Predicting vegetation patterns from attributes of plant growth in grassland species

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Abstract
This study examined the relationship between vegetation patterns at three spatial scales and five plant-growth attributes that were suspected to affect competitive ability in 10 species collected from two hay field plots of different ages (cultivated in 1974 and 1984). Relative abundance of species at the plot scale (30 × 100 m) showed no relationship with any of the attributes. Species diversity within 1 × 1 m quadrats, however, had a significant negative relationship with mean seed weight in the 1984 plot and a significant negative relationship with mean plant height, mean lateral spread, mean growth rate, and "potential growth index" (combining all five attributes) in the 1974 plot. Multiple regression analysis indicated that the relationship between the five plant attributes and species diversity within the 1 × 1 m quadrats was stronger for the older (1974) (r2 = 0.67) than for the younger plot (r2 = 0.32). These data suggest that (i) the role of "competitive ability" attributes in affecting community structure becomes more evident in later stages of community development, (ii) different attributes may affect competitive ability at different stages of grassland community development, and (iii) the consequences of attribute differences among species may be revealed only in patterns at the local neighbourhood scale within vegetation. Key words: competitive ability, diversity, grassland, vegetation patterns.