Tree spatial patterns of Abies alba and Fagus sylvatica in the Western Carpathians over 30 years

The decline of Abies alba (fir) in natural fir–beech forests in Europe has fascinated scientists for over a century. During this period, Fagus sylvatica (beech) became the dominant species in this forest type. We hypothesised that (1) the success of beech over fir is significantly connected with the fact that beech suffers less than fir from the presence of conspecific neighbours; that (2) shade tolerance is not a factor which favours beech over fir; and that (3) this is due to a significantly reduced proportion of litter treethrow mounds with suitable conditions for the successful regeneration of fir. We investigated these hypotheses by means of tree spatial pattern analysis. Eight rectangular plots (2–8 ha) were analysed in mountain fir–beech forests of the Outer Western Carpathians, Czech Republic. Various types of the pair correlation function and L function were used to describe the tree density variability of trees with DBH ≥10 cm. The analyses were carried out on datasets from the 1970s, 1990s and 2000s. Our results suggest that negative density dependence is not responsible for the current decline of fir. It seems that a higher shade tolerance of the advanced regeneration could be one of the factors which favour beech over fir. It is evident that fir trees have a markedly stronger positive association to mounds than beech trees.     

Spatial variability of nutrient stocks in the humus and soils of a forest massif (Fougères, France)

In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones).     

Spatial patterns of forest fires in Catalonia (NE of Spain) along the period 1975–1995: Analysis of vegetation recovery after fire

This paper revises the results of applying a semiautomatic methodology for fire scars mapping from a time series of Landsat MSS images over the forest and shrubby surface of Catalonia (1975–1993). Perimeters of fires which occurred in 1994 and 1995 were added enlarging the whole series to 21 years from TM imagery. Results are a map series of fire history during 21 years as well as a map of the fire recurrence level. Omission errors are 23% for burned areas greater than 2 km² while commission errors are 8% for areas greater than 0.5 km². Detected fire scars were incorporated into a geographic information system in order to characterise the fire regime of the study area. Fire size distribution and the number of spot fires originated from each fire as well as the maximum distance reached from the main fire are analysed. A first approach to monitor post-burn regeneration through normalised difference vegetation index is also shown.     

Modelling the management of fragmented forests: Is it possible to recover the original tree composition?: The case of the Maulino forest in Central Chile

In the fragmented Maulino forest (in Central Chile), differences in the relative frequencies of species between seedlings and mature trees are strong indicators of a changing replacement dynamics in the community. Stationary Markov chain models predict that the future tree composition such Maulino forest fragments will differ from that of continuous, intact forest. We found that the persistence probability was highest for Aristotelia chilensis and lowest for Nothofagus glauca. These two tree species are the most affected by fragmentation, and changes in their abundances appear to be the main drivers of the long-term change in stand composition. The aim of our study was to test if the management of just these two species would be sufficient to avoid long-term changes in the composition of forest fragments or would recover their composition toward a state more similar to the continuous forest. For this purpose, we constructed a Markov matrix model from published information, and calculated the future stable stand composition under different management simulations: (1) reduction of A. chilensis recruitment, (2) increased recruitment of N. glauca, and (3) a combined treatment. To evaluate the effectiveness of management treatments, the future composition of fragments was compared with the composition expected for continuous (i.e., undisturbed) Maulino forest. We performed a sensitivity analysis of the stable composition in order to assess the intensity of changes in the future composition driven by the treatments, and to determine to what extend the recruitment of other coexisting species contributes to changes in relative frequencies of A. chilensis and N. glauca.     

Current distribution of older and deciduous forests as legacies from historical use patterns in a Swedish boreal landscape (1725–2007)

We combine historical maps and satellite derived data to reconstruct the development of a Swedish boreal landscape over the past 300 years. The aim is to understand legacies from past use patterns in present-day forest composition and consequences for conservation objectives from a landscape perspective. We analyze landscape development in cross-tabulation matrixes, building change trajectories. These trajectories are tested in linear models to explain the distribution of present-day landscape composition of coniferous, mixed, and deciduous forests >110 years. Of 49 tested change trajectories, 11 showed a significant association. Associations for mixed and coniferous forests were similar and linked to characteristics such as forest continuity, which characterized the studied landscape. Deciduous older forests did not show any association to forest continuity but were more likely to occur on areas that specifically shifted from forests with grazing in the 1720s to open impediment (likely indicating low tree coverage) in the 1850s. There were large shifts and spatial redistribution in ownerships over time. Use patterns and legacies varied between small- and large-scale ownership categories as well as within small-scale categories. The legacies found in the study indicate a complex origin of heterogeneous landscape elements such as older deciduous forests. Additionally, the origin of the legacies indicates a potential need to diversify conservation management based on the influence of past use patterns. Despite large inconsistencies in historical and contemporary data we argue that this type of analysis could be used to further understand the distribution of landscape elements important for conservation objectives.     

