Tree diversity, composition and stand structure across postlogged lowland tropical forest on Santa Isabel, Solomon Islands. (2020)
Type of ContentTheses / Dissertations
Degree NameMaster of Forestry Science
PublisherUniversity of Canterbury
The rate of deforestation in the Solomon Islands is alarming with more than half of the nation's primary commercial forest resource having already been subject to timber harvesting leaving behind extensive areas of degraded forest without current management. This study aims to determine the species composition, tree species diversity and stand structure of the post-logged lowland tropical forest on Isabel Island, Solomon Islands. In this study, I compared the species composition, tree diversity and stand structure of the understory saplings and canopy trees in an unlogged forest and forests that were logged 3-years and 20-years ago to assess the recovery dynamics of these forest after selective timber harvesting.
A total of 168 different tree species from 92 genera and 43 families were identified in all the forest categories. The total number of species identified across the three forest types were 95, 110 and 116 in the 3-year-old forest, the 20-year-old forest and the unlogged forest, respectively. This study determined that even 20-years after timber harvesting, the tree community composition in the post- logged forests has not recovered for both the saplings and canopy vegetation. Tree diversity for saplings and canopy trees in the 3-year-old logged forest was significantly lower than the unlogged forest. Tree species richness was significantly higher for the saplings but considerably lower for the canopy vegetation in the 3-year logged forest. However, tree species diversity and richness for the sapling and canopy vegetation in the older 20-year-old logged forest were more similar to the unlogged state.
In terms of stand structure, there is rapid regeneration of pioneer trees dominated by Macaranga species in the newly logged (3-years) forest which has a considerably high stem density and basal area in the understory saplings compared to the saplings of the old logged (20-years) forest and the unlogged forest. Stem density for the canopy vegetation of the 3-year-old logged forest was significantly lower while the 20-year-old forest stem density did not differ to that of the unlogged forest. With increasing diameter class, the stem density reduced for the mature commercial tree species in the 20-year-old logged forest compared to the unlogged forest. This study shows that stem density for mature trees DBH ≥ 60 cm in the two logged forest was considerably reduced. Basal area of the canopy trees in the logged forest was also significantly lower compared to the unlogged forest. This highlights that timber harvesting has dramatically reduced the commercial tree species and timber stocking in the lowland forest in Isabel Island, which requires more than two decades for the forest to replenish for another commercial crop.
Managing the forest resources for the logged and unlogged forest is crucial for continuous provision of forest goods and services. I suggest that communities and resource owners can utilise and manage their forest through a number of management strategies such as land-use planning, small-scale sawmilling and enrichment planting. Land-use planning ensures resource owners properly assess the forested land and its potential for various land uses. Emphasis on allowing ample time for the forest to recover after initial logging before the next harvesting is paramount to ensure restocking and the continuous supply of timber. Small-scale sawmilling and enrichment planting are equally vital for sustainable harvesting of timber and to established mature-phase and diverse tree species that support resilient forest communities.
RightsAll Right Reserved
Showing items related by title, author, creator and subject.
Structure and dynamics of lowland podocarp-broadleaved forest in the Central North Island, New Zealand : the effects of different silvicultural regimes on stand structure and tree species composition. Roschak, Christian (University of Canterbury, 2017)Podocarp-broadleaved forests and their alliances form one of the largest forest groups in New Zealand and cover an area of approximately 2.9 million hectares. Their vast exploitation and deterioration in the past 150 years ...
Keremama, Milton; Holland, Elizabeth; Khan, MGM; Hiriasia, David; Tahani, Lloyd (Macmillan Brown Centre for Pacific Studies, 2019)Past climatological studies .use only one or two local stations to describe the full climate of Solomon Islands. In this paper, we examined all available daily minimum and maximum surface air temperature data between 1951 ...
Lyons, Kristen; Walters, Peter; Shewring, Annabel (Macmillan Brown Centre for Pacific Studies, 2019)Climate change is widely recognised as one of the biggest threats to livelihoods, security and wellbeing in the Pacific. Carbon markets represent one of a number of global responses, with projects expanding across the ...