Bernard J. Lewis

Variation in carbon storage and its distribution by stand age and forest type in boreal and temperate forests in northeastern China.

The northeastern forest region of China is an important component of total temperate and boreal forests in the northern hemisphere. But how carbon (C) pool size and distribution varies among tree, understory, forest floor and soil components, and across stand ages remains unclear. To address this knowledge gap, we selected three major temperate and two major boreal forest types in northeastern (NE) China. Within both forest zones, we focused on four stand age classes (young, mid-aged, mature and over-mature). Results showed that total C storage was greater in temperate than in boreal forests, and greater in older than in younger stands. Tree biomass C was the main C component, and its contribution to the total forest C storage increased with increasing stand age. It ranged from 27.7% in young to 62.8% in over-mature stands in boreal forests and from 26.5% in young to 72.8% in over-mature stands in temperate forests. Results from both forest zones thus confirm the large biomass C storage capacity of old-growth forests. Tree biomass C was influenced by forest zone, stand age, and forest type. Soil C contribution to total forest C storage ranged from 62.5% in young to 30.1% in over-mature stands in boreal and from 70.1% in young to 26.0% in over-mature in temperate forests. Thus soil C storage is a major C pool in forests of NE China. On the other hand, understory and forest floor C jointly contained less than 13% and <5%, in boreal and temperate forests respectively, and thus play a minor role in total forest C storage in NE China.

The progress and challenges in sustainable forestry development in China

Forestry development in China has undergone a series of reforms over the past six decades. This article examines temporal changes in forest resources and policies, the current status of forestry, and future challenges toward sustainable forest management in China. Excessive logging in the 1950s to 1980s badly damaged the nation’s forests, but the adoption of enlightened forest policies in the late 1990s has led to increases in China’s total forest area and growing stock. Forest degradation was ecologically and economically costly, and rehabilitation processes have become increasingly more expensive. The low quality and young age of forest resources, loss of natural forests, and more difficulties in afforestation and reforestation pose severe challenges for China’s sustainable forestry. It is critically important for China to enhance forest productivity through intensive management, strengthen enforcement, and educational programs for protecting and restoring natural forests, narrow the gap between domestic timber supply and rapidly expanding consumption, improve coordinating networks for management, finance, and technology transfer, and accelerate efforts to clarify and stabilize tenure arrangements for non-state forests. China’s experience and lessons in forestry may be helpful for other developing countries that are seeking to achieve the goal of sustainable forest management.

Major Forest Types and the Evolution of Sustainable Forestry in China

In this article, we introduce China’s major forest types and discuss the historical development of forest management in China, including actions taken over the last decade toward achieving SMF. Major challenges are identified, and a strategy for SFM implementation in China is presented. China’s forests consist of a wide variety of types with distinctive distributional patterns shaped by complex topography and multiple climate regimes. How to manage this wide array of forest resources has challenged forest managers and policy-makers since the founding of the country. Excessive exploitation of Chinas forest resources from the 1950s to the late 1990s contributed to environmental problems and calamities, such as floods, soil erosion, and desertification. At the start of the new millennium, the Chinese government decided to shift its emphasis from timber production towards the achievement of sustainable forest management (SFM). With a series of endeavors such as the implementation of the “Six Key Forestry Projects” and the reform of forest tenure policies, and the adoption of a classification system for Chinas forests, a beginning has been made at reversing the trend of environmental degradation that occurred throughout the latter half of the last century. At the same time, huge challenges remain to be tackled for the development of forestry in China.

Effects of experimentally-enhanced precipitation and nitrogen on resistance, recovery and resilience of a semi-arid grassland after drought

Resistance, recovery and resilience are three important properties of ecological stability, but they have rarely been studied in semi-arid grasslands under global change. We analyzed data from a field experiment conducted in a native grassland in northern China to explore the effects of experimentally enhanced precipitation and N deposition on both absolute and relative measures of community resistance, recovery and resilience—calculated in terms of community cover—after a natural drought. For both absolute and relative measures, communities with precipitation enhancement showed higher resistance and lower recovery, but no change in resilience compared to communities with ambient precipitation in the semi-arid grassland. The manipulated increase in N deposition had little effect on these community stability metrics except for decreased community resistance. The response patterns of these stability metrics to alterations in precipitation and N are generally consistent at community, functional group and species levels. Contrary to our expectations, structural equation modeling revealed that water-driven community resistance and recovery result mainly from changes in community species asynchrony rather than species diversity in the semi-arid grassland. These findings suggest that changes in precipitation regimes may have significant impacts on the response of water-limited ecosystems to drought stress under global change scenarios.

Effect of freezing-thawing on nitrogen mineralization in vegetation soils of four landscape zones of Changbai Mountain

Abstract• IntroductionWe 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.• ObjectivesThe 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.• ResultsThe 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.

Biomass carbon storage and its sequestration potential of afforestation under natural forest protection program in China

Based on the data from China’s Seventh Forest Inventory for the period of 2004–2008, area and stand volume of different types and age-classes of plantation were used to establish the relationship between biomass density and age of planted forests in different regions of the country. Combined with the plantation area in the first-stage of the Natural Forest Protection (NFP) program (1998–2010), this study calculated the biomass carbon storage of the afforestation in the first-stage of the program. On this basis, the carbon sequestration potential of these forests was estimated for the second stage of the program (2011–2020). Biomass carbon storage of plantation established in the first stage of the program was 33.67 Tg C, which was majority accounted by protection forests (30.26 Tg C). There was a significant difference among carbon storage in different regions, which depended on the relationship of biomass carbon density, forest age and plantation area. Under the natural growth, the carbon storage was forecasted to increase annually from 2011 to 2020, reaching 96.03 Tg C at the end of the second-stage of the program in 2020. The annual growth of the carbon storage was forecasted to be 6.24 Tg C/yr, which suggested that NFP program has a significant potential for enhancing carbon sequestration in plantation forests under its domain.