Deer prevent western redcedar (Thuya plicata) regeneration in old-growth forests of Haida Gwaii: Is there a potential for recovery?

The current increase in deer populations in many forests has fostered a growing concern about their impact on forest ecology. Sitka black-tailed deer (Odocoileus hemionus sitchensis) were introduced to Haida Gwaii (British Columbia, Canada) in the late 19th century, and they have dramatically affected the regeneration of woody species in both old- and second-growth forests since then. The lack of recruitment in western redcedar (Thuja plicata) in old-growth forests has been attributed to deer. The objectives of this study were to (1) experimentally confirm that deer browsing causes a lack of western redcedar recruitment and (2) assess the potential for and speed of recovery after a prolonged exclusion of deer. We installed a set of 20 enclosures and monitored them over a period of 8 years from 1997 to 2005. We compared temporal changes in redcedar cover and in the survival and growth of marked seedlings in plots that were or were not accessible to deer. Redcedar cover in the vegetation layer accessible to deer was generally low (from 3 to 5%) but higher inside the enclosures (an average difference of 2.3%). Protected seedlings survived better, were higher, presented more leafed shoots, and had less stems than unprotected individuals, features that suggest that deer were key to the lack of regeneration. However, growth was very slow (protected marked seedlings grew 2.5 cm on average in 8 years) and, under the current conditions, the time required for a protected seedling to escape deer would probably take over two decades. This very slow growth rate under closed canopy conditions probably reflects a gap-phase regeneration strategy and/or sensitivity to competition with other woody species. The combination of a very slow growth with a high palatability and a lack of physical defences, in contrast to the other dominant conifers in this ecosystem, probably explain why redcedar regeneration can be eliminated from old-growth forest by abundant deer populations.     

Monitoring of stored tobacco insect pests by means of pheromones: the case ofEphestia elutella (Hübner) andLasioderma serricorne Fabricius in South Europe

Results obtained in the monitoring of stored tobacco pests by pheromones are reported. In GreeceEphestia elutella (Hübner) is likely to have at least 3 generations per year: the first one appears in early May, the second one during the last week of June and the third one— the most populated and the longer lasting—in August. In the same environmentsPlodia interpunctella (Hübner) has shown about 5 generations per year. The first on appeared in late May; the remaining 4—definitely overlapping—are placed in mid-June, in July, in early August and early September. In Italy four commercial pheromone dispensers effective in trappingLasioderma serricorne Fabricius have been compared. The results pointed out highly significant differences of the efficacy of the four different dispensers tested.L. serricorne was present in the tobacco store from June to October with a quite remarkable increase between August and early September.     

New Forest Owners: Change and Continuity in the Characteristics of Swedish Non-industrial Private Forest Owners (NIPF Owners) 1990–2010

This paper presents a total survey of the characteristics and changes over time (1990–2010) within the entire population of Swedish non-industrial private forest owners (NIPF owners). By charting the changed demographic, socio-economic and geographic profile of the NIPF owners, it also provides a baseline for a discussion and analysis of potential implications for forest management, policy and values. NIPF owners differ in important ways from the general population of Sweden. However, the gap has narrowed over time with regard to, e.g., educational level and sex composition. The ongoing urbanization process is evident in the growing share of non-residential NIPF owners who live at a distance from their forest property and who differ from their residential (rural) peers through, e.g., higher education, higher income and a higher prevalence of co-ownership of their forest holdings. Although these changes might translate into updated views on forest values among NIPF owners, there could be a delay before this impacts on forest management practices and output.     

Dynamic changes of telomeric restriction fragment (TRF) lengths in cells during the developmental process from embryos to seedlings and a comparison with the embryonal calli in Ginkgo biloba L.

Telomeres are the structures that locate at the terminals of linear eukaryotic chromosomes. They can play essential roles in many cellular processes. The terminal location of Arabidopsis-type TTTAGGG tandem repeats were thought to be highly conserved. The terminal location of Ginkgo biloba L. consisting of TTTAGGG tandem repeats, were confirmed by Bal31 exonuclease degradation and Southern blotting. By comparing telomeric restriction fragment (TRF) lengths at different developmental stages from embryos to seedlings, a fluctuant tendency towards variation was found in these samples. The TRF length of embryos was also compared with that of embryonal calli and an upward trend was discovered in callus culture. The results suggest that there should be a telomerase mechanism or/and ALT mechanism for the maintenance of telomere length.