Conceptual models of forest dynamics in environmental education and management: keep it as simple as possible, but no simpler
© The Author(s). 2016
Received: 26 April 2016
Accepted: 30 June 2016
Published: 5 August 2016
Conceptual models of forest dynamics are powerful cognitive tools, which are indispensable for communicating ecological ideas and knowledge, and in developing strategic approaches and setting targets for forest conservation, restoration and sustainable management. Forest development through time is conventionally described as a directional, or “linear”, and predictable sequence of stages from “bare ground” to old forest representing the “climax-state”. However, this simple view is incompatible with the current knowledge and understanding of intrinsic variability of forest dynamics.
Overly simple conceptual models of forest dynamics easily become transformed into biased mental models of how forests naturally develop and what kind of structures they display. To be able to communicate the essential features and diversity of forest dynamics, comprehensive conceptual models are needed. For this end, Kuuluvainen (2009) suggested a relatively simple conceptual model of forest dynamics, which separates three major modes of forest dynamics, and incorporates state changes and transitions between the forest dynamics modes depending on changes in disturbance regime.
Conceptual models of forest dynamics should be comprehensive enough to incorporate both long-term directional change and short-term cyclic forest dynamics, as well as transitions from one dynamics mode to another depending on changes in the driving disturbance regime type. Models that capture such essential features of forest dynamics are indispensable for educational purposes, in setting reference conditions and in developing methods in forest conservation, restoration and ecosystem management.
Much of the persistent controversy surrounding succession stems from the different starting points or pioneer stages following varied kinds and degrees of disturbance, from which the seral sequence begins.
Robert McIntosh 1981
Since the formulation of the first concise scientific theory of plant succession in the early 20th century by Frederick Clements (1916), forest succession has conventionally been described as an orderly, directional and well predictable development of vegetation community change through time (McIntosh 1981; Peet 1981; but see Cowles 1911). Similar to the seral stages in Clements’ theory, successional development of forests has been divided into more or less arbitrarily defined developmental stages (Bormann and Likens 1979; Oliver 1980). Perhaps the simplest and most widely used and well known is the classification of Oliver (1980), dividing forest stand succession into four stages: stand initiation, stem exclusion, understorey re-initiation and old-growth stages. Over time, several alternative ways to divide stand succession into contiguous phases have been proposed (for a review see Franklin et al. 2002).
Although many of the elements of Clements’ original theory, such as the existence of clearly separable contiguous seral or successional stages and the idea of a static successional end point, the climatic climax, have by and large been abandoned (McIntosh 1981; Pickett et al. 2008; Christensen 2014), the directional “linear” representation of forest succession has been persistent, even in the leading ecological textbooks (for example Begon et al. 2006, p. 479-488). Although recent studies have put more emphasis on the effect of disturbance characteristics and legacies on forest dynamics, and variability of successional pathways (Glenn-Lewin and van der Maarel 1992; Pickett et al. 2008; Larsen and Chen 2011; Burton 2013), directional representations of forest succession have until recently been dominant in research literature as well (e.g. Franklin et al. 2002; Donato et al. 2012).
In forest conservation and restoration, simple conceptual models of forest dynamics based on outdated information can lead to biased definitions of natural reference conditions (natural range of variation), which are crucial in setting goals and choosing management methods (Landres et al. 1999; Halme et al. 2013). In forest management, simplified conceptual models can lead to “knowledge lock-ins”, where outdated views of intrinsic forest structure and dynamics are used as a basis and framework of management actions (Moen et al. 2014). This can in turn lead to failure in attaining ecological sustainability goals because the targeted habitat conditions deviate much more from natural reference conditions than realized. For example, conventional even-aged “command-and-control” management approaches may have been argued to be “nature-based” (Holling and Meffe 1996; Moen et al. 2014), although they actually differ drastically from natural forest dynamics (Gauthier et al. 2009; Kuuluvainen 2009; Puettmann et al. 2008). Therefore, realistic conceptual models are indispensable tools for communicating up-to-date ecological knowledge concerning intrinsic forest dynamics, for efficient forest conservation and restoration and for developing novel strategies of sustainable forest ecosystem management (Gauthier et al. 2009; Halme et al. 2013).
