An Analysis of Land Use Changes in DPR Korea Using Land Cover Maps from the Late 1980s to the Late 2010s

Abstract

DPR Korea has been creating cropland across the country due to its chronic food shortage. Cropland was about 17.4% at the end of the 1980s, but it increased steadily to 19.6% at the end of the 1990s, 24.8% at the end of the first decade of 2000s, and 25.4% at the end of the 2010s. On the other hand, the forest land declined from about 74.8% in the late 1980s to 69.5% in the late 2010s. Urbanization is also progressing, increasing from about 1.15% at the end of the 1980s to 1.68% at the end of the 2010s. Most of the deforestation that occurred in DPR Korea was caused by conversion to cropland. These characteristics of land cover changes in DPR Korea provide useful information and implications for international and inter-Korean cooperation for DPR Korea.

1. Introduction

The land cover map is important for understanding the condition of the ground surface and how people use the land. It provides essential information for land planning and environmental management of a country or a society. Land cover data reflects changes in the demand and value of land which provide precious information for various policy developments. Since the land cover maps over years accumulate land surface information from the past to the present, it can be used as an effective data to identify the direction of development and the areas with high land use demand.

Recently, interest in the environment is increasing as land degradation and desertification are expanding around the world, and as biodiversity, which is the basis of human welfare and economic activity, has been severely destroyed. In particular, there is an increasing awareness of the importance of promoting ecosystem services, which is the benefit that a healthy ecosystem provides to humans (Portner et al., 2021, IPCC, 2019, Orr et al., 2017). OECD (2018) has stated that measuring land cover changes helps monitor the status of ecosystems and biodiversity. Time series data of the land cover not only allows identification of the changes in various types of land cover, but it also enables monitoring of changes over a wide area in an economical and effective way.

DPR Korea (Democratic People’s Republic of Korea) has been continuously diverting forests into cropland, and has also been destroying forests for fuel production. For the sustainable development of the Korean Peninsula, it is indispensable to understand the land use in DPR Korea and basic information related to it. Therefore, this study aims to grasp the flow of land cover change in DPR Korea by using the accumulated land cover maps over time. This study analyzed the land use change from the late 1980s to the present in order to understand the environmental changes related to land use in DPR Korea, including cropland and forest using the land cover maps.

2. Materials and Methods

In order to understand changes in land cover in DPR Korea, this study used land cover maps provided by the Ministry of Environment of the Republic of Korea. The Ministry of Environment has been providing seven classes of land cover maps for the entire Korean Peninsula every 10 years since the late 1980s (https:// egis.me.go.kr/api/land.do). The imagery used for the land cover classification for DPR Korea was taken by Landsat satellites at the end of each decade since the 1980s (Table 1).

Table 1. Imagery Used for Land Cover Classification

The land cover maps were produced using Landsat 4, 5, 7, and 8 equipped with sensors such as Thematic Mapper (TM), Enhanced Thematic Mapper (ETM+), Operational Land Imager (OLI), Thermal Infrared Sensor (TIRS), which provided more than seven spectral bands including blue, green, red, NIR bands with 30 meter resolution depending on sensors (https://eos.com/find- satellite/). The land cover map of the late 2010s used Kompsat-2, Kompsat-3A (Arirang) satellite imagery when acquiring detailed information for land cover classification and accuracy assessment processes.

The land cover maps used for this analysis were classified into seven types of land cover: settlements, cropland, forest land, grassland, wetlands, water, and bare land, which are similar to IPCC (Intergovernmental Panel on Climate Change)’s land use categories (Fig. 1).

Fig. 1. The Land Cover Map of DPR Korea in the Late 2010s.

In the classification, “Settlements” refers to the urbanized developed area where people usually live. “Cropland” is the agricultural area such as rice paddies and other agricultural fields. “Forest land” is the forested area with deciduous, coniferous, or mixed forests. “Grassland” is mainly the herbaceous covered area. “Wetlands” is the wet area that is temporarily flooded with water, or dry if the dry season lasts for a long time. “Water” is water body like rivers or lakes, and “bare land” refers to the land that is not covered with vegetation and the soil is exposed (Table 2).

Table 2. Land Cover Description

The maps used for this study are the land cover maps – of the late 1980s, the late 1990s, the end of 2000 2010, and the late 2010s (Fig. 2).

