Contribution Of Land Use Change Research Articles

The impacts of climate change, early agriculture and internal fluvial dynamics on paleo-flooding episodes in Central China

Floods clustered in episodes are the most prevalent natural disaster worldwide, causing substantial economic and human losses. Although these events are often linked to time-periods of extreme rainstorms and unique atmospheric circulation patterns, the river basin characteristics affected by anthropogenic land use changes could exert a strong influence. However, the way and extent of how land use changes across different time scales affect flooding periods are still unclear, especially considering the historical land use changes. This study uses the Landlab landscape evolution model, coupled with an evapotranspiration model, to investigate the forcing factors for the paleo-flooding trends in the Wei River catchment over the last 5000 years. The results indicate that the flooding period from 4400 to 4000 BP was caused by an increase of 28 % in antecedent moisture content as well as a decrease of 28 % in its spatial variability, which are primarily due to climate change, and that the contribution of land-use change is less than 5 %. The increases of about 14 % and 8 % in main channel sedimentation rate play a leading role in flood generation during the time periods from 3400 to 2800 BP and 2000–1400 BP, respectively. These two periods of increased flooding are primarily caused by the erosional effects of increasing anthropogenic land use, whose contributions range from 33 % to 64 %. Furthermore, based on our modelling results, we suggest that the downstream propagation of the main flooding locations, from the Wei River to the lower reaches of the Yellow River, can be explained by the downstream migrating sediment wave. In conclusion, our simulation results give new insights into the causes of Holocene flooding periods in the middle Yellow River from the perspective of dynamic changes in catchment characteristics, which is helpful to improve regional flood risk management under future climate change and anthropogenic activities.

Evaluating net primary productivity dynamics and their response to land-use change in the loess plateau after the 'Grain for Green' program

Assessing net primary productivity (NPP) dynamics and the contribution of land-use change (LUC) to NPP can help guide scientific policy to better restore and control the ecological environment. Since 1999, the “Green for Grain” Program (GGP) has strongly affected the spatial and temporal pattern of NPP on the Loess Plateau (LP); however, the multifaceted impact of phased vegetation engineering measures on NPP dynamics remains unclear. In this study, the Carnegie-Ames-Stanford Approach (CASA) model was used to simulate NPP dynamics and quantify the relative contributions of LUC and climate change (CC) to NPP under two different scenarios. The results showed that the average NPP on the LP increased from 240.7 gC·m−2 to 422.5 gC·m−2 from 2001 to 2020, with 67.43% of the areas showing a significant increasing trend. LUC was the main contributor to NPP increases during the study period, and precipitation was the most important climatic factor affecting NPP dynamics. The cumulative amount of NPP change caused by LUC (ΔNPPLUC) showed a fluctuating growth trend (from 46.23 gC·m−2 to 127.25 gC·m−2), with a higher growth rate in period ΙΙ (2010–2020) than in period Ι (2001–2010), which may be related to the accumulation of vegetation biomass and the delayed effect of the GGP on NPP. The contribution rate of LUC to increased NPP in periods Ι and ΙΙ was 101.2% and 51.2%, respectively. Regarding the transformation mode, the transformation of grassland to forest had the greatest influence on ΔNPPLUC. Regarding land-use type, the increased efficiency of NPP was improved in cropland, grassland, and forest. This study provides a scientific basis for the scientific management and development of vegetation engineering measures and regional sustainable development.

