Interspecific divergence in foliar nutrient dynamics and stem growth in a temperate forest in response to chronic nitrogen inputs
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Canadian Journal of Forest Research. 35: 1023-1030.
We studied the effects of excessive nitrogen (N) fertilization on foliar nutrient dynamics and stem growth in three important tree species in a mixed-deciduous forest. Stem diameter growth, foliar N concentrations, nitrogen-phosphorus (NIP) ratios, and nutrient resorption were determined for Acer rubrum L. (ACRU), Liriodendron tulipifera L. (LITU), and Prunas serotina Ehrh. (PRSE) on two 30-year-old wateksheds at the Femow Experimental Forest, West Virginia, USA: WS3, fertilized annually with 35 kg ammonium sulfate-ha-1 since 1989, and WS7, an untreated control watershed. En an earlier (1992) study, foliar N concentrations of all three species averaged 11% higher in WS3 than in WS7. By 2000, that was no longer the case for any species; indeed N in ACRU leaves was 13% lower in WS3 that year. N/P ratios were elevated in WS3 only in PRSE in 1992 and in both ACRU and PRSE in 1997, but by 2001, mean NIP for all three species was lower in WS3. N resorption efficiencies were 30% lower in WS3 in ACRU and PRSE, but not in LITU. Stem diameter growth in WS3 was 55% lower in ACRU and 30% lower in LITU and PRSE compared with that in WS7. Results may indicate declining growth vigor in ACRU and, to a lesser extent: PRSE and LITU in the fertilized watershed. Observed interspecific differences in growth and plant nutrition responses suggest eventual changes in species composition under increasing N saturation.
KeywordsFernow Experimental Forest
May, Jeffrey D.; Burdette, Sarah Beth; Gilliam, Frank S.; Adams, Mary Beth. 2005. Interspecific divergence in foliar nutrient dynamics and stem growth in a temperate forest in response to chronic nitrogen inputs. Canadian Journal of Forest Research. 35: 1023-1030.