Prospects and challenges of achieving sustainable urban green-spaces: A case study of urban greening in Dhaka North City Corporation (DNCC), Bangladesh

Urban green spaces and urban forest covers are a significant component of urban planning which is critically ignored in Bangladesh. This study aims to identify the prospects and challenges of achieving sustainable urban green spaces in Dhaka North City Corporation (DNCC), Bangladesh which is a significant indicator of the sustainable development goal (SDG11). We have analyzed the historical land use and land cover change (LULC) from 1992, 2002, 2012, and 2022 using Landsat 4–5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Operational Land Imager (OLI) images by ArcGIS 10.8 and Google Earth-pro software. The use of the Normalized Difference Vegetation Index (NDVI) primarily indicates vegetation greenness as well as determining other land uses such as waterbody, settlements and barren land. The calculated kappa values varied from 80% to 86.7% for all the years and fit the current research. A strength-weakness-opportunity-threat (SWOT) analysis reviewed and analyzed existing sectoral policy and plans to identify challenges to achieve sustainable urban forestry. Fifteen key informant interviews (KII) from Dhaka North City Corporation ( DNCC), Department of Environment (DOE), Bangladesh Forest Department (BFD), and Department of Social Forestry Department (DSF) wing under BFD were taken to identify the status of urban forestry, its problems, opportunities, and threats. The responses were drawn using a Driver-Pres-sure-State-Impact-Response (DPSIR) framework. Of the total measurements of 194.2sq km (2022), normal vegetation cover has decreased significantly from


