城市生态系统中的森林研究

随着城市化水平的提高，城市的环境问题越来越突出，城市森林作为城市中重要的生命支持系统，对于维持城市生态系统平衡起着核心的作用，本文介绍了城市森林的概念和它的研究范畴，并着重分析了城市森林的综合效益，最后指出发展城市森林是人类自身发展的必然需要。     

Evaluating the joint efficiency of German trade forecasts - a nonparametric multivariate approach

ABSTRACT

I analyse the joint efficiency of export and import forecasts by leading economic research institutes for the years 1970 to 2017 for Germany in a multivariate setting. To this end, I compute, in a first step, multivariate random forests in order to model links between forecast errors and a forecaster’s information set, consisting of several trade and other macroeconomic predictor variables. I use the Mahalanobis distance as performance criterion and, in a second step, permutation tests to check whether the Mahalanobis distance between the predicted forecast errors for the trade forecasts and actual forecast errors is significantly smaller than under the null hypothesis of forecast efficiency. I find evidence for joint forecast inefficiency for two forecasters, however, for one forecaster I cannot reject joint forecast efficiency. For the other forecasters, joint forecast efficiency depends on the examined forecast horizon. I find evidence that real macroeconomic variables as opposed to trade variables are inefficiently included in the analysed trade forecasts. Finally, I compile a joint efficiency ranking of the forecasters.     

Machine learning advances for time series forecasting

In this paper, we survey the most recent advances in supervised machine learning (ML) and high-dimensional models for time-series forecasting. We consider both linear and nonlinear alternatives. Among the linear methods, we pay special attention to penalized regressions and ensemble of models. The nonlinear methods considered in the paper include shallow and deep neural networks, in their feedforward and recurrent versions, and tree-based methods, such as random forests and boosted trees. We also consider ensemble and hybrid models by combining ingredients from different alternatives. Tests for superior predictive ability are briefly reviewed. Finally, we discuss application of ML in economics and finance and provide an illustration with high-frequency financial data.     

The Economics of Forest Land Use in Temperate and Tropical Areas

This paper presents economic rules for harvest timing when timber and nontimber goods, services, and ecological functions are produced from forest stands. Forests include stands that are heterogeneous in age, land quality, and distance to market. Rules for allocating land between forest and nonforest use are developed. Key land use margins are identified that are important to land use allocation in temperate and tropical regions (e.g., between unmanaged forest, forest management, and forest conversion). Processes that can change key land use margins are discussed and used to organize recent empirical and theoretical studies of regions where forest land use is in transition, such as where forest land is being converted to alternative nonforest land uses.     

集体林权制度改革的物权法透视与反思

从物权法的视角透视和反思集体林权制度改革,指出其存在纠纷较多、利用机制不健全的缺陷,并提出应完善林权立法,构建良性的利益分配机制,兼顾公平与效率等建议,以充分发挥林权的使用价值和交换价值,从而为林改提供必要的法治支撑。     

Conflict and agreement in stakeholder attitudes: residents’ and hotel managers’ views of tourism impacts and forest-related tourism development

This paper probes differences in attitudes toward tourism impacts between two leading stakeholder groups in tourism, local residents and the managers of tourism facilities. It uses case study surveys of residents and managers in Belek, Antalya, Turkey. Differences in attitudes across seven main areas are investigated, including the positive and negative economic outcomes of tourism; positive and negative sociocultural impacts; negative environmental impacts; views on further tourism development, and benefits and problems related to forested land close to destinations. The results reveal that some attitudes are held in common – especially positive attitudes including tourism's benefits in creating jobs and income. Differences were mostly observed not in the direction but in the strength of opinion. The most significant differences were found in managers' beliefs that tourism's environmental and social impacts were few, while residents were extremely negative about those impacts. Differences of attitudes on the future use of forestland headed the list of all differences between managers and residents. Divergent loyalties were revealed. Managers supported their business and employers; local people supported their local area. The need for further research, including the role of perhaps distant “moral stakeholders”, and for more comprehensive understanding, and more sustainable outcomes, are highlighted.     

退耕还林条件下农民增收的新政治经济学分析——以冀西北为例

退耕还林工程,覆盖面广,投资多,农民参与程度高,对相关农民的收入影响深远。从新政治经济学的角度看,退耕还林属于公共物品,在退耕还林的过程中存在着政府双重垄断现象,农民具有明显的＂经济人＂属性。因此,若想实现生态目标,关键在于以增加农民收入为切入点,在政府和退耕农民之间建立起一种稳定的激励相容的契约关系：建立长期稳定的国家直接补贴制度;建立退耕生态林产权收购制度;培育农村新的经济增长点;提高退耕地区的教育水平。     

Amazon forest on the edge of collapse in the Maranhão State,Brazil

The year 2019 in Brazil was marked by environmental setbacks, which catalyzed the increase of illegal deforestation and fire rates in the Brazilian Amazon. In the Amazon region of Maranhão state, original forest cover diminished from 25 % (24,700 km²) in 2016 to 24 % (23,967 km²) in 2019, and 6,038 km² of remaining forests were degraded by fires and/or illegal logging – processes related to high levels of violence against indigenous and rural communities. Almost half of all deforested areas in the region (36,060 km²) are considered a global restoration hotspot, however secondary vegetation remains unprotected and 8,294 km² were cleared between 2014 and 2018. Due to uncontrolled deforestation and fragmentation, Maranhão has no more forest core areas (outside protected areas) with the minimum size to ensure sustainable forest management practices for timber production. New policies at the state level must promote old-growth and secondary forest conservation and restoration. However, the trends point to the opposite direction: the Ecological-Economic Zoning (ZEE) allows the reduction of forest protection and the State Forest Policy reinforces federal legislation setbacks. The Amazon region of Maranhão state has forest aptitude, and forest and agroforestry product chains would bring social and environmental benefits, making them the best opportunity for sustainable economic development in the region. Therefore, the forest must be re-planted for the benefit of people and nature.