Natural and anthropogenic impacts on mangrove carbon dynamics: a systematic review protocol

Unraveling land use land cover change, their driving factors, and implication on carbon storage through an integrated modelling approach

Mangroves are vital coastal ecosystems that serve as natural barriers against erosion, support diverse marine life, and play a crucial role in mitigating climate change through carbon sequestration. This study uses remote sensing techniques to examine land use and land cover (LULC) changes in Mjini Magharibi, Zanzibar, from 1994 to 2024. The classification of LULC changes using Landsat images achieved high accuracy in thematic mapping, with overall accuracy and kappa coefficients ranging from 79.7% to 92.5%. The results revealed significant landscape transformations with environmental sustainability and coastal management implications. Furthermore, the results depicted a consistent increase in areas covered with water bodies, from 20,736.27 ha in 1994 to 22,422.51 ha in 2024, suggesting potential sea level rise and coastal land erosion. Concurrently, bare soil and built-up areas expanded from 1,981.44 ha to 3,406.14 ha, indicating rapid urbanization. The study highlights a substantial decrease in mangrove and dense forest cover, with a loss of approximately 35.5% over 30 years, posing significant ecological and socioeconomic challenges. Sparse vegetation and farmland areas also decreased, while mixed land uses increased, reflecting the diversification of land use patterns. These changes underscore the adverse pressure of urban expansion on natural resources, including pristine beaches, mangrove areas, and marine ecosystems. The findings emphasise the urgent need for sustainable management practices and conservation initiatives to protect the remaining mangrove forests, mitigate land use change impacts, and ensure the long-term ecological balance of Mjini Magharibi's mangrove ecosystems.

Climate change and land use land cover (LULC) changes are recognised as two of the most significant causes of environmental change. Climate change and LULC changes are related to one another. Land use change may drive climate change, and a changing climate may result in land cover changes. Climate change and LULC changes are believed to influence soil erosion. This chapter analyses the impacts of climate and LULC changes on soil erosion. The causes and effects of climate change on precipitation, temperature, solar radiation, atmospheric CO2 concentrations, and radiative forcing are discussed. The chapter includes the impacts of climate change on soil characteristics, vegetation cover, runoff, floods, and droughts and extends the impacts of these changes on water and wind erosion. The chapter explores the human alterations of LULC changes in terms of changes in the forest cover, alterations in agricultural lands, increase in urban areas, and decrease in wetland areas. The influence of the LULC changes on soil erosion and sediment production processes is discussed. Also, the combined impact of climate and LULC changes on soil erosion is explored, and mitigation strategies like sustainable land management practices and appropriate policy incentives to conserve soil are discussed.

Land use and land cover (LULC) change in tropical regions can cause huge amounts of carbon loss and storage, thus significantly affecting the global climate. Due to the differences in natural and social conditions between regions, it is necessary to explore the correlation mechanism between LULC and carbon storage changes in tropical regions from a broader geographical perspective. This paper takes Hainan Island as the research object, through the integration of the CA-Markov and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models, based on multi-source data, analyses the dynamics of LULC and carbon storage from 1992 to 2019 and the relationship between the two, and predicts future LULC and carbon storage under different scenarios. The results show that (1) the built-up land area of Hainan Island expanded from 103.59 km2 to 574.83 km2 from 1992 to 2019, an increase of 454.91%; the area of cropland and shrubland decreased; and the area of forest increased. (2) Carbon storage showed an upward trend during 1992–2000, and a downward trend during 2000–2019. Overall, LULC changes during 1992–2019 reduced carbon storage by about 1.50 Tg. (3) The encroachment of cropland in built-up land areas is the main reason for the reduction of carbon storage. The conversion of shrubland to forest is the main driving force for increasing carbon storage. The increase and decrease of carbon storage have obvious spatial clustering characteristics. (4) In the simulation prediction, the natural trend scenario (NT), built-up land priority scenario (BP) and ecological priority scenario (EP) reduce the carbon storage of Hainan Island, and the rate of decrease is BP> NT > EP. The cropland priority scenario (CP) can increase the LULC carbon storage, and the maximum increase in 2050 can reach 0.79 Tg. This paper supplements and improves the understanding of the correlation between LULC and carbon storage changes in tropical regions, and can provide guidance for the optimization of LULC structure in tropical regions with high economic development from a low-carbon perspective.

