Changes In Land Use Types Research Articles

Quantifying the Speed, Landscape Pattern Changes and Its Driving Factors of Shenzhen China

Urban expansion has always been a topic of great concern. The purpose of this study is to explore land use change and the types of urban expansion in Shenzhen from 1995 to 2015, and to indicate the driving factors of this change, so as to provide a paradigm for other similar studies. By analysing the landscape expansion index and the correlation coefficient between urban area and various factors in Shenzhen, the following conclusions are obtained: 1) The main changes of land use types are the decrease of cultivated land and the increase of urban land. The land cover type changed most dramatically from 2000 to 2005, and the urban land transformed from cultivated land and grassland occupied most of the area. 2) Analysis shows that during the 20 years from 1995 to 2015, the main expansion type is edge-expansion. In detail, during the period from 1995 to 2010, the proportion of infilling has been increasing, while that of the outlying has been decreasing. After 2010, the urban area of Shenzhen increased slightly. Besides, according to the landscape expansion index, Shenzhen experienced dramatic urban expansion from 2000 to 2005. 3) Education and population growth are the main factors of urban growth in Shenzhen, which is reflected in the strongest correlation between university enrolment rate and urban area.

Evapotranspiration estimation using three-temperature model and influencing factors of Nanning City, China

Evapotranspiration is the key element of hydrological energy cycle and climate system. It is of great significance to estimate the spatiotemporal variation of evapotranspiration and its response to climate and land use changes for understanding the effects of water cycle and ecological processes in urban basins. Based on the three-temperature model and MODIS Image, we estimated and analyzed the spatiotemporal variation of evapotranspiration in Nanning City from 2001 to 2018, and examined the influence and driving mode of main climate factors and land use types on evapotranspiration. The results showed that the annual average evapotranspiration of Nanning City ranged from 495.7 to 781.1 mm during 2001-2018, with the inter annual relative variability ranging from -22.5% to 23.1%, showing an overall upward trend. The regional evapotranspiration showed a distribution pattern of high north-south and low middle, with the urban evapotranspiration being significantly lower than suburban area. The evapotranspiration had a significant multiple correlation with climate factors. The influence of temperature on the evapotranspiration was stronger than precipita-tion. Evapotranspiration was temperature driven in suburbs, but was driven by multiple factors in urban area. The average evapotranspiration of different land use types in Nanning was forests (823.4 mm) > grasslands (675.6 mm) > croplands (582.9 mm) > urban area (346.6 mm). The change of land use type was the main underlying surface factor leading to the significant change of regional evapotranspiration.

南水北调中线工程途经区生态服务价值的时空变化

南水北调中线工程是我国迄今为止最重要的跨流域调水工程，为沿线二十四个大中城市提供了紧缺的生产和生活用水。但是，迄今为止人们对调水影响下南水北调中线工程途径区生态服务价值的动态变化过程所知甚少，阻碍了人们对该工程生态效益的科学评估与沿线土地资源的合理利用。南水北调中线工程建成前后的生态服务价值变化研究有助于沿线土地的合理规划和科学利用。为此，首先基于改进的当量因子法分析了2000、2005、2010、2015、2018年研究区生态服务的静态价值时空变化，然后利用优先指数重构了研究区生态服务的动态价值并探讨了其时空演变的特征。结果表明：① 2000—2018年，研究区生态服务的总价值先减后增，2018年达到峰值。研究区生态服务价值的增长在一定程度上归因于南水北调中线工程的影响。② 研究区水文调节功能价值占总价值的比例最高，约占30%，养分循环功能的价值占比最低，约为1%；各年份林地、草地、耕地和水体均为研究区生态服务总价值的主要构成部分。③ 2000—2018年，研究区生态服务价值空间分布存在明显差异，自西部向东部递减，调水后北京市和天津市的高值区增加。④ 研究区生态服务的动态总价值（1.38×10¹²元）只有静态总价值（2.58×10¹²元）的一半，主要是由于动态与静态生态服务的价值系数差别较大。因此，应重视土地利用类型变化和薄弱生态服务功能对生态服务总价值的影响，优化土地利用结构，对南水北调中线工程沿线周边开展针对性保护，以稳步提升整个区域生态服务的总价值。;The Middle Route of the South-to-North Water Diversion Project (MRSNWDP) is the most important inter-basin water diversion project in China so far, and provides the scarce production and domestic water for 24 large and medium-sized cities along the route. However, the dynamic change process of the ecosystem service value of the project was studied so inadequate that hindered the scientific evaluation of the project ecological benefits and the rational use of land resources. The study on changes in the value of ecological services before and after the completion of the MRSNWDP is helpful to the rational planning and scientific use of land along the route. This paper analyzed the temporal and spatial changes of the static value of ecological services of the project in 2000, 2005, 2010, 2015 and 2018 based on the improved equivalent factor method, and then reconstructed the dynamic value of its ecological services with the priority index, and discussed its temporal and spatial evolution characteristics. The results showed that:① from 2000 to 2018, the total value of ecological services in the study area first decreased and then increased, and reaching its peak in 2018. The increase in the value of ecological services in the study area can be attributed to the impact of the MRSNWDP to a certain extent. ② The value of the hydrological regulation function was the highest, accounting for 30% of the total value, and that of the nutrient cycle function was the lowest, accounting for only 1%. The forest land, grassland, cultivated land and water body were the main components of the total value of ecological services in the study area in each year. ③ The spatial distribution of ecological service values in the study area was significantly different from 2000 to 2018, which decreased from the west to the east. The high-value areas in Beijing and Tianjin increased after water diversion. ④ The total dynamic value of ecological services in the study area was 1.38×10¹² Yuan, which was lower than the static total value of 2.58×10¹² Yuan, due to the value coefficient of dynamic and static ecological services is quite different. Therefore, we should pay attention to the impact of changes in land use types and weak ecological service functions on the total value of ecological services, optimize the structure of land use, and carry out targeted protections along the MRSNWDP to steadily improve the total value of ecological services in the entire region.

