Edge Effects of Oil Pipeline Canopy Openings on Tree Community Structure and Dynamics in a Montane Atlantic Forest

The Atlantic forest has historically been severely deforested, and only fragments currently remain that are subject to a wide variety of anthropogenic impacts, including edge effects that can cause structural and functional degradation. The Tinguá Biological Reserve-RJ comprises approximately 26,000 hectares of well-preserved Atlantic Forest, but it is subject to impacts caused by two canopy openings along oil pipelines. Comparisons were made between pipeline edges and forest interiors to evaluate edge effects on the structure and dynamics of those tree communities. Tree densities were higher along forest edges, apparently increasing over time. Tree basal areas, on the other hand, have decreased along edges due to higher mortality rates. Linear canopy opening edges showed higher densities of small trees, while the interior had more very large trees, indicating changes in successional processes and community structural patterns due to edge effects.

Natural regeneration characteristics of Pinus sylvestris var. mongolica forests on sandy land in Honghuaerji, China

Natural regeneration in Mongolian pine, Pinus sylvesttis var. mongolica, forest at Honghuaerji of China （the original of the natural Mongolian pine, forest on sandy land） was studied in 2004. The total mean values of regeneration indexes were higher in mature stands （more than 80% individual stems were older than 50 years）, the maximum of regeneration index reached 29 seedlings, m^ 2, with lowest values in the younger stand, e.g., in 32-year old and 43-year old stands. The stand age was an important factor determining the natural regeneration, which was the best in the older stands in this investigation （e.g. about 80-year old）. The regeneration index seemed not to be closely in relation to canopy openness although Mongolian pine is a photophilic tree species. In each type of gaps, natural regeneration was very well. Regeneration indexes were satisfactory at the south and east edges in the circle gaps; and at the east edge of the narrow-square gaps. Results indicated that Mongolian pine, seedlings could endure shading understory, but it would not enter the canopy layer without gap or large disturbance, e.g., fire, wind/snow damage or clear cutting etc. These results may provide potentially references to the management and afforestation of Mongolian pine, plantations on sandy land in arid and semi-arid areas. Researches such as the comprehensive comparisons on regeneration, structure and ecological conditions and so on between natural Mongolian pine, forests and plantations should be conducted in the future.

Diversity of click beetles in managed nonnative coniferous and native beech stands: Consequences of changes in the structural and species composition of tree stands in Central Europe

The natural composition of forests has undergone significant changes over recent centuries.A closer-to-natural tree species composition has long been perceived as key to a high biodiversity.We investigated the impact on communities of click beetles(Elateridae)caused by changes in the tree species composition of spruce monocultures compared to reference sites of recently unmanaged natural beech forests.To collect data,passive interception traps were distributed within managed spruce stands of different age classes and natural beech forests of various developmental stages.The beetle species richness was slightly but not significantly higher in the beech forests.The saproxylic species group was significantly more common in the spruce stands,whereas the group of nonsaproxylic species was significantly more abundant in the beech stands.In the commercial stands,the significantly highest species richness was in the clearings(0–10-year-old stands),and at this forest age class,the vast majority of the beetle species occurred in the spruce stands.In the developmental stages of the natural forest,a slightly higher beetle richness was found at the disintegration stage.The study results suggested that different tree species compositions and stand structures affect the communities of click beetles and substantially change their species composition and thus their response to external influences.Therefore,management of stands using diverse silvicultural systems is recommended for creating diverse ecological niches in forests.

The Impact of Deforestation in Anambra State： The Ekwusigo Example

It is a fact that demographic and socio-economic developments are exploitatively exerting severe pressure on forest resources in Nigeria. Not only has the economy of the people been severely affected but also the environment has witnessed accelerated soil erosion, especially in Eastern Nigeria. Accordingly, this study set out to explore the environmental and socio-economic impacts of deforestation using an empirical case. Two forested and two deforested sites in Ekwusigo L.G.A of Anambra State were closely studied with respect to deforestation indices. From the data generated, Student＇s t-test was used to attempt a statistical comparison of the forested and deforested sites. The findings indicate that forest cover depletion affected both the canopy openness and the number of non-timber forest products in the area, Finally, the paper stressed the need to maintain a sustainable plant cover while economically harnessing forest resources.

Influence of Environmental Variables on the Natural Regeneration of a Forest under Restoration after Bauxite Mining and in a Reference Ecosystem in Southeastern Brazil

The shrub-tree floristic composition of the natural regeneration stratum of a bauxite mine in the process of restoration and in a reference ecosystem(remnant of a preserved secondary Seasonal Semi-Deciduous Forest)were analysed to evaluate forest restoration conditions after five years of planting.The influence of canopy openness,accumulated leaf litter and soil attributes in the regeneration stratum were also investigated in both the forests.The floristic composition of the regeneration stratum in the forest under restoration(16 species and 5,083 individuals ha-1)and in the reference ecosystem(58 species and 26,250 individuals ha-1)are distinct due to the difference in the environmental variables.Results showed that the reference ecosystem favours the presence of species that tolerate environments with greater shading and higher aluminium and organic matter content in the soil like Psychotria carthagenensis Jacq.,while the forest under restoration favours the presence of species adapted to fertile soils and those that tolerate greater luminosity like Vernonanthura phosphorica(Vell.)H.Rob.

The role of light, soil and human factors on the probability of occurrence of an invasive and three native plant species in coastal transitions of coastal mississippi, USA

Aims understanding relationships between the distributions of species and their surrounding environment provides a basis for forecasting how species will respond to future environmental changes.In this study,we examined the effects of environmental factors and human devel-opmental features associated with disturbances on probability of occurrence of juveniles of invasive Triadica sebifera and three native plant species,Baccharis halimifolia,Ilex vomitoria and Morella cer-ifera within a typical coastal transition in coastal mississippi,USA.Methods We recorded presence of juveniles of focal species and measured environmental factors(soil salinity,canopy openness,soil texture and soil carbon to nitrogen ratio)along an 11.3 km transect located at grand bay National Estuarine research reserve.Further,we doc-umented anthropogenic features and associated activities as a proxy for human disturbance.Important Findings With the exception of I.vomitoria,all other species occurrences were significantly influenced by an interaction between soil salinity and canopy openness.The occurrence of I.vomitoria sharply decreased with salinity.B.halimifolia occurrence peaked at moderate levels of salinity and low to moderate levels of canopy openness.occurrences of M.cerifera and the invasive T.sebifera were highest at low levels of salinity and canopy openness.These results indicate that salinity is a strong driver that limits distribution of juvenile native and invasive species in coastal transitions.logistic regression confirmed the positive effects of anthropogenic disturbances on T.sebifera and I.vomitoria occurrence.It appears that while soil salinity is likely to drive retreat of the seaward boundaries of woody plant species distributions,increased human developments along the coast likely enhance the inland spread of species,in particular the invasive T.sebifera by increasing distur-bances and facilitating dispersal.results from this study can offer insight for the development of T.sebifera management and preventive meas-ures for further spread along coastal areas of the southeastern USA.