作者机构：
[Liu, Ji; Liu, Muxing; Zhang, Hailin; Yi, Jun] Key Lab Geog Proc Anal & Simulat, Wuhan 430079, Hubei, Peoples R China.;[Liu, Ji; Wang, Qiuyue; Liu, Muxing; Zhang, Hailin; Yi, Jun] Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Hu, Wei] New Zealand Inst Plant & Food Res Ltd, Private Bag 4704, Christchurch 8140, New Zealand.
通讯机构：
[Jun Yi] K;Key Laboratory for Geographical Process Analysis & Simulation, Hubei Province, Wuhan, 430079, China<&wdkj&>College of Urban and Environmental Sciences, Central China Normal University, Wuhan, 430079, China
关键词：
Volumetric soil water content;Wavelet analysis;Significant coherence area;Time scale;Vegetation type;Slope position
摘要：
Clarifying the mechanisms governing volumetric soil water content (VSWC) dynamics in soil profiles is essential, as it can help to elucidate soil water transport processes and improve the prediction accuracy of soil hydrological processes. Using Spearman's rank correlation and wavelet coherence analysis methods, similarity in soil profile VSWC dynamics and factors governing VSWC soil profile dynamics in upslopes and downslopes under three vegetation types (evergreen forest [EG], secondary deciduous forest mixed with shrubs [SDFS], and deforested pasture [DP]) at different time scales (hourly, daily, weekly, and monthly) and in different seasons were analyzed. The results revealed significant similarity in the VSWC of different soil depths (P < 0.01), with the similarity decreasing in accordance with the increment in soil depth. Greater VSWC similarity was found in EG than SDFS and DP sites and in upslope than downslope areas at both forest sites. The average significant coherence area (SCA) of VSWC similarity among surface and deep soil layers varied with the time scale, which was in the order of monthly (58.6%) > weekly (42.8%) > daily (21.8%). The effects of soil properties (e.g., texture, saturated hydraulic conductivity), rainfall, and potential evapotranspiration (ETp) on VSWC similarity were related to the time scale and season in which VSWC monitoring took place. Soil properties had apparent effects on VSWC similarity at longer time scales (i.e., monthly), with a high SCA. In contrast, the effects of rainfall and ETp on VSWC similarity were concentrated at weekly and daily scales, with a relatively low SCA. Rainfall and ETp dominated VSWC dynamics in the summer and fall, respectively. These results imply the use of measured VSWC at one soil depth to predict the VSWC at other soil depths was a reliable method. While the in-fluence of time scale effects and seasonal variations on prediction accuracy of VSWC should be considered. ](c) 2022 International Research and Training Center on Erosion and Sedimentation, China Water and Power Press, and China Institute of Water Resources and Hydropower Research. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY -NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
作者机构：
华中师范大学城市与环境科学学院,湖北 武汉 430079;中国旅游研究院武汉分院,湖北 武汉 430079;山西财经大学文化旅游学院,山西 太原 030031;安庆师范大学资源环境学院,安徽 安庆 246133;[朱磊] College of Resources and Environment, Anqing Normal University, Anhui, Anqing, 246133, China
通讯机构：
[Hu, J.] C;College of Urban and Environmental Science, Hubei, China
作者机构：
[徐佳慧; 卿琪; 李燕楠] College of Resources and Environment, Anqing Normal University, Anhui, Anqing, 246133, China;[田小波] College of Urban and Environmental Science, Central China Normal University, Hubei, Wuhan, 430079, China;Wuhan Branch of China Tourism Academy, Hubei, Wuhan, 430079, China;[胡静] College of Urban and Environmental Science, Central China Normal University, Hubei, Wuhan, 430079, China, Wuhan Branch of China Tourism Academy, Hubei, Wuhan, 430079, China;[朱磊] College of Resources and Environment, Anqing Normal University, Anhui, Anqing, 246133, China, College of Urban and Environmental Science, Central China Normal University, Hubei, Wuhan, 430079, China, Wuhan Branch of China Tourism Academy, Hubei, Wuhan, 430079, China
通讯机构：
[Hu, J.] C;College of Urban and Environmental Science, Hubei, China
作者机构：
[Chen, Wei; Li, Siliang; Jiang, Bohan] Tianjin Univ, Inst Surface Earth Syst Sci, Sch Earth Syst Sci, Tianjin 300072, Peoples R China.;[Chen, Wei; Li, Siliang; Jiang, Bohan] Haihe Lab Sustainable Chem Transformat, Tianjin 300192, Peoples R China.;[Chen, Wei; Li, Siliang; Jiang, Bohan] Tianjin Bohai Rim Coastal Earth Crit Zone Natl Obs, Tianjin 300072, Peoples R China.;[Dai, Xiaoai] Chengdu Univ Technol, Coll Earth Sci, Chengdu 610059, Peoples R China.;[Xu, Min] Chinese Acad Sci, Aerosp Informat Res Inst, State Key Lab Remote Sensing Sci, Beijing 100101, Peoples R China.