Optimal options of ecological restoration patterns in semi-arid regions: Lessons learned from two-decade ecological restoration projects in Bashang Plateau of China

ABSTRACT In responding to global ecosystem conservation and sustainable social development, numerous ecological restoration projects have been performed in ecologically vulnerable areas around the world, especially in semi-arid areas. Affected by local hydrothermal conditions, whether ecological restoration projects can achieve goals of balanced water-carbon enhancement as well as sustainable development in semi-arid areas is controversial. It is uncertain that to what extent the land use change caused by ecological restoration projects will affect the water-carbon imbalance. This research takes the Bashang Plateau Protection Zone (BPZ), a typical semi-arid area in Hebei Province of China, as a porotype to discover the spatial water-carbon changes and their contributing factors under ecological projects during 2000 to 2020 through root mean square deviation and random forest analysis. Results show: (1) In the past two decades, carbon sequestration in BPZ continued to improve while water conservation decreased significantly. The water-carbon imbalance regions in BPZ increased nearly 6.80 folds, from 338.60 km2 to 2642.38 km2. (2) Precipitation and temperature exerted the most significant impact on the formation of water-carbon imbalance regions, whereas the contribution of land use change could reach 40%, demonstrating that human activities were also strongly responsible for water-carbon imbalance. (3) Ecological restoration pattern of limiting afforestation and agricultural land expansion with priority restoration of grassland is beneficial to achieving water-carbon balance and sustainable goals of ecological restoration in semi-arid regions.

Contribution of Land Use Change and Land Cover to Climate Change Coastal Areas and Their Impacts: Evidence in Jayapura City, Papua Province, Indonesia

Contribution of Land Use Change and Land Cover to Climate Change Coastal Areas and Their Impacts: Evidence in Jayapura City, Papua Province, Indonesia

Impact of Climate-Driven Land-Use Change on O3 and PM Pollution by Driving BVOC Emissions in China in 2050

This study predicted three future land-use type scenarios in 2050 (including the Shared Socioeconomic Pathway SSP126, SSP585, and carbon scenario) based on the Land-Use Harmonization (LUH2) project and the future evolution of land-use types considering China’s carbon neutrality background. The contribution of land-use changes to terrestrial natural source biogenic volatile organic compounds (BVOCs), as well as O3 and PM concentrations, were determined. Under the SSP126 pathway, meteorological changes would increase BVOC emissions in China by 1.0 TgC in 2050, compared with 2015, while land-use changes would increase them by 1.5–7.1 TgC. The impact of land-use changes on O3 and PM concentrations would be less than 3.6% in 2050 and greater in summer. Regional differences must be considered when calculating future environmental background concentrations of pollutants. Due to more afforestation measures under the SSP126 scenario, the impact of land-use change on pollutants was more obvious under the SSP126 pathway than under the SSP585 pathway. Under the carbon scenario, the increase in PM concentration caused by land-use changes would pose a risk to air quality compliance; thus, it is necessary to consider reducing or offsetting this potential risk through anthropogenic emission control measures.

The contribution of forest and grassland change was greater than that of cropland in human-induced vegetation greening in China, especially in regions with high climate variability

Vegetation growth is strongly affected by both human activities and climate change. The contribution of land use change caused by human activities to vegetation growth may correlate with climate change, whereas climate variability has often been overlooked. To quantify vegetation growth during 1982–2017 in China, we used the Leaf Area Index (LAI). We also introduced climate variability to divide climate regimes using assignment entropy and built a relative greening performance indicator to identify the contribution of land use (forest, grassland, and cropland) changes to vegetation growth. The results showed that climate variability increased based on precipitation classification, and the regions with low and high climate variability accounted for 33.38%–34.41% and 12.18%–32.38% of China before and after 2000, respectively. Areas of vegetation growth affected by human activities accounted for 7.71%–19.31% and were located mainly in low variability regimes. The contribution of forest and grassland change was greater than that of cropland to vegetation greening in China, especially in high variability regimes. However, the contribution of cropland change was greater than that of forest and grassland in low variability regimes. These results imply the importance of forest and grassland change in human-induced vegetation greening, and this information can provide guidance for regional ecosystem management.

