Snow disturbances in secondary Norway spruce forests in Central Europe: Regression modeling and its implications for forest management

Snow is an important ecological factor limiting vegetation distribution, growth, and regeneration, and the importance of snow in the latitudes of Central Europe is expected to increase in the future. We assessed snow damage to secondary spruce stands (not of native provenance therefore not adapted to local conditions) in a mountainous region of 14500 ha in Central Europe (Moravian-Silesian Beskids, Czech Republic). We used neural networks-based regression modeling to study the relationship between stand and environmental parameters and four types of snow damage (top tree, crown, and stem breakage, and uprooting) that occurred during heavy snowfalls in winter 2005/2006 and 2009. Almost 40000 trees were sampled in 345 plots after each of these two events.The results suggest that parameters that can be controlled by forest management (mainly stand density and taper) were not closely associated with spruce forest resistance to snow damage. Investigated snow damage types were primarily related to the developmental stage of the stand, as indicated by stand volume, age, height, and diameter. Damage in 2009, which was caused by shorter-lasting and lower snow loads than the damage in 2005/2006, was also associated with elevation and snow depth. The response of snow damage to all stand development-related variables was clearly unimodal.We infer that forest management can reduce snow damage to secondary spruce forests in Central Europe only to a limited extent, especially under heavy snow loads. This conclusion is supported by the heavy snows that have frequently fallen on forests in Central Europe in the past and the projected increase in winter precipitation in mid- and northern latitudes; thereby increasing snow damage to forest in the future. Therefore, managers of such spruce forests should not specifically consider forest resistance to snow damage but should apply general practices that maintain forest health and productivity.     

Assemblages of wood-inhabiting fungi related to silvicultural management intensity in beech forests in southern Germany

Current silvicultural treatments in beech forests are aimed at achieving thick logs without discoloured hardwood. Therefore intensive thinning is applied already in younger stands with the objective of large-sized trunks at an age of 100 years. However, this approach bears the risk that dead wood structures and broken trees are completely removed from the forest. The impact of three different silvicultural management intensity levels on wood-inhabiting fungi over decades was investigated in a large beech forest (>10,000 ha) in southern Germany in 69 sampling plots: A Intensive Thinning and Logging with high-value trees, B Conservation-Oriented Logging with integration of special structures such as dead wood and broken trees and C Strict Forest Reserves with no logging for 30 years. The analysis of community showed marked differences in the fungus species composition of the three treatments, independent of stand age. The relative frequencies of species between treatments were statistically different. Indicator species for naturalness were more abundant at sites with low silvicultural management intensity. Fomes fomentarius, the most common fungus in virgin forests and strict forest reserves, is almost missing in forests with high-management intensity. The species richness seemed to be lower where intensive thinning was applied (P = 0.051). Species characteristic for coarse woody debris were associated to low management intensity, whereas species with a significant preference for stumps became more frequent with increasing management intensity. A total amount of dead wood higher than 60 m³/ha was found to enable significantly higher numbers of species indicators of naturalness (P = 0.013). In conclusion, when applying intensive silvicultural treatment, the role of dead wood needs to be actively considered in order to maintain the natural biocoenosis of beech forests.     

阿尔山林区人工林经营中存在的问题及对策

本文根据阿尔山林区实际情况，分析了阿尔山林区人工林生长规律及经营中存在的问题，并针对存在的问题，提出对策。     

Modelling long-term impacts of environmental change on mid- and high-latitude European forests and options for adaptive forest management

The process based model SMART–SUMO–WATBAL was applied to 166 intensive monitoring forest plots of mid- and high-latitude Europe to evaluate the effects of expected future changes in carbon dioxide concentration, temperature, precipitation and nitrogen deposition on forest growth (net annual increment). These results were used in the large-scale forest scenario model EFISCEN (European Forest Information SCENario model) to upscale impacts of environmental change and to combine these results with adapted forest management. Because of the few plots available, Mediterranean countries were excluded from analyses. Results are presented for 109 million ha in 23 European countries.     

Trade in forest products between European Union and the Central and Eastern European access candidates

Patterns in forest products trade between European Union and Central and Eastern European access candidates were studied. The results indicated that both production and trade of forest products in Central and Eastern European countries in transition have considerably increased during the 1990s. The European Union has been the most important trading partner for CEE countries, even though the EU share from the external trade has been quite stable. The gravity models estimated explained approximately 66% of the variation in volume of bilateral trade flows in EU and CEE countries in 1997. Results indicated that trade between EU and CEE countries was below the level that would be expected on the basis of income and distance. A model separating the trade flows according to direction suggested that this is due to the low intensity of West–East trade, which probably originates in low levels of consumption of higher value-added products in CEE countries. East–West trade did not significantly differ from the average pattern.     

