Long-term spatial and structural dynamics in Acadian mixedwood stands managed under various silvicultural systems

2008 ◽  
Vol 38 (3) ◽  
pp. 498-517 ◽  
Author(s):  
Mike R. Saunders ◽  
Robert G. Wagner

Using inventory data from a long-term silviculture experiment in east-central Maine, spatial models were developed to analyze 28 years (1974–2002) of stand structural dynamics. Differences in spatial pattern, species mingling, height differentiation, and relative stand complexity index (rSCI) were compared among five treatments: commercial clear-cutting, fixed diameter-limit, 5 year single-tree selection, three-stage shelterwood (both with and without precommercial thinning), and unharvested natural areas. Regardless of treatment, regeneration events (whether induced by natural breakup of the overstory or by harvesting) increased aggregation in spatial pattern and reduced species mingling, more so in the commercial clearcut and fixed diameter-limit treatments where hardwood densities were highest. Regular spatial patterns were rare. Height differentiation values for individual trees and stand-level mean rSCI were generally highest in untreated natural areas and 5 year selection treatments, intermediate in commercial clearcut and fixed diameter-limit treatments, and lowest in three-stage shelterwood treatments. After a brief adjustment period, precommercial thinning in a shelterwood treated stand generally increased species mingling, height differentiation, and rSCI. Two untreated natural areas exhibited divergent pathways of structural development. Dynamics in uneven-aged selection treatments more closely resembled that of the untreated natural areas than did the shelterwood, commercial clearcut, or fixed diameter-limit treatments.


1993 ◽  
Vol 10 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Gary W. Miller ◽  
H. Clay Smith

Abstract When landowners want to develop and maintain an uneven-aged tree structure in eastern hardwood stands, single-tree selection often is suggested as the only advisable, long-term partial regeneration harvest method. Single-tree selection is preferred because it provides a means for improving quality and controlling stocking of the residual stand necessary for sustained yield of desired products. Although studies have shown that single-tree selection is feasible where desirable shade-tolerant species can be regenerated, it is rarely applied because marking stands for harvest can be difficult and time consuming. Instead, diameter-limit cutting is the most common partial regeneration practice used in eastern hardwoods, primarily because it is much easier to apply. Unfortunately, strict diameter-limit cuts do not provide for control of residual stocking or improve the quality of residual trees. However, based on 20-yr results, most objectives of single-tree selection can be attained with flexible diameter-limit harvest guidelines based on potential value increase of individual trees combined with an improvement cut in small sawtimber trees at each periodic cut. North. J. Appl. For. 10(1):32-38.



2014 ◽  
pp. 124-129
Author(s):  
Z. V. Karamysheva

The review contains detailed description of the «Atlas of especially protected natural areas of Saint Petersburg» published in 2013. This publication presents the results of long-term studies of 12 natural protected areas made by a large research team in the years from 2002 to 2013 (see References). The Atlas contains a large number of the historical maps, new satellite images, the original illustrations, detailed texts on the nature of protected areas, summary tables of rare species of vascular plants, fungi and vertebrates recorded in these areas. Special attention is paid to the principles of thematic large-scale mapping. The landscape maps, the vegetation maps as well as the maps of natural processes in landscapes are included. Reviewed Atlas deserves the highest praise.



2017 ◽  
Vol 168 (4) ◽  
pp. 181-185
Author(s):  
Marc Hanewinkel

The forest-game conflict – how can forest economics contribute to solve it? (Essay) Core parameters of forest economics such as land expectation value or highest revenue show that damage caused by wild ungulates can critically influence the economic success of forest enterprises. When assessing and evaluating the damage in order to calculate damage compensation, methods are applied in Germany that look either into the past (“cost value methods”) or into the future (“expected value methods”). The manifold uncertainties related to this evaluation over long-term production periods are taken into account within a framework of conventions through strongly simplifying assumptions. Only lately, the increased production risk due to game-induced loss of species diversity is also considered. Additional aspects that should be taken into account in the future are the loss of climate-adapted species, the change of the insurance values of forest ecosystems and the impossibility of specific management systems such as single-tree selection forestry due to the influence of game. Because of high transaction costs when assessing the damage, financial compensation should only be the “ultimate measure” and a meditation between stakeholder groups with the goal to find a cooperative solution before the damage occurs should be preferred.



Author(s):  
L.V. Vetchinnikova ◽  
◽  
A.F. Titov ◽  
◽  

The article reports on the application of the best known principles for mapping natural populations of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti – one of the most appealing representatives of the forest tree flora. Relying on the synthesis and analysis of the published data amassed over nearly 100 years and the data from own full-scale studies done in the past few decades almost throughout the area where curly birch has grown naturally, it is concluded that its range outlined in the middle of the 20th century and since then hardly revised is outdated. The key factors and reasons necessitating its revision are specified. Herewith it is suggested that the range is delineated using the population approach, and the key element will be the critical population size below which the population is no longer viable in the long term. This approach implies that the boundaries of the taxon range depend on the boundaries of local populations (rather than the locations of individual trees or small clumps of trees), the size of which should not be lower than the critical value, which is supposed to be around 100–500 trees for curly birch. A schematic map of the curly birch range delineated using this approach is provided. We specially address the problem of determining the minimum population size to secure genetic diversity maintenance. The advantages of the population approach to delineating the distribution range of curly birch with regard to its biological features are highlighted. The authors argue that it enables a more accurate delineation of the range; shows the natural evolutionary history of the taxon (although it is not yet officially recognized as a species) and its range; can be relatively easily updated (e.g. depending on the scope of reintroduction); should be taken into account when working on the strategy of conservation and other actions designed to maintain and regenerate this unique representative of the forest tree flora.



