Wood-living Species Research Articles

Do conservation measures in forest work? A comparison of three area-based conservation tools for wood-living species in boreal forests

Loss of natural forests and decline in forest biodiversity has led to several policy initiatives in recent years. Despite this, the importance of smaller set-asides vs forest reserves for conservation measures is poorly understood. We aimed to evaluate the importance of three different area-based conservation measures commonly used in north-European forests; retention patches, woodland key habitats and forest nature reserves. We did this for two contrasting ecological systems; fungi in late-decay spruce logs and beetles in early-decay aspen snags.Eight replicated sites for each of the three conservation measures were investigated in a total of four boreal forest landscapes in south-Norway. Fungi were surveyed on existent late-decay spruce logs in two landscapes, and beetles trapped on experimentally added aspen dead-wood units in three landscapes. Richness and species composition were analyzed separately for specialist and generalist species.We found larger differences in species composition between conservation measures for old-growth fungi specialists than generalists, although species richness patterns were less clear. The main contrast was found between nature reserves and retention patches. On the other hand, specialist beetles associated with early-decay aspen showed no difference between set-asides. The assemblage of aspen generalist beetles tended to be richest in the woodland key habitats and showed clear differences between the conservation measures. There was considerable variation in response to conservation measures between landscapes, related to quality of the set-asides.Species specialized to an ephemeral, early-decay system were able to utilize such substrates in all of the conservation measures, while the smaller and more modified set-asides could not cater for the specialists dependent on stable, late-decay systems. Species with broader habitat demands in general responded to all conservation measures. We conclude that retention patches, woodland key habitats and forest reserves fill complementary functions for wood-living species in boreal forest and should all be part of future forest conservation strategies.

Spatial and temporal scales relevant for conservation of dead-wood associated species: current status and perspectives

Dead wood is a key substrate for forest biodiversity, hosting a rich and often threatened biodiversity of wood-living species. However, the relationship between the occurrence of dead wood and associated species is modified by several environmental factors. Here we review the present state of knowledge on how dead wood on different spatial and temporal scales affects saproxylic biodiversity. We searched for peer-reviewed studies on saproxylic species that compared dead wood distribution on at least two spatial or temporal scales. We scanned close to 300 articles, of which 34 fit our criteria. 20 studies were directed towards the current amount of dead wood at different scale levels and how this relates to the abundance or occurrence of saproxylic species, embracing scales from 10 m to 10 km. 14 studies compared time-lagged effects of dead wood, covering time-lags from 25 years to more than 200 years. The reviewed articles focused mainly on European forest and addressed invertebrates (mostly beetles), alone or in combination with fungi (27 articles), fungi (six articles), or lichens (one article). Although the significance of dead wood for forest biodiversity is firmly established, the reviewed studies show that we still have limited knowledge of the relationship between saproxylic biodiversity and spatial and temporal scales. Based on the reviewed studies, we conclude that there is large variation in response to spatial and temporal dead wood patterns between different taxa and sub-groups. Still, several of the reviewed papers indicate that time-lagged effects deserve more attention, especially on a landscape scale and for specialized or red-listed species. Further work is required before firm management recommendations can be suggested.

Dead wood creation to compensate for habitat loss from intensive forestry

Negative consequences of human activities for biodiversity may be mitigated by compensation measures. Although the interest in applying compensation measures is generally increasing, such measures have rarely been applied in forestry. Many boreal forests are managed by clear felling and used for timber and pulp production. There is an increasing interest in intensifying forestry by also harvesting slash and stumps for biofuel at felling. We evaluated the efficiency of combining intensified forestry production with compensation measures, by estimating the net revenue from slash and stump harvest, the cost of high stump creation, and simulating habitat amount for 680 bark- and wood-living species (fungi, beetles, lichens, and bryophytes) in Norway spruce forests in Sweden under different scenarios of biofuel harvest and compensation. We show that the harvest of slash and stumps has a clear negative effect on the habitat amount available for many species, especially for many fungi and beetles. Combining slash harvesting with the creation of high stumps results in an economic surplus and at the same time provides significantly more habitat in comparison with no slash harvesting and no high stump creation. When undertaking stump harvesting it is currently impossible to achieve such positive effects. Thus, our analyses show that compensation can sometimes be a useful tool when both economic and biodiversity goals must be achieved in forestry, but in other cases it is a better alternative to avoid the activity that causes the negative effects.