Long-term adaptation potential of Central European mountain forests to climate change: a GIS-assisted sensitivity assessment

An ecological risk assessment is described for determining the adaptation potential of the approximately 11 000 Swiss Forest Inventory points (FIP) to a hypothetically changing climate. The core of the study is a spatially explicit forest community model that generates estimates of the potential natural vegetation for the entire potential forest area of Switzerland under today's as well as under altered climate regimes. The model is based on the Bayes formula. The probabilities of the communities occurring along ecological gradients are derived from empirical data featuring the relationships between quasi-natural vegetation types and measured site variables. Bioclimatological input variables are the quotient between July temperature and annual precipitation (model version A) or mean annual temperature (model version B). Other site variables include aspect, acidity of top soil and, to account for continentality, geographical region. Climate change scenarios are defined as follows: ‘Moderate climate change’ implies an increase of the mean annual temperature of 4°C to 1.4°C depending on the region (model version B) or an increase of the July temperature of 1.5°C (model version A). ‘Strong climate change’ implies an increase of the mean annual temperature of 2°C to 2.8°C (model version B) or an increase of the July temperature of 3.0°C (model version A).

The simulation experiment showed that the geographical distribution of 15 potential natural forest types (distinguished on the basis of floristic affinities) varies considerably with changing temperature. Under moderate warming 30–55% of the FIP change their potential natural vegetation type, whereas under strong climate change the values increase to 55–89% depending on the model version used. In the ecological risk assessment the existing tree species composition on any FIP was compared with the expected tree species composition under today's as well as under altered climate regimes. A major finding indicated that, under the current climate conditions, approximately 25–30% (depending on the model version used) of all FIP must be considered as poorly adapted, i.e. less than 20% of the actual basal area consists of tree species that are expected as dominating taxa. This definition applies for trees with a diameter at breast height (DBH) ≥ 12 cm. Moderate warming increases the percentage of poorly adapted FIP by 5–10% (relative to all FIP considered), strong warming leads to a 10–30% increase of poorly adapted FIP (relative to all FIP considered). If trees with a DBH < 12cm are considered, the percentage of FIP that have to be classified as poorly adapted is reduced significantly. There are strong regional differences as exhibited in risk maps of 10 km × 10 km resolution.     

西藏天然林资源保护与可持续经营

探讨了西藏天然林资源的现状、特点、问题，提出了天然林资源的可持续经营措施。     

Future development of the Leningrad region forests under nature-oriented forest management

Russian forests are of high importance for the Russian economy, the European wood market, for nature conservation, and for carbon sequestration. However, the ongoing changes in forest management and administration in Russia led to uncertainty about forest ownership, wood harvesting levels, and long-term impacts of alternative management plans. Therefore, better insight in their current and future state is highly desirable. We present a study for the Leningrad region forests in which alternative management regimes for wood production and nature conservation values are balanced in varying ways. The total forest land area in the Leningrad region forest fund is 4.8 million ha. Coniferous species dominate and due to the natural succession occurring, the forests are divers in vertical structurally.

A timber assessment model was used to project the forest until 2040. Five forest management scenarios were run. Special attention was paid to a scenario that simulates recovery of the Russian forest sector in combination with the incorporation of a ‘set-aside for nature conservation’ policy. All scenarios showed that recovery of the forest sector in the Leningrad region is biologically feasible. A sustainable continuous annual production of 10.6 million m³ per year (2.8 m³ ha⁻¹ per year) by 2040 was found. The ‘Recovery with Nature Conservation’ scenario showed that recovery of the forest sector in combination with the establishment of set-aside areas is very well feasible. It was possible to set aside 28% of the forest area for nature conservation while still developing a forest sector to a production level higher than that achieved in the late eighties.

The timber assessment model applied was not specifically designed to incorporate nature-oriented forest management. We, therefore, discuss ways of improving the required methodology to analyse long-term effects of nature-oriented forest management in Europe.     

