Human-induced Land Cover Changes Research Articles

The synergy between protected area effectiveness and economic growth

Protected areas conserve biodiversity and ecosystem functions but might impede local economic growth. Understanding the global patterns and predictors of different relationships between protected area effectiveness and neighboring community economic growth can inform better implementation of the Kunming-Montreal Global Biodiversity Framework. We assessed 10,143 protected areas globally with matched samples to address the non-random location of protected areas. Our results show that protected areas resist human-induced land cover changes and do not limit nightlight increases in neighboring settlements. This result is robust, using different matching techniques, parameter settings, and selection of covariates. We identify four types of relationships between land cover changes and nightlight changes for each protected area: "synergy," "retreat," and two tradeoff relationships. About half of the protected areas (47.5%) retain their natural land cover and do so despite an increase of nightlights in the neighboring communities. This synergy relationship is the most common globally but varies between biomes and continents. Synergy is less frequent in the Amazon, Southeast Asia, and some developing areas, where most biodiversity resides and which suffer more from poverty. Smaller protected areas and those with better access to cities, moderate road density, and better baseline economic conditions have a higher probability of reaching synergy. Our results are promising, as the expansion of protected areas and increased species protection will rely more on conserving the human-modified landscape with smaller protected areas. Future interventions should address local development and biodiversity conservation together to achieve more co-benefits.

Spatio-temporal analysis of LAI using multisource remote sensing data for source region of Yellow River Basin

Introduction: The Leaf area index (LAI) of source region of yellow river basin is an important indicator for environmental sustainability. Most studies focus on the trend of LAI in Yellow River Source Region (YRSR) in accordance with both climate change and human actives. However, quantifying the effect of human activities on LAI is difficult but urgently needed. Specifically, Particle Matter 2.5 (PM2.5) can be an indirect indicator of human activities.Methods: In this study, we explored the potential dependence of LAI on temperature, precipitation, and PM2.5 in different land cover types in YRSR with linear regression and correlation analysis.Results: Over the period of 2001–2020, the climate in the region has been warming and becoming more humid, leading to overall improvements in vegetation. The mean LAI values varied between seasons, with summer having the highest and winter having the lowest LAI. The analysis of the LAI trends revealed that the mean LAI has been steadily increasing, particularly in the eastern region. The correlation analysis showed a significant positive correlation between annual average LAI and both annual precipitation and temperature, indicating that temperature has a greater impact on vegetation growth. The analysis of land cover types showed that most types exhibited a unimodal trend in LAI throughout the year, except for construction land which had two distinct peaks. Human-induced land cover change had a small impact on the overall increase in LAI. Furthermore, the interannual variation of PM2.5 showed a downward trend, with a strong correlation with the trend of LAI. Additionally, multiple linear regression analysis and residual trend analysis showed that climate factors had the strongest impact on LAI.Conclusion: The study highlights the spatiotemporal variations of LAI in the YRSR and its correlation with climatic and human factors. The findings suggest that climate change plays a crucial role in the vegetation growth and LAI in the region.

The relationship of land tenure, land use and land cover changes in Lake Victoria basin

