Ecological and Economic Benefits of Vegetation Management Measures in Citrus Orchards on Red Soils

A three-year experiment was conducted to investigate and compare the economic and ecological benefits of six types of vegetation management measures in citrus orchards of the hilly red soil region of the eastern part of China.Six vegetation treatments,including tillage without herbicide(clean tillage)and no tillage without herbicide(sod culture) and with herbicide paraquat(paraquat),glyphosate(glyphosate),glyphosate-glyphosate-paraquat(G-G-P),and paraquat- paraquat-glyphosate(P-P-G),were applied in the citrus orchards on a clayey red soil with slopes of 8°and 13°and a sandy soil with slope of 25°.The results showed that the sod culture,paraquat,glyphosate,G-G-P,and P-P-G treatments reduced surface runoff by 38.8%,42.5%,18.7%,28.7%,and 37.5%,then the soil-water losses by 55.5%,51.7%,39.9%,46.8%, and 50.0%,and the N,P,and K nutrient losses by 60.3%,50.2%,37.0%,41.8%,and 45.4%,respectively,as compared with the clean tillage treatment.The weed regeneration ratios with the treatments of clean tillage without herbicide,paraquat, glyphosate,G-G-P,and P-P-G were reduced by 55.1%,67.2%,30.3%,36.8%,and 51.2%,respectively,as compared with the sod culture.The sod culture,paraquat,glyphosate,G-G-P,and P-P-G treatments could increase the soil fertility (annual accumulation of N,P,K,and OM)by 7.1%,6.9%,5.3%,6.2%,and 6.6%,respectively,whereas the clean tillage treatment without herbicide reduced soil fertility by 4.4% after the three-year experiment.The citrus fruit yields in the treatments of paraquat,glyphosate,G-G-P,and P-P-G increased by 7%-10%;the soluble solid,total sugar,total acidity,sugar-acid ratio,and single fruit weight of citrus fruits of all treatments except sod culture significantly(P>0.05) exceeded that of the clean tillage treatment.In general,the paraquat treatment showed the best economic and ecological benefits among the six treatments;therefore,it could be regarded as the best available vegetation management measure in citrus orchards of hilly red soil region to retain water and soil,enhance soil fertility,and improve the yield and quality of citrus.

An Evaluation of Training Needs of Supervisors of South African Chemical Weeding Plantation Forest Operations through Forester Perceptions

The success of an annual plan of operations （APO） for a plantation forest management unit （FMU） has great reliance on the capacity of field supervisors who execute it with workers. Foresters＇ perception of skills and performance levels of field supervisors in charge of chemical weeding operations, which are keys to integrated vegetation management strategies at FMUs, were evaluated through a researcher-administered questionnaire implemented through telephone interviews. The research focussed on chemical weeding, of which implementation quality impacts directly on operational costs, worker safety, negative environmental externalities and crop performance. The study was done to establish capacitation requirements （training needs） for the plantation forest sector in the Eastern Cape, Western Cape and KwaZulu-Natal provinces of South Africa. The results of the research identified skills gaps and emotional issues that could be addressed through training. Overall, chemical weeding field supervisors （CWFS） were adequately prepared to perform in most key result areas of planning and leadership. They, however, faced considerable challenges in functions related to controlling and organizing work. In all three provinces, the highest levels of performance inadequacy were in safety and team discipline. Some province-associated peculiarities in field supervisor performances were also identified. Remedial action that foresters recommended was related mostly to the need to strengthen technical and workplace culture management skills. It was observed that effective skills development in CWFS would require planned continuous improvement programmes.

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.