喀斯特山区土地利用方式转变对土壤酶活性及其化学计量特征的影响

土地利用变化引起的土壤理化性质改变会显著影响土壤碳氮磷养分含量及其化学计量特征，然而由于不同研究区域环境异性较大，土壤胞外酶活性及其化学计量特征与各土壤因子间的协同变化规律仍不明确。以喀斯特山区7种典型土地利用方式（马尾松林地、柏树林地、灌木林地、梯田菜地、梯田撂荒地、坡面撂荒地和坡耕地）为研究对象，采用时空互代法研究土地利用方式转变过程中6种土壤胞外酶活性（β-1，4-葡萄糖苷酶、β-1，4-木糖苷酶、纤维素二糖水解酶、β-1，4-N-乙酰葡萄糖苷酶、亮氨酸氨基肽酶和酸性磷酸酶）及其化学计量特征的变化规律，并分析它们与土壤理化因子之间的关系。结果表明坡耕地转变土地利用方式后，土壤养分状况和酶活性得到明显改善，并且土壤微生物通过调节酶的表达和活性提高了磷素的有效性，促进了土壤养分的平衡。总体来看，坡耕地转马尾松和柏树林地后土壤质量改善的效果更加显著，但加剧了土壤磷素的限制。此外，土壤全氮含量、C∶N、N∶P和pH是土壤酶活性变化的主要驱动因素，土壤酶活性与养分含量具有趋同性且受土壤pH的调控。因此，喀斯特地区马尾松和柏树人工林的经营管理过程中应考虑磷素的投入以缓解人工林生态系统的磷限制。;Changes of soil physicochemical properties caused by land use conversion will significantly affect the content of nutrients (carbon, nitrogen and phosphorus) in soil and its stoichiometric characteristics. However, it is still unclear about the synergistic change between soil extracellular enzyme activity as well as its stoichiometric characteristics and soil factors due to the large environmental difference in different study areas. In this study, 7 kinds of typical land use types (Pinus massoniana land, Platycladus orientalis land, shrub land, terrace of vegetable field, terrace of abandoned land, sloped abandoned land, and sloped farmland) were selected as research objects in karst mountainous area. Taking the existing sloped farmland as the reference substance, the variation of 6 kinds of extracellular enzyme activity and its stoichiometric characteristics (β-1,4-glucosidase, cellobiohydrolase, β-1,4-xylosidase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase and acid phosphatase) were compared before and after the change of land use types using the spatio-temporal contrast method, and the relationship between them and soil physical and chemical factors were also analyzed. The results showed that soil nutrient status and enzyme activity were significantly improved after the conversion of land use type from sloped farmland to other, which not only significantly increased the nutrient content but also promoted the soil nutrient balance, because soil microorganism regulated the expression and activity of enzymes and the availability of phosphorus was greatly improved. In general, land use conversion from the sloped farmland to Pinus massoniana land and Platycladus orientalis land showed similar and best effect of soil quality improvement, whereas it also increased the restriction of soil phosphorus. In addition, soil total nitrogen content, C:N, N:P and pH value were the main factors driving the change of soil extracellular enzyme activity. The change of soil enzyme activity was consistent with that of nutrient content, and was regulated by the power of hydrogen. Therefore, the phosphorus input should be considered in the management of Pinus massoniana and Platycladus orientalis forest land in karst areas for alleviating the phosphorus restriction of artificial forest ecosystem.