Natural development and regeneration of a Central European montane spruce forest

Montane Norway spruce forests of Central Europe have a very long tradition of use for timber production; however, recently there has been increasing concern for their role in maintaining biological diversity. This concern, coupled with recent severe windstorms that led to wide-spread bark beetle outbreaks, has brought the management of montane spruce forests to the forefront of public policy discussions in Central Europe. In order to shed light on the natural development and current structure of mature montane spruce forests, we established four 0.25 ha research plots in a semi-natural montane spruce forest in the Šumava Mountains (The Bohemian Forest), Czech Republic. We mapped all trees, extracted increment cores for age and growth-pattern analyses, and inventoried all current tree regeneration, including the substrates on which it was found. Stands were characterized by uni-modal tree diameter distributions and high basal areas (56.6 m² ha⁻¹ on average), indicating a natural transition from the stem exclusion phase towards the understory reinitiation phase. The stands showed largely single-cohort recruitment age structures, however, with recruitment spanning seven decades. Our analyses suggest that this cohort existed as advance regeneration prior to major disturbances in the late 1800s, which included post-bark beetle salvage logging. Spatial pattern analyses of living and dead stems combined, showed an increase in uniformity of living trees, pointing to the role of natural density-dependent mortality. However, past growth patterns and historical documentation suggest that low intensity canopy disturbances (wind and snow) also caused mortality and diversified canopy structure. Because the stands developed naturally over the past 120+ years and thus escaped thinning operations, high volumes of coarse woody debris (94 m³ ha⁻¹) and snag densities (546 stems ha⁻¹) have accrued. Advance spruce regeneration was quite abundant and existed primarily on deadwood substrates, even though these occupied only a small percent of stand area. Because of salvage logging in the late 1880s, these stands do not qualify, according to the traditional paradigm, as natural spruce forests. As a result, they are recently subject to active management practices including salvage logging that remove dead and dying trees. Given the importance of deadwood for forest regeneration and recovery from disturbance, as demonstrated in this study, we argue that dead wood removal may limit future natural regeneration in these stands. Thus, the purported benefits of removing dead and dying trees from semi-natural forests must be carefully weighed against the potential detrimental impacts on natural spruce forest regeneration and biodiversity.     

Flexibility in forest management: managing uncertainty in Douglas-fir forests of the Pacific Northwest

Long planning horizons generate substantial uncertainty in forest management, making management flexibility, the ability to choose between multiple options or opportunities, a desirable attribute of managed forests. Flexibility in forest management reflects both the relative rigidity of intervention requirements and the potential range of development pathways for a stand. The wind stability of Pacific Northwest Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) plantations is used to demonstrate the concept of management flexibility. Dense Douglas-fir plantations develop high height to diameter ratios (H/D same units) in the dominant trees making them unstable and prone to wind damage. The management of these plantations is inflexible, because without early and timely thinning, the stands do not contain stable trees that could be expected to survive long rotations or late thinnings. A combination of reduced planting densities and site-specific management reduces both the necessity and rigidity of intervention requirements (e.g., thinning) and expands the number of potential developmental pathways for these stands. The cost of greater management flexibility is reduced efficiency of wood volume production; however, greater adaptability to changing markets, labor conditions, and management objectives may be more important for many forest owners. While this approach to management is complex, it frees owners and managers from rigid management requirements and allows for a wider range of future stand conditions.     

经营强度对高节竹生物量的影响

对集约和粗放经营的高节竹不同器官生物量及凋落物量进行研究.结果表明:相对于粗放经营,集约经营高节竹林的1-3年生竹占比从71％增长至81％,单株叶、枝、秆生物量比粗放经营分别高66.7％、60.8％、79.4％,整株生物量比粗放经营高74.63％.集约经营高节竹林单位面积叶、枝、秆、根鞭、凋落物和总生物量分别为10.1...     

关于林价费用如何计算国内生产总值的探索

本文通过对实行林价和未实行林价制度的企业计算增加值和国内生产值的研究,探索了林业 企业关于林价如何计算国内生产总值的方法。     

Legacies from natural forest dynamics: Different effects of forest management on wood-inhabiting fungi in pine and spruce forests

The species composition of wood-inhabiting fungi (polypores and corticoids) was investigated on 1138 spruce logs and 992 pine logs in 90 managed and 34 natural or near-natural spruce and pine forests in SE Norway.Altogether, the study included 290 species of wood-inhabiting fungi. Comparisons of logs with similar properties (standardized tree species, decay class, dimension class) in natural and managed forests showed a significant reduction in species number per log in managed spruce forests, but not in managed pine forests. The species number per log in managed spruce forests was 10-55% lower than on logs from natural spruce forests. The reduction was strongest on logs of large dimensions. A comparison of 200-400 spruce logs from natural and managed forests showed a 25% reduction in species richness corresponding to a conservative loss of ca. 40 species on a regional scale.A closer inspection revealed that species confined to medium and very decayed spruce logs were disfavored in managed forests, whereas species on early decay classes and decay generalists were unaffected. Similarly, species preferring large spruce logs were disfavored in managed forests. Forest management had strongest impact on low-frequent species in the spruce forests (more than 50% reduction), whereas common species were modestly affected. Corticoid fungi were more adversely affected than polypore fungi.These results indicate that wood-decaying fungi in pine forests are more adapted to forest disturbances than spruce-associated species. Management measures securing a continuous supply of dead wood are more important in spruce forests than in pine forests.     