This study investigated the effect of land use land cover (LULC) changes on carbon sequestration in the Hayat-ul-Mir subtropical scrub reserve forest, Pakistan. Supervised maximum likelihood classification of Landsat satellite imagery was done to assess spatio-temporal changes in LULC during 2007, 2013 and 2019. The CA–Markov model was used to simulate LULC of 2030. Spatial LULC data and carbon pools data was processed in Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) carbon model to investigate the effect of LULC on future carbon dynamics. The analysis revealed increase in cover of A. modesta and O. ferruginea and decrease in agriculture, built up and barren area of forest during 2007–2019 and 2030. The analysis also showed that the forest would additionally sequester 111 Mg C with an overall Net Present Value of $4112.05 in year 2030. The analysis revealed LULC changes on 25% area with increase and decrease in the value of ecosystem service (at some location) from carbon storage and loss as CO2 emissions respectively depending on the type of LULC converted. The study is helpful in identifying areas of potential carbon sequestration to maximize net benefits from management interventions.


 
 
 Floods are one of the most common natural disasters worldwide. Apart from rainfall, Land Use Land Cover (LULC) changes too are a main contributory factor for floods. This study attempted to understand the link between floods and LULC changes in Kalu river basin, which is the second largest river basin and an area that experiences recurrent floods in Sri Lanka. We studied peak water levels, number of flood events, changes in land use types and impacts in rapidly urbanizing two districts, Rathnapura (upper basin) and Kalutara (lower basin) during 2001-2020. The satellite images (LANDSAT) were obtained for 2001, 2009, 2015 and 2020 and land use classification was done using ArcGIS and Remote Sensing Tools. Main land use types and their transformations were investigated and ground-truthing was carried out. Accordingly, the main types of land uses identified were Natural Vegetation and forests (NV), Settlements (ST- housing and industrial lands), Cultivated Lands (CL), Water Bodies (WB) and Bare Lands (BL). The results indicated that the most drastic change was found in the natural areas (NV) and they have diminished while the lands with anthropogenic impacts (ST, CL and BL) have increased across years. The NV had occupied the highest land area in 2001 (42.4%) and has reduced by 14.2% by 2020. The ST and CL have increased by 8.6 % and 5.2% respectively. The monthly rainfall of Rathnapura and Kalutara (Source: Department of Meteorology, Sri Lanka) has increased with time, which is a main reason for the increasing peak water levels of these areas (Source: Department of Irrigation, Sri Lanka). However, a significant correlation also exists between the change of the settlement area with the peak river water levels in the lower basin (p=0.03, R2=99%; regression analysis). Rathnapura has experienced 3 major floods (floods above the high water alert level) from 2001-2020, while 16 major floods have occurred in Kalutara. During the major flood in 2017, the number of child deaths in Rathnapura was 14 while in Kalutara it was 24. Accordingly, the LULC changes of the whole basin along with rainfall seem to influence on the severity of floods in Kalutara more, as it is located in the lowest elevation level. When natural lands are transformed to anthropogenic- impacted areas with disturbances to the water cycle, increased impervious surfaces, reduced water storage capacities and loss of natural drainage, the flood risk tends to increase. Proactive approaches including proper land use planning and rainwater storage are urgently needed as the climate change too would trigger more floods. Thus, the flood mitigatory actions, especially, in the lower river basin should be a priority to ensure resilience and sustainability.
 Keywords: Kalu river basin, Land Use Land Cover (LULC) changes, Floods
 
 

Urbanization-led land cover change impacts terrestrial carbon storage capacity: A high-resolution remote sensing-based nation-wide assessment in Pakistan (1990–2020)