Water basins characterise both physical and social environmental aspects such as land tenure. As such, the basins extend beyond spatial units of physical resources and human relations analysis to policy research and reform units. The comprehensive view of water basins in research goes along with an observed increase in anthropogenic-driven changes, such as land use and land cover changes, and cases of ineffective remedial measures to the adverse change, such as through applying integrated watershed management approaches. The human-induced land cover changes affect the water basin’s biodiversity, for instance, contributing to an increase in zoonotic disease outbreaks like coronaviruses. The Lake Victoria basin exhibits similar patterns of change and effects due to, among other factors, land tenure, whose contribution is less known empirically. Therefore, this paper integrates satellite imagery and catchment survey data to examine the relationship between land tenure and land uses and land cover changes in the Lake Victoria basin of Eastern Africa.Additionally, explore the contextual character and role of three land tenure systems of Customary, Native freehold and Mailo found in the Uganda country segment of the basin in explaining the outcomes. The aim is to provide information that, among other benefits, improves water basin management and governance. The results indicate a statistically significant relationship exists between the perceived extent of land use and land cover change; drivers of change; the extent of adopting sustainable land-use practices, and the prevailing land tenure. Though with different tenure systems, the three case study water catchments experienced adverse land use and cover changes. The changes mainly affected land tenure indicative land use and cover classes, prominently on the Customary, Mailo, and Native freehold land tenure systems. However, marginal differences occur among the land tenure systems, as the systems feature both de jure and de facto systems and an orientation towards customary tenure characters. The situation likely explains the observed closeness in perceptions regarding the role and relationship between land tenure and land use and cover changes, tenure systems character, perceived drivers of change and eventual outcomes, including the sustainable land use practices adoption. In addition to explaining the land use and cover change, land tenure is an essential tool for restoration and sustainable basin development and sustainability. We, thus, recommend land tenure responsiveness in water basin management approaches for sustainable societal development.

The potential distribution of the yellow monitor, Varanus flavescens (Hardwick & Gray) under multiple climate, land cover and dispersal scenarios in Nepal

Context Human-induced changes in climate and land cover have altered the distribution of fauna around the globe. Some reptiles have been found to be vulnerable to these changes; therefore, studies to identify the impact of the changes on other groups of reptiles are necessary. Aims We aimed to study the impact of climate and land cover change on the yellow monitor (Varanus flavescens) in Nepal. We also aimed to identify the current distribution range and predict the potential distribution under multiple climate change, corresponding land cover change, and dispersion scenarios in the near- and mid-future. Methods We used available presence locations with a candidate set of the least-correlated environmental variables and an Ensemble of Small Models (ESM), a Species Distribution Model (SDM) approach suitable for species with small sample size. Additionally, dispersal scenarios of 1 km, 5 km, and 10 km were added to the model to determine the future distribution under the dispersal scenarios. Key results We found soil particle size, distance to forest, precipitation of wettest quarter, bulk density, and elevation were the five most important variables contributing to the distribution of the species. The Terai lowland and wide valleys in Outer Himalayas are currently suitable but are expected to experience a substantial decrease under most future climate projections and dispersal scenarios. Conclusions The distribution is mostly dependent on soil-related variables; however, climatic variables might have a greater impact on future suitability. Implications Limiting emissions contributing to climatic changes, conserving the soil outside the protected areas, and the potential areas where the species will not experience habitat loss might contribute to the conservation of the species.

Unraveling the Differences in Landcover Patterns in High Mountains and Low Mountain Environments within the Valdivian Temperate Rainforest Biome in Chile

The Valdivian temperate rainforest (VTR) is a biome on the South American continent with high endemism that has experienced an intensive land-cover change in recent decades due to the expansion of agriculture, plantations of introduced forests, and urban growth. Today, the biome hosts key parts of the country’s agricultural and forestry industries. Previous studies focused on quantifying native forest and plantation cover area and exotic forest plantation area, among others. However, the importance of mountain areas as refuge of native forest in Chile remains unexplored. The aim of this research is to highlight the role of latitude and slope on land cover in the VTR. A new methodological approach was used combining global classified datasets. Our results indicate that high mountain areas are the core location of the remaining primary forests and endemism whereas low mountain areas are dominated by exotic forest plantations. Between 40–48° S (The Los Ríos, Los Lagos, and Aysén Regions and high-mountain areas), in general, serve as a natural reservoir where human-induced land-cover change has not occurred on a large scale. Most public and private conservation areas are in high mountain areas, whereas low mountain areas and plain areas lack conservation schemes and are more prone to land cover change towards forestry. Considering geomorphological features in land cover change analysis can reveal interesting new perspectives in this research area.

