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Jönsson, Mari T.
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Publications (10 of 10) Show all publications
Jönsson, M. T., Fraver, S. & Jonsson, B. G. (2011). Spatio-Temporal Variation of Coarse Woody Debris Input in Woodland Key Habitats in Central Sweden. Silva Fennica, 45(5), 957-967
Open this publication in new window or tab >>Spatio-Temporal Variation of Coarse Woody Debris Input in Woodland Key Habitats in Central Sweden
2011 (English)In: Silva Fennica, ISSN 0037-5330, E-ISSN 2242-4075, Vol. 45, no 5, p. 957-967Article in journal (Refereed) Published
Abstract [en]

 The persistence of many saproxylic (wood-living) species depends on a readily available supply of coarse woody debris (CWD). Most studies ofCWD inputs address stand-level patterns, despite the fact that many saproxylic species depend on landscape-level supplies of CWD. In the present study we used dated CWD inputs (tree mortality events) at each of 14 Norway spruce (Picea abies) dominated woodland key habitat sites to analyze the spatial and temporal patterns of CWD additions between 1950 and 2002 within a small landscape in central Sweden. We found that inputs were episodic within sites, where local windstorms created pulses in CWD input. Pulses occurred simultaneously in many sites, yielding landscape-level synchrony of CWDinput. These synchronous pulses, and importantly, the breaks between pulses, may have negative implications for saproxylic species that are dependent on large volume inputs of freshly killed Norway spruce. In addition, the inherent small size and relative isolation of these sites may further increase extinction risks due to stochastic events. However, background CWD input rates occurring between pulses varied substantially among sites, presumably the result of the sites' varied histories and structural characteristics. This finding suggests that the different sites have varied abilities to provide habitat for saproxylic species during periods with low landscape-level input of CWD.

Keywords
boreal forest; dendrochronology; disturbance dynamics; Picea abies; tree mortality; woodland key habitats; windstorms
National Category
Ecology
Identifiers
urn:nbn:se:miun:diva-16289 (URN)000300809800011 ()2-s2.0-84856618450 (Scopus ID)
Available from: 2012-05-25 Created: 2012-05-24 Last updated: 2017-12-07Bibliographically approved
Jönsson, M., Fraver, S. & Jonsson, B. G. (2009). Forest history and the development of old-growth characteristics in fragmented boreal forests. Journal of Vegetation Science, 20(1), 91-106
Open this publication in new window or tab >>Forest history and the development of old-growth characteristics in fragmented boreal forests
2009 (English)In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 20, no 1, p. 91-106Article in journal (Refereed) Published
Abstract [en]

Questions: Can small and isolated high-conservation value forests (e.g. designated woodland key habitats) maintain old-growth forest characteristics and functionality in fragmented landscapes? To what extent have past disturbances (natural and anthropogenic) influenced the development of old-growth characteristics of these forests? How long does it take for selectively cut stands to attain conditions resembling old-growth forests?

 

Location: Southern boreal zone of central Sweden.

 

Methods: We linked multiple lines of evidence from historical records, biological archives, and analyses of current forest structure to reconstruct the forest history of a boreal landscape, with special emphasis on six remaining core localities of high-conservation value forest stands.

 

Results: Our reconstructions revealed that several of these stands experienced wildfires up to the 1890s; all had been selectively harvested in the late 1800s; and all underwent substantial structural and compositional reorganization over the following 100-150 years. This time interval was sufficient to recover considerable amounts of standing and downed dead wood (mean 60.3 m3 ha−1), a range of tree ages and sizes (mean basal area 32.6 m2 ha−1), and dominance of shade-tolerant spruce. It was insufficient to obtain clearly uneven tree age structures and large (>45 cm diameter) living and dead trees. Thus, these forests contain some, but not all, important compositional and structural attributes of old-growth forests, their abundance being dependent on the timing and magnitude of past natural and anthropogenic disturbances. Our landscape-level analysis showed marked compositional and structural differences between the historical forest landscape and the present landscape, with the latter having a greater proportion of young forests, introduction of non-native species, and lack of large trees and dead wood.

 

Conclusions: The remnant high-conservation value stands were not true representatives of the pre-industrial forests, but represent the last vestige of forests that have regenerated naturally and maintained a continuous tree cover. These traits, coupled with their capacity for old-growth recovery, make them valuable focal areas for conservation.

