Long-term tending effect on static stability of pure beech (Fagus sylvatica L.) stands

The production stability together with the provision of required functions are the key requirements for the future existence of stable forest stands. Sufficient mechanic stand stability could be developed by the early and long-term thinning where basic tree characteristics, such as stem and crown parameters play the decisive role. We compared selected parameters of static stability in pure beech stands, which have been exposed to heavy low thinning and free-crown thinning with control stands without interventions. Data from twenty-seven long-term research subplots at eight localities across Slovakia were involved in this study. In total 7 693 trees between 30 and 110 years were analysed. Slenderness (h/d ratio), crown length, crown width and crown ratio proved to be the most explanatory parameters for the defining mechanical stability on subplots with free-crown thinning. We found the least favourable results on control subplots. The differences between the subplots with tending (regardless of the tending method) and the control subplots were statistically significant in all studied parameters (P < 0.05).

Sugar Maple, Red Maple, and Yellow Birch Growth and Mortality in Even-Aged Adirondack Northern Hardwoods

Tree diameter growth models for northern hardwoods commonly used large data sets representing a composite of stands with varying management histories, structural characteristics, and age distributions. Yet common predictor variables like diameter can show differences in growth patterns for stands with different age structures and management histories. To address that, we modeled growth and mortality for sugar maple, red maple, and yellow birch in thinned even-aged Adirondack northern hardwoods. Findings indicate that change in diameter depends on initial diameter for sugar maple, with the rate decreasing exponentially from the largest size class to the smallest. Initial diameter did not prove significant with red maple and yellow birch in these thinned stands, perhaps because of the limited sample of trees of small diameter. Stand relative density and time since treatment affected growth for all three species. Those variables also proved significant for predicting mortality of sugar maple. Analyses revealed fewer losses of sugar and red maples among the larger diameter classes, but no relationship with diameter for yellow birch. Plot relative density did not affect mortality with red maple, but time after thinning had a significant effect on survival of all species. Study Implications Crown thinning and other methods that release upper canopy trees within even-aged stands should result in favorable postthinning growth of sugar maple, red maple, and yellow birch. Yet, the small trees of sugar maple will grow slower than larger ones after release by thinning, and small sugar and red maple have greater probability of dying. Residual stand density will temper the growth of all three species and the survival of sugar maple and yellow birch. Findings suggest that management strategies favoring removal of the large-diameter sugar maple trees of upper canopy positions from an even-aged stand (e.g., diameter-limit cutting) will result in lower rates of diameter increment within the residual stand. That should negatively affect stand dynamics and volume production and result in greater mortality among the remaining sugar and red maple. By contrast, crown thinning will enhance residual tree growth and survival, as well as stand development.

The growth of the beech (Fagus sylvatica L.) stand on former agricultural land and its comparison with the naturally regenerated beech stand under comparable conditions

The issue of afforestation of non-forest land (e.g. agricultural land use) is currently a significant trend in land management. Sustainable development and maintenance of its ecological stability are among the reasons. The paper compares the 30-year development of the beech stand originated from artificial regeneration on former agricultural land in the area where the Ipeľ River rises in central Slovakia. Two methods of tending were used on three long-term research plots (LTPs) established at the age of 20 years: negative crown thinning, free crown thinning and the third LTP was left to its spontaneous development. The results confirmed the positive impact of tending on the development of these stands. Compared to naturally regenerated stands under comparable site conditions, their higher quantitative production was found. Regarding the qualitative production expressed by the number of trees of selective quality, the worst results were obtained on the control plot. Based on these results, it is recommended to pay more attention to the planting stock quality used for afforestation.

Assessment of long-term tending in mixed stands of spruce, fir and beech on research plot Korytnica

The paper deals with problems of thinnings in a mixed stand (spruce-fir-beech) situated in the sixth altitudinal forest zone. Three of the five investigated plots were tended by free crown thinning for a long time, and two were left without any planned silvicultural treatments as control. Dynamic changes in tree species composition, stand structure, qualitative and quantitative production were evaluated for a period of 30 years. The changes were compared with respect to differences between the plot with long-term silvicultural treatments and the control plots (without treatments).