Introduction
Urban green spaces are a significant part of urban planning.The terms such as 'green space', 'public open space', 'open space', and 'park' are used interchangeably and synonymously in many kinds of literature [1][2][3].Urban green space encompasses neighbourhood parks, playgrounds, sports fields, recreational green areas, and urban forest covers [4].On the other hand, the urban forest consists of all urban plants, including street trees and patches of park trees, and peri-urban woods extending to the outer metropolis.Land types include natural forest parks and urban forests >0.5 hectares, pocket parks and gardens, street or public squares plants, and other open areas of trees, including pavements, corridors, rooftops, and nurseries [5,6].Urban forests offer necessary ecosystem services for aesthetics, and comforts in urban heat, bad air quality, hydrologic regime and pollution control, and support social stability, public health and well-being [7][8][9].Urban vegetation can store a considerable amount of carbon, ensuring the long-term stability of carbon fluctuation in the environment and thus helpful for mitigating atmospheric CO 2 concentration [10].
However, many megacities worldwide have turned to impervious surfaces with less vegetation growing spaces [11].Consequently, the urban vegetation covers face many challenges in a stressful artificial, rapidly shifting urban environment [7].It is noteworthy that different forms, sizes, and tree covers influence urban climate and temperatures [12].For example, water bodies and urban forest covers influence moderating temperatures and function as thermal buffers [3,4,12].The latest nationwide forest inventory conducted from 2016 to 2019 shows that the forest cover is 12.8% of Bangladesh which is 14.1% of the country's total land area [13,14].Dhaka, Bangladesh's capital, is one of the world's top ten megacities, overgrowing in population of 21 million, trailed by Asian megacities such as Tokyo, Delhi, Shanghai, São Paulo, and Mexico City [15][16][17].For 1528 km 2 of informal urbanization, climate change and environmental pollution have affected 18.2 million inhabitants [18].Therefore, in the urbanization process, Dhaka city's free spaces are being turned into affordable housing while the open fields are turned into the car parking area for shopping malls, and lower lands such as ponds and lakes are being turned into reclaimed build-up lands.However, the lack of open spaces negatively affects the physical and mental health of the inhabitants.In previous studies, it was reported that good quality blue-green infrastructures were associated with better adolescent mental health, the well-being of migrant workers, reducing neighbourhood violence in low-income areas etc. [4,[19][20][21].New research during the pandemic demonstrates the greater importance of access to local parks and recreational activities.During the pandemic, parks, gardens, and other local blue-green spaces have been identified as critical to people's physical and emotional well-being [22].
SDG 11 targets the cities and human settlements to be inclusive, safe, resilient, and sustainable.At the same time, its indicator 11.7.1 aims to monitor the amount of land and green spaces that cities are dedicated to for public space [23,24].This means achieving sustainable development goals (SDG 11) for metropolitan areas that target sustainable, safe, resilient, and inclusive cities by 2030.However, a traditional forest-based economy in urban areas cannot respond to sociopolitical, environmental, and economic challenges [25].Consequently, a forest-based bioeconomy can expand value-added products or implement the non-traditional use of woods in urban areas to achieve SDG 11 [26].Urban green spaces and infrastructure can provide potential bioeconomic activities such as urban farming, gardening, and recreational activities [26,27], ecosystem services, economic stimulation, biodiversity conservation, water resource protection, microclimate improvement, carbon sequestration, and fresh food supply [26,28,29].Therefore, constructing a plan for multifunctional urban green infrastructure is critical to achieving urban sustainability goals to improve city dwellers' quality of life and the environment [30].Since urban green infrastructure encompasses urban green spaces and is a part of the urban green infrastructure concept and the urban forest is also a part of urban green space and therefore a significant component of SDG 11.7.1.The open space area in Dhaka city, Bangladesh was only about 24.5% in 2005 compared to 44.8% in 1975 [31].88% of Dhaka city's dynamic core area is built-up (78.56 km 2 ), replacing green zones or wetlands in the study in 2013 [32].Due to insufficient vegetation cover and a lack of diversified trees, Dhaka city's carbon sequestration is unsatisfactory [9].The average cooling and humidifying effect of medium-sized green areas was most noticeable during hightemperature days.Furthermore, the layout and amount of water basins within a green space have a significant impact on local cooling and humidity [33].Moreover, the loss of urban green zones and wetlands can promote an urban heat island effect, a microclimatic event with significant temperature rise and amplifying heat waves [34].Although the exact human effect is not identified yet, it is evident that microclimatic variation in terms of green space can, therefore impact the human comfort zone which needs to be addressed in urban planning and decision-making.Remote sensing and geospatial information system (GIS) along with land use and land cover change (LULC) can identify trends with image categorization and an excellent tools for decision-making.Availability of images, secondary data, classification technique, and user experiences can accurately produce exact LULC with proper accuracy assessment [35,36].Increased urban expansion and sprawl may result in changes in land usage as well as land alteration.Yet, reliable and current information regarding LULC is essential for a better understanding and assessment of the environmental consequences of such changes [36].
Changes in LULC throughout an area are critical for resource management, sustainable development, and holistic planning to achieve the United Nations Sustainable Development Goals (SDGs) 2030 takes a comprehensive methodology that recognizes all countries to turn to sustainable growth with different targets and indicators in terms of land use.
Compared to all other megacities around the world, where urban forestry and urban greening are highly valued as a means of achieving sustainable urban growth, Dhaka is less focused and concerned, with little initiative in this region.The present study aims to determine the historical LULC in Dhaka North City Corporation (DNCC) and how this scenario can be incorporated into future decision-making in terms of sustainable development goals 11.In addition, it also explores the prospects and challenges for enhancing the urban forestry policy, plans, and programs (PPPs) through key informant interviews to identify the challenges for achieving sustainable urban green space.
The data were analyzed with ArcGIS 10.8 and "Google Earth-pro" software.Reference data for proper boundary delineation was taken, followed by a classification scheme designed for Supervised-Maximum Likelihood Classification (SMLC) of image.Satellite image classification was established by obtaining various sorts of Landsat image spectral signatures.Following the acquisition of the images, the most important aspect for different land classes was the band color composite selection.It can quickly identify various terrain observations.Once the classification was done, the raster images were converted into polygons, and the polygon features dissolved into form a single category of land-use types.Accuracy assessment of the map and production of the initial land cover map was produced.Finally, the map was designed to determine the area of vegetation cover, settlement (built-up urban areas), barren land, and water bodies.
To find out the amount of vegetation cover of DNCC, satellite data was taken from The United States Geological Survey (USGS) server (https://earthexplorer.usgs.gov/).The highest resolution and visibly clear images were chosen to avoid cloud coverage, satellite sensor problem and other issues.Satellite images from 1992 to 2022 are taken for this study for clear image resolution.All the images were selected for the pre-monsoon season in Bangladesh.There is an interval of 10 years between each satellite image.The image for the study area is selected using path 137 and row 044.ArcGIS software is used for pre-processing, classification, and map generation.All other details of the satellite image data are shown in Table 1.
The images from the Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) have a spatial resolution of 30 meters for Bands 1 to 7 and 9. Panchromatic Band 8 has a 15-meter resolution.Thermal bands 10 and 11 are effective for delivering more precise surface temperatures and are collected at 100 meters [39].Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images consist of eight spectral bands with a spatial resolution of 30 meters for Bands 1 to 7. Panchromatic Band 8 has a 15-meter resolution.Band 6 collects both high and low gain for all scenes, while the other bands can only collect one of the two gain settings (high or low) for greater radiometric sensitivity and dynamic range [40].Landsat 4-5 Thematic Mapper (TM) images are formed by seven spectral bands, each with a spatial resolution of 30 meters for Bands 1-5 and 7. Thermal infrared Band 6 has a spatial resolution of 120 meters, but the resolution is resampled to 30-meter pixels (Table 2).

