Farmed landscapes, trees and forest conservation in Saint Lucia (West Indies)

2012 ◽  
Vol 40 (3) ◽  
pp. 211-221 ◽  
Author(s):  
BRADLEY B. WALTERS ◽  
LISA HANSEN

SUMMARYIslands of the West Indies are among the most historically impacted by agriculture, yet agricultural influences on forests there have been little studied. This research compared tree species richness and vegetation structure between farmed lands, post-agriculture secondary forests and mature remnant forests in two watersheds in Saint Lucia, and sought to understand the current distribution of these habitats in terms of land use and watershed topography. Farms devoted to annual crops had few trees and much exposed soil. By contrast, agroforests had abundant (mostly planted) trees and vegetation structure comparable to secondary forests. Secondary forests had highest overall species richness, but mature forests had the most developed vegetation structure. Variations in habitat distribution reflected different land use histories, with the more rugged west coast long dominated by tree crop farming and the east coast experiencing a recent boom-bust cycle in bananas. Mature and secondary forests were more likely found at higher altitude, further from roads and at sites more difficult to access, the combined result of government protection of key forest and watershed reserves and farmers’ preferential abandonment of marginal lands. For conservationists, this return of forests is reason for optimism and it presents strategic opportunities for public land acquisition or collaborative management to further forest and watershed protection objectives.

2016 ◽  
Vol 33 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Anu Valtonen ◽  
Geoffrey M. Malinga ◽  
Margaret Nyafwono ◽  
Philip Nyeko ◽  
Arthur Owiny ◽  
...  

Abstract:The relative importance of different bottom-up-mediated effects in shaping insect communities in tropical secondary forests are poorly understood. Here, we explore the roles of vegetation structure, forest age, local topography (valley vs. hill top) and soil variables in predicting fruit-feeding butterfly and tree community composition, and tree community composition in predicting fruit-feeding butterfly community composition, in different-aged naturally regenerating and primary forests of Kibale National Park, Uganda. We also examine which variables are best predictors of fruit-feeding butterfly species richness or diversity. Butterflies (88 species) were sampled with a banana-baited trap and trees (98 taxa) with a 40 × 20-m sampling plot at 80 sampling sites. The environmental variables explained 31% of the variation in the tree community composition, the best predictors being local topography, forest age and cover of Acanthus pubescens (a shrub possibly arresting succession). The fruit-feeding butterfly community composition was better predicted by tree community composition (explaining 10% of the variation) rather than vegetation structure, local topography or soil factors. Environmental variables and tree species richness (or diversity) were poor predictors of butterfly species richness (or diversity). Our results emphasize the importance of tree community to recovery of herbivorous insect communities in tropical secondary forests.


2021 ◽  
Vol 120 ◽  
pp. 106929 ◽  
Author(s):  
Saskia Dröge ◽  
Dominic Andreas Martin ◽  
Rouvah Andriafanomezantsoa ◽  
Zuzana Burivalova ◽  
Thio Rosin Fulgence ◽  
...  

2018 ◽  
Vol 66 (4) ◽  
pp. 1481
Author(s):  
Ernesto Gómez Cardozo ◽  
Guillaume Xavier Rousseau ◽  
Danielle Celentano ◽  
Heriberto Fariñas Salazar ◽  
Christoph Gehring

Diverse agroforestry systems conciliate food production, biodiversity conservation, and the provision of ecosystem services as atmospheric carbon sequestration. However, the role of floristic richness in the production of biomass in these systems is not clear. This study evaluated the effect of species richness and vegetation structure on aboveground biomass carbon in different agroforestry systems in the Southern Amazon of Bolivia. For that, 25 agroforestry systems and 4 secondary forests were studied in the departments of Santa Cruz and Beni. In each system, a 1 963 m2 circular plot was installed, where the vegetation (trees, shrubs and herbaceous) and necromass (leaf litter, branches and dead trees) were sampled. Linear and logarithmic functions were used to evaluate the effect of vegetation richness and structure on carbon, and the variance partition was used to examine the pure and shared effect of the richness and vegetation structure variables on carbon. Regressions showed a positive strong relationship between species richness and carbon (r2 = 0.74; P < 0.001). The partition of carbon variance showed that richness, structure and variation of the structure explained 85.7 %. Alone the richness explained 12.7 %, the structure 8.8 % and the variation of the structure 4.8 %. These results confirm that carbon in the aboveground biomass increases with species richness and structural variation of the vegetation. Therefore, more biodiverse and stratified agroforestry systems are more efficient in the use of resources and can contribute with climate change mitigation.


2022 ◽  
Vol 7 (2) ◽  
Author(s):  
Peter Stroh ◽  
John Bragg ◽  
Peter Carey ◽  
Carol Laidlaw ◽  
Martin Lester ◽  
...  