通讯机构：
[Wei Chen] I;[Xiaoai Dai] C;College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China<&wdkj&>Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China<&wdkj&>Haihe Laboratory of Sustainable Chemical Transformation, Tianjin 300192, China<&wdkj&>Tianjin Bohai Rim Coastal Earth Critical Zone National Observation and Research Station, Tianjin 300072, China
作者机构：
[Tao, Jianbin; Zhou, Yang; Zhang, Xinyue; Jiang, Qiyue; Zhou, Y] Cent China Normal Univ, Key Lab Geog Proc Anal & Simulat Hubei Prov, Sch Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Liu, Yiqing] Beijing Normal Univ, Inst Disaster Risk Sci, Fac Geog Sci, Beijing 100875, Peoples R China.
通讯机构：
[Zhou, Y ] C;Cent China Normal Univ, Key Lab Geog Proc Anal & Simulat Hubei Prov, Sch Urban & Environm Sci, Wuhan 430079, Peoples R China.
关键词：
cropping intensity;temporal mixture analysis;endmember;unmixing;time series images
摘要：
Agricultural cropping intensity plays an important role in evaluating the food security and the sustainable development of agriculture. The existing indicators measuring cropping intensity include cropping frequency and multiple cropping index. As a nominal measurement, cropping frequency classifies crop patterns into single-cropping and/or double-cropping and leads to information loss. Multiple cropping index is calculated on the basis of statistical data, ignoring the spatial heterogeneity within the administrative region. Neither of these indicators can meet the requirements of precision agriculture, and new methods for fine cropping intensity mapping are still lacking. Time series remote sensing data provide vegetation phenology information and reveal temporal development of vegetation, which can be used to facilitate the fine cropping intensity mapping. In this study, a new temporal mixture analysis method is introduced to estimate the abundance level cropping intensity from time series remote sensing data. By analyzing phenological characteristics of major land-cover types in time series vegetatiosacan indices, a novel feature space was constructed by using the selected PCA components, and three unique endmembers (double-cropping, natural vegetations and water bodies) were found. Then, a linear spectral mixture analysis model was applied to decompose mixed pixels by replacing spectral data with multi-temporal data. The spatio-temporal continuous, fine resolution, abundance level cropping intensity maps were produced for the North China Plain and the middle and lower reaches of the Yangtze River Valley. The experiments indicate a good result at both county and pixel level validation. The method of manually delineating endmembers can well balance the accuracy and efficiency. We also found the size of the study area has little effect on the unmixing accuracy. The results demonstrated that the proposed method can model cropping intensity finely at large scale and long temporal span, at the same time with high efficiency and ease of implementation.
期刊：
Global Change Biology,2023年29(5):1377-1389 ISSN：1354-1013
通讯作者：
Yongshuo H. Fu<&wdkj&>Fanghua Hao<&wdkj&>Yongshuo H. Fu Yongshuo H. Fu Yongshuo H. Fu<&wdkj&>Fanghua Hao Fanghua Hao Fanghua Hao
作者机构：
[Zhang, Xuan; Chen, Shouzhi; Zhang, Jing; Wu, Zhaofei; Geng, Xiaojun; Fu, Yongshuo H.] Beijing Normal Univ, Coll Water Sci, Beijing 100875, Peoples R China.;[Geng, Xiaojun] Minist Water Resources, Gen Inst Water Resources & Hydropower Planning &, Beijing, Peoples R China.;[Hao, Fanghua; Wu, Hao] Cent China Normal Univ, Coll Urban & Environm Sci, Wuhan 430079, Peoples R China.;[Tang, Jing] Lund Univ, Dept Phys Geog & Ecosyst Sci, Lund, Sweden.;[Tang, Jing] Univ Copenhagen, Dept Biol, Terr Ecol Sect, Copenhagen, Denmark.
