Forest transitions in tropical landscapes: A test in the Atlantic Forest biodiversity hotspot

Analyzing temporal changes in forest amount and configuration is paramount to better design future forest management interventions. Such analyses are especially required for tropical biomes, which are usually subject to dynamic and heterogeneous land uses. Recent studies have suggested that many tropical biomes are passing through the process of “forest transition”, i.e. an overall change from forest loss to forest gain. However, this hypothesis remains scarcely tested, due to the difficulty of obtaining detailed, quantitative historical records of forest cover. In this study, we investigate 38 years of land use change in Brazil's Atlantic Forest, a biodiversity hotspot, from 1976 to 2014, using multitemporal datasets from aerial photographs and satellite images. We classified the historical series to produce land use maps and calculated a set of landscape metrics, including total forest cover, patch size, patch shape and patch connectivity. Our results indicated non-linear changes through time in forest loss and gain and also in landscape structure, which can be classified into two distinct periods. The first period (1976–1996) was marked by expressive forest loss and fragmentation, whereas the second (1996–2014) was characterized by a much less intense forest dynamics, with little deforestation being balanced by forest regeneration. We attribute the forest dynamics observed to temporal changes in socioeconomic factors, such as increasing human settlements and changes in environmental protection policies. Our results show that current forests are a heterogeneous mosaic of forests with different ages, and support the hypothesis that forest transition is occurring in Atlantic Forest landscapes.     

论土地利用转型的研究框架

当前,土地变化研究尚缺乏统一的理论指导。探索土地利用转型理论对构建土地变化研究的理论基础具有重要意义。本文试图梳理土地利用转型研究的缘起、拓展及启示,辨析土地利用转型与土地利用变化的内涵差异,构建土地利用转型的研究框架。结果表明：① 耕地及城乡建设用地利用转型研究对构建土地利用转型的研究框架具有重要价值;② 土地利用转型与土地利用变化在基本类型、时间尺度、空间尺度、价值主体、驱动因素、轨迹特征和结果/影响方面存在显著差异;③ 土地利用转型的研究框架涵盖转型诊断、机制研究和效应研究。其中,转型诊断的关键在于,从数量变化视角、景观格局变化视角和经营格局变化视角,以及外部性视角和政策发展视角,构建土地利用空间形态及功能形态的分析指标和转型的诊断准则;转型机制表现为人口、经济、技术、制度、文化和区位因素等土地利用变化深层驱动因素的级联驱动效应。转型机制研究应当着重探讨土地利用空间转型与功能转型的互动机制环;土地利用转型效应包括社会、经济、环境3个方面;④ 1961-2011年法国耕地利用转型能够支撑本文提出的研究框架及中国耕地保护创新。     

Understanding the dynamics of sustainability transitions: the Home Insulation Program

The Home Insulation Program (HIP) in Australia is an outstanding example of a contemporary attempt to intervene in a socio-technical regime. The program, implemented in 2009 under the then Australian Labor Party government led by Kevin Rudd, was targeted at stimulating the retrofit insulation industry. The objective was to both improve the energy efficiency of homes and thereby contribute to Australia’s emissions reduction targets by reducing greenhouse gas emissions and to stimulate the Australian economy at the time of the global financial crisis. The program ended early following a number of economic issues and health and safety concerns. Despite previous investigation into the HIP reviewing its design and implementation, the focus has been on economic issues and health and safety concerns. To date there has been no investigation of the HIP as a sustainability transition. This article integrates socio-technical transition theory (STTT) and political ecology (PE) approaches to analyse the HIP and identify lessons for future sustainability transition initiatives. This is achieved by illustrating the effect of regime management (RM) on the orientation of niche governance (NG) which highlights the importance of considering the RM and NG aspects of STTT with a PE approach in symmetry, in order to adequately account for political and economic contest and power relations, which are ubiquitous in environmental management governance.     