Quantifying relative contribution of land use change and climate change to streamflow alteration in the Bengawan Solo River, Indonesia

ABSTRACT This study investigated the influence of land use change and climate change on changes in streamflow in the Bengawan Solo River (BSR, 16 389 km2) basin, Indonesia. We applied the excess water and energy approach to three tributaries of the BSR, namely Pidekso, Madiun and Kening rivers, which represent the up-, mid-, and downstream parts of the BSR, respectively. This study used hydrological data from 1982−2013 and land use data for the years 1994 and 2013. The results show that from 1982 to 2013, the annual streamflow of the Pidekso and Madiun River increased, while in the Kening River it decreased. Based on attribution measures, the increasing streamflow trend in the Pidekso and Madiun rivers is mainly attributed to land use change, while the decreasing streamflow trend in the Kening River is mainly attributed to climate change. These conclusions are supported by statistical analyses and land use change analysis.

Quantitatively distinguishing the impact of climate change and human activities on vegetation in mainland China with the improved residual method

ABSTRACT In recent decades, vegetation has faced the dual challenges posed by climate change and human activities. Quantitatively distinguishing the influences of climate change and human activities on vegetation changes is key to developing adaptive ecological protection policies. This study examined changes in temperature and precipitation to determine if anthropogenic land use changes have affected vegetation in mainland China. The contribution rates of temperature and precipitation changes and land use changes to vegetation dynamics are further calculated by the improved residual trend method, which considers the nonlinear relationship between vegetation and climate factors and time-lag effects from a spatiotemporal perspective and sets the base period for the equation. The results show that 68.81% of the vegetation in mainland China is in a state of sustained growth, where cultivated vegetation and grasses are the main greening vegetation types. The contribution of land use changes to vegetation changes in mainland China is higher than that of temperature and precipitation changes. Planting trees and grasses and returning farmlands to forests and grassland has increased the area covered by grasses and mixed coniferous broad-leaved forests, while cultivated vegetation coverage has decreased. Swamps are more sensitive to temperature and precipitation changes. We show that the improved residual trend method that considers temporal and spatial dimensions can reduce the uncertainty in quantifying the effects of climatic and anthropogenic factors on vegetation dynamics. This study provides a theoretical basis and a useful tool for future governmental implementation of ecological management strategies.

Quantitative analysis of the contributions of land use change and CO2 fertilization to carbon use efficiency on the Tibetan Plateau

Carbon use efficiency (CUE) is a key element in the vegetation carbon cycle, and determines how vegetation allocates carbon. Here, our research provides the spatio-temporal variations of CUE on the Tibetan Plateau (TP) based on ensemble simulations from 12 terrestrial ecosystem models. Moreover, the experimental design of simulations adds one time-varying driver at a time, thus quantitative analysis of the response of CUE to climate factors (i.e., temperature, precipitation and radiation), land use and land cover change (LULCC), and CO2 fertilization can be investigated. Results show that average CUE value of the multi-model simulations (0.583 ± 0.064) on the TP is slightly lower than that derived from the satellite-based product, the Moderate Resolution Imaging Spectroradiometer (0.646). However, CUE varies greatly among models due to differences in simulating plant photosynthetic productivity and respiratory rate, with range of 0.489–0.661. LULCC and CO2 fertilization contribute 4.24% and 0.79% of the annual mean CUE, respectively. Among the climatic factors, temperature and precipitation have positive correlations with CUE over most areas of the TP while solar radiation shows a negative impact.

Evaluations of water yield and soil erosion in the Shaanxi-Gansu Loess Plateau under different land use and climate change scenarios

