Mixed litter decomposition in a managed Missouri Ozark forest ecosystem

We monitored the decomposition of mixed leaf litter (Quercus spp., Carya spp., and Pinusechinata) in a Missouri Ozark forest eight years after experimental harvest. Leaf litter mass losses and changes in carbon chemistry (extractive, acid soluble, and acid insoluble fractions) were measured over 32 months in field incubations to determine the effects of litter composition and stand manipulation on decomposition and nitrogen (N) concentration in the remaining litter. The decay (k) rate over this period ranged between 0.39 (±0.010) and 0.51 (±0.002) year⁻¹ for oak, oak–hickory, and oak–pine litter. There were significant main effects of stand manipulation (p = 0.03) and litter type (p < 0.01) on decay. Mass losses of oak and oak–hickory litter were 7% (p = 0.02) and 4% (p = 0.04) higher on harvested stands than controls, respectively. Mass loss of oak–hickory litter was 3% faster than oak–pine (p = 0.03) and 6% faster than oak (p = 0.02) litter on control stands, whereas the oak–hickory litter mass loss was 5% higher than oak litter on harvested stands (p = 0.01). The decay (k) rate had a linear relationship with initial leaf litter nitrogen content and lignin-to-N ratio. The nitrogen concentration in remaining litter had a nonlinear relationship to cumulative mass loss suggesting an exogenous source of N. In summary, this study demonstrated significant effects of timber harvest and litter mixtures on decomposition and N dynamics in a managed Missouri Ozark forest.     

A management planning system for even-aged and uneven-aged forests in northeast China

The most common scientific approach to numerical landscape-level forest management planning is combinatorial optimization aimed at finding the optimal combination of the treatment alternatives of stands. The selected combination of treatments depends on the conditions of the forest, and the objectives of the forest landowners. A two-step procedure is commonly used to derive the plan. First, treatment alternatives are generated for the stands using an automated simulation tool. Second,the optimal combination of the simulated treatment schedules is found by using mathematical programming or various heuristics. Simulation of treatment schedules requires models for stand dynamics and volume for all important tree species and stand types present in the forest.A forest planning system was described for Northeast China. The necessary models for stand dynamics and tree volume were presented for the main tree species of the region. The developed models were integrated into the simulation tool of the planning system. The simulation and the optimization tools of the planning system were described. The optimization tool was used with heuristic methods, making it possible to easily solve also spatial forest planning problems, for instance aggregate cuttings.Finally, the use of the system is illustrated with a case study, in which nonspatial and spatial management plans are developed for the Mengjiagang Forest District.     

Inventory and modelling for forests in transition from even-aged to uneven-aged management

In plantation forestry, as well as in forests managed according to the single tree selection system (Plenter forest), there are well established methods available to control sustainable management in terms of timber resources. If a shift from even-aged to uneven-aged management is intended, there is usually a lack of a clear, numerically defined aim. Then individual tree growth models help to (i) check if certain aims can be achieved at all and (ii) to define these aims more clearly and numerically, e.g. in terms of structural indices. Regular inventories, based on permanent sample plots, help to determine deviations from these aims. As a feedback of these results, management may be changed or aims may be adjusted. Two forest management districts in Austria were investigated. In one of them, continuous cover forestry was intended where, as soon as regeneration has reached a certain height, the upper layer was removed. In the other case, individual tree harvesting has been performed for 30 years, and a single tree selection system is intended. In both cases, permanent inventories based on angle-count sampling have been installed and re-measured at least once after 10 years. Using the individual tree simulator PrognAus it is shown, that the intended management strategy for the single tree selection system leads to an equilibrium of harvests and growth after about 80 years, accompanied by the intended high structural diversity of the stands, while species diversity and between-stand variation cannot be enhanced by much. In the natural regeneration system without single tree selection, species diversity, structural diversity and between-stand variation is enhanced, but during the 100 years simulated no equilibrium between harvests can be reached. Periods where there is a lack of large timber to be harvested occur regularly. From these examples it is concluded that inventories with permanent sample plots, together with individual tree growth simulators are appropriate tools to evaluate forest management changes.     

