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With the continuous development of socialist market economy, more and more enterprises use digital technology to realize digital transformation. Digital transformation has an important impact on enterprise R&D and innovation. Based on the data of Shanghai and Shenzhen A-share listed companies from 2016 to 2020, this paper empirically tests the impact of enterprise digital transformation on R&D innovation. It is found that digital transformation has a significant positive impact on R&D innovation, and the degree of this impact is related to regional differences and the nature of equity. Digital transformation has a more significant impact on enterprise R&D innovation in high marketization areas. This effect is generally significant in areas with low degree of marketization, but the degree of influence is lower than that in areas with high degree of marketization. The digital transformation of non-state-owned enterprises has a more significant impact on R&D innovation; The influence of state-owned enterprises on the whole is significant, but the influence degree is lower than that of non-state-owned enterprises. Therefore, it is a feasible path to enhance the level of enterprise R&D innovation and strengthen digital investment to realize the digital transformation of enterprises. The government should also support the digital transformation of enterprises according to the location and nature of enterprises.

In the European Union, the 2020 Climate & Energy Package and 2030 Climate & Energy Framework envisaged gains in energy efficiency and reduction in the greenhouse gas emissions in order to ensure sustainable development of the economy. However, the European Union Member States differ in their energy systems and level of economic development. In this context, the paper seeks to identify the possible outcomes of increase in the production of cleaner energy in the major European Union countries. This provides evidence on the possible energy-mix across different European Union Member States. The study applied the Pinch Analysis in order to identify the energy-mix for electricity generation which corresponds to the goal of the GHG emission reduction of major electricity producers in Europe taking into account the possible promotion of the different types of RES. The countries chosen for the analysis include Poland, the Netherlands, Germany, Italy, the United Kingdom, Spain, France and Sweden. The carried out Pinch Analysis revealed the possible pathways for increasing the penetration of specific types of renewables in selected countries which may lead to GHG emission reduction.

The maintenance of a timely, reliable and accurate spatial database on current forest ecosystem conditions and changes is essential to characterize and assess forest resources and support sustainable forest management. Information for such a database can be obtained only through a continuous forest inventory. The National Forest Continuous Inventory (NFCI) is the first level of China's three-tiered inventory system. The NFCI is administered by the State Forestry Administration; data are acquired by five inventory institutions around the country. Several important components of the database include land type, forest classification and ageclass/ age-group. The NFCI database in China is constructed based on 5-year inventory periods, resulting in some of the data not being timely when reports are issued. To address this problem, a forest growth simulation model has been developed to update the database for years between the periodic inventories. In order to aid in forest plan design and management, a three-dimensional virtual reality system of forest landscapes for selected units in the database (compartment or sub-compartment) has also been developed based on Virtual Reality Modeling Language. In addition, a transparent internet publishing system for a spatial database based on open source WebGIS (UMN Map Server) has been designed and utilized to enhance public understanding and encourage free participation of interested parties in the development, implementation, and planning of sustainable forest management.

We studied the effect of freezing-thawing on nitrogen (N) mineralization of four vegetation soils from typical vegetation zones of Changbai Mountain with a laboratory incubation experiment. The soils were treated with two levels of soil water content, representing the low and high soil water contents found during late autumn and early spring in Changbai Mountain, respectively, and underwent cycling of freezing at −5 or −25°C and thawing at 5°C up to 15 times. The main purpose of this study was to examine the effects of freezing temperature, frequency of freezing-thawing cycles, and soil water content on N mineralization of four soils to reveal the different effects of spring and autumn freezing-thawing on soil N mineralization in Changbai Mountain. The results showed that inorganic N in the soils increased 1.67–26.77 times after 15 cycles of freezing-thawing, but N mineralization rate decreased with increased cycling of freezing-thawing. The lower freeze temperature and higher soil water content generally enhanced soil N mineralization. The results implied that freezing-thawing of vegetation soils to increase soil N mineralization to favor the growth of plants, and also increase the possibility of runoff loss of soil nutrients, is more effective in the spring than in the autumn.

Long-term ecological studies are essential for understanding the dynamics of natural systems. However, describing long-term dynamics in old-growth forests is often hindered by a lack of archival data. In this study, we investigated (1) changes in forest structure and tree species composition and (2) population dynamics of the dominant tree species over a 29-year period (1981–2010) in two old-growth forests with stand ages exceeding 200 years on Changbai Mountain in Northeast China. Results showed that the stem density of the broad-leaved/conifer mixed forest at 740 m asl increased slightly from 510 to 515 trees per hectare and the total basal area increased significantly from 36.19 to 46.53 m2 ha−1, suggesting that the forest was still maturing over the study period. However, the coniferous forest at 1,680 m asl displayed structural changes in the form of a significantly decrease in both stem density and total basal area over the study period. No changes in tree species composition in the two forests were observed. Wind was considered to be a frequent natural disturbance affecting the forest structure and dynamics, especially for the coniferous forest at the higher altitude. Dominant tree species in the two forests exploited different biological characteristics in maintaining their respective populations.