Forest carbon storage and tree carbon pool dynamics under natural forest protection program in northeastern China

The Natural Forest Protection (NFP) program is one of the Six Key Forestry Projects which were adopted by the Chinese Government since the 1980s to address important natural issues in China. It advanced to protecting and restoring the structures and functions of the natural forests through sustainable forest management. However, the role of forest carbon storage and tree carbon pool dynamics since the adoption of the NFP remains unknown. To address this knowledge gap, this study calculated forest carbon storage (tree, understory, forest floor and soil) in the forest region of northeastern (NE) China based on National Forest Inventory databases and field investigated databases. For tree biomass, this study utilized an improved method for biomass estimation that converts timber volume to total forest biomass; while for understory, forest floor and soil carbon storage, this study utilized forest type-specific mean carbon densities multiplied by their areas in the region. Results showed that the tree carbon pool under the NFP in NE China functioned as a carbon sink from 1998 to 2008, with an increase of 6.3 Tg C/yr, which was mainly sequestrated by natural forests (5.1 Tg C/yr). At the same time, plantations also acted as a carbon sink, reflecting an increase of 1.2 Tg C/yr. In 2008, total carbon storage in forests covered by the NFP in NE China was 4603.8 Tg C, of which 4393.3 Tg C was stored in natural forests and 210.5 Tg C in planted forests. Soil was the largest carbon storage component, contributing 69.5%–77.8% of total carbon storage; followed by tree and forest floor, accounting for 16.3%–23.0% and 5.0%–6.5% of total carbon storage, respectively. Understory carbon pool ranged from 1.9 to 42.7 Tg C, accounting for only 0.9% of total carbon storage.

Estimates of Forest Biomass Carbon Storage in Liaoning Province of Northeast China: A Review and Assessment

Accurate estimates of forest carbon storage and changes in storage capacity are critical for scientific assessment of the effects of forest management on the role of forests as carbon sinks. Up to now, several studies reported forest biomass carbon (FBC) in Liaoning Province based on data from Chinas Continuous Forest Inventory, however, their accuracy were still not known. This study compared estimates of FBC in Liaoning Province derived from different methods. We found substantial variation in estimates of FBC storage for young and middle-age forests. For provincial forests with high proportions in these age classes, the continuous biomass expansion factor method (CBM) by forest type with age class is more accurate and therefore more appropriate for estimating forest biomass. Based on the above approach designed for this study, forests in Liaoning Province were found to be a carbon sink, with carbon stocks increasing from 63.0 TgC in 1980 to 120.9 TgC in 2010, reflecting an annual increase of 1.9 TgC. The average carbon density of forest biomass in the province has increased from 26.2 Mg ha−1 in 1980 to 31.0 Mg ha−1 in 2010. While the largest FBC occurred in middle-age forests, the average carbon density decreased in this age class during these three decades. The increase in forest carbon density resulted primarily from the increased area and carbon storage of mature forests. The relatively long age interval in each age class for slow-growing forest types increased the uncertainty of FBC estimates by CBM-forest type with age class, and further studies should devote more attention to the time span of age classes in establishing biomass expansion factors for use in CBM calculations.

Antithetical effects of nitrogen and water availability on community similarity of semiarid grasslands: evidence from a nine-year manipulation experiment

AimsTheoretical and observational studies have suggested that environmental variations would change compositional similarity between plant communities. However, this topic has rarely been examined via experiments involving direct manipulation of resources utilized by plant communities.MethodsA 9-year field manipulation experiment was conducted to examine the effects of nitrogen addition and increased water on community similarity between a steppe and an old field in the semiarid region of northern China.ResultsOver the experimental period, nitrogen addition reduced community similarity between the steppe and the old field, whereas water addition enhanced community similarity. These treatment effects were closely related to changes in diversity characteristics as well as abundance of functional groups and dominant species of plant communities.ConclusionsThese results highlight the importance of resource availability in regulating the trajectory of ecosystem succession, and suggest that the increase in atmospheric nitrogen deposition in northern China will contribute to divergence between the steppe and the old field, whereas the increase in growing-season precipitation may encourage convergence between the two grasslands with respect to species composition during succession. Thus the decrease in community similarity caused by nitrogen enrichment may be counteracted, at least partially, by precipitation increase under changing atmosphere and climate.

The trend of land-use sustainability around the Changbai Mountain Biosphere Reserve in northeastern China: 1977–2007

Extensive land-use and land-cover change, triggered by rapid development of tourism and the expansion of townships, has occurred in the area surrounding the Changbai Mountain Biosphere Reserve (CMBR) in northeast China, a reservoir for distinctive ecosystems and biological diversity. The objective of this study was to examine the land-use changes surrounding the reserve in the context of forest and nature reserve management with the aid of maps from Landsat MSS imagery of 1977 and Landsat TM imagery of 1991 and 2007. The total land area and its change over time for each land-use class were calculated and cell-by-cell change data were used to detect, quantify, and determine the trends in land-use conversions. Results showed that there were large increases in land area for residential, commercial, industrial, and transportation land-use types, whereas the forest area decreased considerably. At the same time, the area under jurisdiction of townships has nearly doubled, with the largest increase in Manjiang. Land-use change was caused by regional population growth as a result of tourism development that triggered the expansion of township boundaries and contributed to shifts in forest management policy. Our study offers land and reserve managers within the CMBR and similar areas a basis for making more informed land-use and management decisions to potentially minimize detrimental ecological impacts of land-use change.