Data from: Canopy leaf area index at its higher end: dissection of structural controls from leaf to canopy scales in bryophytes

There is evidence that mosses with miniature foliage elements have extremely large leaf area indices (LAI), but it is unclear what canopy traits are responsible for these high LAI values in architecturally divergent mosses, and how the inherent tradeoffs limiting maximum LAI in vascular plants can be overcome in mosses. To determine the quantitative significance of different traits in determining LAI, we developed a method to dissect LAI into underlying functionally dependent constituent traits at leaf, shoot and canopy scales. The suites of structural traits were studied altogether for 43 moss canopies from 11 species with contrasting light and water requirements along gap-understory gradients to obtain as large a range of variation in moss architecture as possible and evaluate the differentiation in moss LAI in relation to species ecology. Extensive variation in moss structural traits, 11- (shoot length) to 77-fold (shoot number per area, NS), was observed at all structural scales from leaf to canopy. However, LAI only varied 9-fold, as the result of two key tradeoffs, leaf size vs. number tradeoff and shoot leaf area vs. shoot density tradeoff. Due to these negative relationships, and greater variability in NS, LAI primarily scaled with NS. and LAI increased with site light availability, and LAI was greater in open and dry habitat species. The current study highlights a huge structural diversity among moss canopies, but indicates that canopies converge to a much narrower range of LAI due to trait tradeoffs such that, counterintuitively, minute leaf size and densely leafed stems are not necessarily responsible for high LAI in mosses.