Comparative Study of Plant Diversity between Betula alnoides Plantations and Adjacent Natural Forests

Betula alnoides is one of the most important native, broadleaf timber species for plantation establishment in southwestern China. With the rapid expansion of plantations in the region, it is essential to understand the characteristics and dynamics of artificial B. alnoides communities for the sustainable development and management of these forests. We compared the species composition, richness, diversity, and structure between B. alnoides plantations of different age classes (3, 5, 8, and 13 yr old) and previous vegetation types (naturally regenerated B. alnoides secondary forest and tropical montane rainforest) in a northern tropical region in southwestern China. We established 3 basic sampling plots in each forest community (21 total plots, 20×20 m each) with a similar slope direction, grade, and position. The following results were attained. 1) The 8- and 13-yr-old B. alnoides plantations had higher species diversity than the native forest, a trait that can facilitate the development of plant species under the plantation canopy. 2) The species composition and richness of the B. alnoides plantations were significantly related to the previous vegetation type and land conditions before planting and showed a homologous and similar successional trend. 3) In B. alnoides plantations, the species richness significantly increased along with an increasing age of the plantation, and the species composition of the understory vegetation changed from pioneer species to shade-tolerant plants and sciophytes. 4) Betula alnoides can be used as an important reforestation tree species in tropical southwestern China.