Mixed stands of Scots pine (Pinus sylvestris L.) and Norway spruce [Picea abies (L.) Karst] can be more productive than monocultures. Evidence from over 100 years of observation of long-term experiments

Acclimation of conifer needle anatomy to climate change is poorly understood. We studied needle anatomy, shoot gas exchange, current-year shoot length, and stem diameter growth in Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) seedlings exposed to elevated ozone (1.35× to 1.5× ambient concentration) and elevated temperature (0.9–1.3 °C + ambient temperature) alone and in combination for two exposure seasons in two separate open-field experiments in central Finland. Pines grew also at two soil nitrogen levels. In spruce, warming increased mesophyll intercellular space and reduced gas exchange and shoot growth and made needles narrower and the epidermis and hypodermis thinner. In pine, warming made needles bigger, increased shoot and stem growth, stomatal row number, and proportions of vascular cylinder, phloem, and xylem and reduced the proportion of mesophyll. These responses indicate that pine benefited and spruce suffered from moderate warming. Ozone caused a thickening of epi- and hypo-dermis and a lower stomatal conductance in both species, reduced stomatal density in spruce, and increased proportions of phloem, xylem, and sclerenchyma and reduced growth in pine. Ozone responses suggest increased oxidative stress defense. Stomatal responses were affected by interactions of elevated temperature and ozone in both species. Nitrogen availability modified ozone and temperature responses, particularly in the vascular tissues in pine.

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Current growth differences of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and birch (Betula pendulaandBetula pubescens) in different regions in Sweden

Scandinavian Journal of Forest Research ◽

10.1080/02827580802249126 ◽

2008 ◽

Vol 23 (4) ◽

pp. 307-318 ◽

Cited By ~ 20

Author(s):

Per-Magnus Ekö ◽

Ulf Johansson ◽

Nils Petersson ◽

Jonas Bergqvist ◽

Björn Elfving ◽

...

Keyword(s):

Picea Abies ◽

Pinus Sylvestris ◽

Norway Spruce ◽

Scots Pine ◽

Current Growth ◽

Growth Differences

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A mechanistic model for assessing the risk of wind and snow damage to single trees and stands of Scots pine, Norway spruce, and birch

Canadian Journal of Forest Research ◽

10.1139/x99-029 ◽

1999 ◽

Vol 29 (6) ◽

pp. 647-661 ◽

Cited By ~ 202

Author(s):

H Peltola ◽

S Kellomäki ◽

H Väisänen ◽

V -P Ikonen

Keyword(s):

Wind Speed ◽

Picea Abies ◽

Pinus Sylvestris ◽

Norway Spruce ◽

Scots Pine ◽

Mechanistic Model ◽

Critical Value ◽

Modulus Of Rupture ◽

Snow Damage ◽

Good Agreement

A mechanistic model for assessing the risk of wind and snow damage to single trees and stands of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), and birch (Betula spp.) is presented. The model predicts the critical turning moment and wind speed at which the trees will be uprooted or break at forest margins. The resistance to uprooting is predicted using the estimate of the root-soil plate weight to derive a resistive moment, while the resistance to stem breakage relies on values for the modulus of rupture determined for different species of timber. A tree is assumed to be uprooted if the total turning moment exceeds the support provided by the root-soil plate anchorage. Similarly, a tree is assumed to break if the breaking stress acting on the stem exceeds a critical value of the modulus of rupture. The model is in general quite sensitive to parameter changes, which partly results from the location in the forest to which it was designed to apply (the stand edge). The predictions of the critical turning moments needed to uproot and break trees nevertheless give a good agreement on average with the Finnish tree-pulling data for Scots pine, Norway spruce, and birch.

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