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Leaf Flush (leaf + flush)

Distribution by Scientific Domains

Life Sciences	75%

Selected Abstracts

Phenological patterns in monsoon rainforests in the Northern Territory, Australia

AUSTRAL ECOLOGY, Issue 5 2002
Christine Susanne Bach
Abstract Monsoon rainforests occur as scattered patches within a landscape dominated by eucalypt savannas across the wet,dry tropics of northern Australia. This study formed part of a larger project that investigated the interactions between frugivores and monsoon rainforest patches in the Top End of the Northern Territory. Phenological patterns in a set of 12 wet monsoon forests (WMF) and four dry monsoon forests (DMF) were examined by monitoring individuals of more than 100 species over 30 months. Phenological patterns of both WMF and DMF were closely related to the strongly seasonal climate. Leaf flush occurred before the onset of the wet season in WMF, and coincided with the onset of the wet in DMF. Major flowering peaks coincided with leaf flush in both forest types. Fruiting was concentrated in the wet season in both forest types, but fruiting peaks of WMF and DMF were separated by 3,4 months. Variations in fruiting patterns among forest types, patches, seasons and groupings of plant species (based on life form and ecological positioning) provide a mosaic of food resources for frugivores. This has important implications for the conservation and maintenance of the frugivore,rainforest system in northern Australia. [source]

Occurrence of Appias albina albina (Boisduval, 1836) (Lepidoptera: Pieridae: Pierinae) in northern Australia: phenotypic variation, life history and biology, with remarks on its taxonomic status

ENTOMOLOGICAL SCIENCE, Issue 2 2010
Michael F. BRABY
Abstract Variation in adult phenotype, the life history and general biology of the "White Albatross", Appias albina albina (Boisduval, 1836), are described and illustrated from the monsoon tropics of the northern Australia for the first time. Like elsewhere throughout the species' wide geographical range, the population exhibits sex-limited polymorphism, with females having three distinct color morphs (white, yellow, intermediate). Variation within and among these morphs is compared with populations from elsewhere in South-East Asia, particularly Maluku (including the type locality Ambon), and comments are made on the taxonomic status of the Australian population. The species inhabits coastal semi-deciduous monsoon vine-thicket where its larval food plant Drypetes deplanchei (Brongn. & Gris) Merr. (Euphorbiaceae) grows on lateritic edges and cliffs. The early stages and behaviour are compared with those of A. albina pancheia Fruhstorfer, 1910 from South-East Asia and A. paulina ega (Boisduval, 1836) from Australia. Adults are highly seasonal, their timing of appearance coinciding with annual leaf flush of the larval food plant and onset of the summer monsoon. During this period, the broad flight season lasts about two months, the life cycle is completed in approximately four weeks, and the species is probably univoltine or partially bivoltine. We conclude that breeding populations of A. albina albina in Australia are resident, but it remains to be established how the species survives the long dry season. [source]

Leaf green-up in a semi-arid African savanna -separating tree and grass responses to environmental cues

JOURNAL OF VEGETATION SCIENCE, Issue 4 2007
S. Archibald
Abstract Question: Can satellite time series be used to identify tree and grass green-up dates in a semi-arid savanna system, and are there predictable environmental cues for green-up for each life form? Location: Acacia nigrescens /Combretum apiculatum savanna, Kruger National Park, South Africa (25° S, 31° E). Methods: Remotely-sensed data from the MODIS sensor were used to provide a five year record of greenness (NDVI) between 2000 and 2005. The seasonal and inter-annual patterns of leaf display of trees and grasses were described, using additional ecological information to separate the greening signal of each life form from the satellite time series. Linking this data to daily meteorological and soil moisture data allowed the cues responsible for leaf flush in trees and grasses to be identified and a predictive model of savanna leaf-out was developed. This was tested on a 22-year NDVI dataset from the Advanced Very High Resolution Radiometer. A day length cue for tree green-up predicted 86% of the green-ups with an accuracy better than one month. A soil moisture and day length cue for grass green-up predicted 73% of the green-ups with an accuracy better than a month, and 82% within 45 days. This accuracy could be improved if the temporal resolution of the satellite data was shortened from the current two weeks. Conclusions: The data show that at a landscape scale savanna trees have a less variable phenological cycle (within and between years) than grasses. Realistic biophysical models of savanna systems need to take this into account. Using climatic data to predict these dynamics is a feasible approach. [source]