Summary Latitudinal variation in needle longevity of coni-fers in response to climatic variability is a well-known phe-nomenon, but its significance has only rarely been studied. Scots pine (Pinus sylvestris L.) stands were investigated in four locations in Lapland (northern Finland and northern Swe...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.630.6341 http://treephys.oxfordjournals.org/content/25/10/1265.full.pdf |
| Summary: | Summary Latitudinal variation in needle longevity of coni-fers in response to climatic variability is a well-known phe-nomenon, but its significance has only rarely been studied. Scots pine (Pinus sylvestris L.) stands were investigated in four locations in Lapland (northern Finland and northern Sweden, 67–68 ° N) and in four locations in Estonia (59 ° N) to test the hypothesis that plasticity in needle longevity results in similar needle biomass per foliated shoot length across latitudes. The needle-trace method (NTM) revealed the dynamics of needle fascicles attached to stem shoots. Long-term mean needle age was 2 years greater in Lapland than in Estonia. In both regions, mean needle age was strongly and negatively related to yearly needle-fascicle production rate relative to the number of nee-dles on the same shoot axis. Although significantly fewer nee-dle-fascicles were produced annually in trees in Lapland than in Estonia, the overall number of fascicles attached to the stem shoots, needle-fascicle density and individual needle dry mass did not differ between regions. Consequently, needle biomass per foliated shoot length was similar in trees in both regions. Thus, our results support the theory that plasticity in needle longevity helps Scots pine to compensate for reduced needle production so that the same foliar biomass per shoot is retained under a wide range of growth conditions. |
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