Ecological implications of variation in whole-plant leaf:wood allocation, allometry, costs and benefits.

Improved whole-plant cost:benefit understanding of allocation and activities of leaf versus wood tissues should in principle yield better understanding of differences among species in growth rates and differences among sites in vegetation productivity. To this end we measured whole-plant allocation to sapwood versus leaves in terms of mass and area for 180 woody species sampled from 11 sites arrayed across broad precipitation and temperature gradients in Australia (10-28 ^oC range in mean annual temperature; 380-2600 mm range in annual precipitation). Physiological rates (photosynthesis, sapwood respiration) and other standard traits were also measured. We quantified coordination between tissue-level traits and whole-plant allocation to leaf versus wood, and the role of site climate and soil properties in driving trait variation. Most but not all observed trait–trait and trait–environment relationships were consistent with predictions based on optimality theory and prior knowledge. Sapwood respiration, expressed at a standard temperature, showed clear patterning with site climate and soil nutrients. Mass-basis sapwood:leaf allocation showed clear patterning with site climate but area-basis allocation far less so. Wide variation and clear taxonomic patterning was observed among co-occurring species in key properties suggesting that cost:benefit considerations should include trait coordination and competitive effects as well as environmental drivers. Taken together, our findings suggest a fresh direction for understanding links between plant traits, environmental adaptation and – appropriately scaled up – ecosystem-scale processes.