Lohmus & Lohmus 2005 CWD and forest history (original) (raw)
Related papers
Canadian Journal of Forest Research-revue Canadienne De Recherche Forestiere, 2002
Coarse woody debris (CWD) was studied in old Pinus sylvestris L. dominated forests in three geographic regions in the middle boreal vegetation zone: (i) in Häme in southwestern Finland, characterized by a long history of forest utilization, (ii) in Kuhmo in northeastern Finland, with a more recent history of forest utilization, and (iii) in the Vienansalo wilderness area in northwestern Russia, characterized by large areas of almost natural forest. Within the geographic regions the measured 0.2-ha plots were divided into three stand types according to the degree of human impact: (i) natural stands, (ii) selectively logged stands, and (iii) managed stands. The results showed that compared with natural forests, forest management has strongly reduced both the amount and diversity of CWD. The highest total CWD volumes were found in the natural stands in Häme (mean 67 m 3 ·ha -1 ) and Kuhmo (92 m 3 ·ha -1 ) and in the selective logged stands in Vienansalo (80 m 3 ·ha -1 ), while the lowest CWD volumes were found in the managed stands in Häme (7 m 3 ·ha -1 ) and Kuhmo (22 m 3 ·ha -1 ). The duration of forest utilization also plays a role, as forests with short management histories (Kuhmo region) still carried structural legacies from earlier more natural stages of the forest. In addition to lower total CWD volumes, managed stands also largely lacked certain dead wood characteristics, particularly large dead trees and standing dead trees with structural diversity characteristics (such as stem breakage, leaning stems, and fire scars) when compared with natural and selectively logged stands. The CWD characteristics of stands selectively logged in the past were often comparable with those of natural stands, suggesting that old selectively logged stands can be of high value from the nature conservation point of view.
Annals of Forest Science, 2005
Dead wood is an important structure for conservation purposes and for maintaining biodiversity. In this context, snags were studied under different conditions in silver fir ancient forests of the southern French Alps. The impact of management status and developmental phases were estimated on both quantity and quality of this material. SDT volume averaged 64.6 ± 19.8 m 3 •ha-1 and 15.8 ± 6.0 m 3 •ha-1 in unmanaged and managed ancient forests, respectively. SDT volume varied according to the point in the silvicultural cycle and silvigenesis cycle ranging from 4.3 ± 3.4 m 3 •ha-1 in early aggradation phase of managed forests to 202.3 ± 48.6 m 3 •ha-1 in degradation phase of unmanaged forest. Large SDT significantly belonged to the degradation phase of unmanaged forests. Our research showed that SDT density in this ancient forests was mainly governed by natural processes. An average of 9 large SDT per ha has been proposed to preserve the ecological processes. Alps / ancient forest / dead wood / ecological persistence / silver fir Résumé-Gestion du bois mort sur pied : comparaison entre forêts anciennes gérées et subnaturelles des Alpes du Sud françaises. La quantité de bois mort est un enjeu important dans la conservation et le maintien de la biodiversité forestière. Dans ce contexte, les bois morts sur pied ont été étudiés dans des hêtraies-sapinières anciennes des Alpes du Sud françaises. L'impact du mode de gestion et des différentes phases du cycle sylvicultural et de la mosaïque sylvatique a été estimé. Le volume moyen de bois mort sur pied atteint 64,6 ± 19,8 m 3 •ha-1 dans les forêts anciennes inexploitées, alors qu'il n'est que de 15,8 ± 6,0 m 3 •ha-1 dans les forêts exploitées. Ce volume moyen varie selon la mosaïque sylvatique, passant de 4,3 ± 3,4 m 3 •ha-1 dans la jeune phase d'aggradation des forêts anciennes exploitées à 202,3 ± 48,6 m 3 •ha-1 dans la phase de sénescence des forêts anciennes inexploitées. Cette dernière contient significativement les gros bois sec sur pied (DBH > 43 cm). Nos résultats montrent que dans ces écosystèmes montagnards, la disponibilité en bois mort sur pied, est due essentiellement aux fortes contraintes environnementales en présence. Alpes / bois mort / forêt ancienne / persistance écologique / sapin pectiné
2013
Merci à Annie Desrochers pour ces échanges enrichissants et ses généreux prêts de matériel et d'aides de terrain. Merci à Osvaldo Valeria et Régis Pouliot pour leurs conseils en géomatique. Merci à Claude Lebel et Frédéric Bédard, qui m'ont permis de réaliser un projet avec les industries Norbord co-subventionné par l'organisme Mitacs. Merci aussi à Martin Beaudouin pour le suivi des coupes forestières du dispositif expérimental et encore merci à François Lorenzetti pour son implication dans ce projet. Merci à mes proches : parents, frères et soeurs. Malgré l' éloignement, ils m'ont accompagné et inspiré tout au long de ces années. Merci à ma conjointe, Caroline Trudeau. Merci Caro pour ton aide sur le terrain, tes commentaires sur mes travaux, ton soutien moral, ton écoute au quotidien, tes encouragements et ta patience. Sans toi, je ne me serais vraisemblablement pas rendu là, merci de m'avoir épaulé jusqu'au bout de cette aventure. Et