Tropical forest restoration in the Eastern Himalaya: Evaluating early survival and growth of native tree species

Asian tropical forests have among the highest rates of forest loss in the
world. Ecological restoration is a vital step for biodiversity maintenance
and climate change mitigation. For restoration practice, evaluation of
species performance at early stages is crucial to avoid failure of the
efforts and for screening species suitable to a region. Though the
long-term performance of restoration plantings has been well-documented,
few studies have evaluated the performance during the establishment of the
planted saplings, especially in South and Southeast Asia. Restoration
efforts in Northeast India, a region experiencing high forest loss, is
limited by the lack of species-specific data on survival and growth. We
compared inter-specific variation in seasonal survival and growth rates
(diameter and height) for multiple native rainforest species from this
region. We planted 3022 saplings of 50 species at a degraded open forest
site. After 18 months, sapling survival varied between 9.1–94.3% for 32
species, and only six species showed “excellent” survival after 18 months.
Eight out of 17 species that were tested for seasonal variation in
survival showed significant differences in survival between seasons. While
the diameter growth rate varied for species between seasons, the height
growth rate was different between both species and season, but the
interaction term between species and season was not significant. Certain
animal-dispersed, medium to large-seeded primary forest species performed
well and are vital for future restoration efforts in this region.