The effects of burning and dead-wood creation on the diversity of pioneer wood-inhabiting fungi in managed boreal spruce forests

The loss of natural forest habitats due to forestry is the main reason for the decline in boreal forest biodiversity of the Nordic countries of Europe. Ecological rehabilitation may provide means to recover and sustain biodiversity. We analyzed the effects of controlled burning and dead-wood creation (DWC) on the diversity of pioneer wood-inhabiting fungi in managed Norway spruce (Picea abies) forests in southern Finland. Altogether 18 stands were first subjected to a partial cutting with ordinary logging residues in form of cut stumps and treetops left on site. The subsequent rehabilitation treatments consisted of a controlled burning applied in half of the stands and three levels of dead-wood creation (5, 30 and 60 m³ ha⁻¹). The DWC involved creation of logs; felling of whole trees to mimic downed logs formed by natural disturbance processes. Each treatment was replicated three times. Inside each stand, substrates were sampled in two different biotopes; one on mineral soil and one on mineral soil with a thin peat layer. We surveyed the fungal flora on the logs (n = 364) and the ordinary residue stumps (n = 1767) and tops (n = 845) five years after the treatments.When comparing different stands, controlled burning had a significant effect on species composition; certain species were significantly more frequent on substrates in burned stands than in unburned stands, indicating that these species were favored by controlled burning. By contrast, we found no significant effects of DWC levels or biotope on species composition or richness. When comparing different substrates, 99% of the logs hosted at least one species and the occurrence probability of certain species was significantly higher on logs than on ordinary residue stumps and tops. Yet, volume-based rarefaction analyses showed that residues were more species dense than the logs, indicating that ordinary logging residues constitute important resources for many pioneer species.We conclude that controlled burning combined with DWC have strong effects on biodiversity; it modifies the composition of the pioneer wood-inhabiting fungal species found in managed forests and may thereby also influence the further succession and diversity of the secondary fungal flora.     

Estimating the consequences of habitat fragmentation on extinction risk in dynamic landscapes

Analyzing the population dynamic consequences of spatio-temporal changes in landscape structure is a formidable challenge for spatial ecology. One key population dynamic process in fragmented landscapes is the influence of isolation on colonization rate and thereby on the occurrence of species in habitat fragments, but it is not obvious how isolation should be measured in landscapes that are affected by on-going habitat loss and fragmentation. We suggest the following procedure for the measurement of spatio-temporal isolation. First, a historical record of habitat loss and fragmentation in the landscape is prepared based on snapshots of the extent of the suitable habitat for the focal species. Second, a metapopulation model is used to simulate the occurrence of the species in this landscape, assuming the empirically observed landscape change. The model-predicted pattern of habitat occupancy at a particular point in time (usually the present time) is then compared with empirical observations on the occurrence of the species. We describe a metapopulation model that has been constructed for this purpose, and we apply it to a changing landscape of boreal forests in eastern Finland. We give an example on the occurrence of four threatened polyporous fungi in 18 small fragments of old-growth forest. In none of the species does the current isolation of the fragments nor the time since their isolation explain the occurrence of the species in the study fragments, but in three species the model-predicted occupancy probability had a significant effect on the observed abundance of the species. The model-predicted occupancy probabilities were also calculated by ignoring past landscape changes, that is, by assuming that the landscape had remained in the present configuration for a long time. These probabilities had a significant effect on the abundance of only one of the four species, suggesting that the occurrence of the species tracks landscapes changes with a noticable time lag.This revised version was published online in May 2005 with corrections to the Cover Date.     

Applying spatial conservation prioritization software and high-resolution GIS data to a national-scale study in forest conservation

We apply a recently developed conservation prioritization method (Zonation algorithm) to a national-scale conservation planning task. The Finnish Forest and Park Service (Metsähallitus) was given the mandate to expand the current protected areas in southern Finland by 10 000 ha. The question is which areas should be selected out of the total area of 1 760 000 ha. The data available include a nation-wide GIS data set describing general features of forests at the resolution of 25 m × 25 m for entire Finland and another data set about biodiversity features within the current state-managed conservation areas. Ecologically, the key information includes forest age and the volume of growing stock for 20 forest types representing different productivity classes and dominant tree species. Our analysis employs four different connectivity components to identify forest areas that are (i) locally of high quality and internally well connected, (ii) well connected to surrounding high-quality forests, (iii) well connected to existing conservation areas, and (iv) large enough to allow efficient implementation. Expert evaluation of the results suggested that the present quantitative analysis was helpful in identifying areas with high conservation value systematically across southern Finland. Our analysis also showed that the highest forest conservation potential in Finland is located on privately owned land. The present techniques can be applied to many large-scale planning and management projects.     

Cereal yield trends in northern European conditions: Changes in yield potential and its realisation

In recent decades there has been steady reduction in the rate of increase in cereal yields worldwide. This paper aims to (1) characterise the changes in yield trends of spring (barley, oat and wheat) and winter cereals (rye and wheat) grown in Finland and (2) distinguish between plant breeding achievements and other potential contributors to changes in national yield trends and differences among crops. In this work we used long-term datasets from FAO (FAOSTAT, 2007) (1960–2005) and results from multi-location MTT Official Variety Trials (1970–2005). A mixed model technique was used to divide the yield trends in variety trials into two components: genetic improvements and environmental changes. All trends were characterised using 5 years moving averages. The study period was divided into three agronomically relevant sub-periods: (1) in 1960–1980 agriculture was mechanised and improved basic agricultural practices largely introduced, (2) in 1981–1994 intensified crop management practices were increasingly applied and (3) in 1995–2005 Finland had joined the European Union, which resulted in altered agricultural policies and markets. Plant breeding has successfully increased genetic yield potential of all cereal crops without any indication of reduced rates of improvement. Since 1995 the Finnish national yield trends declined for all crops except wheat, for which the trend levelled-off. The main reasons for this are: cereal production has become less intensive because of (1) application of an environmental programme aimed at increasing the sustainability of agriculture by reducing the environmental load it represents and (2) markedly decreased economic incentives to produce intensively as producer prices for cereals decreased and input prices remained unchanged. National yield trends did not decline because of lack of genetic improvement in yield potential. It is likely that future cereals yield trends will again respond to increasing demand for food, feed, biofuel production and global climate change.     

Effect of germination on vomitoxin level in grain.

The present investigation clarified the effect of enzymes or other substances formed during the germination process on the vomitoxin level of contaminated oats. The studies found that oats containing vomitoxin germinated very poorly; the decrease in toxins was also slight. The amount of pure vomitoxin added to toxin-free grain decreased (barley 53%, oats 40%, wheat 20%) during germination (5 d). In homogenized mixture of germinated grain (2.4 and 7 d) and toxic grain no decrease in toxin amount occurred during a 1-7 day period. In contrast, when germinating toxin free grains and toxic oats in a grain mixture the toxin level decreased at first, but later rose considerably. On the basis of these results, the utilization of germination processes for the improvement of grain containing vomitoxin is of questionable value.     

Cyclic dynamics in a simple vertebrate predator-prey community

The collared lemming in the high-Arctic tundra in Greenland is preyed upon by four species of predators that show marked differences in the numbers of lemmings each consumes and in the dependence of their dynamics on lemming density. A predator prey model based on the field-estimated predator responses robustly predicts 4-year periodicity in lemming dynamics, in agreement with long-term empirical data. There is no indication in the field that food or space limits lemming population growth, nor is there need in the model to consider those factors. The cyclic dynamics are driven by a 1-year delay in the numerical response of the stoat and stabilized by strongly density-dependent predation by the arctic fox, the snowy owl, and the long-tailed skua.