Spatio-temporal Patterns of Vegetation Change in Kazakhstan from 1982 to 2015

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1 July, 2017 Journal of Resources and Ecology Vol. 8 No.4 J. Resour. Ecol (4) DOI: /j.issn x Spatio-temporal Patterns of Vegetation Change in Kazakhstan from 1982 to 2015 LUO Liang 1,2, DU Wenpeng 3, YAN Huimin 1,2,*, ZHEN Lin 1,2, DONG Yu 1,2 1. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing , China; 2. University of Chinese Academy of Sciences, Beijing , China; 3. College of Earth Science and Resources, Chang-an university, Xi an , China Abstract: The Normalized Difference Vegetation Index (NDVI), as a key indicator of vegetation growth, effectively provides information regarding vegetation growth status. Based on the Global Inventory Monitoring and Modeling System (GIMMS) NDVI time series data for Kazakhstan from 1982 to 2015, we analyzed the spatial pattern and changes in the vegetation growth trend. Results indicated that the three main types of vegetation in Kazakhstan are cropland, grassland and shrubland, and these are distributed from north to south. While the regional distribution pattern is obvious, the vegetation index decreased from north to south. The average NDVI values of the three main vegetation types are in the order of cropland > grassland > shrubland. During the period from 1982 to 2015, the NDVI initially increased ( ), then decreased ( ), and then increased again ( ). The areas where NDVI decreased significantly accounted for 24.0% of the total land area. These areas with vegetation degradation are mainly distributed in the northwest junction between cropland and grassland, and in the cropland along the southern border. The proportions of total grassland, cropland and shrubland areas that were degraded are 23.5%, 48.4% and 13.7%, respectively. Areas with improved vegetation, accounting for 11.8% of the total land area, were mainly distributed in the mid-east cropland area, and the junction between cropland and grassland in the mid-east region. Key words: Normalized Difference Vegetation Index (NDVI); desertification; land use; trends analysis; Kazakhstan 1 Introduction Arid and semi-arid regions are high-risk areas for desertification and environmental degradation. Resulting from the combined influence of natural and human factors, desertification and environmental degradation have severely threatened the ecosystems of arid and semi-arid areas in recent years (Eisfelder et al., 2014; Mirzabaev et al., 2016). The use of effective monitoring indicators to identify and monitor regions that are at high risk for desertification and environmental degradation is therefore a critically important part of protecting local ecological environments and making improvements. The degradation analysis method based on empirical knowledge requires human intervention, and thus objectivity cannot be guaranteed (Eisfelder et al., 2014; Eisfelder et al., 2017). The ground survey method can be used to obtain information on the structural changes of ecosystems and to study desertification and environmental degradation. Although relatively high accuracy can be achieved through the use of this method, a field investigation is labor intensive and requires considerable material and financial resources. As such, it is not suitable for large- scale research (Paul et al., 2004; Karnieli et al., 2008). Due to their high efficiency when applied to large-scale areas, the Global Inventory Modeling and Mapping Studies (GIMMS), Moderate Resolution Imaging Spectroradiometer (MODIS), Landsat time series and other remote sensing data have been Received: Accepted: Foundation: National Key Research and Development Program of China(2016YFC ) *Corresponding author: YAN Huimin, yanhm@igsnrr.ac.cn Citation: LUO Liang, DU Wenpeng, YAN Huimin, et al Spatio-temporal Patterns of Vegetation Change in Kazakhstan from 1982 to Journal of Resources and Ecology, 8(4):

2 LUO Liang, et al.: Spatio-temporal Patterns of Vegetation Change in Kazakhstan from 1982 to used to extract or invert ecological degradation indicators. With the help of remote sensing time series data and trend analysis, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Net Primary Productivity (NPP) and other related information, which can objectively and quantitatively reflect vegetation growth status, are often used to extract large-scale information on vegetation dynamics and growth status (Jeong et al., 2011; Spivak et al., 2011; Beurs et al., 2015; Eckert et al., 2015; Sternberg et al., 2015). Terrestrial vegetation is very sensitive to changes in ecosystem structure such as changes in soil moisture, surface photosynthetically active radiation (PAR), surface runoff and other factors, and provides feedback through changes in growth status (Lunetta et al., 2004; Almaganbetov and Grigoruk, 2008; Kraemer et al., 2015). Vegetation degradation has emerged as a key indicator of land desertification and degradation. As such, Chinese and foreign researchers examine various indicators to measure vegetation growth status and, subsequently, use these indicators to study land desertification and degradation. Commonly used monitoring indicators include the soil erosion index, which