Photosynthesis and respiration rates depend on leaf and root morphology and nitrogen concentration in nine boreal tree species differing in relative growth rate

Abstract

1. To test several hypotheses about acclimation and adaptation of photosynthesis and respiration to differing light conditions, we investigated the interspecific relationships between leaf and root metabolism, chemistry and morphology in high and low light conditions for young seedlings of nine boreal tree species that differ in relative growth rate (RGR). 2. Light‐saturated net photosynthesis (Asat), whole‐plant nitrogen (N) uptake rates, leaf and root respiration and morphology, and RGR all varied in parallel among the nine species when grown in both 5% and 25% of full sunlight. RGR, Asat, leaf and root respiration (Rd), and N uptake rate per unit root mass or length differed significantly among species, ranking (from high to low): Populus, Betula and Larix spp. (all deciduous) and then to five evergreen conifers (Pinus, Picea and Thuja spp.), which were generally comparable in these measures. 3. A sat, leaf and root Rd and N uptake rates were all correlated (r≈ 0·8 to 0·9) with species traits, such as seed mass, leaf life span and shade‐tolerance rankings. Mass‐based Asat was greater in conifer seedlings raised in low than high light. In contrast, area‐based Asat was higher for plants grown in high than low light, especially in the deciduous species. Once adjusted for differences in plant mass, leaf or root respiration rates did not differ for plants grown in low vs high light. 4. Interspecific variation in RGR was positively correlated (r≈ 0·9) with rates of photosynthesis, respiration and N uptake. Leaf photosynthesis and respiration rates were correlated to specific leaf area and leaf N concentrations (r≈ 0·9). Root respiration rates, N uptake rates, specific root length (root length per root dry mass) and root N concentrations were all highly correlated with each other (r≈ 0·8 to 0·9). These data suggest a close coupling of tissue‐level metabolism, chemistry and structure with whole‐plant performance and species ecophysiological and life‐history traits.

Building roots in a changing environment: implications for root longevity

“…For example, Reich et al (1998) found root respiration and N uptake to be highly correlated with SRL among nine boreal tree species (Fig. 3).…”

Spatial and temporal patterns of root distribution in developing stands of four woody crop species grown with drip irrigation and fertilization

“…Despite soil environmental conditions created by irrigation and fertilization treatments, cottonwood genotypes produced roots Discussion with consistently higher SRL (narrower diameter) and greater root length densities as expected h m fast Ranking among genotypes in root system charactergrowing species originating from resource rich bottomistics were unaffected by resource availability and not land or alluvial sites (Comas and Eissenstat 2004; for the complete model with all parameters Genotypes were analyzed separately for Reich et al 1998), however, since sycamore is also a bottomland species, it too was expected to share these characteristics with cottonwood and to be unique from sweetgum, a more stress tolerant species with robust site requirements. Yet SRL values of sycamore and sweetgum were equivalent and distinct from that of cottonwood.…”

“…Broadleaved deciduous species are distinct from needle-leaved evergreen species (Comas and Eissenstat 2004;Einsmann et al 1999), yet other functional categories may also influence root characteristics. Stress tolerant tree species such as those living on upland well drained soils or those with robust site requirements are expected to have roots with larger diameters lower specific root length (SRL), lower specific respiration rates (Comas and Eissenstat 2004;Reich et al 1998) and lower turnover rates (Chapin 1980). They are also expected to be less responsive to heterogeneous resource availability (Einsmann et al 1999;Mou et al 1995) and have greater dependence on symbiotic mycorrhizal associations (Harley and Smith 1983).…”

Evidence of higher photosynthetic plasticity in the early successional Guazuma ulmifolia Lam. compared to the late successional Hymenaea courbaril L. grown in contrasting light environments

“…The values for shade plants are lower because respiration rates are very low, therefore small assimilation rates are sufficient to bring the rates of CO 2 evolution to zero. Low respiratory rates seem to represent a basic adaptation that allows shade plants to survive in light-limited environments, since it is of utmost importance to minimise carbon losses via respiration in order to maintain a positive net carbon balance in highly shaded environments (Givnish, 1988;Reich et al 1998;Pearcy, 1998). Both species showed greater values of dark respiration (Rd) in the high light compared to the low light (p < 0.05), being significantly higher in G. ulmifolia than in H. courbaril only in high light (Table 1).…”