In this paper, I review and visualize the main types of suggested conceptual models of forest dynamics and discuss and compare their basic properties. Based on this, I present a relatively simple but comprehensive conceptual model, suggested by Kuuluvainen (2009) for boreal forests, which incorporates both long-term directional and shorter-term cyclic forest dynamics, as well as transitions from one forest dynamics mode to another depending on the characteristics of the driving disturbance regime. Finally, I discuss the stand and landscape level implications of the reviewed conceptual models for forest restoration and ecosystem-based management.
From directional to cyclic conceptual models of forest dynamics
This kind of dichotomic conceptual model could be applicable to old-growth dominated landscapes driven predominantly by small scale gap dynamics, which are punctuated with relatively rare but severe fires or storms (Syrjänen et al. 1994; Seymour et al. 2002). In such a case the forest landscape would consist of a combination of two very different kinds of dynamics, which are spatially and temporally separated: old gap dynamic forest (small cycle) and patches of younger even-aged forest regenerating after stand-replacing disturbance (large cycle) (Sirén 1955; Kuuluvainen et al. 1998).
Worrall et al. (2005) suggested, based on their studies on Picea-Abies forests in New Hampshire, that the two types of dynamics are not spatio-temporally distinct but they can operate as mixed both in space and time. The small scale gap phase cycles would operate as nested dynamics within larger scale infrequent non-stand-replacing disturbance cycles that occur at landscape scale. This kind of dynamics was also described in Sweden by Fraver et al. (2008) and by Kuuluvainen et al. (2014) in the primeval forest of the Archangelsk region in NW Russia. In this “nested bicycle” model of Worrall et al. (2005), the large cycle is driven by a disturbance that is partial and selective affecting only dominant trees (e.g. wind storms) or one species (e.g. host-specificity of fungi or insects).
The multi-cohort model has also been suggested as a conceptual basis for forest management that aims to emulate natural forest disturbances and structures, as driven by fire, both at stand and landscape scale. The structural cohorts and their dynamics are emulated using adapted silvicultural methods such as selection and group cutting, and by leaving retention trees. The landscape level target proportions and spatial pattern of different structural cohorts can be derived for example from historical disturbance reconstructions of the landscapes (Bergeron et al. 2002). It is obvious that the success of this approach in creating a functional “coarse filter” habitat mosaic depends on how realistic is the description of forest development and how well it can be emulated in management.
The Panarchy concept provides perhaps the most general cyclic representation for multi- and cross-scale ecosystem dynamics (Holling 2001). This model, which is not restricted to forests, can be used to explain how ecosystems maintain their biodiversity and resilience through cyclic cross-scale dynamics of change and rearrangement over time (Gunderson and Holling 2002). In the Panarchy cycle, disturbances and subsequent successions, leading to a reorganization of the ecosystem through colonization and early development, are crucial stages of the cycle allowing novel species and genotype combinations to appear and their viability to be tested against continuously changing biota and environmental conditions. This process, fostering resilience and adaptive capacity of ecosystems, can be seen as connected to recent findings concerning eco-evolutionary dynamics (Schoener 2011). However, being very general or even metaphorical, the Panarchy concept in its basic form does not specifically deal with details of ecosystem succession or variability in disturbance characteristics (Drever et al. 2006). However, the model adequately emphasizes the ecological importance of disturbance and subsequent ecosystem reorganization, as well as long term cyclic ecosystem dynamics, for ecosystem resiliency and adaptive capasity.
One obvious shortcoming of the reviewed directional, as well as simple cyclic models of forest dynamics is that, although they acknowledge disturbance as part of the forest dynamics, they only pay limited attention to the crucial role of disturbance properties on ecosystem dynamics (but see Belleau et al. 2011). Here especially the variability of disturbance quality and severity, and the resulting diversity of disturbance legacies, as well as the existing species pool of the surrounding landscape, are known to be crucial factors affecting forest regeneration dynamics, successional pathways and reorganization of the whole biotic community after disturbance (e.g. Bengtsson et al. 2003; Worrall et al. 2005; Johnstone and Chapin 2006; Pickett et al. 2008).
