Built-up Land Use Research Articles

Contribution of land use changes to meteorological parameters in Greater Jakarta: Case 17 January 2014

The impact of land use changes on meteorological parameters during a heavy rainfall event on 17 January 2014 in Greater Jakarta (GJ) was examined using the Weather Research and Forecasting (WRF) model. This study performed two experimental simulation methods. The first WRF simulation uses default land use (CTL). The second simulation applies the experiment by changing the size of urban and built-up land use (SCE). The Global Forecast System (GFS) data is applied to provide more realistic initial and boundary conditions for the nested model domains (3 km, 1 km). The simulations were initiated at 00:00 UTC January 13, 2014 and the period of modeling was equal to six days. The air temperature and the precipitation pattern in GJ shows a good agreement between the observed and simulated data. The results show a consistent significant contribution of urban development and accompany land use changes in air temperature and precipitation. According to the model simulation, urban and built-up land contributed about 6% of heavy rainfall and about 0.2 degrees of air temperatures in the morning. Simulations indicate that new urban developments led to an intensification and expansion of the rain area. The results can support the decision-making of flooding and watershed management.

Land susceptibility to soil erosion in Orashi Catchment, Nnewi South, Anambra State, Nigeria

Abstract. Soil erosion is one of the most critical environmental hazards that causes land degradation and water quality challenges. Specifically, this phenomenon has been linked, among other problems, to river sedimentation, groundwater pollution and flooding. This paper assesses the susceptibility of Orashi River Basin (ORB) to soil erosion for the purpose of erosion control measures. Located in the South Eastern part of Nigeria, the ORB which covers approximately 413.61 km2 is currently experiencing one of the fastest population growth rate in the region. Analysis of the soil erosion susceptibility of the basin was based on four factors including; rainfall, Land use/Land cover change (LULC), slope and soil erodibility factor (k). The rainfall was assumed to be a constant and independent variable, slope and soil types were categorised into ten (10) classes each while the landuse was categorised into five classes. Weight was assigned to the classes based on the degree of susceptibility to erosion. An overlay of the four variables in a GIS environment was used to produce the basin susceptibility to soil erosion. This was based on the weight index of each factors. The LULC analysis revealed that built-up land use increased from 26.49 km2 (6.4 %) in year 1980 to 79.24 km2 (19.16 %) in 2015 at an average growth rate of 1.51 km2 per annum while the light forest decreased from 336.41 km2 (81.33 %) in 1980 to 280.82 km2 (67.89 %) in 2015 at an average rate 1.59 km2 per annum. The light forest was adjudged to have the highest land cover soil erosion susceptibility. The steepest slope ranges between 70 and 82∘ (14.34 % of the total land area) and was adjudged to have the highest soil susceptibility to erosion. The total area covered of the loamy soil is 112.37 km2 (27.07 %) with erodibility of 0.7. In all, the overlay of all the variables revealed that 106.66 km2 (25.70 %) and 164.80 km2 (39.7 %) of the basin has a high and very high susceptibility to soil erosion. The over 50 % high susceptibility of catchment has serious negative implications on the surface water in terms of water quality and downstream siltation with great consequences on biodiversity and ecosystem services including domestic and industrial usage.

Utilizing publicly available satellite data for urban research: Mapping built-up land cover and land use in Ho Chi Minh City, Vietnam

Urbanization is a fundamental trend of the past two centuries, shaping many dimensions of the modern world. To guide this phenomenon and support growth of cities that are competitive and sustainably provide needed services, there is a need for information on the extent and nature of urban land cover. However, measuring urbanization is challenging, especially in developing countries, which often lack the resources and infrastructure needed to produce reliable data. With the increased availability of remotely sensed data, new methods are available to map urban land. Yet, existing classification products vary in their definition of “urban” and typically characterize urbanization in a specific point (or points) in time. Emerging cloud based computational platforms now allow one to map land cover and land use (LC/LU) across space and time without being constrained to specific classification products. Here, we highlight the potential use of publicly available remotely sensed data for mapping changes in the built-up LC/LU in Ho Chi Minh City, Vietnam, in the period between 2000 and 2015. We perform a pixel-based supervised image classification procedure in Google Earth Engine (GEE), using two sources of reference data (administrative data and hand-labeled examples). By fusing publicly available optical and radar data as input to the classifier, we achieve accurate maps of built-up LC/LU in the province. In today's era of big data, an easily deployable method for accurate classification of built-up LC/LU has extensive applications across a wide range of disciplines and is essential for building the foundation for a sustainable human society.