Evolution in the deep sea: a combined analysis of the earliest diverging living chitons (Mollusca : Polyplacophora : Lepidopleurida)

Lepidopleurida is the earliest diverged group of living polyplacophoran molluscs. They are found predominantly in the deep sea, including sunken wood, cold seeps, other abyssal habitats, and a few species are found in shallow water. The group is morphologically identified by anatomical features of their gills, sensory aesthetes, and gametes. Their shell features closely resemble the oldest fossils that can be identified as modern polyplacophorans. We present the first molecular phylogenetic study of this group, and also the first combined phylogenetic analysis for any chiton, including three gene regions and 69 morphological characters. The results show that Lepidopleurida is unambiguously monophyletic, and the nine genera fall into five distinct clades, which partly support the current view of polyplacophoran taxonomy. The genus Hanleyella Sirenko, 1973 is included in the family Protochitonidae, and Ferreiraellidae constitutes another distinct clade. The large cosmopolitan genus Leptochiton Gray, 1847 is not monophyletic; Leptochiton and Leptochitonidae sensu stricto are restricted to North Atlantic and Mediterranean taxa. Leptochitonidae s. str. is sister to Protochitonidae. The results also suggest two separate clades independently inhabiting sunken wood substrates in the south-west Pacific. Antarctic and other chemosynthetic-dwelling species may be derived from wood-living species. Substantial taxonomic revision remains to be done to resolve lepidopleuran classification, but the phylogeny presented here is a dramatic step forward in clarifying the relationships within this interesting group.

Theoretical expectations for thresholds in the relationship between number of wood-living species and amount of coarse woody debris: A study case in spruce forests

Summary To identify thresholds in the relationship between the number of species in viable populations and habitat availability is useful for nature conservation. However, to obtain such empirical data may be extremely laborious. Many saproxylic (wood-living) species are under threat because there is little coarse woody debris (CWD) in managed forests. Based on computer simulations of CWD dynamics, and information about the substrate requirements of red-listed saproxylic species, we conclude that it is unlikely that any specific quantity of CWD can be defined as the extinction threshold for large numbers of species, since different species are specialists in utilising different types of CWD. In our analysis, we identified a curvilinear relationship between total CWD and the number of red-listed species in viable populations, even assuming that there were sharp extinction thresholds for individual species. Thus, it is highly unlikely that it will ever be possible to identify simple targets for maintenance of CWD based on extinction thresholds for the whole community of saproxylic species. Instead other strategies are necessary when formulating conservation targets.

Effects of enhanced tree growth rate on the decay capacities of three saprotrophic wood-fungi

The structure of Scandinavian boreal forests has changed in many ways as a result of modern intensive forestry. One of the most fundamental changes is the loss of coarse woody debris (CWD), which has adversely affected many wood-inhabiting species. The consequences of reductions in CWD and its variability have received much attention in the literature recently. However, a neglected substratum change with possible profound ecological implications is enhanced tree growth rate due to forestry practices such as thinning and fertilization. In the study presented here we investigated how tree growth rate influenced the decay capacity of two threatened species, Phlebia centrifuga and Fomitopsis rosea, and a common species, F. pinicola, of saprotrophic wood-decay fungi. Their decay capacity was measured as the weight loss they caused in Picea abies wood-discs categorised as fast-, moderately-, and slow-grown. The results show that the rates of decay caused by all three species were highest in fast-grown wood cut in thinnings, and lowest in slow-grown wood cut in extensively managed stands. None of the stands had been fertilised. Interestingly, rate of decay caused by the common generalist fungus F. pinicola was 50% higher in fast-grown wood than in slow-grown wood, suggesting that the turnover of dead wood is much higher in intensively managed forests. Thus, the time window for wood-living species to colonize CWD, which is a transient habitat even in old-growth forests, is even shorter in intensively managed forests. This may adversely affect species with poor dispersal ability. Moreover, F. rosea decayed the slow-grown wood significantly more rapidly than the other species. This suggests that it may be adapted to such substrates, and that F. rosea may be favoured in old-growth forests where trees generally have slower growth rates than in managed forest. For P. centrifuga, there was a large variation in its decay capacity among genets, indicating a need for further studies on the genetics of threatened wood-fungi, given the species’ fragmented distribution.