More water yield and less soil erosion are crucial to the sustainable development of the Loess Plateau and Yellow River basin. Different land use policies and climate change scenarios may have great implications on water yield and soil erosion. In this paper, four land development scenarios and two climate change scenarios are designed and applied to the Shaanxi-Gansu Loess Plateau. The InVEST model is applied to quantitatively evaluate the water yield and soil erosion modulus in 2030. It showed: (1) Arable land and grassland is always the dominant land types in the Shaanxi-Gansu Loess Plateau and cover more than 76% of the area. The business-as-usual and ecological protection priority scenarios may lead to increases in the local food security risks, with 1.9% and 1.4% gaps in the total food requirements. (2) Under the RCP2.6 scenario, the annual water yield and annual soil erosion amount increased by more than 63% (2.84*109 m3) and 22% (96.0*106 t), respectively. Under the RCP4.5 scenario, the annual water yield and annual soil erosion decreased by more than 48% (2.17*109 m3) and 26% (114.3*106 t), respectively. (3) The influence of climate change on water yield and soil erosion is far greater than that of land use change. The contribution of climate change to the water yield changes is 92.8–99.6%, while the contribution of land use change is 0.4–7.2%. The contribution rate of climate change to soil erosion changes is 84.8–91.1%, while the contribution rate of land use change is 8.9–15.2%. The key ecological services, such as food production, water yield, soil and water conservation, should be carefully weighed and coordinated in the Loess Plateau and areas with limited land surfaces, such as small island development states.

Impact of land use and land cover changes on temperature trends over India

This study estimates the temperature trends over India and seeks to understand the contribution of land use and land cover (LULC) changes towards the change in the temperature trends (warming or cooling) during 1981–2006 by using ‘Observation minus Reanalysis’ (OMR) method. We find that the India got warmer by 0.1 °C per decade during 1981–2006 and the LULC changes contributed to cooling over India by 0.02 °C per decade during this period. The contribution of land use changes to the temperature trends depends on the type of LULC and their conversion from one type to another. With the exception of dense forest, all land cover conversions to agriculture lead to cooling whereas conversion from dense forest to agriculture results in warming. The contribution of LULC changes towards cooling over India during 1981–2006 is due to the reduction of area under shrubs/ small vegetation and subsequent increase of the area under agricultural/ fallow land. The analysis shows that even though the LULC changes contributed towards overall cooling during 1981–2006 over India, it contributed towards warming during 1991–2006. We find that the cooling caused by LULC changes during 1981–2006 is due to the cooling contributed during 1981–1990. Our overall results have implications for future land use change strategies that can be undertaken over India in order to avoid further worsening the Indian climate.

Effects of the Land Use and Check Dams on Flood in Upper Catchment of Fuping Hydrological Station by Hydrological Modeling

Flood peaks and volumes had been detected a downward trend in Fuping hydrological station. To quantify the effects of check dams on flood peaks and volumes, a hydrological model integrating land use was established. The model performed well in flood processes simulation, and the Nash efficiency of the model was 0.72. Then the model was used to identify the comprehensive effects of land use and land cover change on flood processes by comparing the simulation results of the selected flood events under 1980 and 2000 land use and land cover conditions. 24.5, 37.7 and 51.3% decrease in flood peaks for flood events of greater than 10 years, 5~10 years and less than 5 years return periods, respectively, and 16.3, 27.9 and 28.5% decrease in flood volumes for the three groups flood events of different return periods. Contributions of land use change and check dams to decrease in flood peak and volume were simulated, and it was found that peak discharge and volume for each flood event responded differently to the two factors. The results in this study can provide valuable information on design flood calculation in the basin under land use and land cover change.

Novel 3D geometry and models of the lower regions of large trees for use in carbon accounting of primary forests.

There is high uncertainty in the contribution of land-use change to anthropogenic climate change, especially pertaining to below-ground carbon loss resulting from conversion of primary-to-secondary forest. Soil organic carbon (SOC) and coarse roots are concentrated close to tree trunks, a region usually unmeasured during soil carbon sampling. Soil carbon estimates and their variation with land-use change have not been correspondingly adjusted. Our aim was to deduce allometric equations that will allow improvement of SOC estimates and tree trunk carbon estimates, for primary forest stands that include large trees in rugged terrain. Terrestrial digital photography, photogrammetry and GIS software were used to produce 3D models of the buttresses, roots and humus mounds of large trees in primary forests dominated by Eucalyptus regnans in Tasmania. Models of 29, in situ eucalypts were made and analysed. 3D models of example eucalypt roots, logging debris, rainforest tree species, fallen trees, branches, root and trunk slices, and soil profiles were also derived. Measurements in 2D, from earlier work, of three buttress 'logs' were added to the data set. The 3D models had high spatial resolution. The modelling allowed checking and correction of field measurements. Tree anatomical detail was formulated, such as buttress shape, humus volume, root volume in the under-sampled zone and trunk hollow area. The allometric relationships developed link diameter at breast height and ground slope, to SOC and tree trunk carbon, the latter including a correction for senescence. These formulae can be applied to stand-level carbon accounting. The formulae allow the typically measured, inter-tree SOC to be corrected for not sampling near large trees. The 3D models developed are irreplaceable, being for increasingly rare, large trees, and they could be useful to other scientific endeavours.