 

Keywords
Coarse Woody Debris • Dendrochronology • Fire Ecology • Historical Records • Land-Use History • Picea Abies • Southern Boreal Zone • Stand Dynamics • Stand Reconstruction • Sweden • Woodland Key Habitats
National Category
Ecology
Identifiers
urn:nbn:se:miun:diva-7692 (URN)10.1111/j.1654-1103.2009.05394.x (DOI)000263701500011 ()2-s2.0-70249110379 (Scopus ID)
Available from: 2008-12-11 Created: 2008-12-11 Last updated: 2017-12-14Bibliographically approved
Jönsson, M., Edman, M. & Jonsson, B. G. (2008). Colonization and extinction patterns of wood-decaying fungi in a boreal old-growth Picea abies forest. Journal of Ecology, 96(5), 1065-1075
Open this publication in new window or tab >>Colonization and extinction patterns of wood-decaying fungi in a boreal old-growth Picea abies forest
2008 (English)In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 96, no 5, p. 1065-1075Article in journal (Refereed) Published
Abstract [en]

1. Wood-decaying fungi are ubiquitous and functionally important organisms within forest ecosystems world-wide, but remarkably little is known of their population dynamics in relation to the dynamics of their host substrates. Living in transient environments, where local extinctions are caused by gradual substrate (patch) destruction or deterioration due to wood decomposition, the long-term persistence of these species requires successful colonization of new patches.2. During a 6-year period, we examined the colonization-extinction dynamics of wood-decaying fungi (Aphyllophorales: Polyporaceae and Corticiaceae) in relation to the spatiotemporal distribution of host logs within a boreal old-growth Norway spruce (Picea abies) forest.3. The dynamics of the species studied were strongly influenced by both local log characteristics (within patch) and connectivity (between patch). Several species (e.g. Asterodon ferruginosus, Phellinus ferrugineofuscus, P. viticola, Phlebia centrifuga) showed a positive effect of connectivity, mainly colonizing logs in the vicinity of previously occupied logs. This implies that some wood-decaying fungi may be dispersal limited in terms of successful colonizations. The relative importance of patch conditions and connectivity was however, highly species specific.4. Our results further illustrate the importance of life-strategies adopted by species that are present during different stages of wood decomposition. Early colonizers were primarily affected by the stage of decomposition; secondary colonizers were affected by a variety of within patch and/or between patch variables, maintaining high species coexistence within intermediate stages of decay. Phellinus nigrolimitatus was the dominant polyporous decayer at the final stages of decomposition, clearly gaining a competitive advantage from specializing on highly decomposed wood and having very low mean annual mortality rates.5. Local extinction rates were higher on small diameter logs than large diameter logs, and generally increased as decay proceeded, illustrating the importance of deterministic patch destruction due to wood decomposition.6. Synthesis. The fungi-log study system was highly dynamic, illustrating that both characteristics and spatiotemporal availability of logs are important in explaining the distribution patterns and population dynamics of wood-decaying fungal communities. The result implies that the dynamics of some wood-decaying fungi can be characterized as patch-tracking metapopulations, with connectivity-dependent colonizations and local extinctions caused by the turnover of the patches.

National Category
Biological Sciences
Identifiers
urn:nbn:se:miun:diva-7249 (URN)10.1111/j.1365-2745.2008.01411.x (DOI)000258379800024 ()2-s2.0-49649125885 (Scopus ID)
Available from: 2008-11-30 Created: 2008-11-30 Last updated: 2017-12-14Bibliographically approved
Fraver, S., Jönsson, M. & Jonsson, B. G. (2008). Demographics and disturbance history of a boreal old-growth Picea abies forest. Journal of Vegetation Science, 19(6), 789-798
Open this publication in new window or tab >>Demographics and disturbance history of a boreal old-growth Picea abies forest
2008 (English)In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 19, no 6, p. 789-798Article in journal (Refereed) Published
Abstract [en]