<p>The use of a dynamic vegetation model, CARAIB, to estimate carbon sequestration from land-use and land-cover change (LULCC) offers a new approach for spatial and temporal details of carbon sink and for terrestrial ecosystem productivity affected by LULCC. Using the remote sensing satellite imagery (Landsat) we explore the role of land use land cover change (LULCC) in modifying the terrestrial carbon sequestration. We have constructed our LULCC data over Wallonia, Belgium, and compared it with the ground-based statistical data. However, the results from the satellite base LULCC are overestimating the forest data due to the single isolated trees. We know forests play an important role in mitigating climate change by capturing and sequestering atmospheric carbon. Overall, the conversion of land and increase in urban land can impact the environment. Moreover, quantitative estimation of the temporal and spatial pattern of carbon storage with the change in land use land cover is critical to estimate. The objective of this study is to estimate the inter-annual variability in carbon sequestration with the change in land use land cover. Here, with the CARAIB dynamic vegetation model, we perform simulations using remote sensing satellite-based LULCC data to analyse the sensitivity of the carbon sequestration. We propose a new method of using satellite and machine learning-based observation to reconstruct historical LULCC. It will quantify the spatial and temporal variability of land-use change during the 1985-2020 periods over Wallonia, Belgium at high resolution. This study will give the space to analyse past information and hence calibrate the dynamic vegetation model to minimize uncertainty in the future projection (until 2070). Further, we will also analyse the change in other climate variables, such as CO<sub>2</sub>, temperature, etc. Overall, this study allows us to understand the effect of changing land-use patterns and to constrain the model with an improved input dataset which minimizes the uncertainty in model estimation.</p>

Understanding the impacts of Land Use and Land Cover (LULC) changes and their drivers is crucial for sustainable management of natural resources. Thus, this rigorous study aimed to examine the trends, drivers, and consequences of land use land cover changes (LULC) in the Lake Ziway catchment, central rift valley of Ethiopia. The study followed a mixed- methodological systematic and justified approach that included remote sensing and GIS techniques, household surveys, focus group discussions, and in-depth interviews. The rigorous study shows that the conversion of forest land into agricultural and settlement lands is the major detected LULC change over the last 30 years in the catchment. Cultivated land has increased by 40.60% and settlement and plantation lands have increased by 61.54% and 60%, respectively. On the other hand, forest land decreased by 54.85% and grazing land have decreased by 15.85% respectively. Water bodies and wetlands have also decreased by 8.70% and 19.32% area coverage, respectively. Both the direct and indirect driving forces of the LULC changes were identified. The study also indicates that the participation of local communities in watershed management is low. The study further indicates that LULC changes observed in the Lake Ziway Catchment had statistically and practically significant environmental and socio-economic impacts. Over all, the rigorous study showed the changes in land use land cover and its drivers were common in Lake Ziway Catchment. Therefore, appropriate policies and strategies are required to address LULC change impacts and enhance sustainable utilization and management of the Lake Ziway catchment.

Land Use and Cover Change (LUCC) has emerged as a primary driver of terrestrial carbon storage changes. However, the contributions of LUCC to Above-Ground Carbon (AGC) storage in subtropical forests remain unclear due to the complex and diverse LUCC trajectory. Quantitative assessment of the impact of different LUCC trajectories on carbon storage is essential for regional carbon cycle mechanisms. Therefore, this study focuses on Zhejiang Province, a representative subtropical forest region in China, to accurately assess the contribution of LUCC to AGC storage changes from 1984 to 2019. We first mapped the land cover patterns using the random forest and spatiotemporal filtering algorithm and then applied these patterns to drive an optimized BIOME-BGC model to simulate the spatiotemporal distribution of AGC density. Finally, the LUCC trajectories were classified into three categories: afforestation, deforestation, and forest type transformations. Their contributions to AGC changes were isolated and analyzed through the trajectory analysis. The results demonstrated that the forest area of Zhejiang Province increased from 5.35 × 106 ha to 6.83 × 106 ha (+27.66%) and the total forest AGC storage increased from 80.52 Tg C to 124.16 Tg C (+54.19%) between 1984 and 2019. The increase in forest AGC due to LUCC amounted to 31.26 Tg C, contributing 71.63% to the total. Specifically, the afforestation, deforestation, and forest type transformations contributed 82.37%, −17.27%, and 6.53% to the change in AGC, respectively. Overall, the afforestation within the LUCC trajectories was the primary contributing factor to the growth of forest AGC in Zhejiang Province from 1984 to 2019. This study obtained accurate LUCC and AGC data, clarifying the contribution of different LUCC trajectories and providing a better understanding of the responses of the forest carbon storage to LUCC dynamics.