街区尺度城市内部动态度的量化——以深圳市为例

城市动态度反应城市土地利用/土地覆盖动态变化的剧烈程度，对其进行量化是理解城市景观变化和进行城市生态空间监管的基础。现有研究主要聚焦城市扩张引起的特定地类（如人工表面、植被等）的动态变化，缺乏对城市内部精细尺度上（如街区尺度）景观动态的研究。以深圳市为例，首先利用多等级道路数据划分街区，进而基于高分辨率卫星影像解译的土地覆盖数据，利用土地利用动态度和土地利用强度指数量化街区尺度城市内部动态度。研究结果表明：（1）深圳市城市内部动态度较高，2017-2018年期间，14.93%的街区发生了不同程度的变化，热点区域主要分布在南山区、宝安区、盐田区等。（2）街区的变化包括多种地类的转变，其中，林地转变为裸土最为常见，占比为12.59%。由城市更新引起的地类变化也较普遍，如其他不透水地表向裸土的转移和建筑到裸地的转变分别为6.20%、5.59%。此外，深圳市街区的土地利用强度也存在较大差异，表现为土地利用强度增加的街区多分布在城市外围，而土地利用强度降低的街区则多分布在城市内部。（3）街区动态度与街区大小之间呈现非线性关系，街区动态度随着街区面积的增大，先急剧下降，后趋于平缓。本研究揭示了深圳市城市内部街区尺度上土地覆盖的动态变化特征，可为城市规划和生态空间管理提供科学支撑。;Urban landscapes are highly dynamic. Understanding the within-city dynamics in land cover and land use is important. Previous studies have largely focused on the changes of specific land use type (impervious surface, urban vegetation etc.) resulted from urban sprawl on large or medium scales. However, research on quantifying the urban dynamics on block scale is lacking. Taking Shenzhen as a case study area, this paper aims to use the land cover thematic maps interpreted from very high-resolution remote sensing images to quantify the urban dynamics within city at street block level. The results showed that: (1) there was high dynamics at street block level in Shenzhen, which was manifested as that the blocks with dynamic changes account for 14.93%. The hotspots of degree of urban dynamics were distributed in Nanshan, Baoan and Yantian district. (2) The contribution of dynamic changes (CDC) was significantly different between different land use changes on block scale. For all blocks, the CDC of change from woodland to bare soil was the highest (12.59%). In addition, CDC of land use and land cover changes which mainly resulted from urban renewal was high. For example, CDC of changes from other impervious surface and building to bare soil were 6.20% and 5.59%, respectively. In addition, the land use intensity of different block was obviously different. The blocks with increased land-use intensity were mostly distributed in the periphery of the city, while the blocks with decreased land-use intensity were mostly distributed in the interior of the city. (3) The relationship between dynamics of block and block size was nonlinear. With the block size increasing, the dynamics of block decreased sharply and then the decreasing trend became flat. Our study revealed the characteristics of the land use dynamics at street block level in Shenzhen, and it would provide a reference for urban planning and ecological space management.

基于InVEST模型的金沙江流域干热河谷区水源涵养功能评估

以金沙江流域干热河谷区1990年、2000年、2010年和2019年4期Landsat遥感影像为基础数据，通过目视解译和最大似然相结合的方法进行土地利用类型分类，定量分析金沙江流域干热河谷区土地利用类型的时间变化与空间转移过程；采用InVEST模型，结合气象、土壤和地形等数据评估了1990-2019年金沙江流域干热河谷区及不同土地利用类型的产水功能和水源涵养功能。结果表明：1）1990-2019年金沙江流域干热河谷区土地利用类型以草地、乔木林地和耕地为主；近30年来，灌木林地、建设用地、交通运输用地和水域的面积不断增加，建设用地面积增幅最大；草地、乔木林地、耕地和裸地面积均减少。2）1990-2019年，建设用地、灌木林地、交通运输用地和水域面积的增加来源于草地、耕地和乔木林地。3）金沙江流域干热河谷区多年平均产水量为26.09×10⁸ m³，水源涵养量为7.26×10⁸ m³，产水量的变化与分布直接影响着区域的水源含养量；平均水源涵养能力68.74 mm，呈现上升-下降-上升的波动变化趋势。4）1990-2019年不同土地利用类型的水源涵养量变化明显，不同地类平均水源涵养量的大小依次为耕地 > 草地 > 建设用地 > 乔木林地 > 交通运输用地 > 灌木林地 > 裸地 > 水域。;Using Landsat remote sensing images in 1990, 2000, 2010 and 2019, land use types in the dry-hot valley area of Jinsha River Basin are classified by combining visual interpretation with maximum likelihood, and the spatiotemporal change and transfer process of land use types in the dry-hot valley area of Jinsha River Basin are also studied. The InVEST model combining meteorological, soil and topographic data are used to evaluate the water-producing and water-conserving function of different land use types in the dry-hot valley area of Jinsha River Basin from 1990 to 2019. The main conclusions are as follows:(1) from 1990 to 2019, grassland, forestland and cultivated land were the main types of land use in the dry-hot valley area of Jinsha River Basin. In the past 30 years, the area of shrubland, construction land, transportation land and water area has been increasing continuously and the area of grassland, forestland, cultivated land and bareland has been decreased. (2) The area increase in construction land, shrubland, transportation land and water area came from grassland, farmland and forestland from 1990 to 2019. (3) In the dry-hot valley area of Jinsha River Basin, the annual average water yield was 26.09×10⁸ m³, the water conservation amount was 7.26×10⁸ m³, and the average water conservation capacity was 68.74 mm showing a fluctuation of up-down-up. (4) From 1990 to 2019, the water conservation amount of different land use types changed significantly, and the average water conservation amount of different land types was from large to small:farmland > grassland > construction land > forestland > transportation land > shrubland > bareland > water area.