CELLULAR AUTOMATA MODELING IN THE BUILT UP AREAS WITHIN URBAN DEVELOPMENT AT PONTIANAK, WEST BORNEO, INDONESIA

This research integrated the GIS-Cellular Automata model with the regression model to predict urban development in Pontianak within the built up area change phenomena approach. The research aimed to understand built-up land use development in Pontianak during 1990-2015 and to predict its regional development in 2033. The employed method were satellite the image interpretation approach, hybrid interpretation, and built up land development prediction using transition rules like driving factors and inhibiting factors of urban development. The driving ones are accessibility related to distances to CBD, to main roads, and to the existing built regional areas while the inhibiting ones are peatland and the protected areas. The result showed that the hybrid interpretation, between visual and digital interpretations from the landsat images, can be used to map the built up lands with 94.8% of sampling point’s precision. The non-built up areas in Pontianak during 1990-2015 were 83.52 Ha/year, and the modelling result predicts that non-built regional areas in Pontianak during 2015-2033 will be 80.51 Ha/year heading toward northern and central areas of Pontianak.

Government, enterprise and resident: Roles of local agents in regulating and simulating built-up land use and change in a mining city

Various agents are involved in decision-making when built-up land is allocated and regulated, but the roles of these agents must be clarified. To aid this process, the agents in Wu’an (a mining city in China) were classified as government, enterprise and resident, and then their roles were analyzed to establish a decision-making mechanism. The model of physical site selection for enterprises and residents was quantitatively simulated, taking into account the qualitative constraints from government and enterprises. Based on these rules, eight scenarios under economic development-driven scenario (EDdS) series and the environmental conservation-driven scenario (ECdS) series were set up, and vertical and horizontal comparisons were implemented for analysis. Our study showed that the established models could be well fitted for simulation, and that economic development could stimulate the allocation of more built-up land. The most important achievement is that the proposed comparison can effectively distinguish among the roles of various agents, as well as quantify government and enterprise incentives.

Antibiotic resistance genes in lakes from middle and lower reaches of the Yangtze River, China: Effect of land use and sediment characteristics

Freshwater lakes provided an ideal media for the accumulation and propagation of antibiotic resistance genes (ARGs), because they were susceptible to anthropogenic impacts. Land reclamation and urbanization exerted severe anthropogenic impacts on lakes from middle and lower reaches of the Yangtze River, China over the past decades. In this study, 15 lakes in the region were selected to understand the level and variability of ARGs. Proportion of different land use types was applied to display the land reclamation and urbanization around each lake. For sulfonamide resistance (sul) genes, sul1 had the highest relative abundance in sediments, with maximum 2.11 × 10−1 copies/16SrRNA copy in Gehu Lake. For tetracycline resistance (tet) genes, tetG had the highest average value of relative abundance (4.74 × 10−3 copies/16SrRNA copy), followed by tetB, tetA, tetQ and tetM. Class I integron (intI1) played an important role in acquisition and dissemination of sul1 and tetG. Sediment characteristics (moisture, density, total nitrogen, total carbon, ammonium, and nitrate) were found to have no significant effect on ARG distribution. Taihu Lake and Yangcheng Lake which exhibited high sul and tet genes had the high proportion of built-up land use.

Integration of Markov chain analysis and similarity-weighted instance-based machine learning algorithm (SimWeight) to simulate urban expansion

ABSTRACTThis study simulates urban expansion using Kaduna in North-West Nigeria as a case study. A hybrid model that integrates the similarity-weighted instance-based machine learning algorithm for transition potential modelling and the Markov chain model to quantify and allocate land-use change was used to overcome the identified weaknesses of known modelling techniques such as the cellular automata, Markov chain and standard logistic regression models. Environmental and urban physical variables that act as constraints and/or incentives to urban expansion were operationalized to create transition potentials for spatiotemporal states of built-up land use for the year 1990 and 2001. Model evaluation and validation was carried out using the relative operating characteristic and kappa index of agreement statistics. Having obtained satisfactory outcomes from the validation process, the modelled transition potentials were used to predict future urban expansion for forthcoming years. The simulated land-use maps provide valuable insights into the location and type of urban expansion that is likely to occur in Kaduna in the foreseeable future. This provides city managers and planners much needed information that could inform urban policy aimed at better planning and management of urban development.

