Development of the Vegetation Lower Layer under the Tropical Forest Canopy in Vietnam

The article presents the study results of natural regeneration of tree species on post-agrogenic lands and lands of former settlements in Vietnam. The experiment was carried out on the lands of the Cuc Phuong National Park, previously affected by management impact. Two experimental sites were selected: lands of former settlements and post-agrogenic lands. Methods developed by the Vietnamese scientists, as well as by the staff of the Forestry Department of the Saint-Petersburg State Forest Technical University have been used when laying out study plots, carrying out research, and processing the results. The studies have revealed that the undergrowth composition on the lands of former settlements is relatively complex. The number of species presented in the undergrowth composition ranges from 2 to 9. These species are pioneers at the initial stage of woody vegetation recovery on the lands of former settlements and they are of great environmental importance, though have a short life cycle. Species having a long life cycle are also found in the undergrowth. They are usually light-demanding, fast-growing and competitive with the other species for nutrients and light. In adulthood, they are presented in the stand composition. The presence of thesespecies increases the tree species diversity and broadly improves the stability of plantation. The undergrowth composition on the post-agrogenic lands is relatively simple. The number of species presented in it varies from 2 to 4, which is twice lower, than on the former settlements lands. These plants have a short life cycle, little economic value and low ability to compete for light and nutrients. Species that have a long life cycle are absent on the post-agrogenic lands. Viable and high undergrowth of seed origin prevails both on the lands of former settlements and on post-agrogenic lands. At both sites, the species diversity of the live ground coverand shrub layer is small and pretty much the same. The live ground cover is represented by herbs and sub-shrubs, and the shrub layer – by shrubs. These are light-demanding and fastgrowing species. The average projective coverage of live ground cover and shrub layer in both sites exceeds 85 %, which complicates the development of woody species undergrowth. In general, undergrowth, live ground cover, and shrub layer on the lands of former settlements are more diverse in terms of species composition and structure, than on the post-agrogenic lands. However, the density of the undergrowth in both areas is insufficient for the formationof further highly productive tropical phytocenosis. In this regard, it is necessary to carry out assistance measures for the subsequent successful reforestation on both types of lands.For citation: Beliaeva N.V., Nguyen Thi Thu Huong, Danilov D.A., Gryazkin A.V. Development of the Vegetation Lower Layer under the Tropical Forest Canopy in Vietnam. Lesnoy Zhurnal [Russian Forestry Journal], 2019, no. 6, pp. 39–51. DOI: 10.17238/issn0536-1036.2019.6.39