Peer review report 1 on “Relative contribution of land use change and climate variability on discharge of upper Mara River, Kenya”

Peer review report 1 on “Relative contribution of land use change and climate variability on discharge of upper Mara River, Kenya”

Understanding the impacts of climate change and human activities on streamflow: a case study of the Soan River basin, Pakistan

Climate change and land use change are the two main factors that can alter the catchment hydrological process. The objective of this study is to evaluate the relative contribution of climate change and land use change to runoff change of the Soan River basin. The Mann-Kendal and the Pettit tests are used to find out the trends and change point in hydroclimatic variables during the period 1983–2012. Two different approaches including the abcd hydrological model and the Budyko framework are then used to quantify the impact of climate change and land use change on streamflow. The results from both methods are consistent and show that annual runoff has significantly decreased with a change point around 1997. The decrease in precipitation and increases in potential evapotranspiration contribute 68% of the detected change while the rest of the detected change is due to land use change. The land use change acquired from Landsat shows that during post-change period, the agriculture has increased in the Soan basin, which is in line with the positive contribution of land use change to runoff decrease. This study concludes that aforementioned methods performed well in quantifying the relative contribution of land use change and climate change to runoff change.

Modeling the Relative Contributions of Land Use Change and Harvest to Forest Landscape Change in the Taihe County, China

Forests are under pressure from land use change due to anthropogenic activities. Land use change and harvest are the main disturbances of forest landscape changes. Few studies have focused on the relative contributions of different disturbances. In this study, we used the CA-Markov model, a land-use change model, coupled with a forest landscape model, LANDIS-II, to simulate dynamic change in Taihe County, China, from 2010 to 2050. Scenarios analysis was conducted to quantify the relative contributions of land use change and harvest. Our results show that forestland and arable land will remain the primary land-use types in 2050, whereas the built-up land will sprawl drastically. Land use change and harvest may result in the significant loss of forest area and changes in landscape structure. The simulated forest area will increase by 16.2% under the no disturbance scenario. However, under harvest, forest conversion, and integrated scenario, the area will be reduced by 5.2%, 16.5%, and 34.9%, respectively. The effect of harvest is gradually enhanced. The land use change will account for 60% and harvest will account for 40% of forest landscape change in 2050, respectively. Our results may benefit from the integration of regional forest management and land-use policy-making, and help to achieve a trade-off between economy and ecological environment.

Quantifying the contribution of land use change to surface temperature in the lower reaches of the Yangtze River

Abstract. Anthropogenic land use has a significant impact on climate change. Located in the typical East Asian monsoon region, the land–atmosphere interaction in the lower reaches of the Yangtze River is even more complicated due to intensive human activities and different types of land use in this region. To better understand these effects on microclimate change, we compare differences in land surface temperature (Ts) for three land types around Nanjing from March to August, 2013, and then quantify the contribution of land surface factors to these differences (ΔTs) by considering the effects of surface albedo, roughness length, and evaporation. The atmospheric background contribution to ΔTs is also considered based on differences in air temperature (ΔTa). It is found that the cropland cooling effect decreases Ts by 1.76° and the urban heat island effect increases Ts by 1.25°. They have opposite impacts but are both significant in this region. Various changes in surface factors affect radiation and energy distribution and eventually modify Ts. It is the evaporative cooling effect that plays the most important role in this region and accounts for 1.40° of the crop cooling and 2.29° of the urban warming. Moreover, the background atmospheric circulation is also an indispensable part in land–atmosphere feedback induced by land use change and reinforces both these effects.

