragoso¹,

Carpanezzi²,

Koehler³

et al. 2017

Ciênc. Florest.

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RESUMOA pressão exercida sobre as florestas tropicais devido à fragmentação de paisagens naturais tem causado alterações no padrão de substituição das espécies presentes na comunidade vegetal. No caso de pastagens abandonadas, verifica-se uma maior vulnerabilidade do ambiente à colonização por gramíneas exóticas invasoras, as quais representam uma barreira ao estabelecimento de plantas nativas, desde a dispersão e germinação das sementes, até estádios mais avançados do seu desenvolvimento. Em vista disso, propôs-se discorrer sobre alguns dos processos da regeneração natural em áreas de pastagens, abordando aspectos que impedem o recrutamento de espécies lenhosas desejáveis e, nesse contexto, a exposição de algumas metodologias embasadas no conceito de nucleação que podem auxiliar nesse processo. Por meio da compreensão dos mecanismos envolvidos na manutenção das comunidades vegetais, verifica-se que a germinação de sementes e o recrutamento de plântulas são passos cruciais do processo de restabelecimento da vegetação. Como apenas uma estreita faixa de condições é adequada (safe sites) ao recrutamento, o sucesso da regeneração está relacionado à capacidade do ambiente em proporcionar um leito adequado para germinação de sementes (seedbed). A utilização de metodologias que visem à regeneração natural, para serem eficazes em áreas de pastagens, devem ser bem estabelecidas tecnicamente e adequadas à realidade local, pois, embora apresentem resultados iniciais promissores, podem deixar de ser efetivas com o passar do tempo. Palavras-chave: gramíneas inibidoras; nucleação; sítio seguro; cama de sementes. ABSTRACTThe pressure on rainforests due to fragmentation of natural landscapes has caused changes in the substitution pattern of the species present in the plant community. In the case of abandoned pastures, there is an increased environmental vulnerability to colonization by invasive exotic grasses, which represent a barrier to the establishment of native plants, since the dispersion and seed germination until the later stages of their development. We proposed to discuss some of the processes of natural regeneration in pastures, addressing issues that hinder the recruitment of desirable woody species and, in this context, the exposure of some methodologies based on the concept of nucleation that can help this process. Through understanding of the mechanisms involved in the maintenance of plant communities, we observed that the seed germination and seedling recruitments are crucial steps in the process of vegetation restoration. Because only a narrow range

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“…Using CLAS satellite data products on selective logging extent, combined with new subpixel satellite observations of forest canopy gap fraction, we quantified the spatial distribution of forest damage levels throughout Ͼ46,000 km 2 of logged forest distributed across 2,030,637 km 2 of the Brazilian Amazon, and we tracked the rates of canopy closure after timber harvest. Canopy gap fraction is used here, because it determines the immediate and long-term impacts of logging by regulation of key processes such as photosynthetic rates and primary production; canopy energy and water balance; mammal and insect behavior; population dynamics; and, critically, the probability of fire (9,(20)(21)(22)(23) …”

mentioning

confidence: 99%

Condition and fate of logged forests in the Brazilian Amazon

Asner

Broadbent

Oliveira

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

307

216

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The long-term viability of a forest industry in the Amazon region of Brazil depends on the maintenance of adequate timber volume and growth in healthy forests. Using extensive high-resolution satellite analyses, we studied the forest damage caused by recent logging operations and the likelihood that logged forests would be cleared within 4 years after timber harvest. Across 2,030,637 km 2 of the Brazilian Amazon from 1999 to 2004, at least 76% of all harvest practices resulted in high levels of canopy damage sufficient to leave forests susceptible to drought and fire. We found that 16 ؎ 1% of selectively logged areas were deforested within 1 year of logging, with a subsequent annual deforestation rate of 5.4% for 4 years after timber harvests. Nearly all logging occurred within 25 km of main roads, and within that area, the probability of deforestation for a logged forest was up to four times greater than for unlogged forests. In combination, our results show that logging in the Brazilian Amazon is dominated by highly damaging operations, often followed rapidly by deforestation decades before forests can recover sufficiently to produce timber for a second harvest. Under the management regimes in effect at the time of our study in the Brazilian Amazon, selective logging would not be sustained.Brazil ͉ forest disturbance ͉ remote sensing ͉ selective logging ͉ tropical forest S atellite observations show that deforestation, defined here as clear-cutting of forests for pasture, agricultural, urban, and other uses, is a major force of ecological change throughout tropical regions (1). The pattern and process of deforestation have thus received considerable attention in ecological, socioeconomic, and policy studies (2, 3). Other human-caused forest disturbances, such as from selective timber harvesting and fire, are also common in tropical forests (4-7).Selective logging is an economically important land use that results in less forest damage than deforestation, but the amount of canopy damage associated with logging can leave tropical forests highly susceptible to drought and fire (5,(8)(9)(10)(11). If canopy damage levels are low, then selective logging has relatively small immediate and long-term impacts on forest resources (12, 13). If damage levels are high, however, then fundamental ecological processes (e.g., regeneration and succession) can be radically altered (14-18). Moreover, deforestation has long been associated with logging according to the theory of ''invasive forest mobility'' (19), whereby logging roads permit settler access into forests (3). However, neither the amount of forest disturbance caused by selective logging nor the amount of logged forest converted to cleared land has been directly quantified over large regions of tropical forest.Selective logging is a diffuse but ubiquitous forest disturbance that occurs throughout the Brazilian Amazon. Using the Carnegie Landsat Analysis System (CLAS; see Supporting Text, which is published as supporting information on the PNAS web site), we have shown ...

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Avian Seed Dispersal of Three Neotropical Gap‐Dependent Plants

Cited by 293 publications

References 97 publications

Rapid recent radiation of S-RNase lineages in Witheringia solanacea (Solanaceae)

Rapid recent radiation of S-RNase lineages in Witheringia solanacea (Solanaceae)

Barreiras Ao Estabelecimento Da Regeneração Natural Em Áreas De Pastagens Abandonadas

Condition and fate of logged forests in the Brazilian Amazon

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