Do nitrogen additions change the sensitivity of detached shoots from Sitka and Norway spruce to freezing temperatures? Evidence from three field manipulation studies

• Controversy surrounds the impact of atmospheric nitrogen (N) deposition on frost hardiness. There are no specific field studies and the relevance of data from N fertilizer studies is questionable. Field N manipulation experiments with Norway spruce [Picea abies . (L) Karst.] at Skogaby, Sweden, and Sitka spruce [P. sitchensis . (Bong.) Carr.] at Aber in Wales and Deepsyke in Scotland were sampled in November/December to assess hardiness. The N was supplied with different accompanying ions, from 35 to 100 kg N ha(-1) yr(-1), as solid fertilizer, in irrigation water or to the canopy. Detached shoots were experimentally frozen and damage was assessed from electrolyte leakage. Frost hardiness was not significantly affected by the N treatments irrespective of site, dose, species or length of treatment. Shoots that had received N were generally the most hardy. The results are consistent with the nutritional status of the foliage at the time of sampling.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

Nyckelord

field manipulation

frost hardiness

nitrogen

Norway spruce

Sitka

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