Phenology, seed dispersal and regeneration patterns of Horsfieldia kingii, a rare wild nutmeg

We present observational data on the flowering and fruiting patterns, seed dispersal, seedling recruitment and survival of a dioecious Myristicaceae species, Horsfieldia kingii, that occurs in the tropical forests of Arunachal Pradesh. Horsfieldia is rare (1 tree ha1) with a scattered distribution; Horsfieldia trees did not flower every year, and flowering was staggered from April to July. Peak ripe fruit availability of Horsfieldia is from February to March. Failure of fruiting occurred in most years, and only 0-33% of sampled trees bore ripe fruits. Initiation of hornbill breeding coincides with the ripe fruit availability of this species. The percentage of hornbill nests in which nesting is initiated each year varies from 50 to 100% of nests, and our results show a significant positive relationship between the percentage of hornbill nests that are active in a given year and the contribution of the species to hornbill diet (n = 6 years). However, the overall contribution to the breeding season diet of hornbills is very low because of poor fruit availability in most years, resulting in limited seed dispersal at nests. Recruitment and survival of Horsfieldia seedlings below parent trees and hornbill nest trees were low; however, seedling survival was marginally higher at nest trees, suggesting that dispersal by hornbills even in a spatially contagious manner may be critical for this species. However, current recruitment of Horsfieldia at hornbill nests (2010) is significantly lower than at parent trees. This species appears to be seed-limited, while dispersal limitation may play a secondary role in determining its abundance.