Towards a comprehensive conceptual model of boreal forest dynamics
It has been wisely stated that things should be made as simple as possible, but no simpler (the Einstein principle). This also applies to conceptual and visual descriptions of forest dynamics. A crucial question in formulating a comprehensive conceptual model for forest dynamics is how to incorporate the inherent complexity and variability of forest structural dynamics in sufficient detail, but at the same time simplify the phenomenon sufficiently to facilitate efficient communication of the main ideas (Bunnell and Johnson 1999). In boreal forest management this “complexity challenge” is related to the accumulating body of research results documenting the prevalence of small scale and partial disturbances driving the development of variable and heterogeneous stand structures (Kuuluvainen 2009; Kuuluvainen et al. 2015). This makes it necessary to abandon the simple directional models, and the conventional dichotomic ‘large cycle - small cycle’ conceptions, and to develop novel and more realistic conceptual representations of natural forest dynamics.
Figure 5 shows a comprehensive conceptual model of forest dynamics with three broad modes of dynamics and their relationships (Kuuluvainen 2009). In this model a forest can undergo directional succession after stand-replacing disturbance or remain in any one of the three modes if the driving disturbance type is not changed. On the other hand, if the driving disturbance regime type changes transition to another forest dynamics mode is likely to occur (Fig. 5).
The bottom line in Fig. 5 represents the classical directional successional sequence, from stand-replacing disturbance to gap-dynamic old forest. Stand initiation and competition driven stem exclusion phases represent even-aged forest dynamics. The next step is a transition phase where the oldest tree age cohort starts to die due to competition and tree senescence-related insect and fungi damages, and non-stand-replacing windstorms or fires. As a result, the canopy gradually opens up and a cohort-type dynamics and tree age distribution and emerge. Finally, fine scale gap dynamics commences and a truly uneven-aged forest is developed in the late-successional phase (Fig. 5; Aakala et al. 2009).
Each of the three dynamics types, stand-replacing, cohort or small scale gap dynamics, can be maintained indefinitely if the driving disturbance regime type remains. For example, in continental areas of Canada, stand-replacing fires with relatively short rotation cycles are common and maintain even-aged forest dynamics over extensive areas (Payette 1992). On the other hand, in areas where low-severity partial disturbances are common, cohort dynamics may dominate. This means that the forest is composed as a mix of older tree age classes (cohorts) surviving disturbances, and younger tree cohorts regenerating after disturbance events. Examples are provided by Fennoscandian Scots pine forests, which historically have been characterized by low-intensity surface fires (Lassila 1920). Due to the fire-resistance of large pine trees, repeated fires combined with other disturbances have historically created and maintained relatively open structurally complex stands consisting of multiple age cohorts of trees (Kuuluvainen and Aakala 2011). Finally, where major disturbances are absent for long periods of time, forest dynamics is driven by small scale gap disturbances related to senescence of trees (Kuuluvainen 1994). Examples are provided by nonpyrogenic old spruce forests in northern Fennoscandia (e.g. Aakala et al. 2009).
Comparison of the properties of the different proposed conceptual models of forest dynamics and the comprehensive model proposed in this paper
Transitions between modes of forest dynamics
Classical directional model
Large vs. small cycle model
Directional and cyclic
Large and small scale
Mosaic cycle model
Directional and cyclic
Conceptual and visualized models of forest dynamics are powerful cognitive tools that can be used – or misused - in communicating ecological ideas and knowledge in education and training of ecologists and foresters, and in forest management (McInerny et al. 2014). In many instances conceptual models can undoubtedly be more influential in directing human thinking and action than, for example, complicated mathematical and simulation models, which of course have their scientific and practical merits. Therefore, conceptual models, which are able to capture and demonstrate the essential features of forest dynamics, are indispensable for educational purposes, in setting goals and developing methods of forest conservation, restoration and ecosystem-based management (Bergeron et al. 2002; Kuuluvainen 2009; Kuuluvainen et al. 2015).