基于野外观测检验动物廊道选址模型的准确性——以白头叶猴为例

廊道构建是减少栖息地破碎化负面影响的重要策略之一。目前，已经有许多模型用于动物廊道的选址，而"选址模型是否能准确预测动物迁移的实际发生位置"一直是保护生物学最为关注的问题。最小成本路径模型（LCP）和条件最小成本廊道模型（CMTC）是两种较为常用的廊道选址模型。以白头叶猴（Trachypithecus leucocephalus）为目标物种，分别运用LCP和CMTC模拟生成白头叶猴迁移廊道，将模拟结果与野外观测廊道进行对比，检验两种方法的准确性。结果表明：与野外观测实际廊道相比，LCP模型模拟结果的完全准确率为46.7%，部分准确率为20%，完全不准确率为33.3%；CMTC模型模拟结果的完全准确率为26.7%，其余73.3%为部分准确，无完全不准确的结果；总体上看，CMTC廊道的准确率较LCP高，因而CMTC模型模拟白头叶猴实际迁移廊道位置的准确性优于LCP模型。输入"源"要素类型、阻力面栅格尺度设定、栖息地土地利用类型变化以及动物迁移行为复杂性4个因素是影响该模拟结果准确性的主要原因。;Habitat fragmentation is a hot issue of global biodiversity conservation, and corridor construction is one of the important strategies to reduce the negative impact of habitat fragmentation. To date, many models have been used for the prediction location of animal corridors, one key concern from conservation biologist is whether these models can accurately predict actual dispersal paths of target species. In this work, the white-headed langur (Trachypithecus leucocephalus), an unique endangered primate to Guangxi, China, was chosen as target species, it inhabits karstic rocky mountain areas, where is facing severe fragmentation problems due to increased human disturbance. During the last century, this species experienced a severe population declines, with an estimated 80% contraction in its distribution and a 60% reduction in its total population. They are now only distributed in small isolated habitat patches with limited opportunities to exchange gene among populations. The corridors can help this species disperse from one patch to another, and the connectivity of isolated patches is enhanced consequently. Least Cost Path (LCP) model and Conditional Minimum Transit Cost (CMTC) model are two commonly used corridor site selection models, whereas their outputs have never been validated using the actual observations data. For this purpose, LCP model and CMTC model were used to simulate the dispersal corridors of T. leucocephalus, respectively, and the simulation results from two models were further compared with field observated data for the accuracy test of these two models. The results revealed that:The fully accuracy rate for predictions of LCP model was 46.7%, partial accuracy was 20%, the complete inaccuracy rate was 33.3%. The full accuracy rate for predictions of CMTC model was 26.7%, the remnant 73.3% were all partially accurate and there was no completely inaccurate outputs from CMTC model. In general, the accuracy rate for predictions of CMTC model was higher than the outcome of LCP model, and thus the CMTC model had better performance on prediction for corridor location of T. leucocephalus than LCP model. The type of input source feature, grid size configuration of cost surface, changes in habitat land use types and complexity of animal movement behavior were four main factors affecting the accuracy of model prediction results.

Soil fungal communities across land use types

Abstract: Land use change is one of the major causes of biodiversity loss, mostly due to habitat change and fragmentation. Belowground fungal diversity is very important in terrestrial ecosystems, however, the effect of land use change on soil fungal community is poorly understood. In this review, a total of 190 studies worldwide were analyzed. To monitor the effect of land use change, different fungal parameters such as richness, diversity, community composition, root colonization by arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi, spore density, ergosterol, and phospholipid fatty acid (PLFA) content and AM fungal glomalin related soil protein (GRSP) were studied. In general, results from analyzed studies often showed a negative response of fungal quantitative parameters after land use change from less-intensive site management to intensive site management. Land use change mostly showed significant shifts in fungal community composition. Considering land use change types, only 18 out of 91 land use change types were included in more than 10 studies, conversion of primary and secondary forest to various, more intensive land use was most often represented. All these 18 types of land use change influenced fungal community composition, however, the effects on quantitative parameters were mostly inconsistent. Current knowledge is not sufficient to conclude general land use impacts on soil fungi as the reviewed studies are fragmented and limited by the local context of land use change. Unification of the methodology, detailed descriptions of environmental factors, more reference sequences in public databases, and especially data on ecology and quantitative parameters of key fungal species would significantly improve the understanding of this issue.