Understanding spatial patterns in the drivers of greenness trends in the Sahel-Sudano-Guinean region

ABSTRACT The region-wide spatial pattern of the drivers of vegetation trends in the African Sahel-Sudano-Guinean region, one of the main drylands of the world, has not been fully investigated. Time-series satellite earth observation datasets were used to investigate spatiotemporal patterns of the vegetation greenness changes in the region and then a principal component regression method was applied to identify the region-wide spatial pattern of driving factors. Results find that vegetation greening is widespread in the region, while vegetation browning is more clustered in central West Africa. The dominant drivers of vegetation greenness have a distinct spatial pattern. Climatic factors are the primary drivers, but the impacts of precipitation decrease from north to south, while the impacts of temperature are contrariwise. Coupled with climatic drivers, land cover changes lead to greening trends in the arid zone, especially in the western Sahelian belt. However, the cluster of browning trends in central West Africa can primarily be attributed to the human-induced land cover changes, including an increasing fractional abundance of agriculture. The results highlight the spatial pattern of climatic and anthropic factors driving vegetation greenness changes, which helps natural resources sustainable use and mitigation of climate change and human activities in global dryland ecosystems.

Global/Regional Impacts on Present and Near-Future Climate Regimes in the Metropolitan Region of Belém, Eastern Amazon

Impact studies have contributed to a better integrated scientific understanding of the climate and environment of the Amazon, in the present, past, and future. This work aims to describe the regional impacts of human-induced landcover changes on the RAINY (January to April) and DRY (July to November) regime of the Metropolitan Region of Belém (MRB), the first frontier of Amazonian occupation. Furthermore, a dynamic downscaling (RegCM4 driven by HadGEM2-ES under the RCP8.5 scenario) was performed to investigate future global climate change impacts. A present climate (1985/2020) quantitative analysis showed that the disorderly urban enlargement in Belém and the forest suppression that led to the uncontrolled expansion of pasture/agriculture area over MRB has conditioned a local warmer climate with a significant increasing air temperature trend in both seasonal regimes. Another clear piece of evidence was the systematic intensification of the precipitation during the RAINY period. RegCM4 simulations indicate that the region will be impacted by the global climate change, such that warmer conditions in the DRY and intensified rainfall in the RAINY regime are expected to persist in the coming decades (2021/2045). Our findings for the MRB (area 3565 km2 for a population about 2.5 million inhabitants) are relevant and should be considered in the tasks of long-term planning and elaboration of advanced strategies to mitigate future climate-related risks and urban disaster management.

Long-term monitoring of NDVI changes by remote sensing to assess the vulnerability of threatened plants

Little is known about how much continuous landscape transformation might affect the most vulnerable elements of biodiversity. In this study, we quantified changes in the normalized difference vegetation index (NDVI) over the past 35 years across locations with threatened plants and in Natura 2000 (N2000) protected areas, in an environmentally heterogeneous region of Southern Europe. First, we estimated the intensity and duration of NDVI gains and losses based on Landsat time series using the LandTrendr algorithm in Google Earth Engine. Then, we tested: 1) whether populations of threatened plants were located in more stable sites than non-threatened plants (i.e., lower NDVI changes); 2) whether NDVI changes around populations of threatened plants differed across habitats and inside/outside N2000 areas, and 3) whether lower NDVI changes occurred in N2000 areas than unprotected areas, thereby indicating their effectiveness at preserving biodiversity. Threatened plants tended to be concentrated in sites with less change irrespective of the habitat where they occurred and their location within protected areas. Occurrence in stable sites also reduced the risk associated with small-sized populations. N2000 areas were in line with the overall greening trend but they experienced less loss events than the unprotected areas, thereby supporting their role in slowing down human-induced land cover changes. Our approach demonstrates how long-term remote sensing monitoring can help to assess the effects of both slow processes and drastic landscape transformation events on priority plants in a comprehensive and rapid manner. This method can identify hidden patterns in extensive regions and guide effective conservation management.

