Using Multi Techniques Analysis in Biogeoclimatic Ecosystem Classification and Mapping of Mambilla Plateau in Taraba State Nigeria

This work used multi techniques analysis comprises GIS models, geostatistics, clustering analysis as against the traditional single layer thematic approach to characterize Mambilla Plateau, a cold highland in Taraba state of Nigeriainto biogeoclimatic ecosystem zones needed for natural resources management. The principal criteria used in classifying and mapping the ecosystems are: climate and bioclimate data, physiography (slope, relief and aspect), vegetation/landcover data. In classifying and mapping the physiography of Mambilla Plateau, the topographic layer was produced from 90 m NASA/SRTM digital elevation model. Principal component analysis, agglomerative hierarchical cluster analysis (AHC) and geostatistical techniques (Kriging) were applied to develop bioclimatic layer. A combination of vegetation field survey conducted on selected sites, un/supervised classification and the application of NDVI values was used to produce landcover map and delineation of the Plateau into vegetation units. These layers of physiographic, bioclimatic and vegetation were spatially combined using fuzzy (sum) overlay in Arc GIS 10.2 to produce 5 major and 1 subunit biogeoclimatic ecosystem zones on the Mambilla Plateau and the adjoining landscape namely: humid lowland forest/humid shrubby forest, montane forest, escarpment stream valley forest, grass cypress cool mountain and, grass eucalyptus cold high mountain. It is expected that this approach to biogeoclimatic ecosystem mapping shall form the bedrock for vegetal/forest resources management not only in the region but find application especially in most of the highland of the world.

Modeling the Resilience of Power Distribution Systems Subjected to Extreme Winds Considering Tree Failures:An Integrated Framework

Overhead electrical power distribution systems(PDS)are very susceptible to extreme wind hazards.Power outages can cause catastrophic consequences,including economic losses,loss of critical services,and disruption to daily life.Therefore,it is very important to model the resilience of PDS against extreme winds to support disaster planning.While several frameworks currently exist to assess the resilience of PDS subjected to extreme winds,these frameworks do not systematically consider the tree-failure risk.In other words,there is no integrated framework that can simultaneously consider tree failures,PDS component failures induced by falling trees,resilience assessment,and evaluation of resilience enhancement with vegetation management.Therefore,this study proposed an integrated simulation framework to model the resilience of PDS against extreme winds,which includes tree fragility modeling,PDS fragility modeling,PDS component failure estimation,system performance evaluation,system restoration modeling,and resilience enhancement evaluation.The framework is demonstrated with a power distribution network in Oklahoma.The results show that the estimated system resilience will reduce if tree failures are considered.Crown thinning can effectively enhance the system’s resilience,but the effectiveness is affected by both wind speed and direction.

Do subtropical grasslands recover spontaneously after afforestation?

Aims South American Pampa grasslands are habitats of great conservation interest,with a distinct and rich flora,but have been intensely con-verted to other land uses,including tree plantations.While neces-sity for restoration grows,no information on restoration potential of grasslands after afforestation exists.Here,we aim at analyzing composition and structure of grassland vegetation with a history of eucalyptus plantations in order to assess recovery potential of these areas.We hypothesized that areas with history of eucalyptus would differ from reference grasslands with no history of land-use change in terms of floristic and functional composition and would present lower species richness.Methods Our study region comprised four sites in the southeastern part of the Pampa biome,in the coastal plain in the extreme south of Brazil,always with sites with long(50 years)history of eucalyptus plantation and reference grassland.We sampled vegetation at post-eucalyptus sites(with and without resprouting)10 years after clear-clutting and in natural grasslands.We analyzed data by analysis of variance and ordination techniques,considering compositional parameters and life forms,and indicator species analysis.Important Findings Species richness and vegetation cover were higher in reference grassland than in resprout areas but did not differ from post-eucalyp-tus areas.Exotic species cover was significantly higher in areas with afforestation history.In terms of total composition,natural grasslands differed significantly from areas with past plantation use.Indicator species analyses revealed considerable differences between grass-land types.In conclusion,vegetation development led to grassland communities that are still quite distinct from reference sites.Likely,the specificity of grassland management has a high importance in defining vegetation trajectories in time and importance for grassland recovery,and restoration needs to be addressed in more studies.