Worldwide decomposition rates depend both on climate and the legacy of plant functional traits as litter quality. To quantify the degree to which functional differentiation among species affects their litter decomposition rates, we brought together leaf trait and litter mass loss data for 818 species from 66 decomposition experiments on six continents. We show that: (i) the magnitude of species-driven differences is much larger than previously thought and greater than climate-driven variation; (ii) the decomposability of a species' litter is consistently correlated with that species' ecological strategy within different ecosystems globally, representing a new connection between whole plant carbon strategy and biogeochemical cycling. This connection between plant strategies and decomposability is crucial for both understanding vegetation-soil feedbacks, and for improving forecasts of the global carbon cycle.

Little is known about the differences in physiology between temperate and tropical trees. Australian rainforests extend from tropical climates in the north to temperate climates in the south over a span of 33° latitude. Therefore, they provide an opportunity to investigate differences in the physiology of temperate and tropical trees within the same vegetation type. This study investigated how the response of net photosynthesis to growth temperature differed between Australian temperate and tropical rainforest trees and how this correlated with differences in their climates. The temperate species showed their maximum rate of net photosynthesis at lower growth temperatures than the tropical species. However, the temperate species showed at least 80% of maximum net photosynthesis over a 12-16°C span of growth temperature, compared with a span of 9-11°C shown by the tropical species. The tropical species showed both larger reductions in maximum net photosynthesis at low growth temperatures and larger reductions in the optimum instantaneous temperature for net photosynthesis with decreasing growth temperature than the temperate species. The ability of the temperate species to maintain maximum net photosynthesis over a greater span of growth temperatures than the tropical species is consistent with the greater seasonal and day-to-day variation in temperature of the temperate climate compared with the tropical climate.

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Numerous authors have attempted to quantify the physical properties of leaves in relation to aspects of leaf ecology, including decomposition, sclerophylly, herbivory, and leaf function and longevity. This paper examines the relative merits of the punch-and-die, tearing and shearing tests for assessing leaf physical properties. We conducted a series of these three mechanical tests on leaves of Solanum laciniatum, and determined the effect of various test parameters on the measurement of fracture properties. For the punch-and-die test, the parameters considered were machine speed, clearance between the punch and the die, edge definition of the punch, and area of the punch. Aspects of the tearing test examined were notch length, end effects, and length-to-width requirements of test strips, and for shearing tests the effects of blade proximity, angle and sharpness were investigated. All the test parameters investigated were found significantly to affect the assessment of leaf-fracture properties. In addition, fracture properties were found to vary significantly within leaves. Some general principles for designing and implementing tests are outlined. This study suggests that while punching and shearing tests are useful means of quantifying leaf fracture properties, the value of the tearing test may be reduced as it is most constrained by the biological nature of the test material.