长江流域土地利用时空变化特征及其径流效应

土地利用变化的径流效应是水循环研究中的重点内容之一。长江流域是中国最大的流域,土地利用变化及其径流效应分析是研究该流域径流演变、水旱灾害的基础。本文利用1980、1990、1995、2000、2005年五期土地利用数据,采用土地利用转移矩阵计算土地利用动态度、交换变量等指标,评价了长江流域土地利用的时空变化特征,识别关键变化区域及其变化原因。在此基础上,利用SCS模型的降水—径流方程,分析了土地利用变化的径流效应。研究结果表明：1980-2005年时期,长江流域土地转移活跃程度在第一(1980-1990年)和第四(2001-2005年)时期内明显高于1991-1995年和1996-2000年,中上游四川及其北部地区的活跃程度最大。1980-2005年期间水田、旱地、林地和草地面积变化幅度都在8%以内。但受不同时期环境保护和经济发展因素影响,耕地(水田和旱地)和林地、草地呈现相反的变化,而水域、未利用地和城镇用地相对变化较大;其中快速的城镇化导致城镇用地增幅最高,可达196.58%。土地利用变化直接导致流域的平均径流系数变大,变幅从-0.67%到0.80%,平均增幅0.05%,变化最显著的地区在城市化水平较高的长三角一带。径流系数的增加导致洪水发生的可能性增大。     

TBB DATA-REVEALED FEATURES OF ASIAN-AUSTRALIAN MONSOON SEASONAL TRANSITION AND ASIAN SUMMER MONSOOM ESTABLISHMENT

Based on T_BB data from Meteorological Institute Research of Japan, study is carried out of the features of seasonal transition of Asian-Australian monsoons and Asian summer monsoon establishment,indicating that the transition begins as early as in April, followed by abrupt change in May-June; the Asian summer monsoon situation is fully established in June. The winter convective center in Sumatra moved steadily northwestward across the "land bridge" of the maritime continent and the Indo-China Peninsula as time goes from winter to summer, thus giving rise to the change in large scale circulations that is responsible for the summer monsoon establishment over SE Asia and India; the South China Sea to the western Pacific summer monsoon onset bears a close relation to the active convection in the Indo China Peninsula and steady eastward retreat of the subtropical TBB high-value band,corresponding to the western Pacific subtropical high.     

A probabilistic description of the wind over Liverpool Bay with application to oil spill simulations

Surface winds from the UK Meteorological Office mesoscale (12 km grid) atmospheric model have been used to define the wind at a location in Liverpool Bay during 1997–2001. Winds from the SW (centred on 240°) with a speed of about 10 m/s (20 knots) were the most frequent, although weaker winds from the SE were also common. The wind spectra were red in character and showed no evidence for a peak at the synoptic (2–5 day) time scale; however, a zero-up-crossing analysis suggested a dominant periodicity at 3.1 days, and at this time scale the winds were spatially coherent over a distance of 300 km. A wind direction transition matrix was derived to quantify the probability with which the wind changed between two specified directions. This information was then used with an estimate of the mean duration of a wind event to compute a stochastic wind time series that contained a similar energy level, periodicity, and direction variability to the archived wind data. The archived and stochastic winds were then used in 1000 oil spill contingency simulations during which estimates of the mean and minimum times taken for oil to reach the coastline, and the percentage of the oil impacting selected sites were computed. The stochastic winds provided more realistic results, when compared against those derived using the wind archive, than those obtained using a wind rose representation of the winds. The derivation and use of a stochastic wind time series has application to a range of modelling studies.     

基于农户利用效率的平原和山区耕地利用形态比较

土地利用形态是土地利用转型研究的核心内容。农户土地利用决策是引起土地利用系统变化与土地利用转型的深层因素,当前学者从多个视角对耕地利用形态展开了系列的理论与实证研究,但从农户层面深入探讨耕地利用隐性形态及其形成机理的研究相对较少。为揭示农户耕地利用隐性形态的差异及其影响因素,本文以农户耕地利用效率为切入点基于平原区寿光市和山区沂源县农户调研数据,从农户家庭劳动力要素变动与农业生产决策视角对农户的耕地利用效率进行了测算,构建结构方程模型探讨了农户耕地利用效率的驱动机制。研究表明,寿光市和沂源县耕地利用效率较低,并且存在地貌类型和农户类型上的差异,平原（寿光市）耕地利用效率要高于山区（沂源县）,老年农户耕地利用效率低于年轻农户。在影响路径方面,农户耕地经营规模、生产要素投入和耕地产出直接影响耕地利用效率,而种植结构对耕地利用效率的影响不显著。     