measures the degree of soil erosion, and vegetation NPP, NDVI and EVI, which reflect vegetation growth status (Alexandrov et al., 2002; Karnieli et al., 2008; Spivak et al., 2011; Eisfelder et al., 2014; Eisfelder et al., 2017). Trend analysis with long-term NDVI time series (Alexandrov et al., 2002; Xu et al., 2017) not only focuses on land degradation and desertification processes (Alexandrov et al., 2002; Xu et al., 2017), but can also help reduce interference from confounding factors. It has thus been widely used in land desertification and degradation research. Kazakhstan is almost exclusively arid and semi-arid territory (ADB, 2010; Eisfelder et al., 2012). As the problems of environmental degradation and desertification have become more intense, factors such as gradually decreasing vegetation coverage, degraded soil quality and soil erosion have come together in a vicious cycle. Land degradation and desertification present major challenges to the ecological environment in Kazakhstan (ADB, 2010). Due to the impact of human and political factors, Kazakhstan has experienced significant ecological and environmental losses, including the decline of the Aral Sea and losses connected to the Virgin Lands Program, which have led to the degradation of large areas of grassland (Beurs and Henebry, 2004; ADB, 2010). Although there was a temporary boost in food yield as a result of cultivated land expansion, unsustainable land use practices ultimately led to severe land degradation. Following the collapse of the Soviet Union, agriculture and animal husbandry in Kazakhstan switched to individual small-scale businesses. A large area of cropland went to waste. Additionally, land degradation was exacerbated by decreased governmental support, and poor irrigation conditions and water conservation infrastructure. The number of livestock shrank remarkably, resulting in small-scale grazing. Because a nomadic lifestyle is difficult for herdsmen (Beurs and Henebry, 2004; Alimaev et al., 2008; Eisfelder et al., 2014), signs of over grazing started to appear in residential areas, and this poses a great threat to the local ecological environment (Astana, 2005; Kerven et al., 2008; Hauck et al., 2016). Since 2000, the Kazakh government has made increasing efforts to develop agriculture and animal husbandry. Through these efforts, approximately 50% of abandoned or wasted lands have been recovered, and the land expansion and cultivation intensity are expected to increase steadily in the future (Kraemer et al., 2015). It is important to keep in mind that conducting land reclamation without ensuring sustainable land use will inevitably increase the risk of land degradation and desertification (Beurs and Henebry, 2004; Kamp et al., 2015). In addition to the human factor interferences noted above, climate change plays a critical role in the eco-environment of arid and semi-arid areas. Climate conditions are another major factors in environmental degradation of arid and semi-arid areas (Lioubitseva et al., 2005; Eisfelder et al., 2014; Wang et al., 2017). In the early 20th century, records indicate that the average annual temperatures in Kazakhstan began to increase. It is projected that average temperatures in Central Asia will increase by 1 2 C by (Lioubimtseva et al., 2005). Previous studies reported that precipitation in Kazakhstan has decreased slightly in recent years, and the warmer-drier trend will become increasingly obvious in the future. Therefore, the local ecological environment is under severe threat (Astana, 2005; Lioubimtseva and Henebry, 2009). Given the challenges facing the arid and semi-arid areas in Kazakhstan, analysis of the dynamic spatial and temporal variations of NDVI will help elucidate the evolution of the terrestrial ecosystem in arid and semi-arid areas under the impact of natural and human interferences. The results of this analysis will provide a scientific basis for land management, sustainable land use and ecological governance in arid and semi-arid areas. The objectives of this study are as follows: (1) to reveal the trajectory and trends of regional ecological degradation based on long-term NDVI time series; (2) to understand the pattern of ecological degradation and its spatio-temporal interactions with the driving factors; and (3) to predict future trends in the ecological degradation processes, and thereby provide a reference for the development of sustainable land use programs and ecological governance. 2 Data and methods 2.1 Study area Kazakhstan has a total area of 2,724,900 km 2, accounting for 2% of the global land area. As a typical landlocked country, Kazakhstan is almost entirely arid and semi-arid in area composition. It has a typical arid continental climate. Annual precipitation is between 100 and 400 mm. The Tian Shan and Altai Mountains are located in eastern and south-