Regarding boreal forests, the conception of simple directional and deterministic forest development, starting from ‘bare ground’ and ending in static old-growth “climax” state, has by and large been the ‘norm model’, which is underlying the contemporary forest management paradigm and practices. However, the original reason why this conception received a dominant position was not the lack of realization that more complex forest structures and dynamics are naturally common, but rather the necessity to adopt a sufficiently simple conceptual model that could be used to organize rational forest management and for example to construct forest yield tables to predict forest growth. It was only afterwards that the conception of even-aged forest development was canonized as a ‘natural’ model of boreal forest dynamics. Hence, virtue was made out of necessity. As a result this history, the assumption that the directional model of even-aged forest development adequately represents intrinsic boreal forest dynamics has become deeply rooted in the mindset of forestry professionals and has therefore also profoundly influenced the adoption and development of silvicultural and forest management methods. What is worse, the adoption of this simplified conception has created “knowledge lock-ins” among professionals, which have seriously impeded the application of ecological knowledge in forest management (Puettmann et al. 2008; Moen et al. 2014).
For example, in Finland in the early 20th century, silvicultural methods were outlined by leading forest authorities and researchers based on the premise that even-aged fully stocked stands represent the idealized ‘normal forest’. In reality the motivation to promote this simple even-aged conceptual model was that it was a prerequisite for constructing yield tables that would also fit the adopted site type classification system developed by Cajander (1926). However, it was later admitted that such idealized even-aged ‘normal forests’ forests were extremely difficult to find in naturally dynamic forests (Ilvessalo 1937).
This example from Finland demonstrates more generally the case of boreal forests, where the adoption of the compartment-wise even-aged management system has been motivated by overly simplified ideas about forest structure and dynamics (Puettmann et al. 2008). Although it is currently widely recognized that forest dynamics are naturally more complex, including small scale gap and patch dynamics, and partial disturbances (Kuuluvainen and Aakala 2011; Taylor and Chen 2011), forest management continues to be predominantly grounded on the even-aged management approach. However, as expectations of ecological sustainability and provisioning of different ecosystem services from forests are growing (Burton et al. 2010), problems related to even-aged management are becoming more and more evident (e.g. Kuuluvainen et al. 2012). As a consequence, there is increasing interest in management approaches based on emulation of natural forest dynamics (Bergeron et al. 2002; Kuuluvainen et al. 2012), including continuous cover forestry utilizing single tree or group selection harvesting. Although such management approaches have traditionally been considered economically less profitable compared with even-aged management, this prejudgment has been questioned by recent research (Kuuluvainen et al. 2012; Rämö and Tahvonen 2014; Pukkala 2016).
Assumptions concerning forest dynamics are fundamentally important for setting reference forest conditions not only at stand scale but also at the landscape scale. This is because they affect what kind of landscape forest age structure and composition is considered as natural and desirable from the forest management, restoration or conservation point of view (Kuuluvainen et al. 2015). Theoretically, following the negative exponential distribution model of landscape forest age structure (Johnsson 1996), and assuming a random occurrence stand replacing disturbances on one percent of forest area with a 100 year fire cycle, 37 % of the landscape would be covered by forest older than 100 years (Bergeron et al. 2002). However, in most cases this is not a realistic assumption about forest dynamics, because it ignores the prevalence of non-stand-replacing disturbances and associated forest dynamics, like gap and cohort dynamics. Compared to stand-replacing disturbances, these disturbance types support a continuous presence of much higher coverage of old forest in the landscape (Pennanen 2002; Kuuluvainen 2009; Kuuluvainen and Aakala 2011).
