RECONCILING APPARENT DISCREPANCIES AMONG STUDIES RELATING LIFE-SPAN, STRUCTURE AND FUNCTION OF LEAVES IN CONTRASTING PLANT LIFE FORMS AND CLIMATES - THE BLIND MEN AND THE ELEPHANT RETOLD

1. Data on leaf structure, physiology and life span from studies in contrasting plant life forms and biomes - alpine and lowland herbs in Austria, lowland temperate trees in Japan and lowland tropical trees in Venezuela - have led researchers to different conclusions about the relationships between leaf life span and other leaf traits. Results of the alpine/lowland study with herbs questioned the validity of a general theory of leaf life span, whereas results of the tropical forest study supported the theory and the temperate forest study fell in between. 2. In this paper I evaluate whether these different results reflect innate differences among plant life forms, biomes and/or communities in this respect, or whether these apparent discrepancies can be reconciled with one explanation. 3. When the data from all three studies were combined, leaf life span was well correlated (P<0.001) with maximum mass and area-based net photosynthetic rate (r(2)=0.86 and 0.70, respectively), specific leaf area (r(2)=0.69) and leaf nitrogen concentration r(2)=0.74), and the relationships were predicted well by equations previously generated in an independent study. Data for alpine and lowland herbs generally fit along the regression lines as well as data from either the temperate or tropical trees. 4. These data thus show that within plant communities where most species have relatively similar leaf traits, minimal or weak relationships among leaf traits may occur, yet without departing from broad general relationships. These results support the idea of a relatively fixed interdependence among leaf life span, specific leaf area, net photosynthetic rate and leaf nitrogen concentration across broad gradients of species, plant life forms and environments.