Effects of flooding on leaf development, transpiration, and photosynthesis in narrowleaf cottonwood, a willow-like poplar

Abstract

The narrowleaf cottonwood, Populus angustifolia, occurs in occasionally flooded, low elevation zones along river valleys near the North American Rocky Mountains. This small poplar has narrow leaves and fine branching and thus resembles willows, which are commonly flood-tolerant. We investigated the flood response of narrowleaf cottonwoods and a related native hybrid, jackii cottonwood (P. x jackii = P. balsamifera x P. deltoides), by studying saplings of 24 clones in a greenhouse, with some pots being inundated to provide the flood treatment. Flooding slightly reduced leaf numbers (-10%), and leaf sizes were reduced by about 21% in female P. angustifolia versus a 50% reduction in the female hybrids. Flooding-reduced stomatal conductance and net photosynthetic rate, and reduced transpiration particularly in P. x jackii. The effects on foliar gas exchange declined over a 5-week interval, suggesting compensation. The moderate impact of flooding supports the hypothesis that narrowleaf cottonwoods are flood-tolerant, and we anticipate that these trees could provide traits to increase the flood tolerance of fast-growing hybrid poplars. The results further indicate that female cottonwoods may be more flood-tolerant than males, and females could be more successful in lower, flood-prone sites.

Ecophysiological and morphological adaption to soil flooding of two poplar clones differing in flood-tolerance

“…Negative effects of flooding on plant growth and total biomass accumulation have been demonstrated in many species with different tolerance to flooding (Du et al, 2008;Gong et al, 2007;Liu and Dickmann, 1992;Rood et al, 2010). Both Lux and Simonii had a lower growth rate in flooded than under control conditions in the present study, including biomass accumulation of root, stem and leaf, as well as height and root-collar diameter growth.…”

“…Stomatal closure is one of the earliest responses to flooding, as reported from a number of species (Blanke and Cooke, 2004;Kozlowski, 1997;Rood et al, 2010). When hypertrophied lenticels and adventitious roots appear, stomata can reopen rapidly.…”

Root architecture of riparian trees: river cut-banks provide natural hydraulic excavation, revealing that cottonwoods are facultative phreatophytes

“…A challenge to the phreatophytic root distribution follows from the seasonal variation in river stage and groundwater elevation. With high streams flows, much of the deep root system would be inundated and this would impose anoxia and physiological stress, reducing water uptake and growth (Pezeshki 2001;Nielsen et al 2010;Rood et al 2010). While cottonwoods are flood-dependent for reproduction (Scott et al 1996;Mahoney and Rood 1998), the established trees are inundation-intolerant.…”

United States Gulf of Mexico Coastal Marsh Vegetation Responses and Sensitivities to Oil Spill: A Review

“…Caudle and Maricle [38] reported that photosynthetic rates in leaves were sensitive to oiling in the soil and varied across the six species studied, indicating metabolic dysfunction due to non-stomatal inhibition of photosynthesis. Such inhibitions are found in response to environmental stressors including flooding and drought, and generally a result of decreased activity of photosynthetic enzymes, chlorophyll breakdown, and reduced light-harvesting complexes [36,38,[53][54][55][56]. Caudle and Maricle [38] further reported that certain chlorophyll fluorescence parameters (including FV/FM) did not change in response to oiling.…”