Sedative activity of stem bark of the Sri Lankan endemic plant, Vateria copallifera

An aqueous bark extract of Vateria copallifera showed marked sedative activity, which supports the therapeutic effects claimed by Sri Lankan traditional physicians.     

Antioxidant activity of water extract of Scoparia dulcis

An aqueous extract of Scoparia dulcis showed marked antioxidative activity in vitro, which supports the therapeutic effects claimed by traditional practitioners.     

Estimating above-ground biomass by fusion of LiDAR and multispectral data in subtropical woody plant communities in topographically complex terrain in North-eastern Australia

We investigated a strategy to improve predicting capacity of plot-scale above-ground biomass （AGB） by fusion of LiDAR and Land- sat5 TM derived biophysical variables for subtropical rainforest and eucalypts dominated forest in topographically complex landscapes in North-eastern Australia. Investigation was carried out in two study areas separately and in combination. From each plot of both study areas, LiDAR derived structural parameters of vegetation and reflectance of all Landsat bands, vegetation indices were employed. The regression analysis was carded out separately for LiDAR and Landsat derived variables indi- vidually and in combination. Strong relationships were found with LiDAR alone for eucalypts dominated forest and combined sites compared to the accuracy of AGB estimates by Landsat data. Fusing LiDAR with Landsat5 TM derived variables increased overall performance for the eucalypt forest and combined sites data by describing extra variation （3% for eucalypt forest and 2% combined sites） of field estimated plot-scale above-ground biomass. In contrast, separate LiDAR and imagery data, andfusion of LiDAR and Landsat data performed poorly across structurally complex closed canopy subtropical minforest. These findings reinforced that obtaining accurate estimates of above ground biomass using remotely sensed data is a function of the complexity of horizontal and vertical structural diversity of vegetation.     

Variation in canopy structure, light and soil nutrition across elevation of a Sri Lankan tropical rain forest

Mixed dipterocarp forests are perhaps the single most important rain forest type in the wet tropics. Only a few studies have purposefully examined differences in resource availability across mixed dipterocarp forest landscapes by simply measuring the abiotic variables of light, soil nutrition and soil water availability in relation to forest structure. We sought to directly measure the environment of canopy gaps across elevation and geology—from lowland mixed dipterocarp forest (100 m amsl) to lower montane dipterocarp forest (1200 m amsl) in southwest Sri Lanka. Middle elevation gap sites (300–900 m amsl) were subdivided into valley, mid-slope and ridge topographic positions. Eighteen natural disturbances all of which were canopy openings caused by tree fall, were randomly selected within primary rain forest that ranged across 100–1200 m elevation. Plots were placed in gap centers and in adjacent understories and measurements taken of forest structure (basal area, canopy height, canopy cover index, CCI), shade (light sensors—photosynthetically active radiation [PAR], canopy hemispherical photographs—global site factor [GSF]) and soil nutrition (pH, exchangeable Al, K, Mg and Ca; Total N; and plant available P). Soil moisture was measured at bi-weekly intervals for five years across middle elevation sites only (300–900 m amsl). Stand basal area, mean canopy height, and canopy cover index all declined with increase in elevation. Understory PAR and GSF decreased with increases in canopy height, basal area and CCI. Size of canopy opening decreased with increase in elevation, but PAR and GSF increased. Valley sites had significantly greater levels of mean percent soil water content as compared to mid-slope and ridge sites of middle elevation sites. However, at the onset of the southwest monsoons in May all sites were similar. Differences were most pronounced during the dry season (December–April). No differences in soil moisture content could be found between gap and understory microsites. K and Ca in gap centers and adjacent forest understories increased with increase in elevation and change in associated geology. pH increased and Al decreased with elevation and associated geology but only for forest understory conditions. Results demonstrate strong differentiation in soil and light resources with elevation that appears related to size of tree-fall disturbance, stature of the forest, topographic position and underlying geology and soil-weathering environment. This suggests that forest management and conservation practices need to develop and tailor techniques and treatments (silviculture) to the forest that emulate and/or account for change in elevation, geology and topographic position. Further studies are needed to identify which are the primary underlying mechanisms (e.g. temperature, wind, soil nutrients, soil moisture availability) defining change in forest structure across elevation.