An individual-tree diameter growth model for managed uneven-aged oak-shortleaf pine stands in the Ozark Highlands of Missouri, USA

The Pioneer Forest encompasses more than 60,000 ha in the Ozark Highlands of Missouri, USA and has been managed using single-tree selection since the early 1950s. This paper quantifies the influence of tree size and competitive position, stand density, species composition, and site quality on ten-year (1992-2002) diameter increment within oak (Quercus spp.) and shortleaf pine (Pinus echinata Mill.) stands on the Pioneer Forest. An individual-tree model was developed for each species using mixed-effects regression and 290 inventory plots. Model efficiency (R²) ranged from 0.26 to 0.57 and fit was generally better for oak species. Basal area in larger trees (BAL) and tree diameter were significant predictors for all species and crown competition factor improved prediction for shortleaf pine and hickory (Carya spp.). Effect of species composition and site quality on diameter growth was not consistent across species. Models were evaluated using a subset of data not included in model fitting and the effect of single tree and standwise (1, 3, or 5 sample trees) calibration on model predictions were evaluated. Inclusion of random effects through calibration improved model prediction for all species and fit was best following single tree and 3 tree calibration.     

Simulating conversion of even-aged Norway spruce into uneven-aged mixed forest: effects of different scenarios on production,economy and heterogeneity

European Journal of Forest Research - Despite a general lack of knowledge on the effects of different strategies, conversion of even-aged stands to uneven-aged forest is ongoing across Europe....     

Effects of even-aged timber harvest on stream salamanders: Support for the evacuation hypothesis

Habitats worldwide are increasingly threatened by degradation and conversion. Critical to the process of habitat loss is the organismal response, which can have effects on immediate conservation measures or future restoration. Among the most threatened and underappreciated habitats are headwater streams, which are small but abundant features of montane forests. These habitats comprise a significant proportion of the total stream length, can harbor remarkable biodiversity, and are critical for numerous ecosystem processes. One of the most abundant organisms in montane headwater ecosystems are salamanders, and therefore what happens to salamanders when the forest habitats surrounding headwater streams are altered? Three main hypotheses exist: (1) mortality hypothesis; (2) retreat hypothesis; and (3) evacuation hypothesis. To examine these hypotheses we evaluated the impacts of even-aged riparian timber harvest on stream-breeding salamanders. Riparian forests along headwater streams were logged, leaving riparian buffers of 0 m, 9 m, and 30 m. Responses to each riparian alteration were measured in terms of salamander terrestrial habitat use and growth in the riparian habitat, as well as changes in population density within headwater streams. Adult and juvenile salamander densities measured in headwater streams were significantly greater in logged riparian treatments than in unaltered riparian treatments. In addition, salamanders significantly reduced their terrestrial habitat use following riparian logging with both the average distance from the stream and the relative abundance of salamanders decreasing. It is unlikely that salamanders will persist in highly modified riparian habitats, as we measured significantly reduced body conditions over short periods of time at these sites. We present corroborative evidence that salamanders evacuate the riparian habitat following intensive riparian logging, emigrating to adjacent headwater streams. Our results underscore the sensitivity of stream salamanders to riparian habitat alteration as well as the importance of riparian buffers in preserving amphibian assemblages.     

The compatibility of timber and non-timber forest product extraction and management

We discuss the extent of compatibility of timber and non-timber forest product (NTFP) extraction in two neotropical localities from biophysical, social, and institutional perspectives: the community concession forests of the Petén, Guatemala, and extractivist communities in northern Bolivia. In both localities, timber is harvested via reduced-impact logging (RIL) practices. In Guatemala, the main NTFP extracted is foliage from the understory xate palm (Chamaedorea spp.); in northern Bolivia, the fruits of the Brazil nut tree (Bertholletia excelsa). The Guatemalan case suggests a relatively high degree of compatibility due to low timber harvesting intensities, coupled with temporal, spatial, and social segregation of xate extraction in a well-defined land tenure system. In northern Bolivia, forest management regulations pay little attention to NTFPs and land tenure issues and related conflict complicate efforts to limit timber harvesting impacts on Brazil nut trees. The introduction of timber management plans overlain on customary property rights systems in which the extraction of Brazil nut is organized could undercut its management system. The two case studies suggest that specific legislative, education, and project interventions may help to promote the compatibility of timber and NTFP extraction and management. These include formal training of foresters on NTFP ecology and management while taking into account the perspectives of multiple stakeholders in the design of management plans. Tropical forest users, research managers, and policy makers will also better understand the need for integrated management of timber and NTFPs, if the trade-offs and potential economic benefits from NTFP extraction are clarified.     

