Leaf gas exchange in a clonal eucalypt plantation as related to soil moisture, leaf water potential and microclimate variables

Abstract

In order to determine how environmental and physiological factors affect leaf gas exchange in a 9-year-old clonal eucalypt plantation (Eucalyptus grandis Hill ex. Maiden hybrids) in the State of Espirito Santo, Brazil, the diurnal patterns of predawn leaf water potential (Ψ pd ), and leaf gas exchange were monitored from November 1995 to August 1996. Soil water content (Θ) and microclimatic variables were also recorded. Most of the rainfall during the experimental period occurred from October to December 1995 and from March to April 1996, causing a significant variation in Θ and Ψ pd . A high positive correlation (r 2 =0.92) was observed between Ψ pd and Θ measured at 0.3 m depth from the soil surface. During conditions of high soil water availability, the maximum values of stomatal conductance for water vapor (g s ) and net photosynthetic rate (A) were over 0.4 mol m -2 s -2 and l5 µmol m -2 s -1 , respectively. The results showed that Ψ pd and leaf gas exchange of the examined trees were susceptible to changes in the water content of the upper soil layers, where the major concentration of active roots occur. Multiple linear regression analysis indicated that photosynthetic active radiation (Q), vapor pressure deficit (VPD), atmospheric CO 2 molar fraction (C a ), and Ψ pd were the most important factors controlling g s whereas Q and VPD were the main microclimatic variables controlling A.Leaf gas exchange in a clonal eucalypt plantation as related to soil moisture, leaf water potential and microclimate variables

Impact of the leaf miner Cameraria ohridella on whole-plant photosynthetic productivity of Aesculus hippocastanum: insights from a model

“…Similar seasonal changes of leaf gas exchange rates have been reported in several temperate (Mielke et al 2000;Nardini et al 2003) and tropical (Brodribb and Holbrook 2003) trees. A possible explanation for early reduction of leaf gas exchange might be that stems, petioles, and even leaves undergo precocious cavitation leading to consequent blockage of xylem conduits in early summer.…”

Implications of leaf-scale physiology for whole tree transpiration under seasonal flooding and drought in central Cambodia

“…Reductions in m or C i /C a during the dry season have been reported in evergreen trees in other studies in the Amazon (Choat et al, 2006;Craven et al, 2011), in monsoon regions (Liu et al, 2010;Prior et al, 2004), in savanna habitat (Eamus et al, 1999;Franco et al, 2005;Mielke et al, 2000), and in the Mediterranean region (Goulden, 1996). While most species in these studies also reduced A at light saturation, species in this study reduced m alone.…”

“…In this seasonally changing environment, transpiration rates are thought to differ among trees and sites because of the site-specific environmental conditions (Pinker et al, 1980;Tanaka et al, 2003Tanaka et al, , 2008 and species-specific ecophysiological traits (Eamus et al, 2001;Kelliher et al, 1995;Kunert et al, 2010;O'Grady et al, 2009). Transpiration and its relationship with species and environmental conditions have been intensively investigated in regions experiencing seasonal droughts because the water demands of fast-growing plantation species can pose a threat to local water resources (Bruijnzeel, 2004;Calder et al, 1993;Mielke et al, 2000;Whitehead and Beadle, 2004).…”

Growth and water balance of Eucalyptus grandis hybrid plantations in Brazil during a rotation for pulp production

“…It is located at 19851 0 S, 40814 0 W on Brazil's Atlantic coast and is representative of 40,000 ha of plantation land for dominant soil type, soil texture, vegetation cover, drainage network, climate and topography (Soares and Almeida, 2001;Almeida and Soares, 2003;Almeida, 2003). The site was conveniently located, of adequate size and had a good road network (Mielke et al, 2000) (Fig. 1).…”

“…www.elsevier.com/locate/foreco Forest Ecology and Management 251 (2007) [10][11][12][13][14][15][16][17][18][19][20][21] Setting up an experimental catchment for long-term monitoring within its extensive eucalypt plantations was part of a programme carried out by Aracruz Celulose S.A. in Brazil to address their hydrological issues (Soares and Almeida, 2001;Almeida and Soares, 2003). We also used data from several intensive ecophysiological campaigns carried out under different conditions of water availability, starting in 1995 (Mielke et al, 1999(Mielke et al, , 2000Almeida, 2003). A complete network of hydrological, meteorological and forest growth measurements provided most of the data analysed in this work.…”