TY - JOUR
T1 - Tree height and age-related decline in growth in Scots pine (Pinus sylvestris L.)
AU - Martínez-Vilalta, Jordi
AU - Vanderklein, Dirk
AU - Mencuccini, Maurizio
PY - 2007/1
Y1 - 2007/1
N2 - Growth and seasonal water use was measured amongst trees growing in an old growth Scots pine forest in the Scottish Highlands. Three sites which differed in their recent management history and contained old and naturally regenerated young trees growing together were monitored in the field. Our results showed a clear decrease in growth efficiency with age, from values of around 0.25 kg m-2 leaves year-1 in approximately 25-year-old trees to less than 0.1 kg m-2 leaves year-1 in trees over 200 years old. When the old trees in one of the field sites were released from competition by thinning, their growth efficiency reverted to that of coexisting young trees, indicating that the decline in growth was reversible. This is consistent with the results of a parallel study showing that cambial age had no effect on the physiology or growth of grafted seedlings originating from the same population studied here (Mencuccini et al. 2005). Our detailed study of tree water use in the field showed an overall decrease in whole-tree hydraulic conductance and stomatal canopy conductance with tree height in the unthinned stands, in agreement with the hydraulic limitation hypothesis. However, the effect of this reduction in hydraulic efficiency on growth was comparatively small, and old trees also showed consistently lower nitrogen concentrations in needles, suggesting that hydraulic and nutritional factors combined to produce the decline in growth efficiency with age observed in the studied populations.
AB - Growth and seasonal water use was measured amongst trees growing in an old growth Scots pine forest in the Scottish Highlands. Three sites which differed in their recent management history and contained old and naturally regenerated young trees growing together were monitored in the field. Our results showed a clear decrease in growth efficiency with age, from values of around 0.25 kg m-2 leaves year-1 in approximately 25-year-old trees to less than 0.1 kg m-2 leaves year-1 in trees over 200 years old. When the old trees in one of the field sites were released from competition by thinning, their growth efficiency reverted to that of coexisting young trees, indicating that the decline in growth was reversible. This is consistent with the results of a parallel study showing that cambial age had no effect on the physiology or growth of grafted seedlings originating from the same population studied here (Mencuccini et al. 2005). Our detailed study of tree water use in the field showed an overall decrease in whole-tree hydraulic conductance and stomatal canopy conductance with tree height in the unthinned stands, in agreement with the hydraulic limitation hypothesis. However, the effect of this reduction in hydraulic efficiency on growth was comparatively small, and old trees also showed consistently lower nitrogen concentrations in needles, suggesting that hydraulic and nutritional factors combined to produce the decline in growth efficiency with age observed in the studied populations.
KW - Ageing
KW - Growth efficiency
KW - Hydraulic limitation hypothesis
KW - Nitrogen
KW - Water relations
UR - http://www.scopus.com/inward/record.url?scp=33845803633&partnerID=8YFLogxK
U2 - 10.1007/s00442-006-0552-7
DO - 10.1007/s00442-006-0552-7
M3 - Article
C2 - 16983553
AN - SCOPUS:33845803633
SN - 0029-8549
VL - 150
SP - 529
EP - 544
JO - Oecologia
JF - Oecologia
IS - 4
ER -