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Ecol Lett ; 22(3): 506-517, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30609108


Earth system models (ESMs) use photosynthetic capacity, indexed by the maximum Rubisco carboxylation rate (Vcmax ), to simulate carbon assimilation and typically rely on empirical estimates, including an assumed dependence on leaf nitrogen determined from soil fertility. In contrast, new theory, based on biochemical coordination and co-optimization of carboxylation and water costs for photosynthesis, suggests that optimal Vcmax can be predicted from climate alone, irrespective of soil fertility. Here, we develop this theory and find it captures 64% of observed variability in a global, field-measured Vcmax dataset for C3 plants. Soil fertility indices explained substantially less variation (32%). These results indicate that environmentally regulated biophysical constraints and light availability are the first-order drivers of global photosynthetic capacity. Through acclimation and adaptation, plants efficiently utilize resources at the leaf level, thus maximizing potential resource use for growth and reproduction. Our theory offers a robust strategy for dynamically predicting photosynthetic capacity in ESMs.

Aclimatação , Dióxido de Carbono , Fotossíntese , Adaptação Fisiológica , Nitrogênio , Folhas de Planta , Ribulose-Bifosfato Carboxilase
Trends Ecol Evol ; 3(12): 343-5, 1988 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21227288


The pollen record of the past 10-20 thousand years is a source of data both on long-term climatic change and on the dynamics of plant populations in response to climatic change. Time sequences of pollen accumulation rates record invasions of tree taxa over 10(1)-10(3) years. Palaeoecologists have fifted such data with simple population dynamic models that assume a constant climate. Population doubling times estimated from the pollen record are consistent with species' life-history characteristics and with estimates based on the population structure of modern forests. This palaeo-ecological approach complements palaeoclimatological studies of longeer-term (10(3)-10(5)-year) population shifts, in which population response is assumed instantaneous. Both approaches depend on population responses being fast compared to the climatic changes that cause them. Pollen data also record the more complex interactions between climate and vegetation that occur during periods of rapid climatic change, and could be used to test more realistic models of vegetation dynamics in a changing environment.