Nearest neighbour analysis applied to synthetic aperture radar images for the description of urban land cover and land use

ABSTRACTThis article presents an analysis method for the creation of an image variable that represents built-up land cover and land use within the urban fabric. The method is inspired by the nearest neighbour analysis and the data are from the synthetic aperture radar systems COSMO-SkyMed (CSK) and Radarsat-2 (RS2). Point features were identified from the extreme high backscattering values for each image and the spatial pattern extracted to represent the proportion of built-up land cover as clustered, random, or dispersed. The coefficient of association between the continuous nearest neighbour ratio image and the land-cover percentage cover in four classes are −0.9 and −0.8 with the CSK and the RS2 images, respectively. Considering a two-class land-cover scheme, the coefficient of association between variables approaches −0.9 for both images. Clustered features highlight individual buildings that are mixed in various neighbouring land-cover and land-use types. Residential land use is particularly well outlined using the CSK image, while large institutional, commercial, and light industry buildings are enhanced through the RS2 cross-polarization nearest neighbour ratio images.

The influence of rapid urbanization and land use changes on terrestrial carbon sources/sinks in Guangzhou, China

Complex changes in carbon sources and sinks caused by rapid urbanization have been observed with extensive changes in the quantity, structure, and spatial pattern of land use types. Based on the modified Carnegie-Ames-Stanford Approach model and on gray relational analysis, we analyzed the influence of land use changes on carbon sinks and emissions in Guangzhou from 2000 to 2012. The aim was to identify suitable options for built-up land expansion that would allow for minimal carbon losses. The key results were as follows: (1) Built-up land increased by 118.91% in Guangzhou city over the study period, with this expansion taking the form of concentric circles extending around the old Yuexiu district. (2) Carbon emissions over the period of analysis significantly exceeded carbon sink capabilities. The total carbon sink decreased by 30.02%, from 535.40×103t to 374.6×103t. Total carbon emissions increased by 1.89 times, from 13.73×106t to 39.67×106t; 80% of carbon emissions were derived from energy consumption. (3) There were large differences in the extent of carbon sink losses at different scales of built-up land expansion and land use change. In Guangzhou, the loss of carbon sink is small when cultivated land (though not prime farmland) and water bodies are converted to built-up land on a small scale. The loss of carbon sink is much smaller when grasslands are converted to built-up land on a large scale. However, forested land, which has excellent carbon sink functions, should not be converted. (4) Changes in carbon sinks were mainly affected by natural factors and land urbanization. Changes in carbon emissions were mainly affected by population urbanization, economic urbanization, and land urbanization. (5) To achieve “economical and intensive use of land”, “urban growth boundary” and “ecological red lines” should be determined for government policies on land use management. These factors have great significance for “increasing carbon sinks and reducing carbon emissions” in urban ecological systems.

Effects of land-use patterns on in-stream nitrogen in a highly-polluted river basin in Northeast China

This study investigated the effects of land-use patterns on nitrogen pollution in the Haicheng River basin in Northeast China during 2010 by conducting statistical and spatial analyses and by analyzing the isotopic composition of nitrate. Correlation and stepwise regressions indicated that land-use types and landscape metrics were correlated well with most river nitrogen variables and significantly predicted them during different sampling seasons. Built-up land use and shape metrics dominated in predicting nitrogen variables over seasons. According to the isotopic compositions of river nitrate in different zones, the nitrogen sources of the river principally originated from synthetic fertilizer, domestic sewage/manure, soil organic matter, and atmospheric deposition. Isotope mixing models indicated that source contributions of river nitrogen significantly varied from forested headwaters to densely populated towns of the river basin. Domestic sewage/manure was a major contributor to river nitrogen with the proportions of 76.4±6.0% and 62.8±2.1% in residence and farmland-residence zones, respectively. This research suggested that regulating built-up land uses and reducing discharges of domestic sewage and industrial wastewater would be effective methods for river nitrogen control.

