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bioRxiv · 10.1101/619981

Factors affecting the survival of tree seedlings following shifting cultivation in the Eastern Himalaya

Teegalapalli, K.·Arthur, R.·Quader, S.·Datta, A.
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Abstract

O_LIThe seedling stage is considered an important bottleneck determining forest community composition during succession. Seedling growth and survival are known to be affected by factors such as light availability, herbivory and competition with existing vegetation. A shifting cultivation landscape with a cycle of clearing and regeneration provides an experimental setup to understand secondary succession.\nC_LIO_LIWe introduced tree seedlings of three species with differing life history strategies in an uncut forest and in sites formed 2, 6, 12, 25, 50 and 100 years following shifting cultivation in a subtropical landscape in the Eastern Himalaya. Seedlings of a pioneer species Saurauia nepalensis, a mid-successional species Terminalia myriocarpa and a mature forest species Castanopsis indica were introduced in plots with a control and three treatments: shading (light manipulated), clearing of vegetation (reduced competition), and exclosures (mammal herbivory excluded) and monitored for 18, 22 and 23 months, respectively.\nC_LIO_LISaurauia survived relatively well in all sites, Terminalia seedlings survived relatively well in the 12 and 25 year sites, and Castanopsis seedlings survived well in the 100 year site and the uncut forest. In the early successional site, survival of Saurauia was higher within exclosures indicating negative effects of herbivory. In the same site, clearing vegetation improved the survival of Terminalia, implying competition with existing vegetation. Castanopsis had the highest survival in uncut forest and survival was almost nil in the early successional site.\nC_LIO_LISynthesis: Seedling survival in a successional landscape depended on species-as well as site-specific factors. The existing vegetation in an early successional site had a negative effect on the survival of the mid-successional species, while herbivory had a negative effect on the pioneer species. Survival of the mature forest species in the early successional site was negligible but was high in old successional and uncut forest sites, indicating that mature forest species can colonize sites and survive only after certain physical and biotic aspects of the environment have been met. Our experiments were useful to examine factors that affect survival of tree species with differing life history strategies in a shifting cultivation landscape.\nC_LI

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Teegalapalli, K., Arthur, R., Quader, S., Datta, A.. 2019-04-26. Factors affecting the survival of tree seedlings following shifting cultivation in the Eastern Himalaya. https://doi.org/10.1101/619981

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