Defoliation by the common pine sawfly (Diprion pini) and subsequent growth reduction in Scots pine: a retrospective approach

Abstract

The foliage status in the main stem of Scots pines (Pinus sylvestris) was studied retrospectively using the needle trace method (NTM) on a stand, seriously defoliated by the pine sawfly (Diprion pini) in the 1980s. Needle density increased abruptly in the seasons following the defoliation. The strongest reduction in annual needle production occurred one year later. As a consequence of lower needle production, the annual number of attached needles decreased three to five years after the defoliation. Needle retention and the average age of attached needles tended to increase after defoliation. In analyses of covariance with the NTM variables, needle density (logarithmic transformed values) and average age of attached needles, had the highest, significant, negative relationship with radial and height increments both in the period prior to the defoliation and in the time when the trees were suffering from defoliation. The relationships between height increment and the number of needles and needle loss were positive and significant. Also radial increment had a positive relationship with the number of needles but not with needle loss. Interestingly, an abrupt increase in the needle density gave a good indication of the effects of a sudden defoliation in pines.

The relationship between the needle age and the growth rate in Scots pine (Pinus sylvestris): a retrospective analysis by needle trace method (NTM)

“…These numbers for each annual needle set seem to be quite realistic, although in nature apical shoots in the branches may produce more than two lateral shoots depending much on light irradiance (Kelloma¨ki and Oker-Blom 1983;Niinemets and Lukjanova 2003), and decreasing shoot growth tends to increase needle density (Ross et al 1986;Kurkela et al 2005). However, the growth decreases in both leader and lateral shoots in the ageing branches, when the increasing needle density may not change the ratio much between the different needle sets.…”

“…The pines were 53 years old, with an average dominant height of 11-13 m in 2001. The nine trees selected had been used previously to study the effect of defoliation on the growth and development of general foliage status after the attack of the common pine sawfly (Diprion pini L.) in the 1980s (Kurkela et al 2005).…”

Climatic influences on needle cohort survival mediated by Swiss needle cast in coastal Douglas-fir

“…Coastal Douglas-fir has been observed to hold needles for up to 7 years in western Oregon and Washington (Mitchell 1974) and 10 years in British Columbia (Silver 1962). Variation in needle longevity is related to many factors, including latitude (Reich et al 1996;Xiao 2003), climate (Xiao 2003;Coop and Stone 2007), site fertility (Balster and Marshall 2000;Niinemets and Lukjanova 2003), and insect and disease history (Hansen et al 2000;Kurkela et al 2005).…”

Growth response of young Scots pines to needle loss assessed from productive foliage

“…The growth reduction in conifers, achieved by the artificial removal of green needles or caused by herbivory (Ericsson et al, 1980;Honkanen et al, 1999;Armour et al, 2003;Piene et al, 2003;Williams et al, 2003;Kurkela et al, 2005;Straw et al, 2005) can not be correctly compared with the growth reduction in trees caused by abiotic stress situations (like drought) or by fungal needle pathogens (like Lophodermium needle cast). The reason is that the first type of needle removal is accompanied by the additional energy-consuming traumatic effects (resin flow etc.…”