Floristic and Structural Analysis of Urban Tree Canopy: From Its Ecology to Its Social Issues

Currently, urban areas are the largest segment of the world’s population, and they can reach up to 80% of it in some countries. Understanding green areas is of paramount importance to also understand the population’s mental health and well-being, as well as to achieve ecological understanding and its impact on urban infrastructure. Thus, the aim of the present study is to carry out a survey on both urban afforestation structure and on its social impact on a Brazilian municipality. It also sought to understand the damages caused by these species to urban infrastructure in comparison to data collected in 2009, to assess forest coverage in this municipality and tree planting underutilized capacity. Accordingly, all the streets in this municipality’s urban area, the botanical data of each tree and its damage to the city’s infrastructure and phytosanitary conditions were surveyed (from 1 to 5). Data were compared to those from the 2009 census, and social issues were analyzed. In total, 5044 individuals belonging to 189 species were recorded. The most often found species were Lagerstroemia indica and Murraya paniculata. Out of the total number of trees, 458 trees scored at least one score “5” in one of the criteria, and this number represents 8.9% of the total of the trees. L. indica was the species accounting for the highest rates of phytosanitary and infrastructure issues. Data comparison evidenced that urban tree canopy lost 25% of its vegetation between the two measurements taken herein, but the number of species has increased. When it comes to damages, many trees started showing phytosanitary issues or damage to urban infrastructure.

Improve the Prediction Accuracy of Apple Tree Canopy Nitrogen Content through Multiple Scattering Correction Using Spectroscopy

Method: Use Multiple Scattering Correction to eliminate the interference of scattering on spectrum in the process of field measurement so as to improve the accuracy of prediction model of tree canopy nitrogen content. Apple trees in Qixia of Yantai City were taken as the test material. The spectral reflectivity of apple tree canopy went through the First Derivative (FD) and Multiple Scattering Correction (MSC) plus first derivative, respectively. The correlation coefficients were calculated between spectral reflectivity and nitrogen content. The Support Vector Machine (SVM) method was used to establish the prediction model. The result indicates that the MSC pre-processing can improve the correlation between spectral reflectivity and nitrogen content. The SVM model with MSC + FD pre-processing was a good way to predict the nitrogen content. The calibration R2 of the model was 0.746;the validation R2 was 0.720;and its RMSE was 0.452 g·kgˉ1. MSC can commendably eliminate scattering error to improve the prediction accuracy of prediction model.

Development of real-time laser-scanning system to detect tree canopy characteristics for variable-rate pesticide application

Improving pesticide application efficiency is increasingly important in orchard spraying.In this study,a laser-scanning system was designed to acquire gridding volumes of a tree to quantify the geometry characteristics of the tree canopy in real-time.A laser-scanning sensor mounted on a linear guide was utilized to measure the structure of a target tree canopy.A computer was used to receive measurement data from the laser scanner and obtain the movement distance of the laser-scanning sensor from a controller.An algorithm written with VC#program was designed to calculate gridding volumes of trees by recognizing valid measurement data from the laser scanner.Laboratory evaluations were conducted on three kinds of regular objects,and the maximum relative errors of section volumes of the cuboid,triangular prism and cylinder objects were 3.3%,7.9%and 9.4%,respectively,which illustrated that the algorithm could calculate the section volumes in different parts of the objects with high accuracy.A conifer tree and an apple tree were chosen to verify detecting accuracy of the laser-scanning system at variable speeds and grid sizes.The variation coefficients of total volumes for each kind of the tree were 0.078 and 0.041,respectively,which indicated that the laser-scanning system could be applied to provide the gridding volumes of different canopy densities in real-time with good reliability for guiding a variable-rate sprayer.

Influences of spherical tree canopy on thermal radiation disturbance to exterior wall under the condition of no shade cast on the wall

Research on the influence of thermal radiation of tree canopies to adjacent exterior walls has relevance to the selection of tree species and the spatial arrangement of trees for urban planning.In the last decade,there have been many studies on the influence of tree shadows on the thermal environment and energy consumption of buildings.However,there is a lack of research on how trees affect the thermal radiation of adjacent buildings,when they do not cast direct shadows on the walls.In view of this,a combination of experiment and simulation was used to explore the influence of spherical canopy on the intensity changes of net long-wave thermal radiation(T_(RDL))and net short-wave thermal radiation(T_(RDS))absorbed by the adjacent wall.Both measured and simulated results show that the tree canopy has a T_(RD)(the sum of T_(RDL) and T_(RDS))effect on the south wall of adjacent buildings in summer.The peak of T_(RD) from the tree to the adjacent wall was obtained by ENVI-met under 27 scenarios.A functional relationship was further given between the peak T_(RD) and the canopy diameter(D_(C)),the minimum distance between wall and tree canopy(D_(W-T)).Moreover,the influence of D_(C),D_(W-T) and leaf area density(LAD)on T_(RD) was discussed by simulation.Additionally,the Trd of canopy decays exponentially in the horizontal direction and linearly in the vertical direction of the wall.The above methods and results can guide the selection of tree species,green space design around buildings and the evaluation of the influence of trees on indoor cooling energy consumption in summer.