通讯机构：
[Yongshuo H. Fu; Fanghua Hao; Yongshuo H. Fu Yongshuo H. Fu Yongshuo H. Fu; Fanghua Hao Fanghua Hao Fanghua Hao] C;College of Water Sciences, Beijing Normal University, Beijing, China<&wdkj&>College of Urban and Environmental Sciences, Central China Normal University, Wuhan, China
关键词：
autumnal foliar senescence;climatic warming;green season;spring leaf-out;thermal season
摘要：
Global warming leads to substantial changes in the thermal conditions for vegetative growth. Based on in situ and remote sensing‐based phenological observations, we show that global warming is extending both the thermal (potential) and green (actual) season of temperate deciduous trees, but green season extensions lag behind the thermal season by 7.9–11.1 days and this mismatch was mainly driven by tree's leaf‐out dates did not follow proportionately the strong advance in the thermal season onset. Our results call for caution when using thermal sums to predict future changes in plant vegetative growth or any processes involving plant development. Abstract Over the past decades, global warming has led to a lengthening of the time window during which temperatures remain favorable for carbon assimilation and tree growth, resulting in a lengthening of the green season. The extent to which forest green seasons have tracked the lengthening of this favorable period under climate warming, however, has not been quantified to date. Here, we used remote sensing data and long‐term ground observations of leaf‐out and coloration for six dominant species of European trees at 1773 sites, for a total of 6060 species–site combinations, during 1980–2016 and found that actual green season extensions (GS: 3.1 ± 0.1 day decade−1) lag four times behind extensions of the potential thermal season (TS: 12.6 ± 0.1 day decade−1). Similar but less pronounced differences were obtained using satellite‐derived vegetation phenology observations, that is, a lengthening of 4.4 ± 0.13 and 7.5 ± 0.13 day decade−1 for GS and TS, respectively. This difference was mainly driven by the larger advance in the onset of the thermal season compared to the actual advance of leaf‐out dates (spring mismatch: 7.2 ± 0.1 day decade−1), but to a less extent caused by a phenological mismatch between GS and TS in autumn (2.4 ± 0.1 day decade−1). Our results showed that forest trees do not linearly track the new thermal window extension, indicating more complex interactions between winter and spring temperatures and photoperiod and a justification of demonstrating that using more sophisticated models that include the influence of chilling and photoperiod is needed to accurately predict spring phenological changes under warmer climate. They urge caution if such mechanisms are omitted to predict, for example, how vegetative health and growth, species distribution and crop yields will change in the future.
作者机构：
[Barnieh, Beatrice Asenso; Jia, Li; Jia, L] Int Res Ctr Big Data Sustainable Dev Goals, Beijing 100094, Peoples R China.;[Menenti, Massimo; Zeng, Yelong; Lv, Yunzhe; Barnieh, Beatrice Asenso; Jia, Li; Jiang, Min; Bennour, Ali; Jia, L] Chinese Acad Sci, Beijing 100101, Peoples R China.;[Zeng, Yelong; Lv, Yunzhe; Barnieh, Beatrice Asenso; Bennour, Ali] Chinese Acad Sci, Inst Geog Sci & Nat Resources Res, 19 Yuquan Rd, Beijing 100040, Peoples R China.;[Kabo-Bah, Amos Tiereyangn; Barnieh, Beatrice Asenso; Nyantakyi, Emmanuel Kwesi] Univ Energy & Nat Resources, Earth Observat Res & Innovat Ctr, POB 214, Sunyani, Ghana.;[Menenti, Massimo] Delft Univ Technol, Fac Civil Engn & Earth Sci, Stevinweg 1, NL-2628 CD Delft, Netherlands.
通讯机构：
[Jia, L ] I;Int Res Ctr Big Data Sustainable Dev Goals, Beijing 100094, Peoples R China.;Chinese Acad Sci, Beijing 100101, Peoples R China.
关键词：
natural vegetation;intensity analysis;spatial patterns;systematic transitions;random transitions;West Africa
摘要：
Land Use/Land Cover (LULC) change is a major global concern and a topic of scientific debate. In West Africa, the key trend among the changes of the past few years is the loss of natural vegetation related to changes in different LULC categories, e.g., water bodies, wetland, and bare soil. However, not all detected changes in these LULC categories are relevant for LULC change management intervention in a resource-constrained continent, as a massive change in the dominant LULC types may be due to errors in the LULC maps. Previous LULC change analysis detected large discrepancies in the existing LULC maps in Africa. Here, we applied an open and synergistic framework to update and improve the existing LULC maps for West Africa at five-year intervals from 1990 to 2020-updating them to a finer spatial resolution of 30 m. Next, we detected spatial-temporal patterns in past and present LULC changes with the intensity analysis framework, focusing on the following periods: 1990-2000, 2000-2010, and 2010-2020. A faster annual rate of overall transition was detected in 1990-2000 and 2010-2020 than in 2000-2010. We observed consistent increases in shrubland and grassland in all of the periods, which confirms the observed re-greening of rangeland in West Africa. By contrast, forestland areas experienced consistent decreases over the entire period, indicating deforestation and degradation. We observed a net loss for cropland in the drought period and net gains in the subsequent periods. The settlement category also gained actively in all periods. Net losses of wetland and bare land categories were also observed in all of the periods. We observed net gains in water bodies in the 1990-2000 period and net losses in the 2010-2020 period. We highlighted the active forestland losses as systematic and issued a clarion call for an intervention. The simultaneous active gross loss and gain intensity of cropland raises food security concerns and should act as an early warning sign to policy makers that the food security of marginal geographic locations is under threat, despite the massive expansion of cropland observed in this study area. Instead of focusing on the dynamics of all the LULC categories that may be irrelevant, the intensity analysis framework was vital in identifying the settlement category relevant for LULC change management intervention in West Africa, as well as a cost-effective LULC change management approach.