Normalized Difference Vegetation Index (NDVI) analysis
Normalized Difference Vegetation Index (NDVI) is used to quantify vegetation greenness and is useful in understanding vegetation density and assessing changes in plant health.Using spectral reflectance in the red and near infrared bands, this index is calculated.The range of NDVI values is -1 to 1. Lower NDVI values (usually between 0 and 0.2) imply light or dark soils, while higher NDVI values suggest dense vegetation [41].NDVI is calculated using the equation below: In Landsat 4-7, In Landsat 8-9, Suitable normalized difference vegetation index (NDVI) ranges identified for the land cover classes are given in Table 3 [42]:

Accuracy assessment
Accuracy assessment is an approach that shows the uniformity between a surface feature of the earth and the classification's outcomes.It is essential to determine changes in land use with absolute precision by classifying satellite images from various years.The kappa statistic is widely used to assess interdependence.The kappa values are a matrix that allows comparison between actual and anticipated accuracy as well as random change.The significance of interrater reliability depends on the fact that it accurately reflects the variables being measured in the study's data.The Kappa value range will always be between 0 and 1 [35].A value of 1 implies perfect agreement and values less than 1 imply less-than-perfect agreement.The scale of Kappa (k) value interpretation is presented in Table 4 [36].
Table 5 states the estimated Kappa coefficient (k) values for image analysis in different years.The calculated Kappa coefficient (k) values indicate "Very Good Agreement" in 1992, 2002, and 2022; while "Substantial Agreement" in 2012.Therefore, image analysis for detecting LULC changes exhibits top-level accuracy.
The overall scheme is shown in Fig 2.

Policy, plan, and program (PPP) Review and Key informant interviews (KII)
Relevant forestry policies and development plans of Bangladesh considering urban forestry were reviewed.Bangladesh forestry policy draft 2016 [43], national environmental policy 2018 [44], Bangladesh forestry master plan draft 2017-2036 [45], Urban and regional planning act draft 2017 [46], 8 th 5-year plan of the Government of Bangladesh [14], forest investment plan draft 2017 [47] were reviewed for content analysis that indicated on urban green space.Fifteen KIIs with the Bangladesh Forest Department (BFD), social forestry wing (SFW) under BFD, Department of Environment (DoE), Dhaka North-City Corporation (DNCC), urban planners, university faculty members were done to identify the effectiveness of urban forestry policy, plans, programs implementation for urban greening in terms of urban forest cover.Key informants were contacted based on their expertise in the relevant field, particularly in urban forestry, urban planning, and environmental expertise.We contacted key informants by email or phone before taking their interviews for their consent.The KII questionnaire is given in Box 1.During the questionnaire development, two strategic frameworks were considered: 1) strength-weakness-opportunity-threat (SWOT) analysis and 2)Driver-Pressure-State-Impact-Response (DPSIR) framework analysis.The questionnaire was prepared and asked in Bengali and translated into English.The comments from the respondents were also Bengali, recorded and later transcribed and translated into English.