Virtual land use change in China 2002–2010: Internal transition and trade imbalance

As the second largest economy with the largest population in the world, China encounters crucial land availability for food security and socio-economic development. In the context of China's booming economy over the past 3 decades, this study intends to reveal the impacts of domestic demand and international trade on land use distribution of China in the period 2002–2010. This study aims to systematically analyze China's land use-related issues comprehensively, considering multi-type land use, high sectoral resolution, and time series input–output data. Obviously, primary industry is the largest virtual land occupier which covers both the local land use and land use trade, while the importance of secondary and tertiary industries should not be ignored. Mainly due to the land use embodied in the secondary and tertiary industries, China is found as a net exporter of cultivated land use. This figure exceeds by 25 times the cultivated land use loss due to built-up land use occupation, which means that the “red line”, China's cultivated land area constraint set as 120 million hectares (ha), is gradually losing its original meaning. With respect to all types of land use, China exports 20 million ha of land use per year, accounting for 1/50 of the total land area. The huge land use trade imbalance raises an alarm for China. In the recent past, the land occupation type is gradually translating from the original “colonial” land to inter-national land use trade imbalance, and obviously China has not been familiar with such hidden aspects remaining in global trade. As both the direct and indirect land use associated with consumption and trade flows become increasingly significant, suggestions from the virtual perspective are urgently needed to initiate a new horizon.

Pengaruh Perubahan Penggunaan Lahan Sub DAS Rawapening terhadap Erosi dan Sedimentasi Danau Rawapening

Konferensi Nasional Danau Indonesia ( KNDI ) di Bali tahun 2009 menetapkan Danau Rawapening sebagai salah satu dari 15 ( lima belas ) danau/waduk yang memerlukan prioritas dalam pemulihan kerusakan danau di Indonesia. Alih fungsi lahan yang terjadi pada Sub DAS Rawapening memicu terjadinya peningkatan kerusakan lahan yang berimbas pada tingginya laju erosi dan s edimentasi di Danau Rawapening. Penelitian ini menggunakan pendekatan positivistik/kuantitatif dengan metode analisis yang digunakan adalah metode penelitian deskriptif yang menggambarkan variabel -variabel dan fenomena-fenomena yang terjadi. Hasil perhitungan erosi dan sedimentasi menunjukkan bahwa erosi dan sedimentasi di Danau Rawapening menurun dari tahun 1991, 2001 dan 2011. Hal ini dikarenakan ada beberapa faktor yang bersifat dinamis pada analisis yang dilakukan. Untuk melihat pengaruh perubahan penggunaan lahan terhadap erosi dan sedimentasi secara mendalam maka digunakan nilai erosivitas rata-rata sebesar 2.523,09. Hasil analisis menunjukkan bahwa penurunan luas lahan tegakan berbanding terbalik dengan laju erosi, jumlah erosi dan sedimentasi. Sedang kan luasan lahan terbangun berbanding lurus dengan laju erosi, jumlah erosi, dan sedimentasi. Perubahan penggunaan lahan yang menyebabkan kenaikan erosi terbesar adalah perubahan penggunaan lahan dengan tegakan menjadi lahan terbangun dan perubahan penggunaan lahan pertanian menjadi lahan terbangun.Kata kunci : perubahan penggunaan lahan, erosi, sedimentasi

Historical trends of wetland areas in the agriculture and pasture interlaced zone: A case study of the Huangqihai Lake Basin in northern China

Wetland degradation has become a serious global environmental issue. The agriculture and pasture interlaced zone (APIZ) in China is often close to the transition zone between arid and semi-arid regions, and it is extremely ecologically sensitive and vulnerable to global change. However, reports on changes in wetland areas in such zones are rarely available. Here, we analyzed remote sensing images to quantify the historical change in the wetland area of the Huangqihai Lake Basin located in the APIZ in China. The comparison indicated an excellent agreement between the results from remote sensing images and historical records for the lake area. Our results showed that 73% of wetland area had disappeared during 1976–2010. About 86% of the lost wetland area was converted to grassland, forest, and bare fields, while 14% was converted to cropland and built-up land use types. The largest lake in this basin, the Huangqihai Lake, was in a state of contraction during this period, and it has been completely dry since 2008. A large share (54%) of the lost area of the lake has become marshes, while about 97% of the original marsh area within the basin disappeared during 1976–2010. Without substantial efforts in wetland management and protection, this trend in natural wetland degradation is likely to continue. Mapping wetland areas with remote sensing images is an effective approach to providing wetland area information in a spatially and temporarily explicit way in regions where monitoring programs are not available. Such information is useful for understanding wetland degradation processes, and is helpful for investigating the driving forces of wetland degradation.