The Wicken Fen Vision (Cambridgeshire, UK) is a landscape-scale habitat restoration project that uses process-driven, open-ended approaches to develop habitats on highly degraded and drained peat soils of former intensive arable land. The project land is extensively grazed with herds of free-roaming, minimally managed herds of Highland cattle and Konik horses. In one 119 ha area, seven 25m x 25 m grazing exclosures were erected and vascular plant species were recorded from 2007 to 2017. Plant species data were analysed to (1) compare changes in plant species composition and diversity in grazed and ungrazed areas; (2) use plant species traits and plant-environment associations to explore the nature of changes in plant composition; (3) use remote sensing to explore changes in vegetation structure; (4) examine the influence of land use histories on grazing outcomes in different parts of the site.There was a clear divergence through time between grazed and ungrazed areas, attributed to significantly greater canopy height, Ellenberg L (Light) and Ellenberg N (fertility) values within the exclosures. Species richness was significantly higher in grazed compared with ungrazed areas and species assemblages separated through the study period. After ten years, extensive free-roaming grazing has had significant impacts on vegetation structure and species richness but effects varied across the study site because of differing historical land use.


Acarologia ◽  
2018 ◽  
Vol 58 (4) ◽  
pp. 951-962
Author(s):  
Julien K. N’Dri ◽  
Pacôme K. Pokou ◽  
Fabrice A. Séka ◽  
Rodolphe A. G. N’Da ◽  
Jan Lagerlöf

The objective of the investigation was to determine the response of different taxa of mites across the land use types and demonstrate that soil mites could be used as an indicator of environmental change after the conversion of secondary forests into rubber plantations. The sampling was performed during the dry season on 12 sampling areas, consisting of four land use types: secondary forests, 7-year-old rubber plantations, 12-year-old rubber plantations, and 25-year-old rubber plantations, with three replications of each treatment. Soil cores were sampled along a 40 m transect with a steel corer. The soil mites were extracted using modified Berlese-Tullgren funnels during a 10 day period. Soil physico-chemical parameters were measured on each sampling area. The conversion of secondary forests into rubber plantations was characterized by a modification of the mean values of mite density (+103 and +262%), species richness (-11 and +32%), water content (-41 and -5%), bulk density (+6 and -3%) and soil organic carbon (-73 and -59%) respectively, after 7 and 25 years of conversion. The density of mites, species richness and soil water content increased with the aging of the rubber plantations, demonstrating an improvement in soil ecological quality and environmental conditions. These results are confirmed by the values of the Maturity Index of Gamasid mites, which increased with the increasing age of rubber plantations. In other words, the severity of environmental impact decreased with the aging of the rubber plantations and was ranked as follows: 25-year-old rubber plantations < secondary forest < 12-year-old rubber plantations < 7-year-old rubber plantations. The Maturity Indexes estimated that 25-year-old rubber plantations (0.84) and in secondary forests (0.74) are relatively similar and characterize stable habitats, which are potentially dominated by Gamasid species with K selection.


2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Stefan Nickel ◽  
Winfried Schröder

Abstract Background The aim of the study was a statistical evaluation of the statistical relevance of potentially explanatory variables (atmospheric deposition, meteorology, geology, soil, topography, sampling, vegetation structure, land-use density, population density, potential emission sources) correlated with the content of 12 heavy metals and nitrogen in mosses collected from 400 sites across Germany in 2015. Beyond correlation analysis, regression analysis was performed using two methods: random forest regression and multiple linear regression in connection with commonality analysis. Results The strongest predictor for the content of Cd, Cu, Ni, Pb, Zn and N in mosses was the sampled species. In 2015, the atmospheric deposition showed a lower predictive power compared to earlier campaigns. The mean precipitation (2013–2015) is a significant factor influencing the content of Cd, Pb and Zn in moss samples. Altitude (Cu, Hg and Ni) and slope (Cd) are the strongest topographical predictors. With regard to 14 vegetation structure measures studied, the distance to adjacent tree stands is the strongest predictor (Cd, Cu, Hg, Zn, N), followed by the tree layer height (Cd, Hg, Pb, N), the leaf area index (Cd, N, Zn), and finally the coverage of the tree layer (Ni, Cd, Hg). For forests, the spatial density in radii 100–300 km predominates as significant predictors for Cu, Hg, Ni and N. For the urban areas, there are element-specific different radii between 25 and 300 km (Cd, Cu, Ni, Pb, N) and for agricultural areas usually radii between 50 and 300 km, in which the respective land use is correlated with the element contents. The population density in the 50 and 100 km radius is a variable with high explanatory power for all elements except Hg and N. Conclusions For Europe-wide analyses, the population density and the proportion of different land-use classes up to 300 km around the moss sampling sites are recommended.


2002 ◽  
Vol 46 (1) ◽  
Author(s):  
Dietrich Schmidt-Vogt

AbstractManagement of secondary tropical forests: a new perspective for sustainable use of forests in Asia. The decline of primary forests in the tropics is leading to a reassessment of the role secondary forests might play within the context of tropical forest management. Recent research has shown that secondary forests in the tropics can be both rich in species and complex in terms of stand structure. There is, moreover, a growing recognition of the importance of secondary forests for traditional subsistence economies in the tropics and of their economic potential for land use systems in the future. Management of secondary forests in Asia as an alternative to the extraction of timber from primary forests but also as one among other options to intensify traditional land use systems has a potential for the future especially because of the existence of vast tracts of valuable secondary forest cover, and because of the store of traditional knowledge that can still be found in tropical Asia.


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