摘要：
Current assessments of urban forest carbon storage were missing or largely underestimating their values due to limited spatial resolution. In this study, combining field plot measurements and satellite imagery, a wall-to-wall forest biomass map were generated at a very high spatial resolution (5 m) over urban areas in Wuhan City, China. Specifically, a series of characteristic metrics were extracted from Jilin-1 satellite images, including multispectral reflectances, vegetation indices, and texture features. The estimations of forest aboveground biomass from three machine learning models were evaluated at sampled field plot level. Results demonstrated that the random forest model achieved the highest accuracy using the leave-one-out cross-validation method, with a test set RMSE of 31.84 Mg/ha. However, discrepancies were observed in low biomass areas due to variations in vegetation species, leading to overestimation of lower values.
摘要：
Exploring the utilization effect of water-land resources under the evolution of dietary patterns is of great significance in achieving sustainable global food consumption and the effective allocation of national resources. Our selected study area was China, a country with rapidly changing dietary consumption patterns, and the research period was between 1987 and 2020. Based on the material called Chinese Dietary Guidelines 2021, this study introduced the "virtual water" and the "virtual land" to quantify the utilization effect of water-land resources under the evolution of Chinese dietary patterns. Results showed that the dietary patterns gradually changed from "cereal-vegetable-based consumption" to "diversified consumption". Food consumption's total water footprint (WF) increased from 471.1 Gm(3) in 1987 to 848.8 Gm(3) in 2020, with a growth rate of 80.2%. Moreover, the total land requirement for food (LRF) increased from 88.8 Mha in 1987 to 129.9 Mha in 2020, with a growth rate of 46.3%. Furthermore, the meat consumption was the major contributor to the increase in total WF (104.0%) and LRF (102.1%). In contrast to the balanced diet pattern, there was no waste of water-land resources consumption for the food consumption of urban-rural residents in China between 1987 and 2020. However, the consumption of water resources would gradually approach the resource cost under the balanced diet patterns. It would eventually break through the critical value and reach the state of resource waste. In addition, the findings showed that urban residents' waste rate of water-land resources for meat consumption increased by 142.3% compared with that in 1987. The research results can provide scientific guidance for resolving the food crisis under the supply of water-land resources in China and have an essential reference for national food security and sustainable development of resources and environment.
摘要：
地理学研究可持续发展旨在构建人与自然命运共同体，实现人类社会的永续发展。该文依托CNKI数据库、读秀资源库以及Web of Science数据库，限定主题词为“可持续” “可持续发展”和“可持续性”，采用CiteSpace软件对1994—2021年中国地理学者“可持续”研究的核心力量、重点区域与重要领域进行文献计量分析，结果表明：1）中国地理学者“可持续”研究的过程可分为快速兴起（1994—2001年）、稳定发展（2002—2011年）和整固深化（2012—2021年）三个阶段。2）中国开展“可持续”研究的地理学者多达624位，主要是自然地理学者和人文地理学者，研究机构多达258个，主要是中国科学院所属地理单位，机构间合作具有空间邻近性，机构空间分布具有东、中、西梯度分异性；中国地理学者“可持续”研究的对象区域以地方行政区域为主，服务国家重大区域发展战略的特色鲜明。3）中国地理学者“可持续”研究的重点领域有资源可持续利用、生态环境保护与建设、农业可持续发展、旅游可持续发展、可持续发展教育、可持续发展伦理、消除贫困与可持续生计、区域人地关系协调、城市可持续发展、农村可持续发展、区域可持续发展战略、区域可持续发展评价等。4）未来中国地理学者的“可持续”研究应在可持续发展专业人才培养、可持续发展理论体系完善、可持续发展研究领域拓展、可持续发展服务能力提升等方面下功夫。
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
通讯机构：
[Wang, Y ] 1;186 Hongqi Middle Rd, Zhifu Dist 410125, Yantai, Peoples R China.
关键词：
Soil ecological stoichiometry;Stream water ecological stoichiometry;Nitrogen and phosphorus loss;Soil nutrient limitation;Water nutrient limitation;Eutrophication
摘要：
Whether and how to synchronously regulate stream water nitrogen (N) and phosphorus (P) concentrations and ratios is a major challenge for sustainable aquatic functions. Soil carbon (C):N:P ratios influence soil N and P stocks and biogeochemical processes that elicit subsequent substantial impacts on stream water N and P con-centrations and ratios. Therefore, bridging soil and stream water with ecological stoichiometry is one of the most promising technologies for improving stream water quality. Here, we quantified the ecological stoichiometry of soil and stream water relationships across nine catchments. Soil C:P ratio was the main driver of water quality, showing negative correlations with stream water N and P concentrations, and positive correlations with the N:P ratio in P-limited catchments. We revealed that soil C:P ratios higher than 97.8 mol mol- 1 are required to achieve the simultaneous regulation of stream water N and P concentrations below the eutrophication threshold and make algal growth P-limited. Furthermore, we found that the relationships between catchment landscape and soil ecological stoichiometry likely provided practical options for regulating soil ecological stoichiometry. Our work highlights that soil ecological stoichiometry can effectively indicate the amount and proportion of soil N and P losses, and can be intervened through rational landscape planning to achieve sustainable aquatic eco-systems in catchments.
