The effect of winter thinning on the spread of Heterobasidion parviporum in Norway spruce stands

2008 ◽  
Vol 38 (10) ◽  
pp. 2589-2595 ◽  
Author(s):  
Tuula Piri ◽  
Kari Korhonen

Genets of Heterobasidion were identified in eight 43- to 56-year-old Norway spruce ( Picea abies (L.) Karst.) stands in southern Finland. Four of the stands had been thinned in winter ca. 10 years prior to the study, and four had been left unthinned. It was hypothesized that the felling of decayed trees promotes the vegetative spread of the fungus from thinning stumps into the adjacent trees, and hence the Heterobasidion genets should be larger in thinned stands. Although the number of infected stumps per areal unit was lower and the genets were slightly smaller in the previous tree generation of thinned plots, the genets, particularly the old ones, in the present tree generation were larger on thinned plots. The genets originating from the previous rotation included, on average, 12.2 trees on thinned plots and 6.7 trees on unthinned plots. The mean number of trees infected by new genets (not found in previous generation) was also slightly higher (p < 0.05) on thinned than on unthinned plots, 1.8 and 1.2 trees, respectively. The results indicate that the rapid expansion of old Heterobasidion infections after a thinning operation may significantly contribute to the occurrence of root rot in the residual stand.

2001 ◽  
Vol 31 (6) ◽  
pp. 937-942 ◽  
Author(s):  
Tuula Piri ◽  
Kari Korhonen

The incidence of Heterobasidion root rot in the advance regeneration of Norway spruce (Picea abies (L.) Karst.) was studied in nine stands at four different localities in southern Finland. The mean age of the unthinned advance regeneration on the 17 sample plots ranged from 14 to 44 years. On infested plots, the proportion of Norway spruce infected by Heterobasidion varied from 22.2 to 75.0% (mean 52.5%) in the overstory and from 1.8 to 68.2% (mean 21.1%) in the advance regeneration. The corresponding values on healthy-looking control plots were 0–6.7% (mean 5.9%) and 1.3–3.9% (mean 2.4%), respectively. Of the 138 Heterobasidion genets identified, 98.5% belonged to Heterobasidion parviporum Niemelä & Korhonen and 1.5% to Heterobasidion annosum (Fr.) Bref. s.s. The incidence of Heterobasidion root rot in advance regeneration was positively correlated with the mean size and age of the advance regeneration and the proportion of infected trees in the overstory and negatively correlated with the regeneration density. Vegetative spread through root contacts from overstory trees to the surrounding regeneration accounted for at least 53% of the Heterobasidion infections in the advance regeneration. The origin of the rest of the infections in advance regeneration remained unclear, but at least part of them may have started from spore infection on injured or dead roots. Our results suggest that, on sites infected by H. parviporum, advance growth of Norway spruce should not be used for regeneration even though the spruces look healthy and show no external signs of infection.


2020 ◽  
Author(s):  
◽  
Oskars Krisans ◽  

Climate change causes gradual decline of economic value of Norway spruce forestry except in boreal and hemiboreal forest zones that will remain suitable for this tree species. However, also in this region frequency and scale of damages caused by natural disturbances (abiotic and biotic factors) are expected to increase. Norway spruce will remain its economic significance and role in carbon sequestration in Latvia, if forest management practices will be changed to prevent or minimize the damages caused by natural disturbances. Information on effect of natural disturbances and their interactions on trees is vital for development of recommendations for adaptation of forestry to climate change. The aim of the thesis is to assess the effect of root rot and bark-stripping on possibility of wind induced damages in Norway spruce stands. Tree mechanical stability was primarily determined by its stem volume; however, the presence of damages, caused by biotic agents, such as root rot and bark-stripping, significantly reduced it. Morphometric parameters of Norway spruce stem and root plate differed significantly between stands on drained peat and mineral soils. Root-rot notably and significantly affected mechanical stability of trees regardless of soil type and volume of root-soil plate, resulting in similar reduction of wind load necessary to cause both primary and secondary failure. Consequences of bark-stripping primarily affected root-soil anchorage, more commonly causing uprooting than stem fracture. Most pronounced was reduction of resistance against primary failure. Changing wind climate, high population density of cervids and presence of root-rot will lead to increased risk of damages caused by (repeated) storms and subsequent legacy effects. The survival of forest stands depends on dimensions of trees and exposure time to different damaging agents, and, at current climate and silvicultural practice, was significantly reduced when transitioning into third age class (41-60 years). Targeted forestry, ensuring planting of improved material, lower initial density, timely precommercial thinning and thus ensuring faster reach of the tree dimension required for final harvest will reduce the time when stands are subjected to significant wind damage risk, thus minimizing the possibility of such disturbance and boosting value of Norway spruce stands.