Fig. 2. Land Cover Maps of DPR Korea over Time from the Late 1980s to the Late 2010s: (a) The Late 1980s, (b) The Late 1990s, (c) The End of 2000–2010, and (d) The Late 2010s.

This study analyzed changes in land cover of DPR Korea by province every decade according to seven types of land cover using ArcGIS Pro.

3. Results

1) Changes by Major Land Cover Type

The analysis of the changes in the seven land cover types in DPR Korea found that there have been many changes over the past 40 years. In DPR Korea, the greatest part of the total land cover is forest, followed by cropland. The ratio of land cover types by decade shows that many changes in land cover occurred in DPR Korea, especially in the 1980s and 1990s (Fig. 3).

Fig. 3. The Land Cover Change of DPR Korea over Time from the Late 1980s to the Late 2010s.

Some changes deserve our concern. Big changes are found in forest and cropland. The land for settlements has been steadily increasing. The grassland increased in the 1990s, but has recently shown a decreasing trend. In the case of wetlands and water, it is difficult to find clear trends. In the land cover status across DPR Korea from the 1980s to the end of 2010, the changes in area and ratio by land use types are seen in Table 3.

Table 3. The Land Cover Change of DPR Korea over Time

2) Changes by Province

Reginal changes were analyzed for each province, focusing on cropland and forest land decade by decade. Although there are differences between metropolitan cities and provinces, overall the proportion of forest decreased and the proportion of cropland increased (Fig. 4 and 5). In other words, region’s agricultural activities have been expanded and forests have been damaged.

In the cases of Hwanghaenamdo and Hwanghaebukdo, which are the major breadbaskets of DPR Korea, the area of cropland has been steadily increasing. In Pyungannamdo and Pyunganbukdo, as well as Jagangdo and Hwanghaebukdo, cropland has increased rapidly since the first decade of 2000s. However, this trend of increasing cropland area has slowed or turned over since the 2010s, especially in the area such as Pyungyang, Pyungannamdo, Hamgyungnamdo, and Hwanghaebukdo.

Fig. 4. Changes in Cropland over Time by Province.

Next, the forest area has been continuously diminishing since the 1980s (Fig. 5).

Fig. 5. Changes in Forest Land over Time by Province.

The continuous decrease of forests is in contrast to the steady increase in cropland. However, since the 2010s, there has been a change in this trend. In regions such as Yanggangdo, Pyungannamdo, Pyunganbukdo, Pyungyang, Hamgyungnamdo, and Hwanghaebukdo, the forest land increased slightly.

4. Discussion

Humans depend on the land for their economic activities and acquire what they need to survive, such as food and timber. The land is bound to undergo changes according to human economic activity, along with the natural changes. At the global level, urbanization with population growth and socioeconomic development has a significant impact on land cover change.

Land cover changes are taking place in DPR Korea as well. This study was able to figure out which types of land cover are mainly changing in DPR Korea through the analysis of data over 40 years from the late 1980s to the late 2010s using land cover maps of each decade. It was found that forest and cropland are the major land cover types that undergo the most changes. This reflects the situation of DPR Korea, which has steadily increased the area of cropland nationwide due to forest conversion in order to increase agricultural production. In other words, the continuous increase in cropland reflects a strong food demand in DPR Korea. Agricultural activities such as field farming and orchard cultivation, especially rice paddy farming, are usually carried out in areas with abundant water resources, mainly in the low-altitude areas of Hwanghaenamdo, Hwanghaebukdo, Pyungannamdo, and Pyunganbukdo. DPR Korea’s cropland has increased greatly in both Hwanghaenamdo and Hwanghaebukdo, the granary region suitable for farming due to its topography and climatic characteristics, and it has also increased in Pyunganamdo and Pyunganbukdo which have a high population density. DPR Korea, which is mostly mountainous, has limited land available for agricultural activities. Accordingly, the country has been increasing cropland by clearing forests on slopes.

From the results of this study, it was confirmed that the forest land has continuously decreased in almost all regions of DPR Korea. The forest land decrease means not only the creation of cropland, but it also means cutting trees in preparation of firewood for heating and cooking, which was pointed out as a cause of deforestation in DPR Korea (Myeong, et al., 2020, 2008; Park, 2014).