Relationships between land use patterns and water quality in the Taizi River basin, China

Using land use types and landscape metrics, as well as statistical and spatial analysis, we determined the relationships between land use patterns and river water quality in the Taizi River basin, China, during dry and rainy seasons in 2009. Correlation and multiple linear regressions indicated that vegetated areas had a positive contribution to river water quality and predicted total nitrogen during the rainy season. Built-up land use strongly influenced nitrogen and phosphorus parameters in river water. Agricultural land use was associated with most physicochemical variables and nitrogen during the rainy season. Landscape metrics during both seasons were significantly associated with river water quality. Shannon's diversity index was the primary predictor for chloride and ammoniacal nitrogen. Mean Euclidean nearest neighbor index defined ammoniacal nitrogen, orthophosphate, and total phosphorus during the dry season. Biological oxygen demand and permanganate index were expressed by Contagion during the rainy season. Factor analysis indicated that the river suffered organic, phosphorus, and nitrogen pollution and a zone dominated by agricultural and built-up land uses in the river basin tended to have worse water quality than other areas. The results provide a useful approach that uses landscape patterns to estimate water quality in rivers for water pollution control and land use management.

Sensitivity of predicted pollutant levels to anthropogenic heat emissions in Beijing

A new parameterization method for anthropogenic heat (AH) parameterization (called NewLUCY) is developed in the WRF-Chem model, which estimates hourly heat fluxes with a single-peak diurnal variation pattern and utilizes updated urban built-up land use data. The impacts of accounting for anthropogenic heat (AH) fluxes on the meteorology and air quality of the Greater Beijing area are studied using this upgraded WRF-Chem model system. Including AH is shown to increase the surface temperature by 0.8°C in daytime and 1.2 °C at nighttime. The Planetary Boundary Layer (PBL) heights are also increased, with a maximum incrementation exceeding 320 m during daytime and 160 m at night. Spatial and vertical distributions of the simulated pollutants are also impacted by the AH. Surface ozone concentrations increase in the urban areas (4ppb for daytime and 18 ppb for nighttime) when AH is included in the analyses. Moreover, the impacts of AH are not limited to the urban centers, but extend regionally. For example, the simulated PM2.5 concentrations increase in the rural areas as well, due to a decrease in rural precipitation rates when AH is included. In general, incorporation of AH increases the accuracy of the predictions comparing to the observations. At the Peking University site (PKU), the mean error (ME) of the 2-m temperature prediction is reduced from 1.55 °C to 0.61 °C. The predictions of the high ozone episodes are also improved.

Human Comfort and the microclimatic drivers across different land use types in Port Harcourt Metropolis, Nigeria

The study identified spatially differentiated thermal human comfort conditions based on heat stress and microclimate data for specific urban built-up land use classes; and examined the influence of certain microclimatic elements on the observed human comfort levels within the coastal milieu of Port Harcourt metropolis. Five days weather (wind speed, air temperature and relative humidity) and human comfort (heat stress) data were obtained for each land use using the Kestrel 4500 weather tracker. In addition, human comfort based on Heat Index (HI) computed using the American Weather Service (AWS) heat index calculator was obtained to determine the associated heat related hazard across the land use types. Data was subjected to descriptive and inferential statistical analysis. Commercial areas had highest mean heat stress (poor human comfort), followed by high density residential areas. A major attribute is the high concentration of population and human activity capable of generating enormous heat. Since relative humidity and air temperature are major determinants of heat stress, the heat Index (HI) obtained using these parameters confirmed that commercial and high density residential areas were more uncomfortable, having higher heat stress and heat index. Port Harcourt may witness continuous increase in heat stress with climate change projections associated with high temperature and relative humidity. Regression Analysis revealed that there is a significant association between microclimate and human comfort, with temperature being a major determinant, followed by relative humidity. Therefore policies that encourage the provision of more vegetation cover should be adopted to curb the effect of urban heat island and heat related diseases on the environment and health of the residents.Key words: Heat stress, human comfort, microclimate, land use, urban, vegetation

Integration of logistic regression, Markov chain and cellular automata models to simulate urban expansion

This research analyses the suburban expansion in the metropolitan area of Tehran, Iran. A hybrid model consisting of logistic regression model, Markov chain (MC), and cellular automata (CA) was designed to improve the performance of the standard logistic regression model. Environmental and socio-economic variables dealing with urban sprawl were operationalised to create a probability surface of spatiotemporal states of built-up land use for the years 2006, 2016, and 2026. For validation, the model was evaluated by means of relative operating characteristic values for different sets of variables. The approach was calibrated for 2006 by cross comparing of actual and simulated land use maps. The achieved outcomes represent a match of 89% between simulated and actual maps of 2006, which was satisfactory to approve the calibration process. Thereafter, the calibrated hybrid approach was implemented for forthcoming years. Finally, future land use maps for 2016 and 2026 were predicted by means of this hybrid approach. The simulated maps illustrate a new wave of suburban development in the vicinity of Tehran at the western border of the metropolis during the next decades.