ECONOMIC PERFORMANCE OF LOBLOLLY PINE STANDS IN SOUTHERN BRAZIL AS A RESULT OF DIFFERENT CROWN THINNING INTENSITIES1

ABSTRACT Approximately 1.6 million hectares of southern Brazil are cultivated with pines, and mainly with the loblolly pine (Pinus taeda L.). More than one third of the stands belong to independent log producers, whose aim is to maximize their economic results. In this study, a thinning experiment was evaluated over a production period of 30 years. The stands evaluated were submitted to three different crown thinning intensities, with an unthinned stand used as a control. The aim of the study was to evaluate economic criteria regarding realistic discount rates and production periods varying between 16-30 years. For the circumstances that were evaluated, 'extreme' and early release from competition of pruned loblolly pine trees lead to the best economic performance (land expectation value = ~36,000 US$ ha-1, i = 3% yr-1). Stands subjected to crown thinnings, independently of intensity, produced three times the economic output of unthinned and unpruned stands. Although the optimal harvest ages, according to the internal rate of return, are between 18-22 years for thinned and unthinned stands, from a long-term perspective (land expectation value) and for the current relationship between log price and size, the optimal economic performance requires that production periods are extended (to 24-26 years) from those currently practised in southern Brazil (15-20 years).

Ten-Year Responses of Underplanted Northern Red Oak to Silvicultural Treatments, Herbivore Exclusion, and Fertilization

Establishing adequate advanced oak reproduction prior to final overstory removal is crucial for regenerating oak forests in the eastern U.S. Many management approaches exist to this end, but benefits associated with any individual technique can depend on the suite of techniques employed and the geographic location. At four mixed-hardwood upland forest sites in central and southern Indiana, we tested factorial combinations of deer fencing, controlled-release fertilization, and various silvicultural techniques (midstory removal, crown thinning, and a shelterwood establishment cut) for promoting the growth and survival of underplanted red oak seedlings. Crown thinning resulted in slow growth and low survival. Midstory removal and the shelterwood establishment cut were nearly equally effective for promoting seedling growth. Seedling survival was strongly influenced by fencing, and differences in survival between silvicultural treatments were minimal when fencing was employed. Fertilization had minimal effects overall, only increasing the probability that unfenced seedlings were in competitive positions relative to surrounding vegetation. We suggest that underplanting oak seedlings can augment natural reproduction, but the practice should be accompanied by a combination of midstory removal and fencing, at a minimum, for adequate growth and survival.

Sustainable Land Management, Adaptive Silviculture, and New Forest Challenges: Evidence from a Latitudinal Gradient in Italy

Aimed at reducing structural homogeneity and symmetrical competition in even-aged forest stands and enhancing stand structure diversity, the present study contributes to the design and implementation of adaptive silvicultural practices with two objectives: (1) preserving high wood production rates under changing environmental conditions and (2) ensuring key ecological services including carbon sequestration and forest health and vitality over extended stand life-spans. Based on a quantitative analysis of selected stand structure indicators, the experimental design was aimed at comparing customary practices of thinning from below over the full standing crop and innovative practices of crown thinning or selective thinning releasing a pre-fixed number of best phenotypes and removing direct crown competitors. Experimental trials were established at four beech forests along a latitudinal gradient in Italy: Cansiglio, Veneto; Vallombrosa, Tuscany; Chiarano, Abruzzo; and Marchesale, Calabria). Empirical results indicate a higher harvesting rate is associated with innovative practices compared with traditional thinning. A multivariate discriminant analysis outlined significant differences in post-treatment stand structure, highlighting the differential role of structural and functional variables across the study sites. These findings clarify the impact of former forest structure in shaping post-treatment stand attributes. Monitoring standing crop variables before and after thinning provides a basic understanding to verify intensity and direction of the applied manipulation, the progress toward the economic and ecological goals, as well as possible failures or need for adjustments within a comprehensive strategy of adaptive forest management.

Applications of single-tree selection guideline following a DBq approach on Nepal’s community forests

There is growing interest by forest users, government forest officers and policy makers on maximising forest goods and livelihood provisions from community forestry in a sustainable manner. However, the way several mature community forests are currently managed based on selection, e.g. negative thinning and crown thinning, is questionable as it results to decline in forest stock, timber quality and regeneration. To assist forest users in managing their community forests, an action research was implemented in Kavre and Lamjung to manage planted Pine (Pinus spp.) and naturally regenerated Sal (Shorea robusta) through selection system. This paper describes the q-factor and its relevance for sustainable community forest management in Nepal. The simple guideline for selection system introduced to 30 community forest users groups in six sites are presented for wider adoption and policy recommendation.Banko JanakariA Journal of Forestry Information for NepalSpecial Issue No. 4, 2018, Page: 104-112