Mangrove is a woody plant which grows in intertidal zones. Mangrove forests are mainly distributed in subtropical and tropical regions, and are valuable for ecosystems and for society. Even in dry regions such as Qatar, mangrove forests provide ecosystem services despite their small area and low productivity compared with tropical mangroves. Carbon sequestration by mangroves is one of the main ecosystem services mitigating climate change, as mangrove forests are carbon-rich ecosystems. In mangrove forests, there is a natural gradient in soil environments between land and sea. Soil salinity and water availability are the major factors influencing mangrove productivity. The objectives of this study were (1) to investigate the change in biomass of Avicennia marina, the only mangrove species in Qatar, along the distance from coast and the relationship between biomass and soil characteristics, and (2) to estimate carbon storage of biomass in a natural mangrove forest in Qatar. Three plots were established in a natural mangrove forest of A. marina in Al-Thakira, Qatar (25°42»15.9»N 51°32»18.4»E), at a distance of 0 m (D0), 50 m (D50), and 100 m (D100) from the coast. Plot size was 2 × 2 m2, 3 × 3 m2 and 4 × 4 m2 at D0, D50, and D100, respectively. Plant abundance was determined by counting the number of individual seedlings ( ≤ 1.3 m high) and trees (>1.3 m high) per plot. Diameter at breast height (DBH) was measured on trees in each plot, and above-ground biomass (AGB) and below-ground biomass (BGB) of trees were estimated using allometric equations for A. marina. Carbon storage in biomass was calculated by carbon fraction of 45.1%. Soil samples at 0-10 cm depth were collected at three random points per plot. Soil samples were air-dried and sieved through a 2 mm mesh screen, and then pH, salinity, water content and nitrogen (N) concentration of each soil sample were measured. Differences in biomass of trees, pH, salinity, water content and N concentration of soil at each distance were analyzed using t-test (SAS 9.4 software). Seedling abundance (no. m-2) was 2.4 ± 0.1 at D0, 7.9 ± 0.8 at D50, and 1.9 ± 0.2 at D100, while tree abundance was 0.9 ± 0.1 at D50 and 1.2 ± 0.1 at D100. There were no trees at D0, so comparisons with this site were excluded. AGB was significantly higher at D100 (41.4 ± 1.9 Mg ha-1) than at D50 (7.3 ± 0.9 Mg ha-1). BGB was higher at D100 (44.9 ± 0.6 Mg ha-1) than at D50 (19.4 ± 2.3 Mg ha-1), but there was no significant difference between two distances. Salinity, water content, and N concentration of soil were 125.1%, 196.3%, and 114.5% higher, respectively, at D100 than at D50 (all differences were significant). Soil pH was significantly 3.1% lower at D100 than at D50. It was reported that growth and biomass of mangroves increased slightly and then decreased continuously along the salinity gradient. However, salinity at the study site was low compared with that in other mangrove forests and might be within the range that biomass increases with salinity. A. marina required a large amount of water and nutrients in high salinity condition (Naidoo, 2009). High water content and N concentration of soil at D100 could meet the requirement for water and nutrient in high salinity condition, and thereby result in the biomass increment. In this study, carbon storage (Mg C ha-1) was 7.3 ± 1.1 for AGB, 9.7 ± 1.1 for BGB, and 18.1 ± 2.4 for total biomass of A. marina. These values are lower than those reported for A. marina in temperate regions (AGB: 57.7 Mg C ha-1, BGB 69.8 Mg C ha-1), subtropical regions (AGB: 49.6-73.1 Mg ha-1, BGB: 49.2-56.8 Mg ha-1), and even dry regions (20.7-66.6 Mg C ha-1). To conclude, biomass of A. marina increased as the distance from the coast and was affected along the gradient of soil characteristics. A better understanding of mangrove biomass distribution between land and sea will contribute to estimate biomass and carbon storage in intertidal zones. * This study was supported by Korea Ministry of Environment (2014001810002).