3 380 Journal of Resources and Ecology Vol. 8 No. 4, 2017 eastern Kazakhstan. The north, west and northwest regions consist of plains, while the central area is hilly. The overall landform in Kazakhstan is highland in the east and southeast, and lowland in the west and northwest. The main ecosystem types in Kazakhstan are grassland, cropland and shrubland. From north to south, the land type changes sequentially from cropland to grassland to shrubland. Cropland is mainly distributed in the southern and northern border areas. Grassland is mainly distributed in the central areas, mid-north, west and northwest areas, while shrubland is mainly in the mid-south and southern areas. 2.2 Data AVHRR NDVI data for the period spanning 1982 to 2015 The GIMMS NDVI data is derived based on wave band data collected by the Advanced Very High Resolution Radiometer (AVHRR) sensor carried onboard the National Oceanic and Atmospheric Administration (NOAA) satellites. GIM- MS NDVI data was downloaded from the National Aeronautics and Space Administration (NASA) website ( ecocast.arc.nasa.gov/data/pub/gimms/). The spatial resolution is 8 km, and the temporal resolution is either 15 days or 1 month. Pre-processing of GIMMS NDVI data was performed, including calibration, atmospheric correction and track deviation correction. To minimize cloud interference, the NDVI data were averaged among the maximum NDVI of each month in each year during the 1982 to 2015 period (Propastin et al., 2007; Fensholt et al., 2012). The formula for NDVI calculation is as follows: NIR red NDVI= 100 NIR red Herein, NIR and red are the reflectivity of ground objects in near-infrared and infrared wave bands, respectively Land use data The land use data in Kazakhstan is from the MODIS global land cover data series ( The spatial resolution is 1 km. To facilitate masking of GIMMS NDVI data and subsequent statistical analysis, the data were resampled to match the 8 km resolution. 3 Results 3.1 Spatial distribution of vegetation growth status in Kazakhstan From north to south, there were three types of vegetation in Kazakhstan (cropland, grassland and shrubland), and these showed an obvious regional distribution pattern. The areas of cropland, grassland and shrubland accounted for 13.5%, 25.9% and 49.4% of the total land area, respectively. By averaging the NDVI data, the mean value was retained as the index for analyzing the spatial distribution of vegetation growth status. The average NDVI generally decreased from north to south. Specifically, the average NDVI values were high in the northern cropland area, as well as in the forest areas along the east and southeast border. In contrast, the NDVI values were low in the central grassland and mid-southern shrubland areas. For the same vegetation type, the NDVI was higher in the northern area than the in southern area. The average NDVI values of cropland, grassland and shrubland in Kazakhstan were significantly different. The highest average NDVI was obtained in the cropland area (0.59), followed by grassland (0.45) and shrubland (0.26). Fig.1 Spatial distribution of average NDVI of main vegetation types in Kazakhstan in

4 LUO Liang, et al.: Spatio-temporal Patterns of Vegetation Change in Kazakhstan from 1982 to Fig.2 Magnification (100x) of average NDVI of main vegetation types in Kazakhstan in NDVI variation trends during the period Between 1982 and 2015, the annual average NDVI increased initially, followed by a period of decrease, and then another period of increase. Between 1982 and 1992, the annual average NDVI exhibited an increasing trend, peaking in Between 1993 and 2007, the NDVI shifted to a declining trend. Specifically, significant decreases were observed during the years and During , the NDVI started to increase again. The temporal variations of NDVI exhibited different patterns for the three vegetation types during In shrubland area, NDVI increased in and then decreased in In grassland area, similar to the overall trend, the NDVI first increased ( ), followed by a decrease ( ), and then increased again ( ). In cropland area, NDVI first increased ( ) and then decreased ( ). 3.3 Spatial distribution of NDVI variations during in Kazakhstan Based on the grid analysis of NDVI variations during the 34 year period, the areas with significantly decreased NDVI are located in the north, northwest and south, while the areas with increased NDVI are located in the east and mid-east regions. The distribution of vegetation degradation was obtained based on the analysis of temporal NDVI variations during the period in Kazakhstan (Fig. 5). The classification standard for vegetation degradation is as follows: NDVI slope < 0.03 (severely degraded), 0.03 < NDVI slope < 0.01 (degraded), 0.01<NDVI slope<0.01 (no change), 0.01 < NDVI slope < 0.03 (improved) and NDVI slope > 0.03 (greatly improved) (Fig. 6). During the period, the areas in Kazakhstan with vegetation degradation were concentrated in the northwestern junction between cropland and grassland, and the cropland area near the Fig.3 Magnification (100x) of annual average NDVI in Kazakhstan in

5 382 Fig.4 Journal of Resources and Ecology Vol. 8 No. 4, 2017 Annual NDVI variation of main vegetation types in Kazakhstan in Fig.5 Distribution of NDVI variation (left, trend; right, p <0.05) Fig.6 Distribution of vegetation degradation in Kazakhstan in