Question: To what extent do tree growth, mortality, and long-term disturbance patterns affect stand structure and composition of an old-growth Picea abies forest?Location: Boreal Sweden.Methods: We linked data from three 50 m × 50 m permanent plots established in 1986 with dendrochronology data to evaluate tree growth and mortality over an 18-year period and to describe a several-hundred-year disturbance history for this forest type.Results: Averaged over all diameters, P. abies trees had an annual mortality rate of 0.60%; however, diameter had a striking effect on both growth and mortality, with trees of intermediate diameters (ca. 20–30 cm) showing faster growth and lower mortality. Their increased vigor gave rise to a diameter distribution resembling the ‘rotated sigmoid’ (not reverse-J) proposed for such conditions, and it led to a deficit of snags of intermediate diameters. Slow-growing trees had an increased likelihood of dying. Although recruitment occurred in most decades over the past 400 years, two prominent recruitment peaks occurred (mid 1700s and 1800s), neither of which appeared to cause a shift in tree species composition. The lack of fire evidence suggests that fire was not responsible for these recruitment peaks.Conclusions: Taken together, these results depict a rather impassive system, where canopy trees die slowly over decades. Field observations suggest that fungal infections, mediated by wind, account for much of the mortality during these periods of relative quiescence. However, these periods are at times punctuated by moderate-severity disturbances that foster abundant recruitment.

 

Keywords
Dendrochronology; Late-successional forest; Mortality;Permanent plot; Rotated sigmoid diameter distribution; Wood-decay fungi; Woody debris
National Category
Ecology
Identifiers
urn:nbn:se:miun:diva-7689 (URN)10.3170/2008-8-18449 (DOI)000264001900006 ()2-s2.0-60049083953 (Scopus ID)
Available from: 2008-12-11 Created: 2008-12-11 Last updated: 2017-12-14Bibliographically approved
Jönsson, M. T. & Jonsson, B.-G. (2007). Assessing coarse woody debris in Swedish woodland key habitats: Implications for conservation and management. Forest Ecology and Management, 242(2-3), 363-373
Open this publication in new window or tab >>Assessing coarse woody debris in Swedish woodland key habitats: Implications for conservation and management
2007 (English)In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 242, no 2-3, p. 363-373Article in journal (Refereed) Published
Abstract [en]

In the mainland Nordic countries and the Baltic States, the delineation and set-aside of woodland key habitats (WKHs) has been one important approach to conserving biodiversity outside traditional protected areas. Though the specifics of the key habitat concept differ from country to country, the intent is to set aside forest areas that (1) exhibit a low degree of exploitation, (2) host or potentially host red-listed species, and/or (3) contain old-growth characteristics (e.g. dead wood, large old trees) or other qualities considered valuable for maintaining biodiversity. However, it is still uncertain to what extent WKHs actually retain quantities and qualities of coarse woody debris (CWD) that are characteristic of old-growth forests. The Biodiversity Monitoring Programme (BMP) recently conducted a detailed inventory of 491 WKHs across Sweden, providing a large dataset with which to evaluate the effectiveness of the WKH program with respect to CWD. In the present study we analyze the BMP data and compare CWD volume and composition between WKHs, mature managed (stand age 81-120 years), overmature managed (age 121-140 years), and published findings from old-growth forests. The national average volume of CWD (standing and downed combined, m3/ha) was higher in WKHs (19.5) than the mature managed (9.3) and the overmature managed forest (12.2), yet was markedly lower than that reported from old-growth forests. CWD volumes in spruce-dominated WKHs had been reduced by 50-63% in the southern and middle boreal regions to 43-64% in the northern boreal region when compared to old-growth forests. In general, CWD amount, variability and quality were greater within WKHs in the boreal regions as opposed to the nemoral and boreonemoral regions in the south of Sweden. The majority of the WKHs (64%) contained key elements (very large and/or decayed dead wood known to be crucial habitat for many threatened wood-dependent species). Considering that these structures are largely absent from managed forests, WKHs have better retained some of the important features of old-growth forests when compared to the surrounding managed forest. WKHs are therefore valuable habitats for dead wood dependent species and representative focal areas for continued and future forest restoration and landscape planning. Our results confirm that large sun-exposed and burned dead wood are underrepresented CWD components within WKHs and emphasize the need to broaden the WKH definition to include locations containing these structures.