SWOT analysis
A strength-weakness-opportunity-threat (SWOT) analysis was prepared (Fig 3), which is an applied analytical tool for strategic planning and analysis and modelling for the responsible institutional capacity assessment [48][49][50].Using SWOT analysis, strengths, opportunities, weaknesses, and threats of the environment have been stated and grouped.Strength and opportunity represent the positive impact, weakness and threats of SWOT show harmful sides.Also, it recognizes internal and external factors.

DPSIR framework analysis
A Driver-Pressure-State-Impact-Response (DPSIR) framework establishes a causal linkage for representing societal and environmental interactions (Fig 4) [51].It is a strategic and linear    tool for assessing, analyzing, and reporting global, regional, national, and local environmental problems at multiple spatial and temporal scales [52][53][54][55].The framework attempts to encompass various stakeholder perspectives conceptually [55].The model has been widely used in forest management for forest land protection, governance, management, and decision-making to identify impacts and responses accordingly [56][57][58][59].This framework was recently used in the strategic environmental assessment of the South-West Region and the Sundarbans [60].
The DPSIR framework is a flexible and easy tool for qualitatively representing an overall scenario, starting from the drivers and ending with identifying responses.The framework was used for the representation of the KII responses.Moreover, this is a qualitative representation; sometimes, a single item can be represented in multiple nodes, which is a limitation of the framework.

Historical LULC in DNCC from 1992-2022
The historical LULC status of the DNCC shows the area of water bodies, vegetation cover, urban settlements, and barren land (  5).The main reason for this was the enactment of various policies and laws related to the protection of water bodies, such as the "The Playground, Open Spaces, parks, and Water Bodies Conservation Act 2000" and "The Public Water Body Management Policy 2009".Furthermore, the government's wetland restoration projects enabled many wetlands to restore their natural position during that period.One of these initiatives is the Hatirjheel Area Development Project, a wetland restoration endeavour that considers the prospect of returning water edge features to the DNCC and a 302-acre region.Although the amount of barren land has decreased, the change in barren land has not been as consistent.The main reason for this is that water bodies and agricultural land turn into barren land within a short period and become build-up areas for settlement and development purposes.The settlement of the DNCC area increased from 77.82 sq km to 151.77 sq km during 1992 to 2022.Due to the augmented housing demand for the large population of the city, the vegetated area, agricultural land, and water bodies are converted into build-up areas in this period.Uttara Model Town, Basundhara Residential Area, Purbachal New Town, and Jalshiri Abason are some mentionable residential projects developed on the converted build-up areas.
In a previous study using LULC techniques, from 1989 to 2014, the total urban growth was reported as 81.54%, resulting in a substantial decrease in natural vegetation cover and agricultural land [61].Incredible urban expansion and sustainable urban development are primary concerns for many developing countries [62].A 2021 study revealed that approximately 10% of commercial buildings, 9% of industrial facilities, and 6% of residential buildings have encroached upon conservation zones (such as open space, flood-prone zones, water bodies, and proposed areas for future road extension) [63].LULC map, 1992 indicates higher vegetation cover in Badda, Khilkhet, Turag, Uttar Khan, and Shah Ali Thana.Some of the western parts of Darus Salam, Adabor, and Mohammadpur