Land Use and Land Cover Change in the Yellow River Basin from 1980 to 2015 and Its Impact on the Ecosystem Services

Land use and land cover change is an important driving force for changes in ecosystem services. We defined several important human-induced land cover change processes such as Ecological Restoration Project, Cropland Expansion, Land Degradation, and Urbanization by the land use/land cover transition matrix method. We studied human-induced land cover changes in the Yellow River Basin from 1980 to 2015 and evaluated its impact on ecosystem service values by the benefit transfer method and elasticity coefficient. The results show that the cumulative area of human-induced land cover change reaches 65.71 million ha from 1980 to 2015, which is close to the total area of the Yellow River Basin. Before 2000, Ecological Restoration Project was the most important human-induced land cover change process. However, due to the large amount of cropland expansion and land degradation, the area of natural vegetation was reduced and the ecosystem value declined. Since 2000, due to the implementation of the “Grain for Green” program, the natural vegetation of upstream area and midstream area of Yellow River Basin has been significantly improved. This implies that under an appropriate policy framework, a small amount of human-induced land cover change can also improve ecosystem services significantly.

Assessing the effectiveness of protected areas against habitat fragmentation and loss: A long-term multi-scalar analysis in a mediterranean region

Landscape fragmentation and human-induced land-cover changes are two of the main current threats to nature conservation. To face such challenges, the development of networks of Protected Areas (PAs) has become a central element of nature conservation policies. The main objective of this study is to evaluate the effectiveness of PAs against long-term natural habitat fragmentation and loss at a regional scale in a South West European context (Andalusia, Spain). A multiscalar approach –covering the entire region, the regional PAs network, the complete set of Andalusian Nature Parks and ten individual Parks– has been adopted for the analysis of four landscape metrics. The study covers a time span of approximately 50 years (1956–2007) divided into two periods (1956–1984 and 1984–2007), which allows for the assessment of the effects of PAs development in the region. The results show that habitat loss has a relatively low incidence and is distributed very irregularly throughout the region under study. In contrast, habitat fragmentation has a strong incidence at all scales of analysis. The loss of habitat continuity is mainly located in non-protected areas. Small losses of natural cover in key areas located outside PAs may lead to a strong increase in habitat fragmentation at the regional scale and indirectly affect valuable natural areas under protection. According to the results, it is highly advisable to reinforce the ecological connections between large PAs and adopt a more ecologically sound and proactive landscape planning approach in non-protected environments.

Impact of land use and land cover change on the magnitude of surface runoff in the endorheic Hayk Lake basin, Ethiopia

This study focused to analyze the main human-induced land use and/or cover changes and their impact on the response to surface runoff from the Hayk Lake endorheic basin between 1989 and 2015. The investigation of Landsat images of years 1989, 2000 and 2015 with the aid of ArcGIS 10.1 indicated an increase in cultivation land by 137.74% at the disbursement of a decrease of 1.34% in lake water, 49.48% in shrubland, 55.84% in plantation, and 17.32% in grassland. Overall accuracy (92%–96%) and kappa values (0.90–0.95) proved that the image classifications were accurate. The impact of the changed land use and/or cover on surface runoff was investigated by simulating the surface runoff for the years 1989, 2000 and 2015, and then quantifying the individual rate of contribution of land use and/or cover change on the magnitude of simulated surface runoff using HEC-HMS modeling tool. The analysis found that land use and cover change alone increased surface runoff by 20.18% and that climate change reduced surface runoff by 120.18%. The combined effect reduced surface runoff and caused a continued decline in water level at Hayk Lake. Therefore, this study advocated basin-based lake water management strategies linked to the negative impacts of land use and land cover, and climate change on the water balance of Hayk Lake for its sustainability.

Crossing a critical threshold: Accelerated and widespread land use changes drive recent carbon and nitrogen dynamics in Vichuquén Lake (35°S) in central Chile

Global afforestation/deforestation processes (e.g., Amazon deforestation and Europe afforestation) create new anthropogenic controls on carbon cycling and nutrient supply that have not been fully assessed. Here, we use a watershed-lake dynamics approach to investigate how human-induced land cover changes have altered nutrient transference during the last 700 years in a mediterranean coastal area (Vichuquén Lake). We compare our multiproxy reconstruction with historical documentation and use satellite images to reconstruct land use/cover changes for the last 45 years. Historical landscape changes, including those during the indigenous settlements, Spanish conquest, and the Chilean Republic up to mid-20th century did not significantly alter sediment and nutrient fluxes to the lake. In contrast, the largest changes in the lake-watershed system occurred in the mid-20th century and particularly after the 1980s–90s and were characterized by a large increase in total nitrogen and organic carbon fluxes as well as negative shifts in sediment δ15N and δ13C values. This shift was coeval with the largest land cover transformation in the Vichuquén watershed, as native forests nearly disappeared while anthropogenic tree plantations expanded up to 60% of the surface area.

