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Sabrina Dookie

  • Biodiversity Journal, 14 (4): 0775-0789

    Sabrina Dookie, Sirpaul Jaikishun & Abdullah Adil Ansari
    Mangrove tree growth, diversity, and distribution in tropical coastline ecosystems
    https://doi.org/10.31396/Biodiv.Jour.2023.14.4.775.789

    ABSTRACT
    Mangrove trees are subject to several environmental stresses, often associated with the prevailing conditions of their ecosystems. We analysed the density, diversity, distribution, and biophysical measurements of more than 900 trees throughout nine natural, degraded, and restored tropical coastline ecosystems in Guyana. A one-year period of systematic sampling was carried out using the point-centred quarter method (PCQM) throughout two clearly defined wet and dry seasons. Significant variations in the distribution, diversity, and spatial arrangement of trees were observed within both the restored and degraded mangrove habitats. The study revealed notable discrepancies in the biophysical measurements of trees [df = 8, p < 2.2e-16], which were further found to have positive correlations [p < 0.05, rs < 0.5] and relationships with their corresponding ecosystem types. The presence of substantial tree species with larger growth measurements in both natural and restored ecosystems indicate a heightened capacity for ecological resistance and resilience in the face of environmental stresses, in contrast to the degraded ecosystems that now exhibit states of vulnerability due to low ecological resistance and resilience attributed to prevailing anthropogenic disturbances.

  • Biodiversity Journal, 14 (4): 0571-0584

    Sabrina Dookie, Sirpaul Jaikishun & Abdullah Adil Ansari
    Morphological traits and chlorophyll content of Laguncularia racemosa leaves in two ecosystem types along the coastline of Guyana
    https://doi.org/10.31396/Biodiv.Jour.2023.14.4.571.584

    ABSTRACT
    Coastline ecosystems are resilient, and the mangrove species that inhabit them are well-suited to deal with harsh environmental stresses. Mangrove leaves are specialised plant structures that enable them to preserve their photosynthetic capability and functionality despite frequent changes in their habitats. Along the coastline of Guyana, we studied the morphological characteristics and chlorophyll content of 400 leaves taken from Laguncularia racemosa (L.) C.F. Gaertn., 1807 (Myrtales Combretaceae) trees found in Number 6 Village and Wellington Park mangrove ecosystems. The nearest individual sampling method was utilised to sample leaves throughout the wet and dry seasons. Our results demonstrate that Laguncularia racemosa leaves are mesophyllous, and leaf characteristics such as length, width, area, perimeter, mass, leaf specific area, and relative water content differed between the two ecosystem types, in both seasons. Significant correlations between leaf parameters were documented (p < 0.05, R > 0.75), with the Number 6 Village ecosystem during the dry season and the Wellington Park ecosystem during the wet season having greater values. Differences in chlorophyll content were also seen in the two types of ecosystems, but not seasonally. The results of our study suggest, to some extent, that plant structures can exhibit site-specific characteristics to preserve their survivability in different ecosystem types.