Xinchuang Wang

Application of China's National Forest Continuous Inventory database.

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.

Forest Biomass Dynamics in Typical Changbai Mountain Forest Area, Northeast of China

Quantifying forest biomass dynamics accurately is important not only to understanding the role of forests in global climate change but also to finding out key causes of the changes in order to enhance the carbon sequestration capacity of forest vegetation. Here, we investigated 210 sample plots to establish biomass-volume models suitable for Luishuihe forest area in Changbai Mountain. Based on the models and forest resource inventory data for management, the forest biomass in Lushuihe in 1987, 1995 and 2003 were estimated. The results showed that the forest biomass decreased from 1.599×107 Mg in 1987 to 1.499×107 Mg in 1995, and then increased to 1.559×107 Mg in 2003. And the forest biomass density in 1987, 1995 and 2003 was 153.553, 135.747 and 136.205 Mg ha-1, respectively. Both of the forest biomass and biomass density first decreased, and then increased. Such temporal dynamics on forest biomass corresponded well to the changes in Chinese forest policy. And the changes of forest management measures affected the distribution of forest biomass for different forest groups, different age classes and different origin. Accordingly we presented forest management recommendations for the forest managers in the study area.

Forest Landscape 3-D Visualization from China's National Forest Inventory Spatial Database

China has conducted a national forest continuous inventory system for sustainable forest management and large forest inventory spatial databases about tree factors and ecological condition have been built during the inventory work. Digital maps generated from GIS are planar and abstract, while explicit and realistic three-dimensional landscape visualization is much more intuitional and appealing to researchers and other users. Forest landscape visualization can be used to visualize forest structure, dynamics, landscape transformations and regional plans. A three-dimensional virtual reality system of forest landscapes from the inventory database for selected units (compartment or sub-compartment) has been developed based on Virtual Reality Modeling Language (VRML). ArcGIS Engine and C# was used get stand structure from the database and the terrain was modeled from the DEM. Our study shows that it is appropriate to use forest spatial database for stand and landscape level visualization and it will benefit the decision-making in forest management.

A Compact High-Accuracy Rail-to-Rail CMOS Operational Amplifier

A compact high-accuracy rail-to-rail CMOS operational amplifier (Op-Amp) is presented using strong inversion techniques to achieve power consumption of 90µW under 1.8V supply voltage. Two complementary differential pair techniques and one-versus-three current mirror compensation techniques are adopted to realize wide input dynamic range, while the output stage provides rail-to-rail output drive through the use of resistor-compensation circuits (RCC) and self-regular circuits (SRC). Simulation results demonstrated that the active area is only 0.001mm2 and the transconductance variation can be restricted to ±±5% hence the accurate of common-mode rang (99.9%) was improved as well as the total harmonic distortion.

Carbon Storage and Density of Forest Ecosystems in Heilongjiang Province, China

Accurately estimating carbon storage for forest ecosystems is important for understanding the role of forests in global warming and also in supporting decision-making processes in forest management. Using forest inventory data in combination with field data, we explored characteristics of carbon storage, density, and distribution for different forest ecosystems and their components in Heilongjiang Province, Northeast China. Results showed that total carbon storage was 4125.002 Tg C. The soil layer accounted for the most storage with 3205.764 Tg C or 77.7% of the total. This was followed by the canopy, litter, and shrub-grass layers with 800.965 (19.4%), 106.568 (2.6%), and 11.705 Tg C (0.3%), respectively. The average carbon density of forest ecosystems was 215.816 Mg C ha^(-1), with the soil layer (167.722 Mg C ha^(-1)) the densest, followed by the canopy layer (41.906 Mg C ha^(-1)), litter (5.576 Mg C ha^(-1)), and shrub layers (0.612 Mg C ha^(-1)). Carbon storage in different forest ecosystems varied 37.87~1306.63 Tg C, while C density ranged 167.68~256.87 Mg C ha^(-1), with the highest and lowest values observed in the soil and shrub-grass layers, respectively. That implies that the soil is the main body for forest carbon storage. The methods and data used for forest carbon storage estimation obviously affected results of the estimates. Rational methods should be adopted based on obtaining sufficient data for estimates. Middle-aged forests accounted for a greater proportion of forests in the province than forests in other age classes, and proper management of forests could increase the carbon sequestration of forest ecosystems.