It is notable that grassland has decreased significantly in the late 2010s. In contrast, forest land increased compared to the late years of the first decade of 2000s. This may be partly the results of forest restoration in the deforested areas. However, since the spectral characteristics of vegetation are similar, the uncertainty in classification is high. Part of the reason may be that the land cover conversion in different time imageries can have the mixed pixel effects, and the classification uncertainties which are the inherited limitations of remote sensing approach. Therefore, it needs to be interpreted carefully and, if possible, enough ground truth data need to be utilized and verified.

For the case of 2010s’ land cover change, it seems certain that the land cover map is reflecting some achievement in terms of reforestation effort by DPR Korea. Actually DPR Korea began to pay attention to slope land management since the first decade of the 2000s to restore areas having deforestation problems. The “Forest Restoration Battle” has been conducted to focus on forest restoration since 2012, which seems to be showing fruitful results recently (Kim et al., 2021). When artificial forest restoration efforts were made, they were made mostly on low-productivity farm land or bare land. Areas converted into forests in the late 2010s were mainly found in grasslands near agricultural land, so forest restoration targeting degraded land is showing substantial results.

There are other types of conversions, too. In addition to the conversion from grassland to forest, there are quite many areas that have been converted from agricultural land to forests, and quite a few areas from bare lands to forests. Also, there are areas that have been converted from grasslands or bare lands to croplands. In other words, the conversions between land cover types are occurring in various combinations.

In general, when forests are extensively damaged, and the land is uncovered with vegetation, the land generally becomes barren and the bare land expands. However, in the case of the late 2010s, the bare land did not increase significantly. It is presumed that this is because the bare land is converted into cropland for farming. It can be seen that DPR Korea, which needs to increase food productivity, continues to develop cropland in areas suitable for agriculture.

In the case of wetlands and water surface, it is difficult to find a clear trend in overall area changes. However, in some areas like in Hwanghaedo, changes were found in the water for agricultural irrigation and dam formation.

In an Ethiopian study on land use and land cover changes (Bufebo and Elias, 2021), forest area decreased from 29.51% in 1973 to 20.52% in 2017, while the agricultural land increased from 70.49% to 79.48%, showing a change trend in land use similar to that of DPR Korea. The study suggested that the driving forces for land cover changes are agricultural expansion, policy change and social unrest, population pressure, shortage of farm land, and biophysical factors. Another study (Mendoza-Ponce et al., 2019) on land cover change by climate change scenario showed that grassland and tropical evergreen forests will be the most endangered ecosystems, and agricultural expansion would be the major driver of land use and land cover changes.

On the other hand, a study on land use in the eastern United States (Drummond and Loveland, 2010) showed different trends. The analysis shows that the agricultural land in the eastern U.S. has continued to diminish, which enabled forest recovery. However, the study pointed out that land cover transition generally shows the decline of forests. That is, forest land gain is not as great as the forest land loss caused by timber cutting, urbanization, and other types of land use demands. And Thawaba et al. (2017) showed that agricultural land has declined because of urbanization. The trend of land cover change has to do with the country’s own socioeconomic circumstances.

Generally, changes in land cover tend to lead to the loss of biodiversity, reduced agricultural productivity, loss of sustainability of natural resources such as forests and water resources, and reduced capacity to respond to climate change and natural disasters. Further research on land cover changes should be conducted for various situations using diverse remotely sensed imageries.

5. Conclusions

Due to the factors such as urbanization and climate change around the world, lands are being degraded, and deserts are expanding (IPCC, 2019; Orr et al., 2017). This is a major impediment to sustainable development. Land degradation is caused not only by natural factors such as soil erosion due to wind or rain but also by urbanization, agricultural activities, cultural and technological conditions, and expansion of infrastructures such as transportation.

Sustainable land management is necessary, because the reduction of land cover of natural ecosystem like forests can accelerate land degradation by increasing vulnerability to disasters. In the case of Asia including DPR Korea, erosion and organic carbon change have been suggested as major threats to soil (Montanarella et al., 2016). Considering the topographical and climatic characteristics of DPR Korea, a careful approach is required when converting forests into other types of land cover, and sustainable management of slopes is required.

Information on changes in land cover in DPR Korea is useful in deriving plans at diverse levels. In the future, various types of satellite will be launched and accordingly, images that provide periodic data are expected to be gathered. Monitoring the land cover status based on satellite images of high temporal and spatial resolution and examining the changes will help us with designing, planning, and implementation of the future inter-Korean and international cooperation projects.