Thus the assumptions behind models of forest dynamics can drastically affect the setting of forest conservation and restoration targets and implementation of forest management. In particular, simplistic assumptions of the dominance of stand replacing disturbances and uncritical use of the negative exponential model of forest age distribution can lead to seriously biased estimation of reference landscape conditions, and hence need of restoration and conservations of different kinds of forest habitat types (e.g. Angelstam and Andersson 2001; Lõhmus et al. 2004). This in turn may easily lead to failure in attaining the goals of forest restoration or sustainable management, including maintenance of biodiversity and natural variability of ecosystem types.
Conceptual models of forest dynamics are powerful and indispensable cognitive tools for communicating ecological knowledge and ideas. They can be used – or misused - in developing methods and setting goals of forest conservation, restoration and sustainable management. In particular, excessively simple and hence misleading models of forest dynamics can lead to seriously biased assessment of targets for forest conservation, restoration and management both at local and landscape scales. This in turn can result in failure in achieving the desired state of forest ecosystems from the point of view of forest conservation, restoration or sustainable management.
Particularly in boreal forest management, forest dynamics has mostly been viewed through the lens of overly simple conceptual models of directional even-aged dynamics. However, the revealed variability in forest dynamics, and particularly the obvious prevalence of small scale and partial non-stand-replacing disturbances, call for more comprehensive models, which would adequately reflect the state of scientific understanding of forest dynamics. It is suggested that more comprehensive but relatively simple conceptual models, as that introduced by Kuuluvainen (2009) and discussed in this paper, are needed. Such models should be able to incorporate and visualize both long-term directional forest development as well as shorter-term cyclic forest dynamics of different kinds. Such models should also incorporate state changes and transitions from one dynamics type to another depending on changes in driving disturbance regime.
I wish to thank Petri Keto-Tokoi, Tuomas Aakala and three anonymous reviewers for insightful comments on the manuscript.
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- Aakala T, Kuuluvainen T, Wallenius T, Kauhanen H (2009) Contrasting patterns of tree mortality in late-successional Picea abies stands in two areas of northern Fennoscandia. J Veg Sci 20:1016–1026View ArticleGoogle Scholar
- Angelstam P, Andersson L (2001) Estimates of the needs for forest reserves in Sweden. Scand J For Res Suppl 3:38–51View ArticleGoogle Scholar
- Angelstam P, Kuuluvainen T (2004) Boreal forest disturbance regimes, successional dynamics and landscape structures – a European perspective. In: Angelstam P, Dönz-Breuss M, Roberge J-M (eds) Targets and tools for the maintenance of forest biodiversity, vol 51, Ecol Bull., pp 117–136Google Scholar
- Begon M, Townsend CR, Harper JL (2006) Ecology. From individuals to ecosystems. 4th edition. Blackwell Publishing, USA, 738pGoogle Scholar
- Belleau A, Leduc A, LeComte N, Bergeron Y (2011) Forest succession rate and pathways on different surface deposit types in the boreal forest of northwestern Quebec. Ecosci 18(4):329–340View ArticleGoogle Scholar
- Bengtsson J, Angelstam P, Elmqvist T, Emanuelsson U, Folke C, Ihse M, Moberg F, Nyström M (2003) Reserves, resilience and dynamic landscapes. Ambio 23(6):389-396Google Scholar
