Abstract:

The mixed broadleaved-Korean pine (Pinus koraiensis) forest (MBKF) represents the climax vegetation type of the eastern mountainous area of Northeast China. It is divided into three categories according to community structure and species composition, including southern MBKF, typical MBKF, and northern MBKF. To monitor long-term dynamics of the typical MBKF, we established a 9-ha plot following the field protocol of the 50 ha plot in Panama (Barro Colorado Island, BCI) in 2005 in Liangshui National Nature Reserve of Heilongjiang Province. All free-standing plant species with DBH (diameter at breast height) ≥1 cm were mapped, tagged, and identified to species in the plot. In the 2010 census, we documented 48 woody species with 21,355 individuals, belonging to 34 genera and 20 families. Most of the species belong to the Changbai Mountain plant flora, with a minor subtropical plant species component. The DBH distribution of all individuals showed a reversed “J” type, indicating well regenerated for the community. The DBH distribution for the canopy, sub-canopy, and middle layers and the understory layer showed the reversed “J” and “L” distributions, respectively. The DBH pattern of the nine dominant species can be classified into three categories: approximate normal, reversed “J”, and “L” distribution. Spatial pattern analysis showed that the major tree species were aggregated, and aggregation intensity decreased as DBH increased. Further analysis showed that spatial distribution was closely related to topography and varied with DBH classes. For example, the distribution of Pinus koraiensis and Tilia amurensis was significantly affected by topography (P < 0.05); however, the distribution of Abies nephrolepis, Acer ukurunduense, and Ulmus laciniata correlated significantly with topography at diameter classes of I (DBH < 10 cm) and II (10 cm ≤ DBH < 30 cm). The distribution of Betula costata and Acer tegmentosum was also significantly correlated with topography at a diameter class I (P < 0.05). Overall, the impact of the topographic gradient on species distribution decreased significantly as DBH class increased.

Key words: Liangshui National Nature Reserve, mixed broadleaved-Korean pine forest, species composition, size class structure, spatial distribution