Parkland trees on smallholder farms ameliorate soil physical-chemical properties in the semi-arid area of Tigray,Ethiopia

Proposed agroforestry options should begin with the species that farmers are most familiar with,which would be the native multipurpose trees that have evolved under smallholder farms and socioeconomic conditions.The African birch(Anogeissus leiocarpa(DC.)Guill.&Perr.)and pink jacaranda(Stereospermum kunthianum Cham.)trees are the dominant species in the agroforestry parkland system in the drylands of Tigray,Ethiopia.Smallholder farmers highly value these trees for their multifunctional uses including timber,firewood,charcoal,medicine,etc.These trees also could improve soil fertility.However,the amount of soil physical and chemical properties enhanced by the two species must be determined to maintain the sustainable conservation of the species in the parklands and to scale up to similar agroecological systems.Hence,we selected twelve isolated trees,six from each species that had similar dendrometric characteristics and were growing in similar environmental conditions.We divided the canopy cover of each tree into three radial distances:mid-canopy,canopy edge,and canopy gap(control).At each distance,we took soil samples from three different depths.We collected 216 soil samples(half disturbed and the other half undisturbed)from each canopy position and soil depth.Bulk density(BD),soil moisture content(SMC),soil organic carbon(SOC),total nitrogen(TN),available phosphorus(AP),available potassium(AK),p H,electrical conductivity(EC),and cation exchange capacity(CEC)were analysed.Results revealed that soil physical and chemical properties significantly improved except for soil texture and EC under both species,CEC under A.leiocarpus,and soil p H under S.kunthianum,all the studied soils were improved under both species canopy as compared with canopy gap.SMC,TN,AP,and AK under canopy of these trees were respectively 24.1%,11.1%,55.0%,and 9.3% higher than those soils under control.The two parkland agroforestry species significantly enhanced soil fertility near the canopy of topsoil through improving soil physical and chemical properties.These two species were recommended in the drylands with similar agro-ecological systems.

Geospatial Analysis of Urban Heat Island Effects and Tree Equity

In recent decades, Urban Heat Island Effects have become more pronounced and more widely examined. Despite great technological advances, our current societies still experience great spatial disparity in urban forest access. Urban Heat Island Effects are measurable phenomenon that are being experienced by the world’s most urbanized areas, including increased summer high temperatures and lower evapotranspiration from having impervious surfaces instead of vegetation and trees. Tree canopy cover is our natural mitigation tool that absorbs sunlight for photosynthesis, protects humans from incoming radiation, and releases cooling moisture into the air. Unfortunately, urban areas typically have low levels of vegetation. Vulnerable urban communities are lower-income areas of inner cities with less access to heat protection like air conditioners. This study uses mean evapotranspiration levels to assess the variability of urban heat island effects across the state of Tennessee. Results show that increased developed land surface cover in Tennessee creates measurable changes in atmospheric evapotranspiration. As a result, the mean evapotranspiration levels in areas with less tree vegetation are significantly lower than the surrounding forested areas. Central areas of urban cities in Tennessee had lower mean evapotranspiration recordings than surrounding areas with less development. This work demonstrates the need for increased tree canopy coverage.

Scale dependence of forest fragmentation and its climate sensitivity in a semi-arid mountain:Comparing Landsat,Sentinel and Google Earth data

Landscape fragmentation is generally viewed as an indicator of environmental stresses or risks,but the fragmentation intensity assessment also depends on the scale of data and the definition of spatial unit.This study aimed to explore the scale-dependence of forest fragmentation intensity along a moisture gradient in Yinshan Mountain of North China,and to estimate environmental sensitivity of forest fragmentation in this semi-arid landscape.We developed an automatic classification algorithm using simple linear iterative clustering(SLIC)and Gaussian mixture model(GMM),and extracted tree canopy patches from Google Earth images(GEI),with an accuracy of 89.2%in the study area.Then we convert the tree canopy patches to forest category according to definition of forest that tree density greater than 10%,and compared it with forest categories from global land use datasets,FROM-GLC10 and GlobeLand30,with spatial resolutions of 10 m and 30 m,respectively.We found that the FROM-GLC10 and GlobeLand30 datasets underestimated the forest area in Yinshan Mountain by 16.88%and 21.06%,respectively;and the ratio of open forest(OF,10%<tree coverage<40%)to closed forest(CF,tree coverage>40%)areas in the underestimated part was 2:1.The underestimations concentrated in warmer and drier areas occupied mostly by large coverage of OFs with severely fragmented canopies.Fragmentation intensity of canopies positively correlated with spring temperature while negatively correlated with summer precipitation and terrain slope.When summer precipitation was less than 300 mm or spring temperature higher than 4℃,canopy fragmentation intensity rose drastically,while the forest area percentage kept stable.Our study suggested that the spatial configuration,e.g.,sparseness,is more sensitive to drought stress than area percentage.This highlights the importance of data resolution and proper fragmentation measurements for forest patterns and environmental interpretation,which is the base of reliable ecosystem predictions with regard to the future climate scenarios.