Potential carbon sequestration across Szentendre Island

Land-use in Hungarian landscapes have generally seen a decrease in agricultural land and increases in uncultivated land cover and forestry. Such types of land-use change have a cumulative impact on the atmospheric carbon that can potentially be sequestered across a landscape. The transformation of natural vegetation into cultivated land-use types and cultivated into uncultivated types alter the operationality of soil carbon storage across a time scale. This study looks at the land-use change and soil carbon storage potential, as an ecosystem service, on the Szentendre Island (59 km2) in the Danube River, Hungary, in 1998 and 2018. Land-use and land-cover (LULC) and topsoil carbon storage in 1998 and 2018 were mapped with the InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) Carbon Storage and Sequestration Model. Current LULC data were matched with carbon pool data as inputs for the Carbon Model. The resulting maps present the potential carbon storage value of landuse types across the Island for 1998 and 2018. Over 20 years, Szentendre Island experienced changes in LULC; an increase in artificial surfaces, forests, and pastures, and a decrease in arable land, natural vegetation, and wetlands. Based on the land-use data, our result showed that potentially 736.97 Mg of carbon was stored in the topsoil (0–20 cm) of the Szentendre Island in 1998, compared to 737.33 Mg of carbon in 2018. In conclusion, consideration is given to the land-use change trends and the need for environmental impact assessments and programs that increase soil carbon storage for the highest level of potential carbon sequestration on Szentendre Island.

Spatial and temporal evolution of habitat quality in Fujian Province, China based on the land use change from 1980 to 2018.

Analyzing the characteristics of spatial-temporal evolution of habitat quality caused by land use change can provide a scientific basis for the coordinated development of regional ecological economy. With Fujian Province (the ecological civilization demonstration area of China) as an example,the InVEST model was used to evaluate the habitat quality based on the land use change data from 1980 to 2018. Further, the influencing factors were analyzed through Geodetector, and the spatial-temporal characteristics of habitat quality was analyzed by combining with the change of land use type. The results showed that the main land use change types included farmland translating to forest land and construction land, forest land translating to farmland, grassland and construction land, and grassland translating to forest land, which accounted for 8.4%, 14.5%, 7.6%, 17.1%, 6.4% and 31.7% of the total land use change, respectively. From 1980 to 2018, the overall habitat quality of Fujian Province was at a high level (0.6-0.8), showing a trend of habitat degradation and habitat quality reduction. The first leading factor for the spatial variation of habitat quality was the change of land use type, with the impact of socioeconomic factors on the habitat quality of coastal counties and cities being significantly higher than that of the entire region and inland counties and cities. The rapid encroachment of construction land on the surrounding forest and grassland accele-rated the degradation of habitat in coastal areas, the process of which was irreversible. The habitat degradation of central urban areas would undergo a similar process in inland area, but might be slower than coastal area in terms of speed and scale. In the long term, the speed of habitat degradation could be slowed by controlling the scale of cities, developing urban ecological greening, and buil-ding an ecological security pattern.

Climate change versus land-use change—What affects the ecosystem services more in the forest-steppe ecotone?

The Ecosystem services (ESs), which play an important role in the balance of the natural ecosystem and social-economic development, are suffering from degradation caused by human activities and climate change. However, the manner in which the ESs respond to the land use/cover changes (LUCCs) and the climatic factors respectively remain elusive, especially in the forest-steppe ecotone, which is highly sensitive to climate change and anthroponotic activities. Based on the remote sensing data and in situ meteorological data, we comprehensively modeled and compared 4 key ESs changes caused by 3 LUCC types, land-use change fraction, and climate changes through two simple comparative experiments. Our results showed that: the Grain for the Green Project improved the mean soil conservation, carbon sequestration, and water yield but reduced the sand fixation. The cropland expansion had a positive influence on the water yield and sand fixation, but it induced a decline in soil conservation and carbon sequestration. The urbanization very likely increased the water yield and decreased soil conservation, carbon sequestration, and sand fixation. The unequal change fractions of the same land-use conversion may affect the ESs differently. The ESs changes have different responses to climate change in different landscapes due to the ecological process. The water yield could be well explained by the temperature, precipitation, radiation, and wind speed. Climate change had a stronger effect on the water yield and carbon sequestration than the land use/cover changes but sand fixation and soil conservation were more likely to be affected by LUCCs. The impact of three types of land-use changes and climate change on the ecosystem services should be considered when formulating land-use policies. This paper might aid the decision-makers in achieving ESs sustainable management and develop land-use strategies in the forest-steppe ecotone.