Sectoral and relevant policy analysis in urban greening
Political changes had prejudiced the policies regarding forestry of Bangladesh for an extended period since 1979 when the first forestry policy was formulated in independent Bangladesh, later in 1994 and the latest policy draft in 2016.The earlier versions of forest policy were characterized by the commercialization of forests used to maximize state revenue while clearing forest cover for urbanization [64][65][66][67][68][69].Draft forestry policy 2016 aims to increase tree cover outside state forests by forming appropriate public-private partnerships, even in urban areas by research and emerging context such as climate change (Table 7).In addition, in this paper, we have reviewed the content of the draft Urban and Regional Planning Act 2017, which has a significant role in strategically managing agricultural land, wetland, forest land, hill areas, and coastal belts [46] (Table 7).These policies and plans have a significant section on improving participatory forestry programs for livelihood improvement and others, which unfortunately had no implications in the urban areas.Although reasonable, approaches carry no advantages to networks except if they are correctly carried out.In developing nations like Bangladesh, policies are regularly all-around detailed-some of the time, with foreign help, it is not satisfactorily carried out due to impedance by persuasive vested parties like local political leaders and social elites [70].Holistic strategies, juridical systems, program creation, adaptive administration, individual environmental control, and adequate finances are required for urban forestry management [5].
The evolution of forest policy results from the continuous changing of people's needs over the year in different situations.Implementing those policies is hard in the social context of this country because of the lack of adequate institutional capacity, proper backup of the legislative point of view, and poor law enforcement.Despite all these obstacles, recently, there has been some significant development in the forestry sector of Bangladesh since the 1994 forest policy [69].From the previous policy of forest exploitation, reforesting activities have been widely developed in marginal, fallow, and unproductive lands to increase 20% forest cover horizontally.Social forestry has evolved into realistic forest management brought under the afforestation scheme with people's engagement and the benefit-sharing approach [43,45,47,69].The policymakers have gradually developed engaging local people as a top-down approach to adjust to the changing circumstances to ensure sustainable development goals, and ecological, and social benefits.
In the 8 th -5-year plan, GoB [14] continued social forestry schemes to empower more than half a million beneficiaries involved with the overall social forestry program.The benefits of social forestry schemes usually go to the beneficiaries at the end of 10 years cycle.Encroached forest lands, depleted forest areas, vacant marginal land, and roadside areas are reforested in this scheme, which is highly significant in urban forestry improvement.As a result, the necessary policy framework already exists, with several positive aspects.All that remains is to be implemented effectively to increase urban forest cover and green spaces.In October 2020, a landscape policy was drafted concerning roadside beautification and safety.This strategy would allow Forest Department and the Local Government Engineering Department to choose suitable plants for roadside plantations concerning traffic protection and embellishment [47].

SWOT analysis.
Here, based on the key informant interviews, we have done a SWOT analysis of the policies.Seven items were identified as strengths and to counter it 7 items were identified as weaknesses, Five items were identified as opportunities to improve in the future, and five items were identified as threats for future implementation by the key informants (Table 8).All the departments are shown higher expectations for the forestry policy 2016 [43] already, which has been drafted by the government of Bangladesh (GoB).If approved, that will fulfil SDG goal indicator 11.7.1 (sustainable cities and communities in terms of open/green spaces).Subsequently, another strength factor is the several bilateral and multilateral development partners of GoB for developing urban forestry by taking on various projects.These two vital factors also have afforestation programs like-road side plantation, homestead, rooftop gardening, and nursery activities.The top weakness factors expressed are informal and unplanned urbanization and improper planning for the urban forest and land tenure problems, personnel shortage, and lack of funds for forest investment.Furthermore, disintegrated management, improper planning, and difficulties in enforcing the law were also expressed.The other weaknesses are shifting of existing green areas to other land use purposes, lack of proper tree species selection, lack of tradition and expertise, lack of regulations adopted to protect the urban forest and trees, a lack of tools for assessing and incorporating sustainable forest management into forest management plans.

Opportunities Threats
1. Extensive research on urban forestry focusing on climate change, urbanization issues can be addressed.Involvement of research organizations, and public and private universities in urban forestry to increase urban green cover and urban forestry.
1.A rapid increase in urban population, and informal and unplanned urbanization to obtain a 20% of the green cover with this workflow will be difficult for the forestry department of Bangladesh.
2. Development of a technically sound workforce and capacity building within the departments.Increase staff training opportunities in new concepts /technologies for sustainable forest management.
2. Institutional corruption of various government authorities and departments in urban forestry and greenspace protection.
3. Collaboration with external NGOs, public-private universities and increase of local public bodies and institutional participation in forestry and greening projects in the urban/peri-urban areas.
Using schools and religious premises for tree plantation 3. Miscommunication and lack of collaborative mindset among the government agencies such as city corporations, ministries and departments at the field level of project implementation.Cross-sectoral strategies are at odds.These opportunity factors in the DNCC region are significant for urban sustainable forestry management (SFM) and monitoring.The opportunity factors expressed as the response higher percentage of the number of institutions members are shown in the updated forest management plan, standards, environmental understanding of problems relating to sustainable forest management, staff education in emerging technology, and sustainability concepts such as urban-forest-based bioeconomy for long-term forest management, participation in projects, urban forest recreation, biodiversity conservation/protection.These opportunity factors also have some other expansion of forest lands, forest contribution to bioeconomy-based GDP, natural disaster prevention, peri-urban forest and urban environmental sustainability.
The top threat factors are shown as the presence of conflicts between the BFD and DNCC, a rapid increase in urban population, forest land encroachment, lack of awareness among the people, not having district urban forest policy in Dhaka city like other cities in the world, lack of monitoring after the plantation.Moreover, inter-departmental cooperation within the BFD, DoE, and DNCC authorities was the top factor.

