Yunnan Pine forest: types and dynamics

The post provided by Cindy Q. Tang

This Behind the paper post refers to the article Forest characteristics, population structure and growth trends of Pinus yunnanensis in Tianchi National Nature Reserve of Yunnan, southwestern China, by Cindy Q. Tang, Li-Qin Shen, Peng-Bin Han, Diao-Shun Huang, Shuaifeng Li, Yun-Fang Li, Kun Song, Zhi-Ying Zhang, Long-Yun Yin, Rui-He Yin and Hui-Ming Xu, published in Vegetation Classification and Survey (https://doi.org/10.3897/VCS/2020/37980)

We heard the call of the pine trees.

We heard the call of the mountains.

We heard the call of the Yunlong Tianchi Lake.

After a long journey, our research team reached the land of Yunnan Pine (Pinus yunnanensis). It is the Tianchi National Nature Reserve, located between elevations 2100 to 3226 m a.s.l. in the Xuepan Mountains, Yunlong County, northwestern Yunnan, China.

Here millions of tall Yunnan Pine lie before the range upon range of green backdrop, the wild-flower embellishes multi-coloured earth.

Yunnan Pine is an evergreen coniferous species that can grow to mature heights over 30 m. Needles are two or three per bundle. Seed cones shortly pedunculate, green, maturing to brown or chestnut brown. Seeds with membranous wings are wind-dispersed. It is the most widely-distributed native tree species of Yunnan and an important constituent of its landscapes. However, virgin forests of this pine are extremely rare. The Tianchi National Nature Reserve is designated to protect old-growth and primary mature forests dominated by Yunnan Pine. It serves as a seed source and gene bank. The area of virgin forests of the pine accounts for 8710.2 ha of the nature reserve. Old-growth (reaching 165 years) or primary mature Yunnan Pine forests are found here, while in other areas of the subtropical zone of Yunnan, the pine is often found in early or intermediate-successional stands after the destruction of the evergreen broad-leaved forest by human activities or after forest fires. The nature reserve provides a unique opportunity to study old-growth Yunnan Pine forests as well as various other forest types.

Our research team is devoted to forest community ecology, and particularly to the mechanisms underlying the structure and dynamics of forests. Having studied the regeneration, recovery and succession of a Yunnan Pine community after a mega-fire in central Yunnan published in Forest Ecology and Management (Tang et al. 2013), our study on forest types, age classes, and growth trend, particularly the old-growth forest stands in the Tianchi National Nature Reserve, enables us to further understand the ecological role in succession and stand dynamics of Yunnan Pine forests. We are proud of our work as reported in Vegetation Classification and Survey (VCS) in 2020. Results from our article in VCS show that this pine is a light-demanding species that depends upon canopy gaps or disturbances for regeneration. It can mono-dominate a forest or co-dominate with diverse species in various mixed forests. The overstory dominance of Yunnan Pine over a wide range of forest types (i.e., coniferous forest; mixed coniferous and evergreen broad-leaved forest; mixed coniferous and deciduous broad-leaved forest; mixed evergreen broad-leaved and coniferous forest; mixed coniferous, evergreen and deciduous broad-leaved forest; mixed coniferous and evergreen broad-leaved forest) and elevations suggests that Yunnan pine plays an important role as an early successional species whose longevity assures presence in later successional stages. We discovered that trees of the older age-classes grew faster than younger trees at the same age in the Tianchi National Nature Reserve. This probably resulted from differences in stand development, such as the timing of canopy closure and the growth and development of competing species. It might also have resulted from differences in the aspect where Yunnan Pine’s light-demanding nature would result in better growth on southern rather than northern slopes. Differences in disturbance regimes such as landslide frequencies and intensities also may have impacted the growth pattern. Finally, rapid global climate changes over many decades appear as an additional important factor influencing growth.

References:

Tang, C.Q., He, L.-Y., Su, W.-H., Zhang, G.-F., Wang, H.-C., Peng, M.-C., Wu, Z.-L., & Wang, C.-Y. (2013). Regeneration, recovery and succession of a Pinus yunnanensis community five years after a mega-fire in central Yunnan, China. Forest Ecology and Management, 294, 188-196. https://doi.org/10.1016/j.foreco.2012.07.019

Brief personal summary: Cindy Q. Tang is a professor of plant ecology at Yunnan University, Yunnan Province, China. She specializes in forest community ecology and ecology of relict, endangered and rare plant species. She also focuses on the macroecology of plant diversity and vegetation in the light of climate change.