Coarse Woody Debris In Stands Research Articles

Persistence of some pine pathogens in coarse woody debris and cones in a Pinus pinea forest

The persistence of Sphaeropsis sapinea, Leptographium serpens and Heterobasidion annosum s.s. in artificially inoculated pine branch pieces ( S. sapinea and L. serpens) and wood blocks ( L. serpens and H. annosum s.s.) was investigated in order to discuss the alternative of leaving coarse woody debris in stands of Italian stone pine ( Pinus pinea). Also, natural colonization by S. sapinea of pine cones of different ages was assessed. Methods used for inoculating branch pieces and wood blocks were highly effective for all fungi. Type of a forest stand in which branch pieces and wood blocks have been incubated did not affect the persistence of the pathogens in the inoculated samples. For branch pieces, the success of re-isolation of L. serpens dropped as the sample incubation time increased, while S. sapinea was always successfully (100%) re-isolated (even 12 months after the inoculation). L. serpens and H. annosum s.s. were re-isolated from most of the buried wood blocks (from more than 95% samples) up to 3 months following the inoculation. Of the observed P. pinea cones (in most cases, more than 2 years old), 74% were naturally infected by S. sapinea. All three investigated pathogens were able to survive in dead plant tissues for long periods of time (at least for several (3–12) months). The persistence of these pine-pathogenic species in dead plant material questions the feasibility of leaving coarse woody debris in managed Italian stone pine forests meant for landscape conservation and leisure activities.

Saproxylic beetle diversity in a managed boreal forest: importance of stand characteristics and forestry conservation measures

ABSTRACTSaproxylic beetles constitute a significant proportion of boreal forest biodiversity. However, the long history of timber production in Fennoscandia has significantly reduced the availability of dead wood and is considered a threat to the conservation of saproxylic beetle assemblages. Therefore, since the mid‐1990s dead wood retention in harvested stands has formed an integral part of silvicultural practices. However, the contribution of this biodiversity‐orientated management approach to conserving saproxylic beetle assemblages in boreal forest landscapes that include production forestry remains largely untested. We examined differences in resident saproxylic beetle assemblages among stands under different management in a boreal forest landscape in Central Sweden, and in particular stands managed according to new conservation‐orientated practices. We also investigated the relationship between beetle diversity and forest stand characteristics. Bark of coarse woody debris (CWD) was sieved for beetles in old managed stands, unmanaged nature reserves, and set‐aside areas, and clear‐cut stands harvested according to certification guidelines [new forestry (NF) clear‐cuts]. All stand types contributed significantly to the total diversity of beetles found. While stand size, position, and distance to nearest reserve were unimportant, both the quality and the quantity of CWD in stands contributed significantly to explaining beetle abundance and species richness. This extends the previous findings for red‐listed invertebrates, and shows that heterogeneous substrate quality and a range of management practices are necessary to maintain saproxylic beetle diversity in boreal forest landscapes that include production forestry. The unique abiotic conditions in combination with the abundant and varied CWD associated with NF clear‐cuts form an important component of forest stand heterogeneity for saproxylic beetles. It is thus essential that sufficient, diverse, CWD is retained in managed boreal landscapes to ensure the conservation of boreal saproxylic beetle assemblages.

Stand specific occurrence of coarse woody debris in a managed boreal forest landscape in central Sweden

Forests long subjected to management for timber production contain only a fraction of the volumes of coarse woody debris (CWD) found in pristine forests. This is a threat to many organisms that depend on CWD. Forest management practices have been altered to achieve an increase in the amounts of CWD. Few studies have attempted to analyze the occurrence of CWD at the landscape level. We studied the occurrence of CWD in stands of different ages and management background in a boreal forest landscape in central Sweden. Volume of CWD in unmanaged stands (nature reserves and set-asides) was twice that in managed stands. The composition of CWD was influenced by stand age and management regime. Standing CWD was more common in unmanaged stands than in managed stands. Pine CWD was particularly prevalent in young forest stands (8–59 years of age). Bark-covered CWD was most common on deciduous and spruce wood and uncommon on pine. Bark area in young forest stands was almost 10 times lower than that in other managed stands. Using the age distribution of stands, we estimated the volume and bark area of CWD in the landscape. Recent clear-cuts harvested in accordance with new management guidelines contained more early decay CWD per ha than old managed stands. Young forests covered over half the landscape and had significantly lower volumes of spruce and deciduous CWD compared with other stands. The consequences of these results for biodiversity-oriented forest management are discussed.

Modelling dead wood in Norway spruce stands subject to different management regimes

Strategies for preserving biodiversity in boreal forests should include the maintenance of coarse woody debris (CWD) because this substrate is a key feature for the preservation of many threatened species. Computer simulation programs are useful tools for predicting the amount of CWD that will arise if certain management practices are applied in the long term. We have constructed and used a simulation program based on stochastic equations, which aims at predicting the amount of CWD in homogenous stands of Norway spruce in central Scandinavia. Because the rate of tree mortality is a critical factor in such simulations, we present such data derived from spruce-dominated forests surveyed in the Swedish National Forest Inventory. A comparison between simulation outcomes and field data shows that the average quantity of CWD in today’s managed forest is possible to predict using the simulation model. If the forest is managed according to the Forest Certification Standard, the amount of CWD (diameter larger than 10 cm) will be almost three times higher as the amount in today’s managed forests. The amount of CWD was found to be highest in old stands and immediately after cutting. In stands of an intermediate age the amount of CWD was low, especially CWD in early decay stages and of larger sizes. High productivity and long rotation time tended, on average, to increase the amount of CWD in stands. Among the management practices recommended in the new biodiversity-oriented forestry, retention of small areas with living trees is the most efficient way to increase the average amount and continuous occurrence of CWD within a stand, at least if the retained areas are as productive as the main part of the stands.