- Bergeron Y, Fenton NJ (2012) Boreal forests of eastern Canada revisited: old growth, nonfire disturbances, forest succession, and biodiversity. Botany 90:509–523View ArticleGoogle Scholar
- Bergeron Y, Leduc A, Harvey BD, Gauthier S (2002) Natural fire regime: a guide for sustainable management of the Canadian boreal forest. Silva Fenn 36:81–95View ArticleGoogle Scholar
- Bormann FH, Likens GE (1979) Pattern and process in a forested ecosystem. Springer, New YorkView ArticleGoogle Scholar
- Bunnell FL, Johnson F (eds) (1999) Policy and practices for biodiversity in managed forests, The living dance. UBC Press, VancouverGoogle Scholar
- Burton P (2013) Exploring complexity in boreal forests. In: Messier C, Puettmann KJ, Coates KD (eds) Managing forests as complex adaptive systems. Building resilience to the challenge of global change. Routledge, London, pp 79–109Google Scholar
- Burton PJ, Bergeron Y, Bogdanski BEC, Juday GP, Kuuluvainen T, McAfee BJ, Ogden A, Teplyakov VK, Alfaro RI, Francis DA, Gauthier S, Hantula J (2010) Sustainability of boreal forests and forestry in a changing environment. In: Mery G, Katila P, Galloway G, Alfaro RI, Kanninen M, Lobovikov M, Varjo J (eds) Forests and Society - Responding to Global Drivers of Change. International Union of Forest Research Organizations (IUFRO), Vienna, Austria, pp 249–282Google Scholar
- Cajander AK (1926) The theory of forest types. Acta For Fenn 29:1–108Google Scholar
- Christensen NL Jr (2014) A historical perspective on forest succession and its relevance to ecosystem restoration and conservation practice in North America. For Ecol Manage 330:312–322View ArticleGoogle Scholar
- Clements FE (1916) Plant succession: An analysis of the development of vegetation. Garnegie institute of Washington Publications, No. 242. Washington, DCGoogle Scholar
- Cowles HC (1911) The causes of vegetation cycles. Botanical Gazette 51:161–183View ArticleGoogle Scholar
- Donato DC, Campbell JL, Franklin JF (2012) Multiple successional pathways and precocity in forest development: can some forests be born complex? J Veg Sci 23:576–584View ArticleGoogle Scholar
- Drever CR, Peterson G, Messier C, Bergeron Y, Flannigan M (2006) Can forest management based on natural disturbances maintain ecological resilience? Can J For Res 36:2285–2299View ArticleGoogle Scholar
- Forcier LK (1975) Reproductive strategies in the co-occurrence of climax tree species. Science 189:808–810View ArticlePubMedGoogle Scholar
- Franklin JF, Spies TA, Van Pelt R, Carey AB, Thornburgh DA, Rae Berg D, Kindenmayer DB, Harmon ME, Keeton WS, Shaw DC, Bible K, Chen J (2002) Disturbances and structural development of natural forest ecosystems with silvicultural implications, using Douglas-fir forests as an example. Forest Ecology and Management 155:399–423View ArticleGoogle Scholar
- Fraver S, Jonsson BG, Jönsson M, Esseen P-A (2008) Demographies and disturbance history of a boreal old-growth Picea abies forest. J Veg Sci 19:789–798View ArticleGoogle Scholar
- Gauthier S, Vaillancourt M-A, Leduc A, De Grandpré L, Kneeshaw D, Morin H, Drapeau P, Bergeron Y (2009) Ecosystem management in the boreal forest. Les Presses de l’Université du Québec, Québec, p 568Google Scholar
- Glenn-Lewin DC, van der Maarel E (1992) Patterns and processes of vegetation dynamics. In: Peet RK, Veblen TT (eds) Glenn-Lewin DC. Plant succession – theory and application, Chapham & Hall, pp 11–59Google Scholar
- Gunderson LH, Holling CS (eds) (2002) Panarchy, Understanding transformations in human and natural systems. Island Press, WashingtonGoogle Scholar