Land use and land cover (LULC) change has greatly altered ecosystem carbon storage and exerted an enormous impact on terrestrial carbon cycling. Characterizing its impact on ecosystem carbon storage is critical to balance regional carbon budgets and make land use decisions. However, due to the availability of LULC data and the strong variability in LULC change, uncertainty remains high in quantifying the effect of LULC change on the historical and future carbon stock. Based on four historical LULC maps and one future LULC projection, this study combined the Land Use and Carbon Scenario Simulator (LUCAS) with a process-based CENTURY model to evaluate the historical and future LULC change and its impact on grassland carbon storage from 1991 to 2050 in northern China. Results showed that grassland experienced a drastic decrease of 16.10 × 103 km2 before 2005, while agriculture and barren land increased by 16.91 × 103 km2 and 3.73 × 103 km2, respectively. After that, grassland was projected to increase, agriculture kept steady, and barren land decreased. LULC change has resulted in enormous total ecosystem carbon loss, mainly in agro-pasture areas; the maximum 8.54% of carbon loss happened in 2000, which was primarily attributed to agriculture to grassland, forest to grassland, grassland to agriculture, and grassland to barren. Before 2000, the grassland net biome productivity was projected to be −15.54 Tg C/yr and −2.69 Tg C/yr with and without LULC change. After 2001, the LULC change showed a positive impact on the grassland carbon balance, and the region was projected to be a carbon sink. Ecological projects have made a significant contribution to grassland carbon storage. The paper provides a framework to account for the effects of LULC change on ecosystem carbon and highlights the importance of improving grassland management in balancing the grassland carbon budget, which is helpful to understand the regional carbon budget and better inform local land use strategies.

Mangrove ecosystems are pivotal to the global carbon budget. However, there is still a dearth of research addressing the impact of regional mangrove land use and land cover change (LUCC) on carbon sequestration and its associated spatial distribution patterns. To investigate the impact of different development scenarios on the carbon storage capacity of mangrove ecosystems, we focused on Hainan Island. We used LUCC data from 2010 to 2020 from mangrove-inhabited regions. The Markov-PLUS model was applied to predict the spatiotemporal dynamics of mangrove coverage under the natural increase scenario (NIS) and the mangrove protection scenario (MPS) over the next 40 years. Carbon storage was estimated using the InVEST model based on field-measured carbon density data. The outcomes show the following: (1) The Markov-PLUS model, with an overall accuracy of 0.88 and a Kappa coefficient of 0.82, is suitable for predicting mangrove distribution patterns on Hainan Island. (2) Environmental factors were the main drivers of historical mangrove changes on Hainan Island, explaining 54% of the variance, with elevation, temperature, and precipitation each contributing over 13%. (3) From 2025 to 2065, the mangrove area on Hainan Island is projected to increase by approximately 12,505.68 ha, mainly through conversions from forest land (12.73% under NIS and 12.37% under MPS) and agricultural land (39.72% under NIS and 34.53% under MPS). (4) The carbon storage increment within Hainan Island’s mangroves is projected at 2.71 TgC over the whole island, with notable increases expected in the eastern, northern, and northwestern regions, and modest gains in other areas. In this study, we comprehensively investigated the spatiotemporal dynamics and future trends of carbon storage in the mangroves of Hainan Island, offering invaluable guidance for the long-term management of mangrove ecosystems and the realization of carbon neutrality goals by 2060.