finalement, merci de m'avoir donné un fils et de me proposer de nouveaux défis. Le soutien financier pour ce projet a été fourni par le Fonds québécois de recherche sur la nature et les technologies (FQRNT), le Conseil de recherche en sciences naturelles et en génie du Canada (CSRNG), et la Chaire industrielle CRSNG-UQAT-UQAM en aménagement forestier durable. A V ANT PROPOS Cette thèse est composée de quatre chapitres rédigés sous forme d'articles scientifiques. Pour chaque article, j'ai été le principal responsable du design expérimental, de la récolte et de la compilation des données, des analyses statistiques, et de la rédaction des manuscrits. Je suis le premier auteur de chacun des articles de ma thèse et mes directeurs ont participé à la révision et 1 'amélioration des manuscrits à titre de co-auteurs. Le style d'écriture varie légèrement entre les chapitres puisqu'il s ont été rédigés dans le but d' être publiés dans des revues scientifiques différentes. Le premier chapitre, intitulé « Effects of forest tent caterpillar defoliation and stand characteristics on deciduous tree mortality » est en préparation pour la Revue Canadienne de Recherche Forestière. Le deuxième chapitre, intitulé « Gap dynamics in aspen stands of the clay belt of northwestern Quebec following a Forest tent caterpillar outbreak », a été publié en 2011 dans la Revue Canadienne de Recherche Forestière (41 : 1606-1617). Le troisième chapitre, intitulé « Effects of a fore st tent caterpillar outbreak on the dynamics of mixedwoods boreal forests of eastern Canada » a été soumis à la revue Écoscience et est actuellement en révision. Le quatrième chapitre, intitulé « Growth and mortality of trembling aspen (Populus tremuloides) in response to artificial defoliation: a three-year experiment at the stand level », a été soumis à la revue Oecologia et est actuellement en révision.
Quaternary International, 2014
An 880 cm-long core retrieved from a peat bog adjacent to Lake Czarne, a small dystrophic lake (1.5 ha) in northeastern Poland, was investigated in terms of woodland changes and human impact. Palaeobotanical proxies including pollen, macrofossils, and non-pollen palynomorphs (NPPs) were used for the reconstruction. The profile was additionally supplemented by an age-depth model based on AMS 14 C dates of good resolution, which reveals that it spanned the period between the Allerød/Younger Dryas and present. The patterns of arboreal taxa succession in the Holocene were rather similar to those from northeastern Poland, but some distinct differences were recorded. Among them were the very early appearance of Taxus baccata (detected as pollen, ca. 10,930 cal. BP), the relatively late Holocene decline of Ulmus not connected with an increase in human impact (ca. 4550 cal. BP), and the Late Holocene optimum of Picea abies (ca. 3660e2800 cal. BP) revealing trends opposite to Betula and to a lesser degree to Carpinus betulus. The process of the late Holocene expansion of Betula (ca. 2420 cal. BP) and its continuous occurrence on the peat bog was probably not related to climate and human factors, but to natural processes of ecological succession. Birch, in spite of being listed as a potential host of Kretzschmaria deusta, clearly revealed poor susceptibility to infection of this fungus. Agricultural activity detected from the Neolithic period until the La Tené period was irregular and probably not significant for local woodland development. From the La Tené period, there was a slight increase in human pressure on the environment, and fire intensity and/or frequency rose. The acceleration of human activity manifested in the strongest deforestations was recorded from the Middle Ages up to the downfall of the local state farms in the 1990s.
Historical human influence on forest composition and structure in boreal Fennoscandia
Canadian Journal of Forest Research, 2010
In studies on natural dynamics, biodiversity and reference conditions legacies of preindustrial human land use are often neglected. In this study, using archaeology and dendrochronology combined with field surveys on present forest characteristics, we assessed the naturalness of a protected forest landscape and examined the role of indigenous peoples in shaping forest structure in the past. Our results show that the studied Scots pine (Pinus sylvestris L.) forest conforms to the generally accepted impression of pristine forests and that it has a long history of human utilization. Areas with human presence over long time periods, especially in and near settlements, show significant differences in current forest characteristics compared with the rest of the landscape: the forest is younger (mean age 140-190 years compared with >300 years), the volumes of deadwood lower (8-13 m 3 Áha -1 compared with >20 m 3 Áha -1 ), and the tree species composition is substantially different from the surrounding forest. We suggest that these disparities are strongly linked to past land use and that indigenous people can alter ecosystems substantially and that the legacies of their activity may last for centuries. Consequently, in ecological research and conservation strategies, forest characteristics should always be considered in the light of their historical context.