Using Aerial Photography to Estimate Riparian Zone Impacts in a Rapidly Developing River Corridor

Riparian zones are critical for protecting water quality and wildlife, but are often impacted by human activities. Ongoing threats and uncertainty about the effectiveness of buffer regulations emphasize the importance of monitoring riparian buffers through time. We developed a method to rapidly categorize buffer width and landuse attributes using 2007 leaf-on aerial photography and applied it to a 65 km section of the Toccoa River in north Georgia. We repeated our protocol using 1999 leaf-off aerial photographs to assess the utility of our approach for monitoring. Almost half (45%) of the length of the Toccoa River was bordered by buffers less than 50 ft wide in 2007, with agricultural and built-up lands having the smallest buffers. The percentage of river length in each buffer width category changed little between 1999 and 2007, but we did detect a 5% decrease in agricultural land use, a corresponding increase in built-up land use, and an additional 149 buildings within 100 ft of the river. Field verification indicated that our method overestimated buffer widths and forested land use and underestimated built-up land use and the number of buildings within 100 ft of the river. Our methodology can be used to rapidly assess the status of riparian buffers. Including supplemental data (e.g., leaf-off imagery, road layers) will allow detection of the fine-scale impacts underestimated in our study. Our results on the Toccoa River reflect historic impacts, exemptions and variances to regulations, and the ongoing threat of vacation home development. We recommend additional monitoring, improvements in policy, and efforts to increase voluntary protection and restoration of stream buffers.

Urbanisation of rural areas: A case study from Jutland, Denmark

Geografisk Tidsskrift—Danish Journal of Geography 110(1):47–63, 2010 The growth of urban areas is one of the most important characteristics of spatial development in Europe during the past decades and is traditionally described with a few indicators on a relatively coarse spatial scale. However, urbanisation is not only a matter of land use change, but also socio-economic changes, which may or may not manifest itself as physical changes in built-up area and land use. It is therefore useful to analyse the urbanisation patterns along an urban-rural continuum, based on a broad range of indicators. This paper analyses urbanisation patterns in rural areas of Region Midtjylland, Denmark using socio-economic data from the entire rural population aggregated at parish level to investigate if this method may contribute to existing classifications. Through multivariate analysis and GIS analysis, five types of urbanization were identified and their spatial distribution analysed. The results indicate that rural areas of Region Midtjylland are very diverse, and generally reflect the pattern described in the 2006 Danish National Planning Report. However, our results offer a more fine-grained analysis based on scientifically selected indicators which is an important step to improve existing classifications. This is especially relevant in a Danish context following the administrative reform in 2007 which renders the traditional classifications less suited for locally adapted planning and policy formulation.

Urban Biogeographical Analysis of Spontaneous Tree Growth on Stone Retaining Walls

Stone retaining walls in urban Hong Kong provided vertical habitats for spontaneous colonization by a diversified humid-tropical flora with large trees. A citywide survey assessed wall and tree characteristics to understand wall-tree relationships and identify conservation candidates. Nonparametric correlations were computed between 28 wall attributes versus tree count, tree biomass, and species-vegetation factors. Most of the 245 walls, with 1275 trees, were in residential areas. Moraceae dominated the 30 tree species, predominantly genus Ficus, and especially F. microcarpa. Natives formed the overwhelming majority, largely with pioneer and ruderal traits. The positive effect of adjacent built-up land use and negative effect of wall exposure indicated sheltering from wind could facilitate tree growth. Wall height was a key determinant as taller walls furnished more surfaces free from human disturbance and conducive to seed deposition by frugivorous birds and bats. Stone width offered more horizontal microsites for seeds to lodge. Stone roughness operated at the microscale to encourage nonarboreal vegetation. Joint attributes exerted strong influence on tree growth and less so on nontree affiliates. The walls-cum-vegetation, many older than 100 years, presented a precious natural-cum-cultural heritage, deserving protection as an urban ecological asset.