DPSIR framework analysis
From the DPSIR analysis, we frame the specific responses to promote and improve urban forestry for DNCC.A 'driving force' is the need to convert the city sustainable, livable city.Improving urban forests is one way of achieving several other United Nations' sustainability targets, particularly SDG 3 (good health and wellbeing), SDG 13 (climate action), and SDG 15 (life on land), making cities healthier and more humane.Unfortunately, the increasing population in the limited urban land areas of DNCC is the driving force behind unplanned, informal, and rapid urbanization (Fgure 7).Moreover, existing institutional corruption is putting pressure on land transformation, as identified in LULC of the DNCC area in the previous section.
The weak forestry governance and conflicting policy plans, programs, and projects from other government ministries and departments are pressurizing urban land use and squeezing green spaces.Furthermore, continuous roads and utility service expansions in the residential areas have created a megacity with fewer blue-green spaces and recreational areas.These human activities have further exerted enormous 'pressures' on land-use change, cutting down old trees, roadside forestry, and shrinkage of park areas and forest covers.Many exotic and fast-growing ornamental species were planted in the cities that do not support local biodiversity.It further created habitat loss for much urban wildlife as we have seen in 2022 LULC change in the individual Thanas (Fig 7).Forestry policies and plans, land-use policies, urban development policies, environmental policies, and social factors significantly influence the spatial distribution and concentration of a country's urban vegetation cover and green spaces.However, land distribution priorities for urban green cover in economic transition countries are generally overlooked [71].
The linkage of unplanned and informal rapid urbanization is foreseeable in the impacts of changing the urban area's physical, chemical, or biological state that determines the quality of ecosystems and human welfare.In other words, changes in the state may have environmental or economic 'impacts' on the functioning of ecosystems and their life-supporting abilities (Fig 8).Changing urban green spaces into roads and highways have increased particulate matter pollution and increased pollution load on human health.Society's economic and social performance has been deteriorating by improving physical and mental health costs.The shrinkage of green spaces and urban forest cover further deteriorated the ecosystem with less carbon sequestration.Innovative community development puts enormous leverage on green spaces and urban forest conservation.Urban forests, plantations, parks, and green spaces are critical components of urban sustainability and resilience [72].However, there are social and political problems and uncertainties related to greening [73] in DNCC that challenge the development and support of urban green spaces, forestry, and human well-being [5].
A 'response' by society or policymakers results from an unfavourable impact on any link in the chain between driving forces and effects.Responses like society and policymakers introduce strategic urban forest policy and remove inter-institutional conflicts.Strategic planning is required for increased green spaces through a sustainable forest-based bioeconomy concept.In addition, strategic programs and projects can be introduced to increase participation from the urban stakeholders to increase and improve green spaces.Plans should include involving participants from retired members, schools, mosques, and local welfare societies to increase green spaces (Fig 8).However, social and political questions and difficulties associated with green space-making, monitoring and inspection in the DNCC need to be responded to by the respective government departments.It is essential that public stakeholder groups and users of urban forestry services are crucial when planning a forestry-based bioeconomy and that they understand the ecosystem services provided by the urban spaces [74].In addition, planting decisions for urban parks, recreational spaces and forestry program ensures the public feel engaged and that governmental decisions have longstanding support from the community [74].The urban population provides urban forests opportunities to grow and offers vital ecological services to human well-being and biodiversity.Strategically expanding urban forests can provide cleaner, more rewarding, and enriched lives for our global populations, especially vulnerable people in developing countries [5].Urban and peri-urban forests should be strategically included in city agendas and policy preparation to promote green and sustainable partnerships between urban and rural areas [75].Urban forestry comprises the whole of society, and its members and experiences help devise holistic strategies, research, and management for sustainable communities [5].
Moreover, failing to consider the public health benefits of urban forest covers and green spaces will contribute to underinvestment in the urban forestry sector [9].Substantial publichealth benefits are likely to be produced by planting trees in high-air pollution suburban areas and public spaces and parks [9].In addition, decentralized green infrastructures such as increased parks, open spaces, and urban forestry can leverage the capacity for infiltration, and redistribution of stormwater volume in soil and vegetation that can support the climate, society, and economy.As stormwater management in Dhaka is extremely poor, policymakers must consider urban forestry programs and plans as critical solutions.