Geographic information system (GIS) based soil loss estimation using RUSLE model for soil and water conservation planning in anka_shashara watershed, southern Ethiopia

Water induced soil erosion has been continued to threaten the land resources in sub humid northwestern highlands of Ethiopia. Human-induced land cover (LC) changes due to improper land management practices are contributing factors in deteriorating soil quality. Soil and water conservation measures have been implemented without site-specific scientifically quantified soil erosion data and priority bases in this regard; this study was conducted with a view to quantifying soil erosion in Anka-Shashara watershed. To do this, we have opted to use the RUSLE model based on geographic information systems. By collecting data on rainfall, soils, vegetation, slopes and conservation practices separately as a layer and determining the pixel values for each of these factors, a quantified assessment of erosion in the basin is obtained. The result reveals that the mean annual soil loss (15.22t/ha/yr) of the most parts of study area falls in tolerable levels and almost 66% (1594 ha), moderate level about 23% and 10% at high level of watershed. The soil loss of watershed is classified in to four main classes. None to Slight rates of soil erosion (0-10t/ha) is cover the almost 66% of watershed moderate about 23% and high about 10% of erosion rate as seen from the erosion rate distribution map. The upstream of catchment needs management and protection of those existing resources and the fundamental attention for SWC as recommended bases. Therefore, to reduce sedimentation problem and ensue sustainability of the watershed need to special attention for implementing recommended SWC intervention at the earlier.

Estimating the Value of Global Ecosystem Structure and Productivity: A Geographic Information System and Emergy Based Approach

We have used the coverages of renewable emergy input developed from satellite derived data to determine the emergy supporting ecosystem productivity and biotic natural capital. In addition, the impact on global productivity and biotic natural capital that has resulted from human induced land cover change was evaluated. The actual evapotranpiration (AET), which is the portion of rain that is used by vegetation was the most significant driver of ecosystems. However, the accumulation of biomass over time is not only affected by the available water used, but also by solar input and negatively affected by wind. Additionally, we have estimated the value of ecosystem function and storages. In pre-anthroponcene era, total annual emdollar value of global gross primary production was em$ 12.3 trillion and the total emdollar value of biotic natural capital which includes below and above ground biomass as well as the soil carbon was em$ 578.5 trillion. However, total losses of biotic natural capital from land cover change since the anthropocene began equal to em$88.5 trillion or about 16% of total pre-anthropocene value.

Assessing the relationship between land tenure issues and land cover changes around the Arabuko Sokoke Forest in Kenya

Land as an essential resource is becoming increasingly scarce due to population growth. In the case of the Kenyan coast, population pressure causes land cover changes in the Arabuko Sokoke Forest, which is an important habitat for endangered species. Forest and bushland have been changed to agricultural land in order to provide livelihood for the rural population who are highly dependent on small-scale farming. Unclear land rights and misbalanced access to land cause uncontrolled expansion and insecure livelihoods. Secure land rights are crucial to improve living conditions for the local smallholders. Socio-economic and land tenure conditions were assessed in a study area close to Malindi in south-east Kenya to understand the human-induced changes in land cover. A combination between biophysical and socio-economic methods was used to identify the relationship between land cover change, land tenure and other socio-economic factors. Analyses in Geographic Information System (GIS) were chosen to examine in historical photographs and recent satellite imagery land cover changes between 1954 and 2017. This analysis was combined with quantitative questionnaires conducted on-site in 2017 and 2018 to identify factors influencing the land cover changes and especially to analyze the effects of land tenure on sustainable land use to reduce further land conversion. Moreover, this study statistically investigated the impact of land tenure issues on the tree population of the respective land plots using non-parametric tests as well as dependency analyses. We found significant relationships between the income of the interviewees and the tree population on land plots. It also appears that the fragmentation of land cover on a plot differs between respondents who have inherited their land and respondents who have purchased their land.