近60年黑龙江省台风暴雨统计及环流特征分析

使用台风最佳路径、黑龙江省83个国家基本气象站日降水量资料及NCEP NC再分析资料,对近60年黑龙江省台风活动规律、台风暴雨时空分布和环流形势及各物理量统计特征等进行分析。结果表明：2010年以后造成暴雨的台风个数增加,2015年之后台风暴雨强度持续增加,2020年达到最强。黑龙江省台风暴雨站次最多的时间是7月下旬至9月上旬。黑龙江省受台风影响出现暴雨的次数自东南向西北递减,暴雨次数多的站点一般与地形有关。将台风暴雨过程的高空环流形势分为3型8类,A型暴雨过程以台风环流降水为主,多数为稳定性降水,降水持续时间较长,B型和C型暴雨过程有较强冷空气参与,对流活跃,通常雨强较大。给黑龙江省带来大范围暴雨的环流形势有5类。以A-Ⅱ和C-Ⅰ两种环流形势出现的台风个数最多,A-Ⅱ和B-Ⅱ造成的暴雨范围最广。黑龙江省台风暴雨过程低空均有低涡活动;水汽主要来自日本海和黄渤海;低层辐合中心与暴雨区有较好的对应关系。A-Ⅱ类台风暴雨的各个物理量特征最突出（假相当位温和比湿略小于B-Ⅱ类）;B-Ⅱ类台风暴雨过程的暖湿空气最强,尽管动力条件稍差,但较好的热力和水汽条件也足以造成大范围的暴雨天气,成为平均单个过程出现暴雨以上站次最多的类型。     

Exploring food choices within the context of nutritional security in Gaborone,Botswana

Food consumption experiences remain largely unexplored in urban Africa, despite mounting concerns regarding both over‐ and undernutrition of city dwellers and the potential impact on overall human health and development. This paper seeks to explore the foodstuffs people consume and the factors that shape consumer choice in Gaborone, Botswana. Empirical data were drawn from food diaries and observations of 40 households and discussions with them, plus key informants interviews in Gaborone. Analysis reveals the range of foodstuff people consume, highlighting the prevalence of diets comprised of energy dense, processed and animal‐sourced foods, which are major nutritional security concerns. However these diets were not summarily western or westernizing as per the nutritional transition thesis, as our analysis suggests subtleties of dietary patterns, including the fact that meat‐based diets are traditionally rooted rather than imported and meals tend to comprise both local and western components. The paper also identifies multiple interacting factors influencing consumer food choices, illustrating how food decisions embody context‐specific personal and social circumstances. Understanding how these factors shape what people eat in Gaborone may enable policy makers to facilitate the conditions within which healthy food choices can be made and to address emerging public health and nutrition challenges in African cities.     

黄淮海平原农区土地利用转型及其动力机制

本文分析了黄淮海平原农区2000-2010 年间土地利用转型的时空格局,在构建土地利用转型动力机制分析概念框架基础上,运用空间计量回归分析方法深入剖析了黄淮海平原农区5种主要土地利用类型转换的动力机制。黄淮海平原农区土地利用转型特征表现为：2000-2010年,耕地、未利用地和草地面积的减少伴随城乡建设用地、水域和林地面积的增加;2000-2005年变化幅度明显大于2005-2010 年的变化幅度。分析结果表明：黄淮海平原农区5 种主要土地利用类型转换是自然环境和社会经济多种因素共同作用的结果,其中交通和区位条件对这5 种土地利用类型转换的影响最为显著,是导致土地利用转型的共性驱动因子。并指出：地方各级政府在制定有关土地利用政策时,既应充分考虑驱动各种土地利用转型的主要因子及其地域分异和社会经济发展规律,还需考虑各地类之间转换的适宜性及难易程度,因地制宜开展土地综合整治与利用,让土地利用转型与当地自然环境条件和区域经济社会发展阶段相适应,并使其发生在适宜的区域范围内。