Discussion
The GoB is committed to protecting and increasing the forest cover in Bangladesh to 15.2% by 2025 and 20% by 2041.Social forestry has a significant role in this expansion [14].Besides, to achieve SDG 11 for DNCC, policy planning on urban forestry, specific information and knowledge gaps should be addressed, and a standard research protocol should be implemented.Tree coverage outside the forests program will have a significant role to play in increasing urban forestry and vegetation cover.Institutions, roads and railway sides, embankments, homesteads, fallow lands, and rooftops can be brought under plantations to expand green coverage with a crucial role in carbon sequestration in urban areas.
According to the draft national forestry policy of Bangladesh, 2016 [43] to halt deforestation and the degradation of forest resources, and to enrich and expand regions under tree cover, at least 20% of the nation to be covered by trees by 2035, with a canopy density of 50%.The policy also urged significantly increasing tree cover in urban areas through appropriate mechanisms such as public and private land [45].Visibly, Dhaka is far behind in achieving 20% tree cover.Besides, the 7 th five-year plan (2016-2020) also had targets to make 20% forest cover, which failed to achieve in DNCC [65].Regarding a healthy and sustainable urban environment, urban green spaces and parks should be within 500 meters.Unfortunately, 22 parks and four playfields are not enough for the 6.1 million population of DNCC, with an average population density of 52920 per Km 2 [65,66].Dhaka city's land use patterns are diversified, with unplanned residential, commercial, industrial, and mixed land use categories predominating, with the same unit simultaneously serving residential, commercial, and even industrial uses [67].Furthermore, a recent study suggests that the built-up and sand fill barren lands have increased by 67% and 679% due to the vast demand for accommodation.Mostly wetlands and agricultural lands around the city were sand-filled to facilitate the building of new satellite towns [68].It is evident that DNCC lacks blue-green and open spaces, which is a significant indicator to achieve SDG 11.
Consistent improvement in measurement approaches would include a more accurate assessment of gains and costs and more economic assessment in the decision-making process, given optimistic targets for raising urban vegetation cover [8].Moreover, it is equally essential to understand how urban green spaces contribute to sustainability considering the disservices.The disservices of infrastructure conflicts, health and safety impacts, aesthetic issues, environmental consequences, and management costs related to ecological disturbances and risk management [76,77].Therefore, a policy mechanism should be adopted to resolve the existing inter-institutional conflicts to promote and improve urban forests for existing resources and the future.Inter-departmental collaboration among BFD, DNCC, DoE, and other ministries and government bodies should be enhanced by developing co-ownership of urban-forestry management.It is essential to establish the role of ecosystem services in any urban forestry policy plans and programs.National Environmental Policy 2018 and the draft forestry master plan 2017-2036 have critical principles in implementing ecosystem services in forest resources management.Forestry policy 2016 has many features to improve urban forestry and many positive attributes.It's a significant step toward people-centred urban forestry, demonstrating the GoB's commitment to protecting and developing forest resources in achieving SDG 11.7.1.Moreover, in 2022 The Detailed Area Plan (DAP) 2016-2035 for Dhaka was published in 2022 by the Capital Development Authority (RAJUK) [78].Among the four major goals of the masterplan are to obtain universal freedom of investment, improved quality of life, a tolerant city and ecological conservation by augmenting blue-green infrastructure, and disaster resilience development.However, it is equally necessary to integrate a strategic environmental assessment of DAP to strengthen inter-institutional implementation of the plan, capacity build-up, and remove inter-institutional conflicts.

