Regeneration and Pattern in the Subtropical Rain Forest

Webb, L. J.; Tracey, J. G.; Williams, W. T.

doi:10.2307/2258559

Cited by 123 publications

(84 citation statements)

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“…A maioria das populações de plantas mostra uma distribuição com predominância de indivíduos nas classes menores e poucos nas maiores (Solbrig 1981). Este padrão pode ser explicado como sendo uma conseqüência da permanência de plântu-las nesta classe, por longos períodos, até ocorrer a queda de uma árvore ou uma alta mortalidade, que ocasionariam um crescimento rápido posterior (Webb et al 1972). C. brasiliense mostra este tipo de distribuição, que é um reflexo da ocorrência de maiores taxas de recrutamento e mortalidade nas classes menores, com progressiva redução nas maiores.…”

Section: Discussionunclassified

Estrutura e dinâmica de uma população de Calophyllum brasiliense Camb. em floresta higrófila do sudeste do Brasil

Marques¹,

Joly²

2000

Rev. bras. Bot.

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-(Population structure and dynamics of Calophyllum brasiliense Camb. in a swamp forest in Southeastern Brazil). Age and spatial structures of a population of Calophyllum brasiliense (Clusiaceae) were studied in a 3600 m 2 area of a swamp forest in Brotas, São Paulo State. During the first census, 1658 plants were tagged and after one year this number increased to 1706. Age structure did not change over the period of study, with a higher number of seedlings (individuals ≤ 0.2 m) and juveniles (> 0.2-2 m) and a smaller number of subadults (> 2-10 m) and adults (> 10 m). Seedling (29.7%) and juvenile (5.3%) mortality was caused, mainly, by soil erosion and deposition during the rainy season, because the plants were buried. Subadult (0.7%) and adult (0%) mortality was very low. A large number of new seedlings was concentrated in the lower parts of the study site and in soil depressions where the water carried seeds which were deposited and germinated. Recruitment rate for seedlings was high (48.1%), while for juvenile (7.3%), subadult (1.9%) and adult (0%) were much lower. Plants of all classes, from seedlings to adults, presented a clustered distribution due to the topography of the study site, which facilitates seed accumulation, and to a higher number of seeds under the canopy of reproductive individuals. Fruit dispersion by bats or water, seed survival under hypoxic conditions, seedling tolerance to waterlogging, age structure with a significant predominance of seedlings, and population growth explain why C. brasiliense is the most abundant species in the forest studied and also in other similar forests in Southeastern Brazil.Resumo -(Estrutura e dinâmica de uma população de Calophyllum brasiliense Camb. em floresta higrófila do sudeste do Brasil). As estruturas de tamanho e espacial de uma população de Calophyllum brasiliense (Clusiaceae) foram estudadas em uma área de 3600 m 2 de floresta higrófila localizada em Brotas, SP. No primeiro censo, foram marcados 1658 indivíduos e, após um ano, este número havia aumentado para 1706. A estrutura de tamanho não mudou durante o período de estudo, com predomínio de plântulas (indivíduos ≤ 0,2 m) e jovens (> 0,2-2 m) e menor número de subadultos (> 2-10 m) e adultos (> 10 m). A mortalidade em plântulas (29,7%) e jovens (5,3%) foi bem maior que em subadultos (0,7%) e adultos (0%), e teve como causa principal o soterramento na época chuvosa. O maior número de plantas novas concentrou-se nos locais mais baixos da área, onde sementes trazidas pela água eram acumuladas. A taxa de recrutamento de plântulas foi alta (48,1%), e a de jovens (7,3%), subadultos (1,9%) e adultos (0%), bem menores. Plantas de todas as classes de tamanho apresentaram distribuição espacial agregada, devido à topografia do terreno, que favorece o encharcamento do solo e o acúmulo de sementes, e à presença de sementes sob os adultos reprodutivos. Dispersão de frutos por morcegos ou pela água, capacidade de sobrevivência em condições hipóxicas, estrutura de tamanho com predomínio de plântulas e j...

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Section: Discussionunclassified

Estrutura e dinâmica de uma população de Calophyllum brasiliense Camb. em floresta higrófila do sudeste do Brasil

Marques¹,

Joly²

2000

Rev. bras. Bot.

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“…Even successional changes do not destroy the deterministic concept. Webb et al (1972), referring to the classic work of Watt (1947), point out that, in a monospecific temperate forest, once the dominant has begun to establish, 'there is only one path open, and such patchiness as exists is composed of different age-classes of one species'.…”

Section: The Community Concept In Terrestrial Ecologymentioning

confidence: 99%

“…These species are not arranged in the tidy blocks of temperate forests; as Aubreville (1938) remarked, they appear to consist of local, apparently random, assortments of species. Nor is there any evidence of regular, ordered succession; as Webb et al (1972) point out, 'the succession is characterized by departures from orderliness'. Such departures had been stigmatized by Gleason (1926) and Watt (1964) as f o r t u i t o u s , a n d b y Daubenmire (1968) a s u n p r ed i c t a b l e. Aubreville (1938), however, regarded the situation as analagous to linear algebra when the number of equations (environmental parameters) is less than the number of independent variables (plant species), so that an indefinite number of alternative solutions will fulfil1 the required conditions.…”

Section: The Community Concept In Terrestrial Ecologymentioning

confidence: 99%

“…Finally, Webb et al (1972), discussing Aubreville's thesis, pointed out that the solutions to his equations were never c o m p l e t e l y unpredictable, in that it was usually possible to define boundary conditions outside which the solution could not lie. They therefore postulated that the tropical rain forest has a two-level structure: a large-scale deterministic framework, largely climatically determined, and a small-scale patchiness which was entirely probabilistic, in that the species-composition of any given patch was determined by which species happened to be flowering at the time the canopy opened to permit regeneration.…”

Section: The Community Concept In Terrestrial Ecologymentioning

confidence: 99%

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The Community Concept and the Phytoplankton

Williams¹,

Bunt²,

John³

et al. 1981

Mar. Ecol. Prog. Ser.

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The community concept of terrestrial ecology is examined with particular reference to its application to phytoplankton dlstrlbutlon. It IS suggested that it is more appropriate to regard phytoplankton distribution as entirely probabilistlc, comparable to a local situation in a tropical rain forest. The oceans of the world would then be regarded collectively as a single essentially uniform environment ~nhabitated by a single diverse population. The probability of encountering any given species in any ocean might then be very low but would be nowhere zero. The thesis is examined mathematically with respect to data from the diatom literature, and its further in~plications are briefly discussed

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“…O padrão de distribuição diamétrica em J invertido registrado para a população estudada caracteriza-se pela diminuição da frequência, à medida que aumenta o tamanho da classe (SCOLFORO et al, 1998) e sugere que uma população estável e auto-regenerativa, havendo um equilíbrio entre mortalidade e recrutamento dos indivíduos. Padrões de crescimento inicial lentos também podem resultar em distribuições na forma de J invertido, devido à permanência dos indivíduos por longo período de tempo na mesma classe (WEBB et al, 1972).…”

Section: Resultados E Discussõesunclassified