a clear trendP < 0.001
There was a clear trend for NRI to increase with increasing stem size of trees ( P < 0.001, Cochran-Armitage test for trend for either seedlings in forest gaps, saplings, treelets and trees or seedlings in forest understory, saplings, treelets and trees; Fig 1 ), indicating an increasing trend in phylogenetic clustering from seedling stratum to forest canopy stratum, regardless of whether seedlings are defined as individuals with DBH < 1 cm or as individuals of < 50 cm in height (compare Fig 1 with S3 Fig ).