退耕还林中如何认定生态林与经济林

1999年开始试点并于2002年全面启动的退耕还林工程,是我国迄今为止最大的林业生态建设工程。该工程国家出台了“三补助一减免”(粮食补助、种苗造林补助费和生活补助费,减免农业税)优惠政策,同时还明确规定了营造生态林和经济林的补助期限和比例要求。生态林与经济林的认定,不但影响到工程建设质量和成效的评价,而且直接关系到国家钱粮补助的兑现和退耕农户的切身利益。为此,本刊特约请国家林业局退耕还林工程管理办公室总工程师杜纪山博士就有关问题撰写了下文,以期能对工程实施起到一定的指导作用。     

Inter- and intra-annual variations in canopy fine litterfall and carbon and nitrogen inputs to the forest floor in two European coniferous forests

? Context

The amount and chemistry of litterfall have been known to strongly vary among the years with important implications for ecosystem nutrient cycles, but there are few quantitative data describing such variations.

? Aims

We studied the climatic implications on the variation in litterfall and its C and N input to soil in two distinct European coniferous forests.

? Methods

Year-to-year variations in canopy litterfall were measured in a Scots pine stand (Hyytiälä, Finland) over 13 years, and a Douglas fir stand (Speulderbos, The Netherlands) over 3 years.

? Results

Important inter-annual variations in litterfall were observed in Scots pine. Litterfall was mainly driven by leaf senescence; however, premature needle fall was observed in high wind speed and early frost events. The seasonal variation in litterfall was characterized by a maximum in September in Scots pine, and by a biphasic variation pattern in Douglas fir, in May and November. Lower seasonal variations and lower annual average in litterfall N content were observed in Scots pine.

? Conclusion

Significant inter- and intra-annual variations in litterfall and chemistry and between the sites were demonstrated; and it depended on year-to-year differences in climate and extreme weather events.     

Bat response to shelterwood harvests and forest structure in oak-hickory forests

Forest management practices, such as shelterwood harvesting, can greatly impact bat habitat relationships. Such practices can alter the amount of structural volume within a forest, which can influence bat foraging patterns. We determined the effects of shelterwood harvests of different retention levels (50% and 70% of full stocking) on bat activity patterns in oak-hickory forests located in southern Ohio. We used the Anabat system to monitor activity during May-September 2006. Our objectives were to quantify the effects of harvesting on structural volume and use the results to explain variations in bat activity. Because harvesting alters vertical structure as well as the total amount of volume within a forest, we also determined the height within the vertical profile where changes in structural volume begin to influence overall and species-specific activity. Overall bat activity did not differ significantly between shelterwood harvest levels, but was significantly different between harvested and control sites, with more passes detected within the harvested sites. Lasiurus borealis (red bat), Eptesicus fuscus (big brown bat), and Lasionycteris noctivagans (silver-haired bat) activity was significantly greater in harvested versus control sites, but did not differ between shelterwood harvest levels. Myotis spp. (Myotis lucifugus (little brown bat) and Myotis septentrionalis (northern Myotis)) and Perimyotis subflavus (tri-colored bat) activity did not vary between shelterwood harvest levels or between harvested and control sites. The greatest reductions in structural volume occurred in the understory to mid-canopy of the shelterwood harvests. Overall activity was most influenced by the amount of volume within 3-6 m above the forest floor, and declined as volume within that height strata increased. Mean bat passes declined by 50% when volume within 3-6 m exceeded 17 m³/ha. Estimated use by L. borealis decreased by 50% at volumes exceeding 1750 m³/ha in the understory to mid-canopy (0-12 m), while E. fuscus and L. noctivagans estimated use was the highest when volumes within 3-6 m were less than 63 m³/ha. Our results suggest that forest management practices that reduce the amount of structural volume in the understory to mid-canopy provide suitable habitat for foraging bats. Quantifying the amount of structural volume at various heights within the vertical profile of the forest can lend valuable insights into overall and species-specific bat activity patterns.