Impacts of land use and cropland management on soil organic matter and greenhouse gas emissions in the Brazilian Cerrado

AbstractThe Brazilian Cerrado is a large and expanding agricultural frontier, representing a hotspot of land‐use change (LUC) from natural vegetation to farmland. It is known that this type of LUC impacts soil organic matter (SOM) dynamics, particularly labile carbon (C) pools (living and non‐living), decreasing soil health and agricultural sustainability, as well as increasing soil greenhouse gas (GHG) emissions, and accelerating global climate change. In this study, we quantified the changes in the quantity and quality of SOM and GHG fluxes due to changes in land use and cropland management in the Brazilian Cerrado. The land uses studied were native vegetation (NV), pasture (PA) and four croplands, including the following management types: conventional tillage with a single soybean crop (CT), and three no‐tillage systems with two crops cultivated in the same year (i.e., soybean/sorghum (NTSSo), soybean/millet (NTSMi) and maize/sorghum (NTMSo)). Soil and gases were sampled in the rainy season (November, December and January) and dry season (May, July and September). The highest soil C and nitrogen (N) stocks (6.7 kg C m−2 and 0.5 kg N m−2, 0–0.3‐m layer) were found under NV. LUC reduced C stocks by 25% in the CT and by 10% in the PA and NT. Soil N stocks were 30% lower in the PA and NTMSo and 15% lower in the croplands with soybean compared to NV. δ13C values clearly distinguished between the C‐origin from NV (−25‰) and that from other land uses (−16‰). Soil (0–0.1 m) under NV also presented higher labile‐C (625 g C m−2), microbial‐C (70 g C m−2) and microbial‐N (5.5 g N m−2), whereas other land uses presented values three times lower. GHG emissions (expressed as C‐equivalent) were highest in the NV (1.2 kg m−2 year−1), PA (1.3 kg m−2 year−1) and NTMSo (0.9 kg m−2 year−1) and were positively related to the higher SOM turnover in these systems. Our results suggest that in order to maintain SOM, it is necessary to adopt “best” management practices, that provide large plant residue inputs (above‐ and belowground). This can be seen as a pathway to achieving high food production with low GHG emissions.

Spatial Variation in Environmental Impacts of Sugarcane Expansion in Brazil

In the past decades, sugarcane production in Brazil has expanded rapidly to meet increasing ethanol demand. The large majority of this expansion occurred in Sao Paulo state. We used an integrated approach considering location-specific biophysical characteristics to determine the environmental impacts of sugarcane expansion and their spatial variation in Sao Paulo state (2004–2015). The included environmental impacts are greenhouse gas (GHG) emissions, biodiversity, soil erosion, and water quantity. All impacts were integrated into a single environmental performance index to determine trade-offs between impacts. Our results show a strong spatial variation in environmental impacts and trade-offs between them. The magnitude and direction of these impacts are mostly driven by the type of land use change and by the heterogeneity of the biophysical conditions. Areas where expansion of sugar cane has resulted in mostly negative environmental impacts are located in the center and east of the state (related to the change of shrublands, eucalyptus, and forest), while areas where sugar cane expansion has resulted in positive impacts are located in the center-west and north (related to the change of annual crops). Identifying areas with mainly positive and negative impacts enables the development of strategies to mitigate negative effects and enhance positive ones for future sugarcane expansion.

The climate impact of land use change in the miombo region of south central Africa

ABSTRACT The African woodlands known as miombo are one of the world’s largest currently relatively unexploited, but potentially arable, land resources. Miombo landscapes one of the top contemporary locations of conversion of dry forests to crop agriculture. This study investigates the net effect on climate forcing that results from different types of land use change in miombo, taking into account the multiple mechanisms through which the land interacts with the climate system, locally and globally. It finds that when miombo is converted tointensively cultivated commercial crops, the landscape-averaged 30-year net greenhouse gas forcing relative to intact woodlands is 309gCO2e m-2 y-1, of which net emission of carbon dioxide amount to 66%, non-CO2 greenhouse gas effects to 33%, plus unquantified contributions from ozone precursors and aerosols. We find that net brightening of the land surface resulting from clearing the woodlands generates a cooling effect larger than the greenhouse gas forcing (-1139gCO2e m-2 y-1). Greenhouse gas forcings resulting from transformation to extensive subsistence agriculture that are 78% lower than those from the intensive commercial agriculture path, and 40% lower if a transformation which sets out to mimic ecological processes in the miombo landscape is undertaken. Once the effect of surface brightening is included, then the total forcing for extensive subsistence agriculture is -834gCO2e m-2 y-1 , about the same as intensive commercial, and eco-agriculture is -102gCO2e m-2 y-1 . Taking into account the account the larger areas required for to achieve the same production, intensive commercial agriculture is the more climate-protective option.Keywords: greenhouse gas, net radiation, deforestation.