Annals of Forest Science, 2009
The secondary succession of wet grasslands to communities of alder carr dominated by Alnus glutinosa was recorded in different parts of Europe during the 20th century. However, knowledge of such development of alder carr remains insufficient. • The development of alder carr was reconstructed at five sites in the Czech Republic, using historical aerial photographs and methods of dendrochronology. The aims were to investigate the succession from wet grasslands to alder carr at sites previously intensively managed for agriculture and to find out the role of fluctuations in the groundwater table, caused by artificial drainage channels, in the observed stand dynamics and tree growth. • The spread of forest (i.e., an increase in forest cover) predominated until the 1970s at all sites. This trend was disrupted by a large-scale dieback of forest stands in four of the five sites after the 1970s, followed by an increase in patch heterogeneity, as indicated by landscape metrics. The radial growth increment in Alnus glutinosa has been affected predominately by local environmental factors, probably including the changing degree of waterlogging. Forest dieback was presumably connected with a lesser extent of drainage channels. • Our results indicate that observed successional pathways at sites of alder carr were probably caused by local changes in the groundwater table.
Can J For Res, 2008
Due to the scarcity of old-growth forests in much of Europe, there is little quantitative information on disturbance processes that influence forest dynamics. However, this information is crucial for forest management that tries to emulate patterns and processes in natural forests. We quantified the gap disturbance regime in an old-growth forest dominated by European beech (Fagus sylvatica L.) and silver fir (Abies alba Miller) in the Dinaric Mountains of Bosnia and Herzegovina. We sampled 87 gaps in four stands using line-intercept sampling. The percentages of forest area in canopy gaps and expanded gaps ranged from 12% to 17.2% and 35.5% to 39.7%, respectively. Although many of the gaps were small (<100 m 2 ) and formed from a single gapmaker, large canopy openings >1000 m 2 with numerous gapmakers made up a disproportionate amount of the total gap area. More than half the gaps had more than one gapmaker and were often in separate decay classes, indicating gaps had expanded over time during separate disturbance events. Furthermore, 51% of all gapmakers were uprooted or wind-snapped, whereas only 22% died standing. These results suggest that wind disturbance plays an important role in creating intermediate to large canopy openings through both gap formation and gap expansion processes.
Perspectives on development of definitions and values related to old-growth forests
Environmental Reviews, 2003
Old-growth forests are those that meet some threshold(s) determined by a scientific and political process. The main issue is what criteria to use to determine these thresholds; they must be practical enough to allow managers to delimit and manage old-growth stands in the field. People value forests with old and (or) big trees and primary forests that have a continuous heritage of natural disturbance and regeneration, even though the latter may include all stages of stand development and succession. We advocate uniting these two and using "primary forest", also called "natural heritage forest", as the criterion for delimiting old growth in regions where primary forest still exists. This criterion recognizes that the stage of development with big, old trees is part of a cycle of development, and it is necessary to have all the parts to continue to produce new examples of the older stages. The best available second-growth stands can be used in regions where primary forests are not available. Alternatively, threshold criteria for delimiting old growth can be based on tree size and age, but arbitrary criteria based on human size and age scales should be avoided in favour of criteria that specify stands dominated by trees relatively large and old for the species and site. Such criteria allow for old growth to occur across a variety of levels of site productivity, with trees of widely varying stature and with varying life-history characteristics, such as longevity, shade tolerance, and successional status. In any case, managers and scientists should work together to make sure that definitions work in the field but also include the ecological processes necessary to maintain the unique biological resources of old growth. The biological resources present in old growth may help to restore the second-growth landscape and allow reconstitution of forests in new places after global warming. Old-growth forests provide a baseline for comparison of effects of logging and natural disturbance, with respect to resilience to climatic change and disturbance, maintenance of species richness, and natural genetic structure of tree populations, which respond to different selective regimes in old growth and harvested forests. The species in old-growth remnants, their interactions and the resilience of the system after disturbance are as important or perhaps more so than the age and size of the trees at a given point in time.
Canadian Journal of Forest Research, 2013
Forest cover has increased in mountainous areas of Europe over the past decades because of the abandonment of agricultural areas (land-use change). For this reason, understanding how land-use change affects carbon (C) source-sink strength is of great importance. However, most studies have assessed mountainous systems C stocks, and less is known about C turnover rates, especially of "fresh" organic material (OM). We studied the decomposition of wood stakes of trembling aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.) placed on the litter layer and in the mineral soil of five ecosystem types (pastures and forests) -representing the successional development after land abandonment in the eastern Swiss Alpsfor 6 years. Wood stake decomposition rates were generally highest in pastures and lowest in early successional forests. Aspen stakes decomposed more rapidly than pine stakes, especially in the mineral soil. Soil temperature (and to a smaller extent soil phosphorus (P) concentration) best explained the differences in decomposition among the ecosystem types. Initial wood decay is temperature-sensitive, and therefore would likely increase under future climate change scenarios.