Vegetation Response to Recent Trends in Climate and Landuse Dynamics in a Typical Humid and Dry Tropical Region under Global Change

The influence of global change on vegetation cover and processes has drawn increasing attention in the past few decades. In this study, we used remotely sensed rainfall and land surface temperature to investigate the spatiotemporal pattern and trend in vegetation condition using NDVI as proxy from 2001 to 2017 in a humid and dry tropical region. We also determined the partial correlation coefficient of temperature and rainfall with NDVI and the response of NDVI to changes in landcover categories due to human activities. We found that the mean annual maximum NDVI was 0.42, decreasing at a rate of 0.06 per decade. About 27.4% of the area was found to have experienced a significant negative trend in vegetation cover, while only 0.34% exhibited significant increasing vegetation vigour. Land surface temperature increased at a mean rate of 0.75°C/decade, with higher rates in agriculture, savanna, settlements, woodlands, and riparian vegetation than in forest and mangrove vegetations. Precipitation also reduced at a mean rate of 58.69 mm/decade, with higher rates in agriculture savanna and riparian vegetation than in sahelian grasslands, mangrove, forest, and woodlands. NDVI was negatively correlated with temperature in savanna, settlements, degraded forest, and sahelian grasslands providing confirmation of ongoing land degradation. It was concluded that vegetation vigour will continue to decline under rainfall and increasing temperature conditions especially in dryer regions. The use of land surface temperature in this study is particularly valuable in highlighting areas where changes in NDVI occurred as a result of synergistic action between climate and human-induced landcover changes. Our findings underscore the importance of landuse policies that account for spatial variation in synergistic relationships between the nexus of climate and land conversion processes that influence vegetation cover change in different landcover types in tropical regions.

Spatiotemporal dynamics of urbanization and cropland in the Nile Delta of Egypt using machine learning and satellite big data: implications for sustainable development.

The Nile Delta of Egypt is increasingly facing sustainability threats, due to a combination of nature- and human-induced changes in land cover and land use. In this paper, an analysis of big time series data from remotely sensed satellite images and the random forests classifier was undertaken to assess the spatial and temporal dynamics of urbanization and cropland in the Nile Delta between 2007 and 2017. Out of thirteen variables, five spectral indices were chosen to build 500 decision trees, with a resulting overall accuracy average of 91.9 ± 1.5%. The results revealed that the urban extent in the Nile Delta has increased, between 2007 and 2017, by 592.4 km2 (1.92%). Particularly, the results indicated that the years 2011 and 2012, which coincided the 2011 political uprising in Egypt, so-called the Arab Spring, were associated with significant land-use changes in the Nile Delta, both in rate and scale. As a result, the cropland area in the region decreased between 2010 and 2011 by 1.63% (502.21 km2). Moreover, the results showed that during the period 2012-2017, the mean annual urbanization rate in the region stood at 60 km2/year. In contrast, croplands decreased during the same period at an average annual rate of 2 km2/year. At the governorates' level, the results suggested that top agricultural producing governorates in the Nile Delta, such as Elmonoufia, Elkalubia, Elbouhyra, and Elghrbia, witnessed the highest rates of decrease in cropland areas during the period 2012-2017. Over the same period, urban areas increased the most in Elkalubia, Domiate, and Elmonoufia by 1.98%, 1.72%, and 1.34%, respectively. The f indings from this analysis are discussed along with their implications for sustainable land-use and urban planning policies.