Projecting regional climate and cropland changes using a linked biogeophysical‐socioeconomic modeling framework: 1. Model description and an equilibrium application over West Africa

AbstractAgricultural land use alters regional climate through modifying the surface mass, energy, and momentum fluxes; climate influences agricultural land use through their impact on crop yields. These interactions are not well understood and have not been adequately considered in climate projections. This study tackles the critical linkages within the coupled natural‐human system of West Africa in a changing climate based on an equilibrium application of a modeling framework that asynchronously couples models of regional climate, crop yield, multimarket agricultural economics, and cropland expansion. Using this regional modeling framework driven with two global climate models, we assess the contributions of land use change (LUC) and greenhouse gas (GHGs) concentration changes to regional climate changes and assess the contribution of climate change and socioeconomic factors to agricultural land use changes. For future cropland expansion in West Africa, our results suggest that socioeconomic development would be the dominant driver in the east (where current cropland coverage is already high) and climate changes would be the primary driver in the west (where future yield drop is severe). For future climate, it is found that agricultural expansion would cause a dry signal in the west and a wet signal in the east downwind, with an east‐west contrast similar to the GHG‐induced changes. Over a substantial portion of West Africa, the strength of the LUC‐induced climate signals is comparable to the GHG‐induced changes. Uncertainties originating from the driving global models are small; human decision making related to land use and international trade is a major source of uncertainty.

Peer review report 1 On “Relative contribution of land use change and climate variability on discharge of upper Mara River, Kenya”

Peer review report 1 On “Relative contribution of land use change and climate variability on discharge of upper Mara River, Kenya”

Impacts of land use change and climate variations on annual inflow into the Miyun Reservoir, Beijing, China

Abstract. The Miyun Reservoir, the only surface water source for Beijing city, has experienced water supply decline in recent decades. Previous studies suggest that both land use change and climate contribute to the changes of water supply in this critical watershed. However, the specific causes of the decline in the Miyun Reservoir are debatable under a non-stationary climate in the past 4 decades. The central objective of this study was to quantify the separate and collective contributions of land use change and climate variability to the decreasing inflow into the Miyun Reservoir during 1961–2008. Different from previous studies on this watershed, we used a comprehensive approach to quantify the timing of changes in hydrology and associated environmental variables using the long-term historical hydrometeorology and remote-sensing-based land use records. To effectively quantify the different impacts of the climate variation and land use change on streamflow during different sub-periods, an annual water balance model (AWB), the climate elasticity model (CEM), and a rainfall–runoff model (RRM) were employed to conduct attribution analysis synthetically. We found a significant (p < 0.01) decrease in annual streamflow, a significant positive trend in annual potential evapotranspiration (p < 0.01), and an insignificant (p > 0.1) negative trend in annual precipitation during 1961–2008. We identified two streamflow breakpoints, 1983 and 1999, by the sequential Mann–Kendall test and double-mass curve. Climate variability alone did not explain the decrease in inflow to the Miyun Reservoir. Reduction of water yield was closely related to increase in actual evapotranspiration due to the expansion of forestland and reduction in cropland and grassland, and was likely exacerbated by increased water consumption for domestic and industrial uses in the basin. The contribution to the observed streamflow decline from land use change fell from 64–92 % during 1984–1999 to 36–58 % during 2000–2008, whereas the contribution from climate variation climbed from 8–36 % during the 1984–1999 to 42–64 % during 2000–2008. Model uncertainty analysis further demonstrated that climate warming played a dominant role in streamflow reduction in the most recent decade (i.e., 2000s). We conclude that future climate change and variability will further challenge the water supply capacity of the Miyun Reservoir to meet water demand. A comprehensive watershed management strategy needs to consider the climate variations besides vegetation management in the study basin.