Land use land cover (LULC) changes are inherently spatial and dynamic with high spatiotemporal variability resulted from complex human-environmental interactions. Current extents, rates and intensities of LULC changes are driving unprecedented changes in ecosystems functions and environmental processes at local, regional and global scales. The study was conducted to assess LULC changes and its drivers using remote sensing (RS) and geographic information system (GIS) in Gojeb River Catchment, Ethiopia. The satellite images at different reference years (1978, 1987, 2001 and 2015) were obtained from Landsat images. Supervised classification with maximum likelihood algorithm was applied for image processing and change analysis. The LULC classes identified were cropland, forestland, shrubland, swamp, and woodland. The study found that the catchment has undergone significant LULC changes. The major changes were expansion of cropland at the expense of other LULC classes at the rate of 29.56% in 1978, 38.91% in 1987, 46.62% in 2001 and 52.74% in 2015. It has gained about 160,736.08 ha with an annual average increment of 4,344.22 ha. Conversely, forestland has undergone reductions at an annual rate of 9,030.0 ha between 1978 and 1987. The conversions of other classes to cropland are mainly associated with more demand for crop production. On the other hand, the conversion of relevant part of forest land to other classes could be due to vegetation degradation. Hence, the conversion of forestland to other land use classes could be attributed to the highly demand of agricultural land, firewood, charcoal, timbers and housing materials. The major driving forces which should be considered in sustainable watershed management were population growth and government induced settlements. Provision of modern alternative sources of energy, agricultural inputs and promoting non-agricultural sectors are also other considerations for the community sustainable livelihood. It is critical to follow holistic view and management of the catchment for successful integrated watershed management endeavours.

This paper discusses results of a Gulf of Mexico Application Pilot project conducted in 2008 to quantify and assess land use land cover (LULC) change from 1974 to 2008. Led by NASA Stennis Space Center, this project involved multiple Gulf of Mexico Alliance (GOMA) partners, including the Mobile Bay National Estuary Program (NEP), the U.S. Army Corps of Engineers, the National Oceanic and Atmospheric Administration's (NOAA's) National Coastal Data Development Center (NCDDC), and the NOAA Coastal Services Center. The Mobile Bay region provides great economic and ecologie benefits to the Nation, including important coastal habitat for a broad diversity of fisheries and wildlife. The Mobile Bay region has experienced considerable LULC change since the latter half of the 20th century. Accompanying this change has been urban expansion and a reduction of rural land uses. Much of this LULC change (largely urbanization) has reportedly occurred since the landfall of Hurricane Frederic in 1979. Regional urbanization threatens the estuary's water quality and aquatic-habitat dependent biota, including commercial fisheries and avian wildlife. Coastal conservation and urban land use planners require additional information on historical LULC change to support coastal habitat restoration and resiliency management efforts. This project quantified and assessed LULC change across the 34-year time frame and at decadal and mid-decadal scales. Nine Landsat images were employed to compute LULC products because of their availability and suitability for the application. The project also used Landsat-based national LULC products, including coastal LULC products from NOAA's Coastal Change & Analysis Program (C-CAP), available at 5-year intervals since 1995. Our study was initiated in part because C-CAP LULC products were not available to assess the region's urbanization prior to 1995 and subsequent to post-Hurricane Katrina in 2006. The study area included the majority of Mobile and Baldwin counties that encompass Mobile Bay. Each date of Landsat data was classified using an end-user defined modified Anderson level 1 classification scheme. LULC classifications were refined using a decision rule approach in conjunction with available C-CAP products. Individual dates of LULC classifications were validated by image interpretation of stratified random locations on raw Landsat color composite imagery in combination with higher resolution remote sensing and in situ reference data. Overall classification accuracies for five separate single-date products ranged from 83% to 89%. The results of the LULC change analysis indicate that during the 34-year study period, urban areas increased from 96,688 to 150,227 acres, representing a 55.37% increase, or 1.63% per annum. Most of the identified urban expansion regarded the conversion of rural forest and agriculture to urban cover types. Final LULC mapping and metadata products were produced for the entire study area as well as for multiple watersheds of concern within the study area. The final project products, including LULC trend information, were incorporated into the Mobile Bay NEP State of the Bay report. Products and metadata were also transferred to NOAA NCDDC to allow free online accessibility and use by GOMA partners and by the public.