Chul Hee Lim

Impact of thinning intensity on the diameter and height growth of Larix kaempferi stands in central Korea

The objective of this study was to examine the effect of thinning intensity on the diameter at breast height (DBH) and height growth of Japanese larch (Larix kaempferi) stands located in the Yangpyeong-gun region of central Korea. In addition, a growth model was developed from the thinning practice. Four sample plots were prepared separately and thinned at different intensities (0%, 10%, 20%, and 40% cutting based on the number of trees, respectively) in 1997. DBH and height of individual trees were measured independently in 1997 and 2009. The mean DBH for LT00, LT01, LT02, and LT03 increased from 12.0, 12.1, 12.0, and 12.7 cm in 1997 to 15.3, 16.1, 16.2, and 17.1 cm in 2009, respectively. In addition, the mean height for each plot increased from 11.9, 13.5, 13.6, and 12.0 m in 1997 to 17.0, 17.0, 17.1, and 18.1 m in 2009, respectively. Thinning intensity was found to have a significant positive effect on DBH growth (P < 0.05), whereas there was no definite effect on height growth (P > 0.05). This result can be attributed to the fact that thinning promotes DBH growth by reducing horizontal-spacing competition between neighboring trees for securing sunlight and growing space. The developed growth model with our results showed a high degree of reliability (R2 = 0.86) and could generalize the thinning intensity based on DBH growth.

Long-term trend and correlation between vegetation greenness and climate variables in Asia based on satellite data

Satellite data has been used to ascertain trends and correlations between climate change and vegetation greenness in Asia. Our study utilized 33-year (1982-2014) AVHRR-GIMMS (Advanced Very High Resolution Radiometer - Global Inventory Modelling and Mapping Studies) NDVI3g and CRU TS (Climatic Research Unit Time Series) climate variable (temperature, rainfall, and potential evapotranspiration) time series. First, we estimated the overall trends for vegetation greenness, climate variables and analyzed trends during summer (April to October), winter (November to March), and the entire year. Second, we carried out correlation and regression analyses to detect correlations between vegetation greenness and climate variables. Our study revealed an increasing trend (0.05 to 0.28) in temperature in northeastern India (bordering Bhutan), Southeast Bhutan, Yunnan Province of China, Northern Myanmar, Central Cambodia, northern Laos, southern Vietnam, eastern Iran, southern Afghanistan, and southern Pakistan. However, a decreasing trend in temperature (0.00 to -0.04) was noted for specific areas in southern Asia including Central Myanmar and northwestern Thailand and the Guangxi, Southern Gansu, and Shandong provinces of China. The results also indicated an increasing trend for evapotranspiration and air temperature accompanied by a decreasing trend for vegetation greenness and rainfall. The temperature was found to be the main driver of the changing vegetation greenness in Kazakhstan, northern Mongolia, Northeast and Central China, North Korea, South Korea, and northern Japan, showing an indirect relationship (R=0.84-0.96).

Assessing vulnerability of forests to climate change in South Korea

This study demonstrated a framework to assess vulnerability of forests to climate change. We focused on how alterations of temperature and precipitation might affect forest type distributions and carbon-related functions. In particular, our framework considered three sectors of forest type distribution, net primary production, and soil carbon storage. Future projections were derived from mechanistic models for South Korean forests under the A1B scenarios of the intergovernmental panel on climate change. Forest type distributions were simulated by the Hydrological and thermal analogy group model, while the MAPSS and CENTURY1 models estimated forest carbon flux/storage. We quantified normalized vulnerability indices for each sector. Our results indicate that the overall vulnerability of forest type distribution is greater in the west central regions and southeastern inlands. The vulnerabilities of carbon flux/storage show that net primary production of South Korean forests is relatively less susceptible to climate change, but a highly vulnerable area of soil carbon storage mainly spreads from the west central to the south east region. The spatio-temporal vulnerability map with a synoptic overview from this study might be useful for policy makers in preparing adaptive measures and identifying management priorities.

Long-term trend of and correlation between vegetation greenness and climate variables in Asia based on satellite data

Graphical abstract