Conclusion
Cities without urban green spaces can mentally, socially, and physically affect their inhabitants.In Bangladesh, rapid informal urbanization has evolved the cities into unsustainable ones, yet the chronological evolution of forestry policies, plans, and programs is inadequate for urban forestry.Moreover, the urban forestry status in the DNCC area is deteriorating.Lack of proper guidelines, existing institutional conflicts, informal city expansions, and utility services expansion have created a mismanaged urban area.Between 1992 and 2022, vegetation coverage has been declined by around 65.9% while the urban area rise by almost 95% simultaneously out of the total DNCC area of 194.2 sq km (2022).The areas of the water body shrinked more than 32.4% during that period.The vegetation coverage in DNCC is merely 16.17%, inferior in meeting sustainable urban greening to fulfil the criteria of sustainable cities and communities.This indicates that we are far behind in making sustainable communities and cities SDG 11 by 2030.Effective urban forestry policies, plans, and programs are required to increase vegetation cover and urban green spaces.Consequently, community-based participatory programs in urban green space protection and introducing a forest-based bioeconomy can promote SDG 11.7.1.Furthermore, political will is one of the determinants of green space protection, which is crucial for a developing country.As policies are often taken in top-down approaches in Bangladesh, a suitable strategy with good political will with the least influence must be taken for a better urban environment.Introducing strategic environmental assessment of urban policy, plans, and programs, removing inter-institutional conflicts, strategic sectoral plans, and programs for increased green spaces through the bioeconomy concept is required.Predicting future land use and change in land cover is essential in urban planning and managing green spaces and forest covers.A significant limitation of this research was the prediction of future change.It is recommended that research on future prediction of land use and land cover change should be incorporated and increased.

Fig 3 .Fig 4 .
Fig 3. SWOT analysis framework of institutional capacity assessment of the policy plans and programs involved in sustainable urban forestry and green space management in Bangladesh.https://doi.org/10.1371/journal.pstr.0000061.g003

Table 1 . Specification of Satellite Data for the Study Area. Data period Time frame Landsat Cloud Coverage
RedÞ

Table 4 . Kappa Coefficient Scale.
1. What are urban forestry status and urban greening policy, plans, and programs in DNCC?2.What are the strengths of urban greening in DNCC?3.What are the problems/weaknesses of urban greening in DNCC?How can these problems be solved?4.What is the status of public participation in urban greening in DNCC?5.What are the impacts/threats of urban greening in DNCC?How PPPs can minimize these impacts?6.What can be the PPP responses to protect urban greening in DNCC?7.What are the opportunities for urban greening in DNCC?Any other comments

Table 6 &
Fig 5).Of the total measurements of 194.2 sq km (2022), vegetation cover decreased significantly from 1992 to 2022 by approximately 65.9%, while urban settlement areas increased by almost 95% simultaneously.The vegetation area has reduced by 33.9% between 1992 and 2002 due to rapid urban settlement expansion by 41.4%.Between 1992 and 2022, the highest amount of water bodies was seen at 8.78% in 2012 (Fig

Table 7 . Relevant forestry and sectoral policy analysis. Policies Policy/plan features statements/outcomes for urban forestry/green spaces
Ecosystem products and services for the national economy, ➢ The reforestation of vacant lands and increased forest cover outside forests to improve ecosystem resources and forest-based employment.➢ Anthropogenic issues and climate change issues are considered.
[14]event unplanned urbanization, and prevent misuse of land ➢ Clearance from the authority to develop arable land ➢ Strategic plans for agricultural land, wetland, forest land, hill areas and coastal belts ➢ Develop coordination among the authorities 8 th 5-year plan[14]➢ To prioritize the ongoing efforts to reduce air and water pollution, strengthen forestry management and implement the BDP2100.https://doi.org/10.1371/journal.pstr.0000061.t007