Site Quality Evaluation for Mixed, Uneven-aged, Natural Forest Dominatedby Korean Pine in Northeast China

Six site types of Korean pine(Pinus koraiensis) forest, Mongolian oak type, Yezo spruce type, Korean spruce type, Amur linden type, Ribbed birch type and Manchurian ash type, are easily found on the south slope of Xiaoxing’an Mountains. The analysis results of H-A and H-Dbh relationships by site type showed that height growth of Korean pine dominant or codominant stems in natural stands is not directly related to its age but is directly related to its diameter, which closely accords with the Chapman-Richards equation(Relativity coefficients more than 0:8668). A method for evaluating site quality using height and diameter of dominant or codominant tree independent of tree age is examined. There are signifi-cantly differences in site quality of Korcan pine among six site types above. The site index was highest on Manchurian ash type, and lowest on Mongolian oak type. Differences of site index with a reference dbh of 40 cm between highest and lowest sites can reach 11 m in maximum., 7 m in average, respectively. Other rationales of the H-D method were discussed.

Optimizing any-aged management of mixed boreal forest under residual basal area constraints

The current trend of forest management in many countries is reduced use of clear-felling and planting, and increased use of continuous cover management. In Finland, the new forest act of 2014 made all types of cuttings equally allowable on the condition that if the post-cutting residual stand basal area is too low, the stand must be regenerated within certain time frame. Forest landowner can freely choose between even-and uneven-aged management. This study developed a method for opti-mizing the timing and type of cuttings without the need to categorize the management system as either even-aged or uneven-aged. A management system that does not set any requirements on the sequence of post-cutting diameter distributions is called any-aged management. Planting or sow-ing was used when stand basal area fell below the required minimum basal area and the amount of advance regeneration was less than required in the regulations. When the cuttings of 200 stands managed earlier with even-aged silviculture were optimized with the developed system, final felling followed by artificial regeneration was selected for almost 50%of stands. Reduction of the minimum basal area limit greatly decreased the use of artificial regeneration but improved profitability, suggesting that the truly optimal management would be to use natural regeneration in financially mature stands. The optimal type of thinning was high thinning in 97-99%of cases. It was calculated that the minimum basal area re-quirement reduced the mean net present value of the stands by 12-16%when discount rate was 3-5%.

Height increment of understorey Norway spruces under different tree canopies

Background:Stands having advance regeneration of spruce are logical places to start continuous cover forestry(CCF) in fertile and mesic boreal forests.However,the development of advance regeneration is poorly known.Methods:This study used regression analysis to model the height increment of spruce understorey as a function of seedling height,site characteristics and canopy structure.Results:An admixture of pine and birch in the main canopy improves the height increment of understorey.When the stand basal area is 20 m2ha-1 height increment is twice as fast under pine and birch canopies,as compared to spruce.Height increment of understorey spruce increases with increasing seedling height.Between-stand and within-stand residual variation in the height increment of understorey spruces is high.The increment of 1/6 fastest-growing seedlings is at least 50%greater than the average.Conclusions:The results of this study help forest managers to regulate the density and species composition of the stand,so as to obtain a sufficient height development of the understorey.In pure and almost pure spruce stands,the stand basal area should be low for a good height increment of the understorey.

A basal area increment model for individual trees in mixed continuous cover forests in Iranian Caspian forests

The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran.Weanalyzed 421 core samples from 6 main species in the forest area to develop our growth model.In each plot,we measured variables such as total tree height(m),diameter at breast height(DBH)(cm)and basal area of larger trees as cumulative basal areas of trees(GCUM)ofDBH[5 cm.The empirical data were analyzed using regression analysis.There was a statistically significant nonlinear function between the annual basal area increment,as the dependent variable,and the basal area of the individual trees and competition as explanatory variables.Reference area from the largest trees,was circular plot with area of 0.1 ha.GCUM was estimated for trees of DBH>5 cm.Furthermore,we investigated the dependencies of diameter growth of different species on stand density at different levels of competition,and diameter development of individual trees through time.The results indicate that competition caused by larger neighborhood trees has a negative effect on growth.In addition,the maximum diameter increment is affected by competition level.Therefore,the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest(40 to 0 m^2 per ha)and when the trees are about 60 to 70 cm in very dense forest(60 to 0 m^2 per ha)which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands.

Herbaceous-Layer Community Dynamics along a Harvest-Intensity Gradient after 50 Years of Consistent Management

In 1958, a demonstrational cutting trial totaling 22.2 ha was established in a northern hardwood forest in Alberta, MI. Eight different treatments were installed, including four diameter-limit treatments (56 cm, 41 cm, 30 cm, and 13 cm), three single-tree selection treatments with residual basal areas of 21 m2·ha–1, 16 m2·ha–1, and 11 m2·ha–1, and an uncut control. Within each treatment, a 0.4-ha permanent plot was established and subdivided into 0.04-ha square subplots. Harvests have been implemented every ten years with the most recent harvest occurring during the winter of 2008 - 2009. We quantified ground layer vegetation response before and after the most recent harvest. Nonmetric multidimensional scaling (NMS) ordination showed a very distinct separation between the most intensive management treatment (13-cm diameter-limit treatment) and the uncut control. Compositionally, the diameter-limit treatments moved with greater directionality and magnitude towards the 13-cm diameter-limit treatment following harvest, while compositional change in the residual basal area treatments was less pronounced and lacked strong directionality. Herbaceous species percent cover generally decreased with increasing residual overstory basal area across treatments. Weedy and early successional species were most abundant under lower residual basal area and diameter-limit treatments. Results based on 50 years of continuous management suggest that diameter-limit harvests likely have a greater impact on the herbaceous community than single-tree selection or no management.

Influence of Residual Basal Area on Longleaf Pine (<i>Pinus palustris</i>Mill.) First Year Germination and Establishment under Selection Silviculture

Even-aged silvicultural methods have been successfully used to manage longleaf pine (Pinus palustris Mill.) forests for wood production;however, successful use of uneven-aged methods to manage this ecosystem is less well documented. In this study, the effects of varying levels of residual basal area (RBA) (9.2, 13.8, and 18.4 m2·ha-1) on longleaf pine germination and establishment under selection silviculture marked using the Proportional-B method were observed. In addition to RBA, photosynthetically active radiation (PAR) was measured, and the relationships between light penetration, germination, and growth were examined. The study found an inverse relationship between RBA and the number of germinants, but the mortality of germinants was not influenced by RBA. PAR also had a significant positive effect on germination, but, did not affect mortality of germinants. In addition, RBA and PAR had no effect on mortality or growth of planted seedlings. Continued monitoring of seedling recruitment into the stand will be required to determine the efficacy of the system. However, nothing in the first year data suggests that this approach will not be successful in sustaining an uneven-aged stand.

A density-dependent matrix model and its applications in optimizing harvest schemes

Based on temporal data collected from 36 re-measured plots, transition probabilities of trees from a diameter class to a higher class were analyzed for the broad-leaved-Korean pine forest in the Changbai Mountains. It was found that the transition probabilities were related not only to diameter size but also to the total basal area of trees with the diameter class. This paper demonstrates the development of a density-dependent matrix model, DM2, and a series of simulations with it for forest stands with different conditions under different harvest schemes. After validations with independent field data, this model proved a suitable tool for optimization analysis of harvest schemes on computers. The optimum harvest scheme(s) can be determined by referring to stand growth, total timbers harvested, and size diversity changes over time. Three user-friendly interfaces were built with a forest management decision support system FORESTAR?for easy operations of DM2 by forest managers. This paper also summarizes the advantages and disadvantages of DM2.