Keywords
Biodiversity Monitoring Programme, Deadwood inventories, Remnants, Set-asides
National Category
Biological Sciences
Identifiers
urn:nbn:se:miun:diva-5148 (URN)10.1016/j.foreco.2007.01.054 (DOI)000246268100030 ()2-s2.0-34047151187 (Scopus ID)4721 (Local ID)4721 (Archive number)4721 (OAI)
Note

VR-Biology

Available from: 2008-09-30 Created: 2009-06-08 Last updated: 2017-12-12Bibliographically approved
Jönsson, M., Fraver, S., Jonsson, B.-G., Dynesius, M., Rydgård, M. & Esseen, P.-A. (2007). Eighteen years of tree mortality and structural change in an experimentally fragmented Norway spruce forest. Forest Ecology and Management, 242(2-3), 306-313
Open this publication in new window or tab >>Eighteen years of tree mortality and structural change in an experimentally fragmented Norway spruce forest
Show others...
2007 (English)In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 242, no 2-3, p. 306-313Article in journal (Refereed) Published
Abstract [en]

Long-term experimental forest fragmentation studies remain uncommon, despite their critical role in the advancement of ecological theory and conservation planning. In 1986 five circular forest fragments (1/16-1 ha) were exposed through clearcutting within an old-growth Norway spruce (Picea abies) forest in northern Sweden. Initial responses to fragmentation (1986-1991) showed very high tree mortality and structural degradation of the fragments. In the present study we re-inventoried these fragments to evaluate tree mortality patterns and structural changes occurring over a longer time period (1991-2004). The fragments can readily be viewed as harvest retention patches or 'woodland key habitats' (i.e., set-aside patches of high conservation value), allowing us to make inferences about the effectiveness of these novel conservation tools. Tree mortality rates dropped markedly (to 1.2-3.9%/year) compared to the initial responses, yet remained elevated over those of control plots in the nearby unfragmented forest (0.7%). Mortality increased with tree diameter, resulting in smaller-diameter, more homogenous stands. Mortality also generally increased with decreasing fragment size and was dependent of tree location within fragments. Standing death (45% of dead trees, 1991-2004) replaced uprootings (71%, 1986-1991) as the dominant mode of mortality. Numbers of dying and standing dead trees increased during the second sampling period, further adding to structural change and reduced stand density. Elevated tree mortality resulted in uncharacteristically high volumes of coarse woody debris. Results clearly show that adverse edge-related changes to forest structure and function persist up to two decades after fragmentation. Fragments of this size largely fail as remnants intended to maintain forest interior conditions and late-successional forest structure. However, when embedded within a harvested landscape, they: (1) provide abundant coarse woody debris and snags for deadwood-dependent species that risk extirpation in the surrounding matrix and (2) retain important structures for the developing stands.

Keywords
Edge influence, Experimental forest fragmentation, Forest dynamics, Picea abies, Tree retention patch, Wind disturbance, Woodland key habitat, skog biologisk mångfald
National Category
Biological Sciences Ecology Agricultural Sciences
Identifiers
urn:nbn:se:miun:diva-3857 (URN)10.1016/j.foreco.2007.01.048 (DOI)000246268100024 ()2-s2.0-34047127294 (Scopus ID)4127 (Local ID)4127 (Archive number)4127 (OAI)
Note

VR-Biology

Available from: 2008-09-30 Created: 2009-11-02 Last updated: 2017-12-12Bibliographically approved
Edman, M., Jönsson, M. & Jonsson, B. G. (2007). Fungi and wind strongly influence the temporal availability of logs in an old-growth spruce forest. Ecological Applications, 17(2), 482-490
Open this publication in new window or tab >>Fungi and wind strongly influence the temporal availability of logs in an old-growth spruce forest
2007 (English)In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 17, no 2, p. 482-490Article in journal (Refereed) Published
Abstract [en]