Spatiotemporal Variations in Biomass Carbon Storage for Three Forest Management Regimes in Northeast China

Forests, which account for 76~98% of terrestrial plant carbon and 2/3 of terrestrial carbon sequestration in the world every year, can store or release large amounts of carbon as a result of natural environmental variability and human activities. Quantifying the spatiotemporal dynamics of forest biomass carbon storage is important not only for understanding the role of forests in global warming but also in supporting decision-making processes in forest management. We established biomass-volume models utilizing investigation data of sample plots in the Luishuihe forest area of Northeast China. Based on the models and a forest resource inventory database, forest biomass carbon storage at Lushuihe in 1987, 1995, and 2003 was estimated and mapped in a geographic information system (GIS). The forest biomass carbon storage in areas with 3 different management regimes during different time periods was also obtained based on area maps and maps of carbon storage in the GIS. The results showed that both carbon storage and density first decreased between 1987 and 1995, and then increased between 1995 and 2003. Such temporal dynamics of forest biomass carbon storage corresponded well to changes in Chinese forest policies. Forest biomass carbon storage and density of natural forests in key ecological welfare forest (EWF) areas, where harvesting is prohibited, steadily increased between 1987 and 2003 due to the prohibition of timber harvesting. Decreases in forest biomass carbon storage and density of natural forests in ordinary EWF areas, where harvesting is allowed under certain presumably beneficial conditions, were much less from 1995 to 2003 than from 1987 to 1995 due to decreased timber harvesting. In commodity forest (CoF) areas these decreases in natural forests were also less from 1995~2003 than 1987~1995 due to decreased timber harvesting. The area and biomass carbon storage of plantations in the 3 areas steadily increased between 1987 and 2003. The rate of decrease of carbon density in CoF areas was even less than that in local EWF areas because the area and carbon storage of fast-growing plantations in CoF areas were much greater than these in local EWF areas from 1995 to 2003.

Carbon Sequestration in Old-Growth Forest and Plantations on Changbai Mountain in Northeast China

Forest management can significantly impact carbon sequestration, which has been a key focus of research topic in relation to climate change at various scales. Based on field data collected from old-growth forests and forest plantations in Lushuihe Forestry Bureau on Changbai Mountain in northeast China, we compared carbon pools of vegetation (arbor, shrub and herbage), woody debris (WD), and soil (0-100cm depth) among different types of forests. Our results showed that arbor carbon increased with the age of larch plantations on Changbai Mountain; however, soil carbon declined with age. WD stored more carbon than did shrub or herbage, especially in old-growth forests. Carbon sequestration in old-growth forests was higher than that in forest plantations. Carbon storage in 35-year-old plantations was about 220.83 Mg• ha-1, still less than carbon storage in old-growth forests 341.27 Mg• ha-1. Accordingly, we suggested that plantation rotation age should be lengthened to at least 35 years for maximizing forest carbon sequestration in the forest landscapes on Changbai Mountain.

The Dynamics of Forest Landscape Pattern in Lushuihe on Changbai Mountain

Changbai Mountain is one of the most important area in northeast of China where large area of temperate forests distribute. Lushuihe Forestry Bureau, located in the center of the region, was selected as a study site. We calculated the areas of different forest landscapes and selected MPS and CONTAG landscape indexes to carry out landscape pattern analysis for Lushuihe from 1987 to 2003 based on forest inventory data and GIS. The results showed that forest landscape in Lushuihe during 1987-1995 was more fragmented than that during 1995-2003 as a result of different logging styles and forestry managements, especially after National Forest Conversation Program (NFCP) in 1998. But the forest ecosystem in Lushuihe is still vulnerable. How to keep the integrity of forest landscape should be taken more considerations in future ecosystem management in order to realize sustainable forestry.