Evaluation of the Temporal and Spatial Changes of Ecological Quality in the Hami Oasis Based on RSEI

Given the restrictions on special geographic locations in development processes, the measurement and analysis of the ecological quality of the Hami Oasis are of great significance for the protection of this fragile oasis. In this study, the ecological quality of the Hami Oasis was monitored by constructing a remote sensing ecological index (RSEI) for arid areas. Using the standard deviation ellipse and moving window method, the ecological status and space–time changes were explored for both their external and internal factors in the Hami Oasis. Finally, a geo-detector was employed to determine the driving factors of the ecological quality of the Hami Oasis. The results revealed that: (1) In the remote sensing ecological index constructed in the Hami Oasis, the main influencing factors were dryness and wetness. The average value of the ecological quality of the oasis was less than 0.5, and the ecological quality level was relatively poor. Among the five grades of ecological quality in the Hami Oasis, the poor grade and the good grade showed the largest changes, decreasing by 200 and increasing by 300, respectively, which were mainly concentrated in the periphery of the oasis. (2) The improved ecological quality of the Hami Oasis was mainly manifested in the expansion of the artificial oasis, while the deteriorated area was manifested as an increase in the built-up area. Moreover, the ecological quality of the Hami Oasis presented a ringlike nesting distribution pattern from the internal built-up area to the artificial oasis periphery. (3) The external expansion direction of the ecological quality of the Hami Oasis featured southeast–northwest expansion, which was consistent with the direction of the rivers and traffic roads. The transformation between different ecological qualities in the oasis and the expansion of the built-up area were the reasons for the fragmentation of the Hami Oasis’ landscape. (4) Compared to a single factor, the dual-factor for the ecological quality of the Hami Oasis had stronger explanatory power. Moreover, changes in land use types caused changes in the ecological quality of the Hami Oasis. During the study period, we found that human activities had a more significant impact than natural factors on the development of the Hami Oasis. (5) The Moran’s I Index increased from 0.835268 in 2000 to 0.923976 in 2018, and the p values in the study area all reached a 0.05 significant level. At the same time, the areas with p values above the 0.01 and 0.001 significant levels have also increased significantly in the past 18 years.

Does land use type impact the demographic and spatial structures of Adansonia digitata L. in the Pendjari Biosphere Reserve in Northern Benin?

Changes in land use type (LUT) are a major driver of biodiversity loss and species decline. Responses to changes in LUT are species-specific, which may in turn be context-dependent. Understanding such responses is essential for the management of socio-economically important wild tree species. The baobab, Adansonia digitata L., is an important traditional agroforestry tree species in Sub-Saharan Africa. This study assesses how LUT affects the demographic and spatial structure of baobab stands. Using data from a census and mapping of baobab trees in 12 plots of 250 m × 250 m each, the study compared baobab tree density, total height and diameter, diameter size-class distribution (SCD), stand stability, and spatial relationships in a strictly protected area (national park), a buffer zone and farmlands (Matéri and Boukombé) in the Pendjari Biosphere Reserve in Benin. The results show that the highest young and adult tree densities are in farmlands (particularly in Matéri), followed by the buffer zone and the national park. No significant differences in tree diameter and total height of baobab trees were found among the different LUT. The SCD had a reverse J-shape with a better negative slope and population stability metrics in farmlands (particularly in Matéri) but a flattened slope in the buffer zone. The spatial distributions of juvenile and adult baobab trees were random, and independent of each other. The spatial distribution of juvenile and adult baobabs was also independent of the other tree species, irrespective of LUT. It was concluded that baobab conservation is better in farmlands than in the national park but that the difference between park and farmlands may be context-dependent, probably linked to local environmental conditions, the socio-ecological context and interactions with baobab trees.

Biophysical and socioeconomic factors influencing soil carbon stocks: a global assessment

Soil is the most important terrestrial carbon (C) reservoir but is greatly impacted by land use change (LUC). Previous analyses of LUC impacts on soil C have focused on biophysical variables, leaving aside the influence of socioeconomics. The aim of our study was to determine global soil organic carbon (SOC) change patterns after LUC and to assess the impacts of both biophysical and socioeconomic factors that influence stocks of SOC after LUC simultaneously. This was done at a global scale using 817 sites from 99 peer-reviewed publications. We performed separate analyses for cases in which there were gains and losses of SOC. The best predictors of SOC stock changes were the type of LUC and predictors related to sampling depth, climate, biome, soil order, relief, geology, years since LUC, and primary productivity. However, also, socioeconomic variables such as indices of poverty, population growth, and levels of corruption were important. They explained 33% of the variability in SOC on their own and helped improve model accuracy from 42 to 53% when considered in combination with biophysical variables. SOC losses were highly correlated to the type of LUC and social variables, while SOC gains correlated most strongly with years since LUC and the biophysical variables. The analyses confirm that one of the biggest drivers of SOC loss is conversion to agroindustrial scale cropping, whereas with regard to the recuperation of SOC after LUC, the factor “time since conversion” emerged as the most important predictive variable, which must be better integrated in respective policy expectations. We conclude that policies should more than ever incentivize holistic approaches that prevent additional loss of native SOC, while at the same time promoting sustainable intensification of existing agricultural regions. Finally future investments on LUC to regain SOC should be aligned with efforts to alleviate poverty and corruption for their potential to achieve mutual gains in soil fertility and socio-economic parameters.