- Halme P, Allen KA, Aunins A, Bradshaw RHW, Brumelis G, Cada V, Clear JL, Eriksson A-M, Hannon G, Hyvärinen E, Ikauniece S, Iršėnaitė R, Jonsson BG, Junninen K, Kareksela S, Komonen A, Kotiaho JS, Kouki J, Kuuluvainen T, Mazziotta A, Mönkkönen M, Nyholm K, Olden A, Shorohova E, Strange N, Toivanen T, Vanha-Majamaa I, Wallenius T, Ylisirniö A-L, Zin E (2013) Challenges of ecological restoration : Lessons from forests in northern Europe. Biol Cons 167:248–256View ArticleGoogle Scholar
- Holling CS (2001) Understanding the complexity of economic, ecological, and social systems. Ecosystems 4:390–405View ArticleGoogle Scholar
- Holling S, Meffe GK (1996) Command and control and the pathology of natural resource management. Cons Biol 10:328–37View ArticleGoogle Scholar
- Ilvessalo Y (1937) Growth of natural normal stands in central North-Suomi. Acta For Fenn 24(2):1–168Google Scholar
- Johnson EA (1996) Fire and vegetation dynamics: studies from the North American boreal forest. Cambridge University Press, Cambridge, UKGoogle Scholar
- Johnstone JF, Chapin SF III (2006) Effects of soil burn severity on post-fire tree recruitment in boreal forest. Ecosystems 9:14–31View ArticleGoogle Scholar
- Kneeshaw D, Bergeron Y, Kuuluvainen T (2011) Forest ecosystem structure and disturbance dynamics across the circimboreal forest. In: Millington AC, Blumler MB, Schickhoff U (eds) The Sage Handbook of Biogeography. Sage, Los Angeles, pp 263–280Google Scholar
- Kuuluvainen T (1994) Gap disturbance, ground microtopography, and the regeneration dynamics of boreal coniferous forests in Finland: a review. Ann Zool Fenn 31:35–51Google Scholar
- Kuuluvainen T (2009) Forest management and biodiversity conservation based on natural ecosystem dynamics in northern Europe: The complexity challenge. Ambio 38:309–315View ArticlePubMedGoogle Scholar
- Kuuluvainen T, Aakala T (2011) Natural forest dynamics in boreal Fennoscandia: a review and classification. Silva Fenn 45(5):823–841View ArticleGoogle Scholar
- Kuuluvainen T, Syrjänen K, Kalliola R (1998) Structure of a pristine Picea abies forest in northwestern Europe. J Veg Sci 9:563–574View ArticleGoogle Scholar
- Kuuluvainen T, Tahvonen O, Aakala T (2012) Even-aged and uneven-aged forest management in boreal Fennoscandia: a review. AMBIO. doi:10.1007/s13280-012-0289-y PubMedPubMed CentralGoogle Scholar
- Kuuluvainen T, Bergeron Y, Coates KD (2015) Restoration and ecosystem-based management in the circumboreal forest: Background, challenges, and opportunities. In: Stanturf JA (ed.) Restoration of boreal and temperate forests. 2nd edition, CRC PressGoogle Scholar
- Kuuluvainen T, Wallenius TH, Kauhanen H, Aakala T, Mikkola K, Demidova N, Ogibin B (2014) Episodic, patchy disturbances characterize an old-growth Picea abies dominated forest landscape in northeastern Europe. For Ecol Manage 320:96–103View ArticleGoogle Scholar
- Landres PB, Morgan P, Swanson FJ (1999) Overview of the use of natural variability concepts in managing ecological systems. Ecol Appl 9:1179–1188Google Scholar
- Larsen AR, Chen HYH (2011) Multiple successional pathways of boreal forest stands in central Canada. Ecography 34:208–219View ArticleGoogle Scholar
- Lassila I (1920) Tutkimuksia mäntymetsien synnystä ja kehityksestä pohjoisen napapiirin pohjoispuolella. Acta For Fenn 14(3):95, in FinnishGoogle Scholar
- Lõhmus A, Kohv K, Palo A, Viilma K (2004) Loss of old-growth, and the minimum need for strictly protected forests in Estonia. Ecol Bull 51:401–411Google Scholar
- McCarthy J (2001) Gap dynamics of forest trees: a review with particular attention to boreal forests. Environ Rev 9:1–59View ArticleGoogle Scholar
- McInerny GJ, Chen M, Freeman R, Gavaghan D, Mayer M, Rowland F, Spiegelhalter D, Stefaner M, Tessarolo G, Hortal J (2014) Information visualization for science and policy: engaging users and avoiding bias. Trends Ecol Evol 29(3):148–155View ArticlePubMedGoogle Scholar