Threshold responses of songbirds to long-term timber management on an active industrial forest

Forest managers often seek to balance economic benefits from timber harvesting with maintenance of habitat for wildlife, ecosystem function, and human uses. Most research on the relationship between avian abundance and active timber management has been short-term, lasting one to two years, creating the need to investigate long-term avian responses and to identify harvest thresholds when a small change in habitat results in a disproportionate response in relative abundance and nest success. Our objectives were to identify trends in relative abundance and nest success and to identify landscape-scale disturbance thresholds for avian species and habitat guilds in response to a variety of harvest treatments (clear-cuts, heavy and light partial harvests) over 14 years. We conducted point counts and monitored nests at an industrial forest in the central Appalachians of West Virginia during 1996-1998, 2001-2003, and 2007-2009. Early successional species increased in relative abundance across all three time periods, whereas interior-edge and forest-interior guilds peaked in relative abundance mid-study after which the forest-interior guild declined. Of 41 species with >10 detections, four (10%) declined significantly, 13 (32%) increased significantly (only three species among all periods), and 9 (22%) peaked in abundance mid-study (over the entire study period, four species had no significant change in abundance, four declined, and one increased). Based on piecewise linear models, forest-interior and interior-edge guilds’ relative abundance harvest thresholds were 28% total harvests (all harvests combined), 10% clear-cut harvests, and 18% light partial harvests, after which abundances declined. Harvest thresholds for the early successional guild were 42% total harvests, 11% clear-cut harvest, and 10% light partial harvests, and relative abundances increased after surpassing thresholds albeit at a reduced rate of increase after the clear-cut threshold. Threshold confidence intervals for individual species overlapped their guild threshold intervals 91% of the time. Even though relative abundance of most species (80%) did not decline as the area affected by timber management increased, implementing management at or below our approximate forest-interior and interior-edge harvest thresholds would reduce the number of declining species by half, maintain higher relative abundances of four species with a net decline in abundance but that peaked in abundance mid-study, and maintain higher relative abundances of ten additional species. In contrast, this management strategy also would prevent the increase in relative abundance of seven species and limit the increase in abundance of three species that increased throughout the study.     

Effects of uneven-aged management on diameter distribution and species composition of northern hardwoods in Upper Michigan

Uneven-aged management using single-tree or group selection has been in practice for many decades, especially in northern hardwood forests. Use of stocking regulation tools is thought to produce and maintain specific stand structures that upon regulation, are sustainable over time. We evaluated stand structures in northern hardwoods in Upper Michigan across three ownerships that practice different approaches toward uneven-aged management. Industry land (MeadWestvaco—MWV) uses primarily diameter limit cutting combined with a sawyer-select harvest method, retaining a maximum diameter of 45.7 cm (18 in.) with a residual basal area of 16.1 m²/ha (70 ft²/ac) and a cutting cycle of 10 years. The Michigan Department of Natural Resources (DNR) uses a crop tree release technique with a residual basal area of 18.4 m²/ha (80 ft²/ac) and a cutting cycle of 20 years. Both ownerships view regeneration of new cohorts as inevitable given the intensity of disturbance and the forest type. The third ownership (the Ford Forestry Center School Forest at Michigan Technological University—FFC) employs strict stocking regulation using the BDq method (residual basal area of 16.1 m²/ha (70 ft²/ac), maximum diameter of 50.8–55.9 cm (20–22 in.), and a q-ratio of 1.3) with a cutting cycle ranging from 12 to 15 years.Stand structure on a total of 25 stands was characterized for these ownerships to assess the impact of management strategy on stand structure and species composition. Differences in species composition and lower diversity indices were found where increasing sugar maple dominance was an objective (FFC ownership). All ownerships showed reduced relative importance values of mid-tolerant species such as yellow birch in their stands as compared to values reported for old-growth or unmanaged stands. Diameter distributions were classified into one of three shape categories (negative exponential, increasing q-ratio, and rotated sigmoid) using the regression of DBH, DBH², and DBH³ on the log₁₀ of trees per hectare. The best model in terms of adjusted-R² and root mean square error (RMSE) was selected for each stand. All management strategies resulted in similar occurrences of distribution shapes, despite some evidence of a trend toward a rotated sigmoid distribution. These trends suggest that several different diameter distribution shapes in uneven-aged northern hardwoods in the Lake States are possible following a variety of management approaches, with sugar maple increasing in dominance with strict adherence to certain stocking regulation guidelines.     

