Radial trends in cation ratios in tree rings as indicators of the impact of atmospheric deposition on forests

Abstract

Concentration ratios of aluminum to calcium, magnesium, and other divalent cations in increment cores obtained from red spruce and eastern hemlock trees growing in the Great Smoky Mountains National Park in Tennessee and North Carolina have increased in an unprecedented manner during the last 15–40 years. These trends, which also occur in other trees growing in eastern North America and Germany may reflect the mobilization of exchangeable aluminum by [Formula: see text] and [Formula: see text] deposition. The soil chemistry and plant physiology bases for this hypothesis are presented. Many of the spruce and hemlock cores from the Great Smoky Mountains also showed an inverse relationship between radial growth and aluminium:alcium ratios in the wood. Changes in the availability of soil cations, as recorded in tree rings, may provide an ecosystem-level method of evaluating the historical response of forest soils to atmospheric deposition.

Element analysis of tree rings in pedunculate oak heartwood: an indicator of historical trends in the soil chemistry, related to atmospheric deposition

“…Over 60% was in the form of NH 4 + ; however, these nitrogen inputs in 1991 were probably underestimated because of the rainfall deficit (22% under the "normal" figures). The increase in the frequency of nitrogen-demanding species between 1970 and 1990, revealed by the floristic survey, is particularly marked on the edges of the forest exposed to the prevailing winds, coming from the Nancy area, which is consistent with the N-deposition hypothesis (Thimonier et al, 1992 (Arp and Manasc, 1988;Bondietti et al, 1989;Helmisaari and Siltala, 1989; Momoshima and Bondietti, 1990;Peterson and Anderson, 1990) in relation to a decrease in the availability of the wood exchange sites for divalent cations with increasing radial distance from the pith (Bondietti et al, 1989Momoshima and Bondietti, 1990). In contrast, K concentration rose or remained constant, and therefore the K/Ca ratio increased from the older to younger heartwood ).…”

“…Second, according to some authors (Bondietti et al, 1989), the absolute values of Ca and Mg concentrations may remain constant or even increase in the wood in some situations, while there is a trend towards acidification in the soil. Indeed, at the beginning of acid deposition on poor soils, exchangeable bases may be mobilized from the raw humus, which may result in an enhanced growth of the trees (Raunemaa et al, 1982;Bondietti et al, 1989; Shortle, 1990; Bondietti and McLaughlin, 1992).…”

“…Tree-ring analysis proved to be more or less in accordance with historical events involving the soil, including: i) contamination of the environment by different elements, in particular Cu, Pb, Zn, Mn, Al, Fe, B, Ni, Cd, generally coming from industrial areas, coal-burning power generators or vehicle exhaust fumes. Species involved were conifers (Robitaille, 1981;Baes and McLaughlin, 1984;Guyette and McGinnes, 1987;Guyette et al, 1991;Zayed et al, 1992) as well as broadleaved species (Vroblesky and Yanosky, 1990;Stewart et al, 1991) including oaks (Herrmann et al, 1978; Kardell and Larsson, 1978;Queirolo et al, 1990;Yanosky and Vroblesky, 1992); ii) fertilization (McClenahen et al, 1989;Kashuba, 1992); iii) acidification of the soil, generally ascribed to atmospheric deposition (Meisch et al, 1986;Arp and Manasc, 1988; Ragsdale and Berish, 1988;Scherbatskoy and Matusiewicz, 1988;Bondietti et al, 1989; Bondietti and McLaughlin, 1992 (Okada et al, 1988;Frelich et al, 1989;De Visser, 1992). Some macronutrients are often partly remobilized from older annual rings and transferred towards younger and more active parts of the wood (Ogner and Bjor, 1988;Häsänen and Huttunen, 1989;Peterson and Anderson, 1990;Chun and Hui-yi, 1992;De Visser, 1992).…”

“…Translocation may also depend on the species under study (Guyette et al, 1992). In particular, each ring is used for sap transport during a variable number of years: so, the initial mineral content of a given ring may be altered over a long period after its formation, by cation exchange processes with the xylem sap Arp and Manasc, 1988;Bondietti et al, 1989;Bondietti and McLaughlin, 1992;McClenahen and Vimmerstedt, 1993). For those reasons, it could be interesting, in particular when investigating macronutrients, i) to pay special attention to the mineral content of the rings in the heartwood; ii) to work on oaks, which are ring-porous species in which sap is mainly transported in the current year or last 2-or 3-year-old vessels (Hinckley and Lassoie, 1981;Hagemeyer et al, 1992;Granier et al, 1994), even though the wood structure of broadleaved species is more likely to allow lateral transfer than that of conifers (Zayed et al, 1992 (Morel, 1973 (Aussenac et al, 1972).…”

“…Indeed, at the beginning of acid deposition on poor soils, exchangeable bases may be mobilized from the raw humus, which may result in an enhanced growth of the trees (Raunemaa et al, 1982;Bondietti et al, 1989; Shortle, 1990; Bondietti and McLaughlin, 1992). An inversion of these trends occurs later, with an impoverishment of nutrients in the soil and a decrease in growth.…”