Tracking leaf area index and coefficient of light extinction over the harvesting cycle of black wattle

The amount of photosynthetic radiation inter- cepted by a crop is a function of the incident solar radiation on the plants, the leaf area index （LAI）, and the light extinction coefficient （k）. We quantified LAI and k in stands of black wattle （Acacia mearnsii De Wild.） over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. LAI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer＇s law. LAI depends on the planting site and stand age. Between the two sites, the LAI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to LAI and was correlated with LAI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter.

Forest fragmentation and human population varies logarithmically along elevation gradient in Hindu Kush Himalaya-utility of geospatial tools and free data set

Hindu Kush Himalaya(HKH) is the largest and the most diverse mountain region in the world that provides ecosystem services to one fifth of the total world population. The forests are fragmented to different degrees due to expansion and intensification of human land use. However, the quantitative relationship between fragmentation and demography has not been established before for HKH vis-à-vis along elevation gradient. We used the globally available tree canopy cover data derived from Landsat-TM satellite to find out the decadal forest cover change over 2000 to 2010 and their corresponding fragmentation levels. Using SRTMderived DEM, we observed high forest cover loss up to2400 m that highly corroborated with the population distribution pattern as derived from satellite observation. In general, forest cover loss was found to be higher in south-eastern part of HKH. Forest fragmentation obtained using ‘area-weighted mean radius of gyration' as indicator, was found to be very high up to 2400 m that also corroborated with high human population for the year 2000 and 2010. We observed logarithmic decrease in fragmentation change(area-weighted mean radius of gyration value),forest cover loss and population growth during 2000-2010 along the elevation gradient with very high R^2 values(i.e., 0.889, 0.895, 0.944 respectively). Our finding on the pattern of forest fragmentation and human population across the elevation gradient in HKH region will have policy level implication for different nations and would help in characterizing hotspots of change. Availability of free satellite derived data products on forest cover and DEM, griddata on demography, and utility of geospatial tools helped in quick evaluation of the forest fragmentation vis-a-vis human impact pattern along the elevation gradient in HKH.

Intelligent automated system based on a fuzzy logic system for plant protection product control in orchards

The spraying of plant protection product(PPP)in orchards is a very hazardous working procedure,owing to the spray drift caused by the uneven operation of conventional axial boom sprayers.This research describes an intelligent automated system for precise(PPP)distribution in real-time.It is based on an intelligent decision-making model using ultrasonic measurements of leaf area density under laboratory conditions,which serve to trigger electromagnetic valves(EMV)on the axial boom sprayer.A fuzzy logic algorithm was an integrated part of the intelligent system for controlling the PPP by generating the pulse width modulation signal and applying it through the EMV of the prototype boom sprayer.The results showed that by using an intelligent decision-making model,the same efficiency as with conventional methods could be achieved,but with reduced usage of plant protection products.Thus,the intelligent automated system used 4.8 times less spray mixture than the conventional one.

Development of a modified thermal humidity index and its application to human thermal comfort of urban vegetation patches

Extremely hot environments can trigger serious health problems.To evaluate the effects of microclimate on thermal comfort,we proposed and validated a modified thermal humidity index(MTHI)that combined air temperature and relative humidity with land surface temperature(LST).MTHI was more sensitive to microclimate changes than the general thermal humidity index that includes only T and RH,and thus the thermal comfort could be better indicated.In an urban riparian buffer study,we estimated the temporal dynamics and spatial distribution of MTHI values for 47 vegetation patches and explored how structural characteristics of patches affect the thermal comfort.The results showed that planting could significantly reduce LST and MTHI.Vegetation patches with complex vertical structures had considerably higher thermal comfort than those with simple structures.Decreasing nearest distance to river or increasing plant abundance could reduce the thermal discomfort.There were significant differences in the structure characteristics between the patches with MTHI<70 and those with MTHI>70,implying the critical thresholds of variations in thermal comfort with patch structure.Given that people always feel uncomfortable during the daytime in July,optimizing the patch structure is essential to improve the microclimate regulation services of an urban landscape.