6 LUO Liang, et al.: Spatio-temporal Patterns of Vegetation Change in Kazakhstan from 1982 to southern border. Areas with severe degradation accounted for 24.0% of total land area. Degradation occurred in 23.5%, 48.4% and 13.7% of the total grassland, cropland and shrubland areas, respectively. Areas with improved vegetation are mainly distributed in mid-east cropland and the cropland-grassland junction areas, which accounted for 11.8% of the total land area. Overall, vegetation growth in Kazakhstan exhibited a degradation trend during the period, especially in the northern, northwestern and southern areas. 4 Conclusions and discussion 4.1 Conclusions Based on the Global Inventory Monitoring and Modeling System (GIMMS) NDVI time series data of Kazakhstan from 1982 to 2015, we analyzed the spatial pattern and changes in the vegetation growth trend. Results indicated that cropland, grassland and shrubland in Kazakhstan are sequentially distributed from north to south. The vegetation index decreased from north to south. The order of average NDVI of the three vegetation types is cropland > grassland > shrubland. During , the annual average NDVI increased initially ( ), followed by a decrease ( ), and then increased again ( ). The NDVI values of all three vegetation types increased in In , the NDVI values of cropland and grassland decreased, while the NDVI of shrubland increased. In contrast to NDVI values of grassland, the values of cropland and shrubland exhibited a decreasing trend in During , severely degraded areas accounted for 24.0% of the total land area. These areas were mainly distributed in the cropland-grassland junction in the northwest and the cropland area near the southern border. Improved vegetation areas were mainly distributed in the mid-east cropland and the cropland-grassland junction areas, accounting for 11.8% of the total land area. 4.2 Discussion In terms of temporal variations in , results indicated that the annual average NDVI in Kazakhstan increased at first ( ), then decreased ( ), and then increased again ( ). This trend is inversely associated with differences in livestock quantity. Specifically, the number of grazing livestock in in Kazakhstan first decreased, then increased, and then decreased again (Kraemer et al., 2015). Meanwhile, the average NDVI of cropland increased in and then decreased in , this result is in close agreement with changes in the cultivation area of forage crops, as reported by Daniel Müller and colleagues (Kraemer et al., 2015). However, there are differences between the NDVI of cropland and the total cultivated land area trends. Prior to 2000, the changes in NDVI of cropland are consistent with the changes in the total cultivated land area reported by Daniel Müller and colleagues. After 2000, the changes in the farmland NDVI trend and the cultivated land area trend are different. This may be a result of changes in crop varieties (compared to the varieties used prior to 2000) due to the change in political system. As such, while the total cultivated land area increased, the NDVI of farmland decreased. Ecological changes due to the joint action of climate change (precipitation, temperature, etc.) and human activities (unreasonable land use, examples of which include excessive reclamation and overgrazing) lead directly to changes in NDVI. The collapse of the Soviet Union in 1991 and the measures implemented by the government of Kazakhstan intended to support the recovery of agriculture and animal husbandry are both key human factors that are associated with variations in NDVI. The annual average NDVI in Kazakhstan first increased ( ), and then decreased ( ), and then increased again ( ). This NDVI trend perfectly reflects the influence of social regimes and policies on ecological status. In arid and semi-arid areas, climate (especially precipitation) is another important factor that influences vegetation growth. In recent decades, the climate in Kazakhstan has exhibited a warm and dry pattern, marked by temperature increases in the winter and reduced precipitation in the summer (Beurs and Henebry, 2004; Bolch, 2007; Eisfelder et al., 2014). These changes have caused deteriorations in natural conditions, which ultimately led to vegetation degradation. The areas in Kazakhstan where vegetation growth increased are concentrated in the eastern and mid-eastern forest regions, and in the cropland-grassland junction. These areas are rich in water resource and are ideal for vegetation growth. In arid and semi-arid areas, rainfall is a major natural factor that affects vegetation growth. Propastin et al. used precipitation data to analyze changes in vegetation coverage in Kazakhstan and found a strong correlation between vegetation growth and precipitation (Propastin, 2012; Chen, 2013). In summary, the process of spatial and temporal ecological degradation in Kazakhstan is the result of various interacting factors. To explore the underlying mechanisms of degradation, these factors, including climate change, social system, cultivated land use and grazing intensity, need to be considered comprehensively. In addition, research in this subject area can provide a scientific basis for the ecological management and restoration strategies in Kazakhstan. References ADB, Central Asia atlas of natural resources/central Asian Countries Initiative for Land Movement. Manila: Asian Development Bank. 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