尼加拉瓜西南部热带雨林生态系统木材生产速率及其对可持续森林经营的启示

积累木材采运数据对森林可持续经营是非常必要的,但这些数据在一些发展中国家却非常缺乏。本文收集和分析了尼加拉瓜Ondo州森林保护区和非保护区内木材生产速率的数据。数据来源于州林业主管部门的官方数据、年度报告和相关文件,包括2003年至2005年间以月采伐量为单位的不同经济术材的物种、材积量和立木数。对收集的数据进T检验和一维方差分析。结果表明:3年间,非保护区内采伐木材的物种数、科数和立木量均高于森林保护区内采伐的。但是,保护区内被砍伐的树木材积总量要显著高于非保护区的(p<0.05)。非保护区内,有25个植物科的60种阔叶树种被砍伐:森林保护区内有23个科的57种阔叶树种被砍伐。3年间,Ondo州森林系统内被砍伐树林共111,377株,材积量约295 089.67m3。年平均伐木数和材积量分别是37,125株和98 363.22 m3。月平均伐木数和材积量分别是3 094和8 196m3。T检验结果表明,森林保护区和非保护区内被砍伐的树木株数和材积量显著不同(p<0.05)。一维方差分析结果表明,03年和04年伐木活动显著增加,但05年有所下降。说明森林系统中经济木材树种正在减少,伐木活动对森林生态系统产生了...     

Production efficiency of community forest management in Nepal

Nepal's forests have been transferred to community management with the twin objectives of supplying forest products and addressing local environmental problems. Community forests provide a range of benefits, from direct forest products such as timber and non-provisioning ecosystem services such as soil protection. There is a need to understand the extent to which environmental and community benefits are joint products or substitutes. Stochastic frontier production analysis (SFPA) was used to study the production relationship between environmental and community benefits and production efficiency analysis to study the extent to which communities were able to achieve maximum benefits. SFPA indicated that the magnitude of direct forest product benefits was influenced by various socioeconomic and forest related factors such as distance to the government office, community forest size, and group heterogeneity negatively affect community forest products benefits. On the other hand, links to the market, forest products dependency, and the number of households in the community augment benefits from community forests. In addition, forest product benefits and environmental benefits were complementary to each other. Production efficiency analysis showed that communities were not producing forest products efficiently. Factors such as social capital contributed positively to production efficiency, whereas caste heterogeneity in the executive committees of community forest user groups was negatively associated with efficiency. These findings can contribute to better implementation of community forestry programmes in Nepal, improving the welfare of communities by increasing direct forest product benefits without environmental harm.     

用材林经营主要技术措施及研究实例

1用材林经营主要技术措施1·1提高生产力的经营措施-林地施肥1·2林分密度调控措施-间伐林分间伐需要研究解决的技术问题:间伐时间(时机、间隔期)、间伐强度、间伐对象。间伐作业需要考虑:间伐的成本和经济收益。同时需要相关的政策、法规、技术标准的支持。1.3合理确定采伐年龄(轮伐期)-森林成熟的论证1.4森林永续利用(可持续利用)-采伐量调整2提高生产力的经营措施-林地施肥的研究实例试验时间:1986年~1993年。试验对象:杉木(2 a生、3 a生、7 a生);马尾松(2 a生);湿地松(2 a生、3 a生);香樟(2 a生)。试验内容:肥料种类(氮、磷、氮 磷)、施…     