2013 ◽  
Vol 43 (9) ◽  
pp. 872-877 ◽  
Author(s):  
Tuula Piri ◽  
Sauli Valkonen

Notwithstanding Norway spruce (Picea abies (L.) Karst.) is highly prone to root rot caused by Heterobasidion parviporum Niemelä & Korhonen, but little is known about the epidemiology of Heterobasidion root rot in spruce stands applied to uneven-aged management. To get insight into the development of Heterobasidion infections in this type of forest, the size and spatial distribution of individual genets of H. parviporum were determined in five uneven-aged managed Norway spruce stands in southern Finland. In these stands, all tree size classes (regeneration, intermediate, and overstory trees) were infected by H. parviporum. The average number of trees and stumps infected by a single genet ranged from 3 to 6.3 (mean 4.4) among study plots. All Heterobasidion genets identified from overstory trees or stumps had spread to the younger tree generation. Secondary infection from overstory trees was the main way of infection (at least 85% of all infections) among the regeneration and intermediate trees. The results indicate that uneven-aged management strategies that maintain continuous spruce regeneration favour the secondary spread of H. parviporum between different tree size classes and may compromise the production of high-quality timber over successive generations.


2014 ◽  
Vol 44 (7) ◽  
pp. 796-809 ◽  
Author(s):  
Juha Honkaniemi ◽  
Risto Ojansuu ◽  
Tuula Piri ◽  
Risto Kasanen ◽  
Mika Lehtonen ◽  
...  

Heterobasidion annosum (Fr.) Bref. s.l., a group of fungi causing root rot, is a serious threat to Norway spruce (Picea abies (L.) Karst.) stands in northern Europe. A new stochastic spatial model (Hmodel) was developed to simulate H. annosum s.l. infection and spread within a stand. Hmodel was combined with the stand-level decision support system MOTTI, resulting in a platform for estimating H. annosum s.l. development and its effect on tree growth and timber quality. Three H. annosum s.l. scenarios, representing different levels of risk for H. annosum s.l. infections simulated for a typical Norway spruce stand in southern Finland, demonstrated that the mycelial growth rate in the roots of living trees was the most critical parameter influencing the simulation results. In addition, the simulation results indicated that the number of infected trees in the previous stand plays a major role in H. annosum s.l. dynamics within the subsequent tree generation. Hmodel was designed to be a flexible platform for researchers to simulate the effects of H. annosum s.l. on stand dynamics and, vice versa, the effects of different silvicultural methods on H. annosum s.l. dynamics.


Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 416 ◽  
Author(s):  
Oskars Krisans ◽  
Roberts Matisons ◽  
Steffen Rust ◽  
Natalija Burnevica ◽  
Lauma Bruna ◽  
...  

Storms are the main abiotic disturbance in European forests, effects of which are expected to intensify in the future, hence the importance of forest stand stability is increasing. The predisposition of Norway spruce to wind damage appears to be enhanced by pathogens such as Heterobasidion spp., which reduce stability of individual trees. However, detailed information about the effects of the root rot on the stability of individual trees across diverse soil types is still lacking. The aim of the study was to assess the effect of root rot on the individual tree stability of Norway spruce growing on drained peat and mineral soils. In total, 77 Norway spruce trees (age 50–80 years) growing in four stands were tested under static loading. The presence of Heterobasidion spp. had a significant negative effect on the bending moment at primary and secondary failure of the tested trees irrespectively of soil type. This suggests increased legacy effects (e.g., susceptibility to pathogens and pests due to fractured roots and altered water uptake) of storms. Damaged trees act as weak spots increasing the susceptibility of stands to wind damage, thus forming a negative feedback loop and contributing to an ongoing decline in vitality of Norway spruce stands following storms in the study region in the future. Accordingly, the results support the importance of timely identification of the decayed trees, lowering stand density and/or shortening rotation period as the measures to counteract the increasing effects of storms on Norway spruce stands.


2010 ◽  
Vol 56 (No. 10) ◽  
pp. 474-484 ◽  
Author(s):  
E. Kula ◽  
W. Ząbecki

Research on merocoenoses of cambioxylophagous insect fauna of Norway spruce (Picea abies [L.] Karst.) was carried out in spruce stands of different age in the area with an endemic population (Moravian-Silesian Beskids, Czech Republic) and in the area with an epidemic population (Beskid Żywiecki, Poland) of the eight-toothed spruce bark beetle Ips typographus (L.). The structure of merocoenoses was characterized separately for standing trees attacked by bark beetles, trees struck by lightning, trees affected by fungal pathogens and wind-felling and trees in the form of snags and fragments. The occurrence of cambioxylophagous insects, mostly bark beetles (Coleoptera: Scolytidae), was compared between the study areas with emphasis on dominant facultative primary bark beetles and types of damage to spruce trees. &nbsp;


2008 ◽  
Vol 53 (Special Issue) ◽  
pp. 63-68 ◽  
Author(s):  
M. Jachym

This article presents a review of data and results of investigations from the period 1958–2006 regarding the occurrence of insects of the genus <I>Cephalcia</I> Panzer (Hymenoptera, Pamphiliidae) in Norway spruce stands of the Beskidy Mountains (Western Carpathians, southern Poland). Currently, eight species are known for the area: <I>C. abietis, C. alashanica, C. alpina, C. annulicornis, C. arvensis, C. erythrogaster, C. fulva</I> and <I>C. masuttii</I>. Information regarding each species is given, with details on identification, local occurrence and importance.


1995 ◽  
Vol 168-169 (1) ◽  
pp. 405-419 ◽  
Author(s):  
Stefan Slovik ◽  
Alfred Siegmund ◽  
Gerald Kindermann ◽  
Rüdiger Riebeling ◽  
Árpad Balázs

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