The regeneration of many climax species in tropical forest critically depends on adequate seed dispersal and seedling establishment. Here, we report the decreased abundance and increased spatial aggregation of younger trees of the Borneo ironwood (Eusideroxylon zwageri) in a protected forest in Sabah Malaysia. We observed a high level of seedling herbivory with strong density dependence, likely exacerbated by local aggregation and contributing to the progressively shrinking size distribution. We also note the largely undocumented selective herbivory by sambar deer on E. zwageri seedlings. This study highlights the combined impact of altered megafauna community on a tree population through interlinked ecological processes and the need for targeted conservation intervention for this iconic tropical tree species.

12The regeneration of many climax species in tropical forest critically depends on adequate seed 13 dispersal and seedling establishment. Here we report the decreased abundance and increased 14 spatial aggregation of younger trees of the Borneo ironwood (Eusideroxylon zwageri) in a 15 protected forest in Sabah Malaysia. We observed a high level of seedling herbivory with strong 16 density dependence, likely exacerbated by local aggregation and contributing to the 17 progressively shrinking size-distribution. We also note the largely undocumented selective 18 herbivory by sambar deer on E. zwageri seedlings. This study highlights the combined impact of 19 altered megafauna community on a tree population through interlinked ecological processes 20 and the need for targeted conservation intervention for this iconic tropical tree species. 21 22 Keywords 23 2 Seedling survival, neighborhood density, dispersal limitation, spatial clustering, threatened 24 species, wildings 25

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