Special Feature 777

Journal of Vegetation Science 11: 777-880, 2000© IAVS; Opulus Press Uppsala. Printed in Sweden

SPECIAL FEATURE

Disturbance dynamics in boreal and temperate forests

Editors

Ola Engelmark, Sylvie Gauthier & Eddy van der Maarel

Contents

Engelmark, O.; Gauthier, S. & van der Maarel, E. — Disturbance dynamics in boreal and temperateforests: Introduction

Gauthier, S.; De Grandpré, L. & Bergeron, Y. — Differences in forest composition in two boreal forestecoregions of Québec

De Grandpré, L.; Morissette, J. & Gauthier, S. — Long-term post-fire changes in the northeastern borealforest of Québec

Kuuluvainen, T. & Rouvinen, S. — Post-fire understorey regeneration in boreal Pinus sylvestris forestsites with different fire histories

Hély, C.; Bergeron, Y. & Flannigan, M.D. —Effects of stand composition on fire hazard in mixed-woodCanadian boreal forest

Ida, H. —Treefall gap disturbance in an old-growth beech forest in southwestern Japan by a catastrophictyphoon

Arévalo, J.R.; DeCoster, J.K.; McAlister, S.D. & Palmer, M.W. — Changes in two Minnesota forestsduring 14 years following catastrophic windthrow

Palmer, M.W.; McAlister, S.D.; Arévalo, J.R. & DeCoster, J.K. — Changes in the understory during 14years following catastrophic windthrow in two Minnesota forests

Tenow, O. & Bylund, H. — Recovery of a Betula pubescens forest in northern Sweden after severedefoliation by Epirrita autumnata

Garin, I.; Aldezabal, A.; Herrero, J. & García-Serrano, A. —Understorey foraging and habitat selectionby sheep in mixed Atlantic woodland

Kirby, K.J. & Thomas, R.C. — Changes in the ground flora in Wytham Woods, southern England from1974 to 1991 – implications for nature conservation

Based on contributions presented at a session of the 41st symposium of the International Association for VegetationScience held at Uppsala University, Sweden, July 1998.

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778 Special Feature

Special Feature 779

Disturbance dynamics in boreal and temperate forests: Introduction

Engelmark, Ola1*; Gauthier, Sylvie2 & van der Maarel, Eddy3

1Swedish Institute for Ecological Sustainability, Box 7980, SE-907 19 Umeå, Sweden; 2Natural Resources Canada,Canadian Forest Service, Laurentian Forestry Centre, P.O. Box 3800, 1055 du P.E.P.S, Sainte-Foy, Qc, Canada,

G1V 4C7 and Groupe de recherche en écologie forestière interuniversitaire (GREFi), Université du Québec àMontréal, C.P. 8888, Succ. Centre-Ville, Montréal, Qc, Canada, H3C 3P8; 3Department of Plant Ecology, Evolu-tionary Biology Centre, Uppsala University, and Department of Plant Biology, University of Groningen, P.O. Box

14, NL-9750 AA Haren, The Netherlands; * Corresponding author; Fax +46907869309; E-mail ola@swecol.se

The papers presented in this issue result from a sessionat the 41st symposium of the International Associationfor Vegetation Science (IAVS) that took place atUppsala University, Sweden in 1998 (Engelmark et al.1998). The session was an initiative from the IAVSWorking Group ‘Disturbance dynamics in boreal forests’,and forms part of a series of workshops on disturbancedynamics. Earlier workshops took place in 1992 atUmeå University, Sweden (Engelmark et al. 1993), andin 1996 at the University of Québec in Abitibi-Témis-camingue, Canada (Bergeron et al. 1998). The primegoals of the working group are to encourage ecologicalresearch on forest disturbance, to build internationalbridges between forest ecologists and to integrate eco-logical thinking in sustainable forestry.

Boreal and temperate forest dynamics are main-tained by different disturbances, such as herbivory, graz-ing, fire and wind (Pickett & White 1985; Engelmark1999). Disturbance, in combination with continuousclimate variability, causes the forest to be in a state ofcontinuous change where species succeed each other inmanners that might be difficult to predict. At present,when sustainability is, more than ever, the keyword forthe use of natural resources as well as society reforma-tion, the need for a deeper understanding of such eco-system interactions has increased. This can partly bemet through re-inforced interdisciplinary studies butalso through intercontinental cooperation. Such studiesserve as a scientific foundation and they facilitate com-mon action and the transformation of words into deeds(Giampietro 1999).

The papers published in this Special Feature can begrouped in three main topics of disturbance, viz. (1) fire(Gauthier et al., De Grandpré et al., Hély et al.,Kuuluvainen & Rouvinen ); (2) wind (Ida, Arévalo etal., Palmer et al.), and (3) herbivory ( Tenow & Bylund,Garin et al., Kirby & Thomas).

Gauthier et al. describe and compare the post-firesuccession patterns of the two ecological regions(mixed-wood and coniferous ecoregions) of northwest-ern Québec. They suggest that both the landscape con-figuration and fire regime parameters such as fire sizeand fire intensity are important factors involved in thedifferences observed between the two regions.

