Exotic Tree Species Outnumbering Native Tree Species: an Alarming Situation for the Sustainable Urban Plantation Development

This present study mainly focuses on the tree distribution and diversity of some selected roadsides in Faisalabad, a major city in Punjab, Pakistan. A total census of the tree population on selected roads was carried out and then studied for various parameters. Shannon–Wiener index, Reciprocal of Simpson’s diversity index, and Shannon Evenness were among the different species diversity indices which were studied. Observational results showed that the selected roads in the city hold low tree diversity, with nearly 2858 trees of 34 species, 30 genera, and 15 families. Mainly exotic tree species dominated the plantation of selected roadsides. The topmost three species contributing approximately 60% of the tree population are Conocarpus erectus, Eucalyptus crebra, and Terminalia mantaly. Despite the dominance of exotic tree species, many native tree species are also growing along selected roadsides. Since, Faisalabad has been reported as one of the most polluted cities in the world due to high suspended particulate matter, appropriate efforts are needed to improve the plantation pattern and also to enhance the canopy of the trees in the city to minimize the problem of air pollution.

Mapping of the urban tree population in gardens of Ulhasnagar, District Thane, Maharashtra using Geographic information system (GIS)

Urban trees today are a crucial component that defines the healthy and liveable environment of a city. A city’s database includes streets, building, footprints, overhead and underground utilities, workforce areas, pest/disease quarantine zones, parks, and pending development areas in addition to the tree database such as tree location, species, diameter at breast height (DBH), and canopy width. The present study aimed at mapping the tree population of some selected gardens and parks in Ulhasnagar using Geographic Information Systems (GIS). GIS is an integrated system of computer hardware, software, data and trained personnel for analyzing and displaying all forms of geographically referenced information. GIS-based map shows the location for each tree species found in the selected 12 gardens of Ulhasnagar. Green colour represents dense green canopy represented by the above-ground biomass, and yellow represents moderate, while red indicates scarce or limited above-ground biomass. The green colour actually represents the volume of biomass and not the density or the number of trees and shows the concentration of carbon pools in the study area. Updating data in GIS is much more cost-efficient and less time consuming than having to redraw maps manually. Urban foresters and urban planners can work together using GIS for better management of this resource. This study is one of the pioneering footsteps towards appreciative resources and thus enabling the researchers in developing an appropriate management strategy. The data will help us to analyze and interpret better and eventually conceptualize the above-ground biomass in the entire area of gardens.

Fire mitigates bark beetle outbreaks in serotinous forests

Bark beetle outbreaks and forest fires have imposed severe ecological damage and caused billions of dollars in lost resources in recent decades. The impact of such combined disturbances is projected to become more severe, especially as climate change takes its toll on forest ecosystems in the coming years. Here, we investigate the impact of multiple disturbances in a demographically heterogeneous tree population, using an age-structured difference equation model of bark beetle outbreaks and forest fires. We identify two dynamical regimes for beetle and fire dynamics. The model predicts that fire helps dampen beetle outbreaks not only by removing host trees but also by altering the demographic structure of forest stands. We show that a stand thinning protocol, which reduces the population size of the largest few juvenile classes by a small percentage, is able to significantly reduce beetle-induced tree mortality. Our research demonstrates one approach to capturing compound disturbances in a mathematical model.

The Effect of Wind Energy on Microclimate: Lessons Learnt from a CFD Modelling Approach in the Case Study of Chios Island

During the last three decades, rapid growth of wind energy has led to questions regarding the possible impacts of wind farms on local weather and microclimates. Physically, the increased turbulence due to the wind turbine operation affects the mixing processes, may slightly disturb the pressure and temperature distributions downstream of wind farms and may have an impact on natural ecosystems such as the famous mastic tree population located on the island of Chios in the North Aegean Sea. This study explores the wind farms and their wake effects downstream with a particular focus on the effect on the southern part of the island where the mastic trees cultivation is located. The analysis is carried out with the use of the commercial CFD code ANSYS Fluent. Steady state computations of full 3D Navier–Stokes equations, using the k-ε turbulence closure scheme are carried out. The development of the multiple wake effects of the wind farms and their propagation downstream is examined under low and high turbulence intensities. Results clearly indicate that for both test cases there is no impact to the local microclimate and to the mastic Tree population.

Potential Contribution of Public Primary Schools in Attaining Ten Percent Tree Cover in Kenya

Purpose: This paper demonstrates the influence of school land-use practices on tree population in public primary schools in Kisumu County. Methodology: A descriptive cross-sectional research design was employed and systematic random sampling used to select 124 schools (20% of 615). Primary data came from self-administered questionnaires to school heads and harmonized using focus group discussions with teachers and pupils. Further, key informant interviews, observation, photography and desk studies were also used. Results: From the study, the average land size of a public primary school is 3.26Ha with approximately 23.7% unused spaces. 32.26% of the schools do not have a documented land use plan hence rely on sheer instincts and ad hoc decisions of the administration or Board of Management (BoM) for space allocation to any land cover. There is a significantly positive correlation between school land-use practices (r2=0.843) and tree population. Out of the common land use practices identified; forestry (p=2e-16), tree nursery (p=2e-16) and kitchen gardening (p=0.017) had a significant positive influence on the total tree population in schools. The findings show that land use practices positively influence tree population in public primary schools. Unique contribution to theory, practice and policy: The study demonstrates that school administration should take advantage of the unused spaces to provide adequate room for establishment of woodlots and gardens to facilitate the achievement of the 10% forest cover. Key Words: Land cover, Land use practices, Public Primary schools, school land size, tree population

Adaptive Management Lessons for Serianthes nelsonii Conservation

The literature covering the biology, ecology, horticulture, and conservation of the critically endangered tree Serianthes nelsonii Merr. was reviewed. The roots, stems, and leaves of this charismatic legume tree revealed highly plastic traits and responded positively to horticultural manipulations to improve the quality of container-grown transplants. Pre-sowing seed treatments of seed coat scarification and 1 h of imbibition generated 85% to 90% germination at a temperature optimum of 26 °C. Adventitious root formation on air layers and successful unions on approach grafts were 100%. Seedling and sapling growth was maximum under 25% to 50% sunlight transmission, limited irrigation to ensure adequate root zone aeration, repetitive stem tip pruning to increase root:shoot quotient, and thigmic stress to retain an orthotropic orientation of stems. In situ regeneration on Guam was substantial but recruitment from seedling to sapling was nil. High quality leaf litter chemistry enabled rapid decomposition, and soils beneath the tree exhibited unique chemical traits that increased ecosystem health by creating spatial heterogeneity. The greatest unanswered questions focus on plant mortality. Research is needed to determine the reasons for the mortality of in situ seedlings, mortality within transplantation projects on Guam, and the mortality of 60% of the mature in situ tree population during the 26-year implementation of the national recovery plan. Horticultural researchers are ideally positioned to answer these urgent questions.