- McIntosh RP (1981) Succession and ecological theory. In: West DC, Shugart HH Botkin DB (eds) Forest succession. Concepts and applications. Springer, New York, pp 10–23View ArticleGoogle Scholar
- Moen J, Rist L, Bishop K, Chapin FS III, Ellison D, Kuuluvainen T, Petersson H, Puettmann KJ, Rayner J, Warkentin IG, Bradshaw CJA (2014) Eye on the taiga: removing global policy impediments to safeguard the boreal forest. Cons Lett 7(4):408–418. doi:10.1111/conl.12098 View ArticleGoogle Scholar
- Oliver CD (1980) Forest development in North America following major disturbances. For Ecol Manage 3:153–168. doi:10.1016/0378-1127(80)90013-4 View ArticleGoogle Scholar
- Payette S (1992) Fire as a controlling process in the North American boreal forest. In: Leemans R, Bonan GB (eds) Shugart HH. New-York, Cambridge University Press, pp 144–169Google Scholar
- Peet RK (1981) Changes in biomass and production during secondary forest succession. In: West et al. (eds) Forest succession. Springer-Verlag, New YorkGoogle Scholar
- Pennanen J (2002) Forest age distribution under mixed-severity fire regimes – a simulation-based analysis for middle boreal Fennoscandia. Silva Fenn 36(1):2113–231View ArticleGoogle Scholar
- Pickett STA, White PS (eds) (1985) The ecology of natural disturbance and patch dynamics. Academic, New YorkGoogle Scholar
- Pickett STA, Cadenasso ML, Meiners SJ (2008) Ever since Clements: from succession to vegetation dynamics and understanding to intervention. Appl Veg Sci 12:9–21View ArticleGoogle Scholar
- Podlaski R (2008) Dynamics of Central European near-natural Abies-Fagus forests: Does the mosaic-cycle provide an appropriate model. J Veg Sci 19:173–182View ArticleGoogle Scholar
- Puettmann KJ, Coates KD, Messier C (2008) A Critique of Silviculture: Managing For Complexity. Island Press, Washington, DCGoogle Scholar
- Pukkala T (2016) Plenterwald, Dauerwald or clearcut? For Pol Econ 62:125–134View ArticleGoogle Scholar
- Rämö J, Tahvonen O (2014) Economics of harvesting uneven-aged forest stands in Fennoscandia. Scand J For Res 29:777–792View ArticleGoogle Scholar
- Remmert H (1991) The mosaic-cycle concept of ecosystems, Ecological Studies 85. Springer, BerlinView ArticleGoogle Scholar
- Schoener TW (2011) The newest synthesis: understanding the interplay of evolutionary and ecological dynamics. Science 331:426–429View ArticlePubMedGoogle Scholar
- Seymour RS, White AS, de Maynadier PG (2002) Natural disturbance regimes in northeastern North America: Evaluating silvicultural systems using natural scales and frequencies. For Ecol Manage 155:357–367View ArticleGoogle Scholar
- Shorohova E, Kuuluvainen T, Kangur A, Jogiste K (2009) Natural stand structures, disturbance regimes and successional dynamics in the Eurasian boreal forests: a review with special reference to Russian studies. Ann For Sci 66. 201.Google Scholar
- Sirén G (1955) The development of spruce forest on raw humus sites and its ecology. Acta For Fenn 62:1–363Google Scholar
- Sprugel DG, Bormann FH (1981) Natural disturbance and the steady state in high-altitude balsam fir forests. Science 211:390–393View ArticlePubMedGoogle Scholar
- Syrjänen K, Kalliola R, Puolasmaa A, Mattson J (1994) Landscape structure and forest dynamics in subcontinental Russian taiga. Ann Zool Fenn 31:19–34Google Scholar
- Taylor AR, Chen HYH (2011) Multiple successional pathways of boreal forest stands in central Canada. Ecography 34:208–219View ArticleGoogle Scholar
- Turner MG, Dale VH (1998) Comparing large, infrequent disturbances: What have we learned? Ecosystems 1:493–496View ArticleGoogle Scholar
- Worrall JJ, Lee TD, Harrington TC (2005) Forest dynamics and agents that initiate and expand canopy gaps in Picea-Abies forests of Crawford Notch, New Hampshire, USA. J Ecol 93:178–190View ArticleGoogle Scholar