Evaluating the effects of forest management on rockfall protection and timber production at slope scale

We used the coupled forest and rockfall model PICUS Rock’n’Roll, linking a hybrid forest patch model and a 3D rockfall model, to assess the effects of four management scenarios (BAU: business as usual age class shelterwood approach; PFM1 and PFM2: rockfall protection management scenarios with slit-shaped gaps; NOM: no management scenario without any active silvicultural intervention) on rockfall protection and timber production on a 38 ha slope over 100 years. Compared to PFM1 and PFM2, we found slightly more harvested timber for the BAU scenario (BAU: 6.7 m³ha^?1yr^?1, PFM: 5.7–5.9 m³ha^?1yr^?1), but lower contribution margins (BAU: 55 €ha^?1yr^?1, PFM: 113–115 €ha^?1yr^?1). Overall, depending on rock size and forest state, 30–70% of the simulated rocks that would otherwise hit the road at the foot of the slope were stopped by the forest. While the PFM scenarios maintained a high rockfall protection level over 100 years (PE between 45–64%) the BAU showed periods of reduced protection (PE between 26–65%). The NOM scenario maintained favorable conditions in the beginning, but declining protection efficiency in the last decades of the century (PE 49–63%). We conclude that rockfall protection management can outperform BAU with regard to both timber production and rockfall protection.     

笋竹两用林高产经营技术

丽水地区笋竹两用林示范基地建设，应着重从立地条件，竹林结构、大小年改置、全垦深翻、科学施肥、留笋养竹以及钩梢、覆盖增温等综合培育技术措施出发，使示范基地达到高产高效的目的。     

Impacts of forest management on liana diversity and community structure in a tropical forest in Ghana: implications for conservation

We studied the impacts of liana cutting as a forest management tool on liana diversity(species richness,Shannon diversity index) and community structure(diameter distribution, basal area, species dominance) in the Asenanyo Forest Reserve, Ghana. Two types of silviculturally treated forests were studied: Logging treated(LT)and Tropical Shelterwood System(TSS) treated forests. An untreated primary forest was included as a control, resulting in three forest management systems. Lianas with diameter C2 cm were identified in ten 40 9 40 m2 plots within each management system. Liana cutting significantly reduced liana species richness, Shannon diversity index, and basal area in the LT forest after two decades.However, liana species richness and basal area werecomparable in the TSS treated and untreated forests, indicating significant recovery in the former after over six decades. S?rensen similarity index of liana species composition between the untreated forest and each of the treated forests was moderate. Our findings suggest that liana cutting most likely influenced the dominance of some liana species. In view of the adverse impact of blanket liana cutting on liana diversity, selective liana cutting is recommended as a means of controlling liana numbers while maintaining liana diversity.     

Assessing the impacts of four alternative management strategies on forest timber and carbon values in northeast China

Forest management strategies, reflecting the cognition and the demands of the human population on forests, have significant effects on the forest structures and functions. Nowadays, numerous forest management strategies have been introduced and implemented worldwide for a long time. However, our knowledge about the impacts of alternative management strategies on forest multipurpose management practices is still insufficient. Therefore, the overall goal of this study quantitatively assessed the impacts of four alternative forest management strategies on forest timber and carbon values in a large forest area in northeast China, as an example. Four alternative forest management strategies: no intervention management (NIM), classical timber management (CTM), multi-purpose management (MPM), and spatial-constraints management (SCM), in conjunction with different management objectives and regulations, were quantitative assessed using optimization methods. The results of numerical analysis showed that implementing eco-friendly forest management strategies such as imposed in MPM and SCM strategies may be economic inefficiencies, mainly due to significant decreases of the joint benefits from forest timber and carbon values (approximately $18.75 and $22.36 million per year) have been observed under the current carbon trading market of China (namely $20 per ton of carbon) when the ecological- and spatial-oriented constraints were further integrated into the typical CTM strategy. However, both MPM and SCM strategies were quite meaningful for the restoration of forest resources in northeast China, in which an additional of 13.6 and 16.2 thousand tons of carbon were sequestrated during the 50 years simulated horizon. Therefore, forest decision makers should evaluate the potential effects carefully prior to altering their forest management strategy in practices.