Historical Trajectory in Vegetation Cover in Northeastern Namibia Based on AVHRR Satellite Imagery (1982–2015)

The negative impact of the reduction of vegetation cover is already being felt in the Zambezi Region in northeastern Namibia. The region has been undergoing various land cover changes in the past decades. To understand the historical trend of vegetation cover (increase or decrease), we analyzed 8-km resolution Global Inventory Monitoring and Modeling Studies (GIMMS) from the Advanced Very High Resolution Radiometer (AVHRR) and 0.25° × 0.25° (resampled to 8 km) resolution Global Precipitation Climatology Center (GPCC). We used the Time Series Segmented Residual Trends (TSS-RESTREND) method. We found that the general trajectory of vegetation cover was negative. Pixel-wise analysis and visual interpretation of historical images both revealed clear signs of vegetation cover change. We observed a single breakpoint in the vegetation trajectory which correlated to the 1991–1992 drought in southern Central Africa. Potential drivers of land cover change are the (il)legal expansion of subsistence farming, population growth, and wood extraction. These findings will serve as a reference for decision makers and policymakers. To better understand the human-induced land cover change at the micro scale and sub-regional level, we recommend using higher resolution remote sensing datasets and historical documents to assess the effect of demographic change, disease, civil unrest, and war.

Are There Sufficient Landsat Observations for Retrospective and Continuous Monitoring of Land Cover Changes in China?

Unprecedented human-induced land cover changes happened in China after the Reform and Opening-up in 1978, matching with the era of Landsat satellite series. However, it is still unknown whether Landsat data can effectively support retrospective analysis of land cover changes in China over the past four decades. Here, for the first time, we conduct a systematic investigation on the availability of Landsat data in China, targeting its application for retrospective and continuous monitoring of land cover changes. The latter is significant to assess impact of land cover changes, and consequences of past land policy and management interventions. The total and valid observations (excluding clouds, cloud shadows, and terrain shadows) from Landsat 5/7/8 from 1984 to 2017 were quantified at pixel scale, based on the cloud computing platform Google Earth Engine (GEE). The results show higher intensity of Landsat observation in the northern part of China as compared to the southern part. The study provides an overall picture of Landsat observations suitable for satellite-based annual land cover monitoring over the entire country. We uncover that two sub-regions of China (i.e., Northeast China-Inner Mongolia-Northwest China, and North China Plain) have sufficient valid observations for retrospective analysis of land cover over 30 years (1987–2017) at an annual interval; whereas the Middle-Lower Yangtze Plain (MLYP) and Xinjiang (XJ) have sufficient observations for annual analyses for the periods 1989–2017 and 2004–2017, respectively. Retrospective analysis of land cover is possible only at a two-year time interval in South China (SC) for the years 1988–2017, Xinjiang (XJ) for the period 1992–2003, and the Tibetan Plateau (TP) during 2004–2017. For the latter geographic regions, land cover dynamics can be analyzed only at a three-year interval prior to 2004. Our retrospective analysis suggest that Landsat-based analysis of land cover dynamics at an annual interval for the whole country is not feasible; instead, national monitoring at two- or three-year intervals could be achievable. This study provides a preliminary assessment of data availability, targeting future continuous land cover monitoring in China; and the code is released to the public to facilitate similar data inventory in other regions of the world.

Assessing climate impact on forest cover in areas undergoing substantial land cover change using Landsat imagery

In this study, we propose to assess climate impact on forest cover (represented by EVI) at multiple scales in areas undergoing substantial land cover change, using Landsat imagery with human-induced land cover change effect excluded. Taking the Qingliu River catchment located in a subtropical humid monsoon area in China as a case study, the results indicate that EVI increases significantly (p < 0.01) during 1989–2014 with a magnitude of 0.026/decade. Spatial distribution of EVI is distinct in summer and growing season. Temperature and precipitation show high partial correlations with EVI, with better partial correlation found between EVI and temperature. Their partial correlations with EVI on monthly scale are higher than those on annual scale. Besides, precipitation and pan evaporation show accumulative lag effects (4 months) on forest EVI, while temperature has no lag effect. Finally, an empirical formula is established to quantify the relationship among EVI and its main driving factors (temperature and precipitation) by considering the precipitation threshold (200 mm). The findings should provide scientific supports for local forest management and ecosystem services, and should also support the hydrological effect assessment of vegetation cover change under climate change for the study area.