The Impact of Urban Growth and Development Trend on Ecological Network Structure with Resilience and Landscape Approach (Case study of Hamedan)

Urban development is an inevitable subject due to the increasing population growth in cities. The city consists of open and living systems and a combination of socio-ecological systems. On the one hand, the hurried process of urban growth resulted in the land use change. Subsequently, this manner will damage to the structure, yield, and ecological processes in each city. Meanwhile, the use of ecologic knowledge with the landscape and resilience approaches can help to analyze the present situation and discover the optimal solutions. The resilience in the pattern of the natural structure of the ecological networks depends on the extent and intensity of the green spots. This research was carried out to determine the vegetation changes in Hamadan city between1982 to 2015 to achieve the evaluation of the ecological network structure in the urban development process with a resilience approach. In this study, a conceptual framework derived from ecological knowledge, resilience ideas and the use of modern technologies, such as GIS and RS, was designed to determine the bio-sensitive areas caused by the substructure urban changes. Besides, this study was performed to preserve the remaining biological resources in this area and preventing damage to the natural ecosystem of this city. A series of satellite imagery was classified in four categories such as such as open area, built land, communication paths, vegetation. After the above classification, these maps were processed and analyzed by the TerrSet software and three types of landscape metrics including creating, loosening and separating were reviewed to identify the types of land use changes in these years. The results show that the vegetated area decreased from 2820.2 hectares in 1982 to 1304.2 hectares in 2015 and, on the other hand, built lands and communication paths were degraded from 606.4 hectares in 1982 to 4274.2 hectares in 2015. In general, it can be concluded that this level of change shows a high urban development, decreases in plant vegetation, and its discontinuation so that the above changes have reduced the resilience of the city's ecology network. At the end of the study, numerous strategies were also provided for the restoration of the entire damage in the natural ecological network of Hamadan and its development.

Effects of Land Use Types on CH4 and CO2 Production Potentials in Subtropical Wetland Soils

Changes in land use types can alter the soil and environmental characteristics of wetlands, which in turn influence the magnitude of greenhouse gas production by soil microbes. However, the effects of land use change on the production potential of methane (CH4) and carbon dioxide (CO2) in subtropical wetland soils and the underlying controls are still largely unknown. In this study, we examined the soil CH4 and CO2 production potentials under five different land use types (natural mangrove, Gei Wai water channel, Gei Wai forest, reedbed, and freshwater pond) and their relationships with soil physico-chemical properties in a subtropical wetland in Hong Kong using aerobic and anaerobic laboratory incubation experiments. Our results showed an overall decreasing trend of CH4 and CO2 production potentials down the soil profile at all sites, which could be attributed to a reduction in the concentrations of soil organic matter (SOM), total Kjeldahl nitrogen (TKN) and ammonium nitrogen (NH4+-N). Moreover, the soil CH4 and CO2 production potentials varied significantly in the surface soils among land use types, but were more similar across the sites in the deeper soils. The conversion of natural mangrove to other land use types significantly reduced both the aerobic and anaerobic CO2 production potentials in the top 10 cm soils, except for Gei Wai forest, which demonstrated significantly higher CO2 production rates (61.15–97.91 μg g−1 day−1). Meanwhile, the mean CH4 production potential in the surface soils of natural mangrove (0.05 μg g−1 d−1) was significantly lower than that in the Gei Wai forest and Gei Wai channel (0.26–0.27 μg g−1 day−1) but slightly higher than that in the freshwater pond and reedbed (0.00–0.02 μg g−1 day−1). The high soil CH4 and CO2 production potentials observed in the Gei Wai forest could be explained by the high soil concentrations of SOM, TKN and NH4+-N. On the other hand, the lower anaerobic CH4 and aerobic CO2 productions observed in the reedbed could be attributed to the lower concentrations of NH4+-N and available phosphorus. Our findings highlighted the significant impacts of land use types on the CH4 and CO2 production potentials of subtropical wetland soils, which had practical implications for wetland management for climate change mitigation.

Analysis of land use change and its influence on runoff in the Puhe River Basin.

This article aims to evaluate the impact of urbanization on land use changes and the effects of land use changes on catchment's runoff. The maximum likelihood method was used to interpret the seven remote sensing images of the Puhe River Basin from 1985 to 2015. The Mann-Kendall test, sliding T test, and double accumulation method are adopted to analyze the impact of land use changes on watershed runoff. The results show that with the development of urbanization, a large amount of cultivated land was replaced by urban construction land. By 2015, the construction land area accounted for 72.16% of the total area. The year 1995 was a turning point in the urbanization development. The change of land use type has substantial influence on runoff and results in the increase of runoff coefficient. Human activities become the main factor affecting runoff change in the Puhe River Basin.