New approaches to study the relationship between stomatal conductance and environmental factors under Mediterranean climatic conditions

摘要

The most frequently models used (Ball-Berry and Jarvis-type models) to estimate stomatal conductance (Gs) valuesrnhave limitations when applied to plants growing in Mediterranean climate. To overcome these limitations, severalrnstatistical methodologies (Multiple Linear Regression, Neural Net Analysis (NNA)) were used to build models to predictrnGs. However, all these models were unable to integrate the physiological response of plants to the overall limitingrnenvironmental parameters in our Mediterranean site especially during the summer drought. With this in mind, it is relevantrnto find alternative approaches which link Gs response to environmental limitations of plants. In this paper, we demonstraternthat: (1) the different linear and nonlinear statistical approaches used significantly affect the weights of the environmentalrnvariables which are utilized in semi-empirical Gs models; (2) a tight relationship exists between summer values of Gs andrnthe rate of accumulated precipitations (α) in the first 5 months of the year, thus allowing to predict Gs in a quantitativernway; and (3) the latter is also related to different water-use strategies adopted by plants in response to drought stress in thernsummer period. Because α is easily calculated, it is an interesting parameter for the Gs modelling addressed to understandrnmany important aspects of the plant-environment interactions, such as water relations and pollutant uptake.