Coarse woody debris (CWD) is a key habitat for many species in forest ecosystems. To ensure the long-term survival of such species, forest management regimes must include measures that promote dead wood dynamics similar to those of natural forests. Thus, information on CWD dynamics under natural conditions is required, including data pertaining to the underlying agents of disturbance. This study examines modes of mortality, decay rates, and temporal patterns in the availability of Picea abies logs in a Swedish old-growth forest affected by internal, small-scale disturbance. All 684 logs in a 6.6-ha plot were mapped and classified into one of six decay classes. Logs in the early stages of decay were examined for the presence of heart-rot fungi. Six years later all logs were re-inventoried, including newly formed logs. Matrix models based on the transition rates between decay classes showed that it took about 60 years for 90% of the logs to decay beyond class 6 (a deformed trunk with soft wood). Large logs (≥26 cm) decayed 40% more slowly than small logs (≤25 cm). The initial volume of logs was 37.6 m3/ha but increased to 44.8 m 3/ha after six years. In addition, there was a large shift in the decay-class distribution. The volume of logs in early and late decay classes increased by 71% and 45%, respectively, while the volume of logs in the intermediate decay classes decreased by 32%. The fluctuations appear to result from pulses in mortality, driven by a combination of strong winds and the heart-rot fungus, Phellinus chrysoloma, which was present in more than 30% of all logs at an early stage of decay. These results show that large temporal fluctuations in dead wood also occur in the absence of large-scale disturbance, and that heart-rot fungi are important factors driving the overall dynamics of dead wood. Since many wood-inhabiting species are naturally rare and have very specific substrate demands, such temporal variability in dead wood availability may have effects on biodiversity and should be taken into account when designing small, protected forest areas.

Keywords
Boreal, Coarse woody debris, Decay rate, Disturbance agents, Forest management, Heart-rot fungi, Norway spruce, Phellinus chrysoloma, Stage matrix, Sweden, Temporal pattern, Tree mortality, skog, biologisk mångfald
National Category
Biological Sciences Ecology Agricultural Sciences
Identifiers
urn:nbn:se:miun:diva-3854 (URN)10.1890/06-0852 (DOI)000245744200016 ()17489254 (PubMedID)2-s2.0-34247246346 (Scopus ID)4124 (Local ID)4124 (Archive number)4124 (OAI)
Note

VR-Biology

Available from: 2008-09-30 Created: 2009-11-02 Last updated: 2017-12-12Bibliographically approved
Edman, M., Jönsson, M. & Jonsson, B. G. (2007). Small-scale fungal- and wind-mediated disturbances strongly influence the temporal availability of logs in an old-growth Picea abies forest. , 170
Open this publication in new window or tab >>Small-scale fungal- and wind-mediated disturbances strongly influence the temporal availability of logs in an old-growth Picea abies forest
2007 (English)Manuscript (preprint) (Other academic)
National Category
Biological Sciences
Identifiers
urn:nbn:se:miun:diva-9401 (URN)
Available from: 2013-12-05 Created: 2009-07-16 Last updated: 2013-12-09Bibliographically approved
Jönsson, M. T. (2007). The importance of small forest set-asides for saproxylic biodiversity at stand- landscape- and regional scales. (Doctoral dissertation). Sundsvall: Mittuniversitetet
Open this publication in new window or tab >>The importance of small forest set-asides for saproxylic biodiversity at stand- landscape- and regional scales
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Sundsvall: Mittuniversitetet, 2007. p. 29
Series
Mid Sweden University doctoral thesis, ISSN 1652-893X ; 32
Keywords
boreal forest, colonization-extinction dynamics, dendrochronology, dead-wood dynamics, disturbance dynamics, forest history, fragmentation, metapopulations, national inventories, old-growth forest, picea abies, saproxylic species, set asides, spatiotemporal dynamics, stand reconstructions, tree mortality, woody debris, wood-decaying fungi, woodland key habitats
National Category
Biological Sciences
Identifiers
urn:nbn:se:miun:diva-8896 (URN)978-91-85317-65-3 (ISBN)
Public defence
(English)
Available from: 2009-05-06 Created: 2009-05-06 Last updated: 2009-07-16Bibliographically approved
Jönsson, M. & Jonsson, B. G.Landscape-level synchrony of dead-wood input in samll set-asides of Norway spruce (Picea abies) forest: Implications for saproxylic populations.
Open this publication in new window or tab >>Landscape-level synchrony of dead-wood input in samll set-asides of Norway spruce (Picea abies) forest: Implications for saproxylic populations
(English)Manuscript (preprint) (Other academic)
National Category
Biological Sciences
Identifiers
urn:nbn:se:miun:diva-9400 (URN)
Available from: 2009-07-16 Created: 2009-07-16 Last updated: 2010-01-14Bibliographically approved
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