Next, a time series consisting of the coefficients of determination (R²) for the NDVI/tree-cover linear regression were computed for the 100 polygons. Secondly, percentage tree-cover data for 100 sample polygons (4 × 4) pixels for areas that have not undergone change in tree cover between 20 were derived using high resolution Google Earth imagery. First, a 16-day NDVI time series was generated from MODIS NDVI data, i.e. annual NDVI profiles of grasses and trees in these semi-arid landscapes provide an opportunity to estimate percentage tree-cover by determining the period of maximum contrast between grasses and trees. The varying proportions of tree and herbaceous cover in the grassland and savanna biomes of Southern Africa determine their capacity to provide ecosystem services. Further experiments are needed to assess whether there is a viability of the root system after shoot senescence due to extreme drought. The water deficit affected the growth and metabolism of comfrey plants, but adjustments in photosynthetic apparatus and increased dry mass productivity indicated a possible adjustment to severe drought. The plant aerial parts were more visually affected than the roots, which showed secondary growth after the water restriction imposition, a possible response of tuberization to drought. Photochemical activities were affected in the first days, with less intensity on the seventh day for the photosystem II performance index (PIabs). Symptoms of water deficit were evident from the third day onwards, such as leaf wilt and senescence of a greater quantity of leaves, as well as reduction of stomatal conductance. Climatological data, growth parameters, pigment content, stomatal conductance, chlorophyll a fluorescence, Normalized Difference Vegetation Index, plant morphological responses, and anatomical differences of roots were evaluated. We aimed to assess the morphophysiological responses of comfrey to short-term severe water restriction (seven days) and to a control treatment under irrigation. On the growing conditions and physiological responses of this plant to stress are scarce. This review represents the first attempt to gather this information together in one place.Symphytum officinale, comfrey, is a medicinal plant known for its healing properties. Based on these results, patents have been obtained and drugs have been developed. Of these 23% were bioactive, as compared to 11% of the non-endemics. Only 31 of the plants tested at UWI are endemic to Jamaica. At least 29 of these NPs were found to be bioactive. Crude extracts from 80 of these plants have reasonable bioactivity and natural products (NP) have been identified from 44 plants. At least 334 plant species growing in Jamaica have been identified as having medicinal qualities, 193 of these have been tested for their bioactivity. Natural product research on Jamaican medicinal plants began with the inception of UWI in 1948, leading to many postgraduate degrees being awarded (22 MPhil and 31 PhD). The plants identified as being medicinal are listed along with their folk use and a summary of the scientific research done at UWI leading to the identification of natural products (NPs) and determination of their bioactivity. This review summarizes research carried out on Jamaican medicinal plants at the Faculty of Pure and Applied Science, The University of the West Indies (UWI), Mona, Jamaica, between 19.
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