			Home About us Contact

Rain Forest Tree (rain + forest_tree)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Phenology of Atlantic Rain Forest Trees: A Comparative Study,

BIOTROPICA, Issue 4b 2000
L. Patnicia C. Morellato
ABSTRACT This paper describes the phenology of leaf, flower, and fruit phenology in the Atlantic rain forests of southeastern Brazil. For 17 months, we observed the phenological patterns of trees from two Atlantic forest types at four sites: premontane forest (Sites I and IV; the "typical" Atlantic rain forest) and coastal plain forest (Sites II and III). All sites experience a nonseasonal, tropical wet climate, characterized by an annual rainfall usually > 2000 mm and lacking a dry season. We tested for the occurrence (or absence) of seasonal phenological patterns within each site and compared the patterns detected among the four different forest sites using circular statistics. The expected weakly seasonal phenological patterns were not observed for these forests. Flowering and leaf flush patterns of Atlantic rain forest trees were significantly seasonal, concentrated at the beginning of the wettest season, and were significantly correlated with day length and temperature. These results stress the influence that seasonal variation in day length has on ever-wet forest tree phenology. Fruiting phenologies were aseasonal in all four forests. Flowering patterns did not differ significantly among three of the four forest sites analyzed, suggesting the occurrence of a general flowering pattern for Atlantic rain forest trees. RESUMO Este estudo descreve, pela primeira vez, a fenologia reprodutiva (flora¸ão e frutifica¸ão) e a mudan¸a foliar em floresta pluvial atlãntica do sudeste do Brasil. Durante 17 meses foi observada a fenologia das árvores de dois tipos de floresta atlãntica: a floresta atlãntica de encosta (áreas I e IV; Floresta atlãntica "típica") e floresta de planície (áreas II c III). Todas ás áreas estão sob clima não-sazonal, tropical úmido, caracterizado por precipita¸ão anual geralmente superior a 2000 mm e ausência de esta¸ão seca. Foi testada a ocorrência (ou ausência) de padrões fenológicos sazonais dentro de cada área e comparados os padrões detectados entre as quatro diferentes áreas de floresta utilizando-se da análise estatística circular. O padrão fenológico fracamente sazonal, esperado neste tipo de vegeta¸ão, não foi observado para as florestas estudadas. A flora¸ão e o brotamento foram significativamente sazonais, concentrados durante o início da esta¸ão úmida, e apresentaram correla¸ão significativa com o comprimento do dia e temperatura. Estes resultados expressam a importãncia da luz na fenologia de árvores tropicais sob clima pouco sazonal. A frutifica¸ão não apresentou padrão sazonal para todas as áreas de floresta analisadas. Os padrões de flora¸ão não diferiram significativamente entre três das quatro áreas de floresta analisadas, sugerindo a ocorrência de um padrão de flora¸ão geral para as árvores de floresta atlãntica. [source]

Reproduction in Wild Populations of the Threatened Tree Macadamia tetraphylla: Interpopulation Pollen Enriches Fecundity in a Declining Species

BIOTROPICA, Issue 3 2009
Philip C. Pisanu
ABSTRACT Macadamia tetraphylla is a subtropical rain forest tree from fragmented lowlands in eastern Australia. Owing to habitat loss and fragmentation, this commercially important species is vulnerable to extinction. Breeding system and fecundity were investigated in nine populations incorporating three habitat types (moderately disturbed, highly disturbed, and intact) to determine if seed set, seed weight, and genetic diversity are compromised by disturbance. Breeding success was also tested using pollen donors from distant (30,100 km), local (2,3 km), neighbor (10,20 m), and near-neighbor (< 10 m) sources. Macadamia tetraphylla is weakly self-compatible but incapable of automatic self-pollination. Across populations, seed to flower ratios were always < 0.1 percent in open-pollinated trees and trees from moderately disturbed habitats had the highest fruit production. Outcross pollen produced more seed per raceme than open-pollinated or self-pollination treatments. Seed set and seed weights were positively influenced by pollen source with local pollen and distant pollen effecting more or heavier seeds. Germination rates and genetic diversity did not vary significantly in seedlings from different pollen sources. Results suggest a pollen source from at least a 2 km distance is an optimal outbreeding distance; however, many wild populations do not have conspecifics at optimal distances owing to habitat fragmentation. Highly disturbed populations are producing seed but the longevity of these sites is threatened by weed invasions. We conclude that small populations in degraded habitats that are at risk of being overlooked should not be ignored but should be a focus for restoration efforts as they are a valuable asset for the conservation of M. tetraphylla. [source]

The Role of Cloud Combing and Shading by Isolated Trees in the Succession from Maquis to Rain Forest in New Caledonia1

BIOTROPICA, Issue 2 2002
L. S. Rigg
ABSTRACT This study examined the role of shading and cloud combing of moisture by scattered trees of the emergent conifer Araucaria laubenfelsii (Corbass.) in montane shrubland-maquis at Mont Do, New Caledonia, in facilitating the succession from shrubland to rain forest. Water collection experiments showed that these trees combed significant amounts of water from low clouds on days when no rainfall was recorded and deposited this moisture on the ground beneath the tree canopy. Analysis of photosystem II function in A. laubenfelsii and five other plant species using fluorometry revealed much lower photosystem stress in plants beneath scattered A. laubenfelsii than for individuals exposed to full sunlight in the open maquis. Transition matrix analyses of vegetation change based on "the most likely recruit to succeed" indicated that the transition from maquis to forest was markedly faster when emergent trees of A. laubenfelsii acted as nuclei for forest species invasion of die maquis. On the basis of these lines of evidence, it is argued that increased moisture and shading supplied to the area directly below the crown of isolated A. laubenfelsii trees in the maquis facilitates the establishment of both conifer seedlings and other rain forest tree and shrub species. In the absence of fire, rain forest can reestablish through spread in two ways: first, by expansion from remnant patches, and second, from coalescence of small rain forest patches formed around individual trees of A. laubenfelsii. [source]

Ecological aspects of seed desiccation sensitivity

JOURNAL OF ECOLOGY, Issue 2 2003
John C. Tweddle
Summary 1The ability of seeds to survive desiccation is an important functional trait and is an integral part of plant regeneration ecology. Despite this, the topic has received relatively little attention from ecologists. In this study, we examine the relationships between seed desiccation tolerance and two important aspects of plant regeneration ecology: habitat and dormancy. This is done by comparative analysis of a data set of 886 tree and shrub species from 93 families. 2The proportion of species displaying desiccation sensitive seeds declines as the habitat becomes drier, and possibly also cooler, although the latter observation requires cautious interpretation. Desiccation sensitivity is most common in moist, relatively aseasonal vegetation zones, but is infrequent in, though not absent from arid and highly seasonal habitats. 3The highest frequency of desiccation sensitivity occurs in non-pioneer evergreen rain forest trees, although 48% of the species examined have desiccation tolerant seeds. In contrast, all pioneer taxa within the data set have drying tolerant seeds. 4Desiccation sensitivity is more frequent in seeds that are non-dormant on shedding (c. 31%), than dormant (c. 9%). Highest frequencies of drying tolerance occur in seeds with physical or combinational dormancy, at 99% and 100%, respectively. 5Although there is an association between non-dormancy and desiccation sensitivity in both tropical and temperate zones, the relationship does not appear to be causal. 6Working from the hypothesis that seed desiccation sensitivity represents a derived state in extant species, we use the results to investigate and discuss possible ecological trade-offs and associated fitness advantages. These may explain the hypothesized repeated loss of this trait. The frequent association between large seed size and desiccation sensitivity is also considered. [source]