2018 ◽  
Vol 48 (9) ◽  
pp. 1108-1113 ◽  
Author(s):  
Gabriel Sangüesa-Barreda ◽  
J. Julio Camarero ◽  
Jan Esper ◽  
J. Diego Galván ◽  
Ulf Büntgen

Long-term fluctuations in forest recruitment, at time scales well beyond the life-span of individual trees, can be related to climate changes. The underlying climatic drivers are, however, often understudied. Here, we present the recruitment history of a high-elevation mountain pine (Pinus uncinata Ram.) forest in the Spanish central Pyrenees throughout the last millennium. A total of 1108 ring-width series translated into a continuous chronology from 924 to 2014 CE, which allowed estimated germination dates of 470 trees to be compared against decadal-scale temperature variability. High recruitment intensity mainly coincided with relatively warm periods in the early 14th, 15th, 19th, and 20th centuries, whereas cold phases during the mid-17th, early 18th, and mid-19th centuries overlapped with generally low recruitment rates. In revealing the importance of prolonged warm conditions for high-elevation pine recruitment in the Pyrenees, this study suggests increased densification and even possible upward migration of tree-line ecotones under predicted global warming.



2016 ◽  
Vol 359 ◽  
pp. 65-73 ◽  
Author(s):  
Therese Johansson ◽  
Joakim Hjältén ◽  
Jörgen Olsson ◽  
Mats Dynesius ◽  
Jean-Michel Roberge




2019 ◽  
Vol 41 ◽  
pp. 61-68

The subject of the paper is protected natural areas of the world and their regional differences. According to the IUCN, a protected natural area is “a clearly defined geographical space, recognized, dedicated and managed, through legal or other effective means, to achieve the long term conservation of nature with associated ecosystem services and cultural values”. States differ in their interpretations of the above definition. Very often, some of the sites that are protected areas in one country may not necessarily be considered protected in another country. In defining and management of protected areas, some countries have adapted their laws to international guidelines, while in other countries the legislation differs significantly from these guidelines. Therefore, the research aims to show regional differences in the identification and management process as well as in the total surface area and abundance of protected natural areas at the world level.



2019 ◽  
Vol 2 ◽  
Author(s):  
Matti Koivula

Many biological responses may develop over long periods of time, and annual community variation should therefore be controlled in ecological research. We sampled carabid beetles over ten years in Norway spruce dominated forests in Southern Finland, harvested using replicated logging treatments of different intensities. We collected carabids in 1995 (prior to logging) and during four post-harvest seasons, 1996-98 and in 2006. The treatments were clear-cutting (no retained trees), modified clear-cutting (retention of three groups of 20-30 trees within one-hectare core) and gap cutting (three 0.16-ha openings within a one-hectare core), and control (mature unharvested forest). Carabids showed remarkable annual and regional variation at assemblage, ecological-group and species levels, such that was independent of treatments. The total species richness, and that of open-habitat carabids, were higher in cleared sites of all treatments than in control stands in 1997-1998 but not in 2006, suggesting that the logging response was ephemeral by many species. The abundances of forest and generalist carabids were little affected by logging. Open-habitat carabids were more abundant in clear-cuts and modified clear-cuts than in gap cuts, which was still detectable in 2006, suggesting a long-term effect. Open-habitat carabids were less abundant in retention sites of modified clear-cuts and gap cuts than in cleared sites, suggesting that retention attenuates assemblage change. Carabid assemblages of logged stands did not differ from control stands in 1996 but they did in 1997-1998, suggesting a one-year delay in logging response. Carabids showed remarkable annual and regional variation at assemblage, ecological-group and species levels, such that was independent of treatments. The total species richness, and that of open-habitat carabids, were higher in cleared sites of all treatments than in control stands in 1997-1998 but not in 2006, suggesting that the logging response was ephemeral by many species. The abundances of forest and generalist carabids were little affected by logging. Open-habitat carabids were more abundant in clear-cuts and modified clear-cuts than in gap cuts, which was still detectable in 2006, suggesting a long-term effect. Open-habitat carabids were less abundant in retention sites of modified clear-cuts and gap cuts than in cleared sites, suggesting that retention attenuates assemblage change. Carabid assemblages of logged stands did not differ from control stands in 1996 but they did in 1997-1998, suggesting a one-year delay in logging response. In 2006, logged and control stands hosted relatively similar assemblages which, together with the above results, suggests a partial faunal recovery. We conclude that even modest retention provides long-term support for forest carabids, but also that their full assemblage recovery takes longer than 10 years.



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