Ash trees along the Potomac River flood plain near Washington, D.C., were studied to determine changes in wood anatomy related to flood damage. Samples were collected as cross sections, and anomalous growth was compared with flood records for April 15 to August 31, 1930August 31, to 1979. Collectively, anatomical evidence was detected for 33 of the 34 growing-season floods during the study period. Evidence of 12 floods prior to 1930 was also noted, including catastrophic floods in 1889 and 1924.Trees damaged after the transition from early wood to latewood growth typically formed "flood rings" of enlarged vessels within the latewood zone. Trees damaged during the earlywood-growth interval developed flood rings within, or contiguous with, the early wood zone. Both patterns are assumed to have developed after refoliation of flood-damaged crowns. Flood rings formed when trees produced a second crop of leaves. Trees damaged by high-magnitude floods developed well-formed flood rings along the entire height of the stem in which the growth ring was present and around the entire circumference of the stem. Smaller floods were generally associated with diffuse or discontinuous anomalies restricted to stem apices. Peak stages were positively related to the frequency of abnormal growth within samples, and the intraring position of abnormal growth relative to total ring width corresponded to the approximate time of the flood. Some trees provided evidence of numerous floods. Those with the greatest number of flood rings grew on frequently flooded surfaces subject to flood-flow velocities of at Jeast 1 meter per second, and more typically greater than 2 meters per second. Tree size, more than age, was related to flood-ring formation. Trees kept small by frequent flood damage had more flood rings than taller trees of comparable age. Flood rings formed only if tree crowns were inundated, presumably because leaves were stripped or damaged.Anatomical evidence of floods, in addition to methods involving age determinations of flood scars and sprouts, can be used to document or extend streamflow records. Reconstructing tree heights in a year of flood-ring formation can provide estimates of peak stages along local stream reaches. Time of flood generation during the tree-growth season can be estimated from the radial position of anomalous growth relative to annual ring width. Further studies might define the minimum anatomical "signal" representing flood-affected growth in ash and other woody species, thus permitting more direct estimates of magnitude.
The annual growth rings of tulip trees (Liriodendron tulipifera L.) appear to preserve a chemical record of ground‐water contamination at a landfill in Maryland. Zones of elevated iron and chlorine concentrations in growth rings from trees immediately downgradient from the landfill are closely correlated temporally with activities in the landfill expected to generate iron and chloride contamination in the ground water. Successively later iron peaks in trees increasingly distant from the landfill along the general direction of ground‐water flow imply movement of iron‐contaminated ground water away from the landfill. The historical velocity of iron movement (2 to 9 m/yr) and chloride movement (at least 40 m/yr) in ground water at the site was estimated from element‐concentration trends of trees at successive distances from the landfill. The tree‐ring‐derived chloride‐transport velocity approximates the known ground‐water velocity (30 to 80 m/yr). A minimum horizontal hydraulic conductivity (0.01 to .02 cm/s) calculated from chloride velocity agrees well with values derived from aquifer tests (about 0.07 cm/s) and from ground‐water modeling results (0.009 to 0.04 cm/s).
A two-part study along the Potomac River flood plain near Washington, B.C., was undertaken to investigate the effects of flooding upon woody vegetation. Floods abrade bark, damage branches and canopies, and often uproot trees. The first study was of vegetation in five monumented flood-plain plots, which differed in the frequency and severity of flood flow over a 10-year period. Basal area and survival of trees appear to be related to velocity of flood flow, which in turn is related to flood magnitude and channel shape. However, the effects of flooding also depend on the nature of the flood-plain surface and size and growth habit of vegetation.In the second study, a catastrophic flood following Hurricane Agnes in June 1972 was found to cause large-scale changes in the age, form, and species composition of flood-plain forests below Great Falls, Va. The impact of the flood depended primarily on the flow regime of the river; destruction was greatest in areas exposed to the maximum flood force, and minimal at sheltered locations. Age determinations from dead trunks and surviving trees suggest that most trees in severely damaged areas started to grow after the last great flood, which occurred in 1942. Trees along sheltered reaches survived several previous catastrophic floods. In addition, species varied in their ability to withstand damage from the Hurricane Agnes flood. The least likely to recover were species growing on infrequently flooded surfaces, which may explain, in part, their absence at lower flood-plain altitudes.
Element analysis by proton induced X‐ray emission spectroscopy was performed on growth rings of baldcypress (Taxodium distichum) growing within the Cape Fear River estuary, North Carolina, USA. Trees from estuarine reaches heavily intruded by saltwater flooding contained larger concentrations of chloride, bromide, and sodium than did trees from less intruded reaches. At three intruded sites, trees nearest open water contained larger concentrations of these elements within outermost sapwood rings than did trees farther from open water and presumably flooded less often. Chloride was translocated from outer to inner sapwood rings of saltwater‐intruded trees, resulting in larger concentrations within heartwood than within the inner sapwood. Chloride concentrations along the heartwood radius were used to estimate the position of the heartwood‐sapwood interface during the beginning stages of intrusion, thus permitting historical estimates of the local onset of intrusion. Element analysis of the wood of baldcypress may aid assessments of tree growth and mortality in regions already subjected to saline flooding, and in coastal forests at risk from predicted sea level rises.
Abstract:The Chickahominy River, arising near Richmond, Virginia, flows southeast toward Newport News, which impounds the river for much of its water supply. Much of the bottomland between the two cities is flooded for extended periods annually. Sediment-deposition rates estimated from tree rings were used in conjunction with multi-element analyses of sediments and of selected growth rings from oak trees to estimate amounts of trapped sediment and trace elements. Mean rates of deposition at eight study sites range from 0.7 to 5.7 mm/yr and are related to stream gradient, stream power, percent wetland, hydroperiod, and land use. Deposition rates are highest downstream from the confluence of upper basin tributaries near Richmond, where stream power is low and there is a high percentage of emergent/shrub-scrub wetlands; rates decrease along downstream reaches toward the Chickahominy reservoir. Tree-ring data suggest that mean sedimentation rates were greater during the last 50 years than during the previous 30-year period, possibly because of urban expansion in the upper basin. Sites nearest the urban area have the highest rates of sedimentation and the highest concentrations of most trace elements in sediments. Trace elements concentrated in sediment include zinc, lead, chromium, copper, nickel, tin, and cadmium. Concentrations in tree rings of zinc, copper, nickel, and lead were generally proportional to those in sediment at a site, and some inter-site correlations were also observed. Unusually high concentrations of zinc were detected in some tree rings, including some that formed before 1950. Concentrations of zinc and lead in the most recently formed rings of those trees suggest that sediment concentrations of those elements may have declined relative to earlier periods. The trapping of substantial amounts of sediment and trace elements by these forested wetlands demonstrates their importance in the maintenance of water-quality.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.