De Grandpré et al. study forest development in thenortheastern boreal forest of Québec with the objectiveto describe succession following fire and to assess thefactors related to the changes in forest composition andstructure. They conclude that fire recurrence affectscommunity development and landscape diversity.

Hély et al. examine surface fuels in the Canadianmixed-wood boreal forest. They found that qualitativeand quantitative changes in fuels, resulting from speciesreplacement and fast decay rates, influence fire hazard.

Kuuluvainen & Rouvinen study the characteristicsof understorey regeneration on two sites with differentfire history in a mature Pinus sylvestris forest in easternFinland. The analysis suggests that in these forests theabundance, quality and spatial pattern of understoreytree population may vary considerably as a function ofdisturbance history.

Ida describes the effects of a catastrophic typhoonwhich created many treefall gaps in an old-growth Faguscrenata forest on Mt. Garyu, southwestern Japan. Dif-ferent DBH distributions were found in forest regrowthafter branch-falls, uprooting and snap-off.

Arévalo et al. measured tree damage and mortalityfollowing a catastrophic windthrow in an oak forest and apine forest in central Minnesota over 14 years. The imme-diate impacts of the storm were to differentially damageand kill large, early-successional hardwoods and pines.Subsequent recovery was characterized by the growth oflate-successional hardwoods. In both forests the distur-bance acted to accelerate succession.

780 Special Feature

Palmer et al. studied the effects of windthrow on theunderstorey plant species composition of the same for-ests. Both forests have increased in understorey speciesrichness, but have not changed substantially in the dis-tribution of growth forms. Although small in magni-tude, there was a directional change in understoreycomposition at both forests, with no apparent sign of areturn to pre-disturbance conditions.

Tenow & Bylund describe the effects of the defolia-tion by Epirrita autumnata caterpillars of a Betulapubescens forest in the Abisko valley of northern Swe-den during an outbreak in 1954-1955. The shoot popula-tion of the damaged forest will, after more than 30 years,need many more years to reach the assumed size of amature forest. The degree of rejuvenation varied be-tween stands, with different consequences for futuredynamics of E. autumnata populations.

Garin et al. investigated sheep foraging behaviour inmixed Atlantic woodland and assess its impact on theforest understorey in four forest types. The intensity offoraging by sheep was negligible for most of the plantspecies. Sheep selected only larch plantations, wheregrasses and Rubus were very abundant. This grazingbehaviour reduced browsing damage of the understoreyof woodland stands with higher conservation value,such as Quercus and Fagus woodlands.

Finally, Kirby & Thomas recorded the ground florain 1974 and 1991 from plots across Wytham Woods,near Oxford (UK). Ancient woodland indicators as agroup showed less change between the years than speciesassociated with the open glades and grassland patches inthe wood. Some typical old-woodland species increasedin frequency across the woodland. More species werelost from plantations than from semi-natural stands.

The papers in this Special Feature include studiesfrom different parts of the globe: Canada, USA, UnitedKingdom, Finland, Sweden, the Basque Country andJapan. It is noteworthy that similarities between theseregions can be found regarding disturbance dynamics.However, this Special Feature mainly deals with spa-tially and temporally relevant interpretations of post-disturbance vegetation dynamics. In some studies theimpact of anthropogenic disturbance on ecosystemprocesses is included. An accurate understanding ofdisturbance dynamics helps us to preserve ecosystemdiversity and to improve the use of forest resources in anecologically sustainable way. This is a challenge in-volving a continuous discussion and learning process.Future workshops and related publications intend tomaintain the general aim of our working group, i.e. thatnatural disturbance dynamics may be used as a templatefor forest management. In the mean time a new work-shop of the working group has taken place in August2000 in Finland.

References

Bergeron, Y., Engelmark, O., Harvey, B., Morin, H. & Sirois,L. (eds.) 1998. Key issues in disturbance dynamics inboreal forests. J. Veg. Sci. 9: 463-610.

Engelmark, O. 1999. Boreal forest disturbances. In: Walker,L. (ed.) Ecosystems of disturbed ground. Ecosystems ofthe World Vol. 16, pp 161-186. Elsevier, Amsterdam.

Engelmark, O., Bradshaw, R.H.W. & Bergeron, Y. (eds)1993. Disturbance dynamics in boreal forest. J. Veg. Sci.4: 729-832.

Engelmark, O., Gauthier, S. & van der Maarel, E. (eds.) 1998.Disturbance dynamics in boreal and temperate forests. In:Sjögren, E., van der Maarel, E. & Pokarzhevskaya, G.Vegetation science in retrospect and perspective (Ab-stracts). Stud. Plant Ecol. 20: 23-31.

Giampietro, M. 1999. Economic growth, human disturbanceto ecological systems, and sustainability. In: Walker, L.(ed.) Ecosystems of disturbed ground. Ecosystems of theWorld 16, pp 723-746. Elsevier, Amsterdam.

Pickett, S.T.A. & White, P.S. 1985. The ecology of naturaldisturbance and patch dynamics. Academic Press, NewYork, NY.