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Biodiversity in fragmented boreal forests: assessing the past, the present and the future
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aims of this thesis are to (1) analyze the predictability (indicators) of plant and fungal species diversity in old-growth forests, and (2) assess the history and biodiversity of woodland key habitats (WKHs) and their potential to maintain species diversity in fragmented boreal forest landscapes.

Predictability was explored in Granlandet nature reserve, an unexploited landscape composed of discrete old-growth Picea forest patches of varying size isolated by wetland, reflecting conditions of insular biota at stochastic equilibrium. Data from 46 patches (0.2-12 ha) showed that most species were rare. However, species richness and composition patterns exhibited a high degree of predictability, which strengthen the possibility to apply biodiversity indicators in old-growth forest stands. Area was a key factor. The increase in species richness starts to level out at 2-3 ha. Large patches host more Red-list species in their interiors than do small ones, i.e. stand size is an important qualitative aspect of old-growth habitat. Nestedness emerged in relation to area but also in equal-sized plots. Structural complexity and habitat quality were important for species richness and compositional patterns, and small habitats of high quality could harbor many rare species. Monitoring of wood-fungi on downed logs showed that species diversity on downed logs changed over periods of 5-10 years and that the occurrences of annual species were unpredictable. It is suggested that monitoring of species with durable fruit bodies (mainly polypores) is likely to be a feasible approach to obtain comparable data over time.

Assessments of biodiversity of WKHs were performed in two areas with contrasting histories of forest exploitation, namely in south boreal and north boreal Sweden. Analyses of the history of 15 south boreal WKHs showed that fire-suppression, selective logging until mid-20th century and abandonment by modern forestry has shaped their forest structure. These WKHs are not untouched forests, they lack key structural components and harbor few Red-list species. Artificial interventions to restore natural processes and patterns are needed to further increase their suitability for threatned species. Modeling analyses of species richness in 32 WKHs in north boreal Sweden, some of which have not been isolated by modern forestry until recently, indicated an excess of crustose lichen species, i.e. WKHs may face delayed species extinctions. By contrast, the results indicate that wood-fungi have tracked the environmental changes. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs may explain the diffeence between species groups. The results indicate that population densities of Red-list species were low, which may result in further depletion of species diversity.

Continuing species declines and extinctions are likely if not conservation of WKHs are combined with other considerations in th managed forest landscape. Both WKHs and their surroundings must be managed and designed to maintain biodiversity over time. For a successful future conservation of boreal forest biodiversity monitoring of WKHs must be combined with monitoring of refeence areas.

Place, publisher, year, edition, pages
2004. , 44 p.
Keyword [en]
Ecology, bryophytes,  CWD,  edge effects,  fragmentation,  fungi,  habitat destruction,  historical records,  indicator,  lichens,  regression,  species-area relationship,  value pyramids,  woody debris 
Keyword [sv]
Ekologi
National Category
Ecology
Research subject
Ecological Botany
Identifiers
URN: urn:nbn:se:umu:diva-220ISBN: 91-7305-610-3 (print)OAI: oai:DiVA.org:umu-220DiVA: diva2:142696
Public defence
2004-04-23, Fälldinsalen (N109), Mälthuset, Mitthögskolan, Sundsvall, 10:00
Opponent
Supervisors
Available from: 2004-03-26 Created: 2004-03-26Bibliographically approved
List of papers
1. Predictability of plant and fungal species richness of old-growth boreal forest islands
Open this publication in new window or tab >>Predictability of plant and fungal species richness of old-growth boreal forest islands
2001 In: Journal of Vegetation Science, Vol. 12, 857-866 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-3813 (URN)
Available from: 2004-03-26 Created: 2004-03-26Bibliographically approved
2. Nested plant and fungal communities: the importance of area and habitat quality in maximizing species capture in boreal old-growth forests
Open this publication in new window or tab >>Nested plant and fungal communities: the importance of area and habitat quality in maximizing species capture in boreal old-growth forests
2003 In: Biological Conservation, Vol. 112, 319-328 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:umu:diva-3814 (URN)
Available from: 2004-03-26 Created: 2004-03-26Bibliographically approved
3. Temporal variation of wood-fungi diversity in boreal old-growth forests: implications for monitoring
Open this publication in new window or tab >>Temporal variation of wood-fungi diversity in boreal old-growth forests: implications for monitoring
2005 (English)In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 15, no 3, 970-982 p.Article in journal (Refereed) Published
Abstract [en]

Monitoring programs that supply reliable and sufficient information on numbers and types of organisms are essential for following changes in biodiversity. In boreal Fennoscandia, forest-dwelling species are threatened in managed forest landscapes and, thus, are of particular concern for conservation strategies. Wood fungi represent key ecological components in the boreal forest that are sensitive to forestry and widely used as indicators in large-scale forest inventories for identifying valuable forest habitats. Knowledge of their natural dynamics is required for designing monitoring programs to assess the adequacy of conservation strategies. We studied the occurrence of corticoids (Corticiaceae) and polypores (Polyporaceae) over time at different spatial scales in unexploited boreal old-growth forests. Data from 70 downed logs followed during an eight-year period showed that the lifespan of fruit bodies of most species was shorter than four years. Even perennial species followed this pattern, although fruit bodies of some species (e.g., Phellinus spp.) remained vital throughout the eight years studied. Both species richness and species composition on individual logs changed markedly over the eight years due to deterministic succession of species paralleling the wood decay. By contrast, data from the stand scale, i.e., seven 0.1 -ha plots, showed that species richness and species composition of polypores did not undergo any major changes during a six-year period. A majority of all recorded polypore species (80%) were already present at the first inventory. However, although species richness remained constant at the stand scale, corticoid species composition differed between years, reflecting their short-lived, annual fruit bodies. This study suggests that monitoring should be performed at stand scale and focus on species with durable fruit bodies, e.g., polypores. This will provide data that can be used both to detect future changes in biodiversity in old-growth spruce forests and to evaluate conservation strategies.

Place, publisher, year, edition, pages
Ecological Society of America, 2005
National Category
Ecology Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-3815 (URN)10.1890/04-0628 (DOI)
Note
Manuscript title: Spatio-temporal variability of wood-fungi diversity in boreal old-growth Picea abies forests: Implications for monitoringAvailable from: 2004-03-26 Created: 2004-03-26 Last updated: 2012-05-15Bibliographically approved
4. History and forest biodiversity of woodland key habitats in south boreal Sweden
Open this publication in new window or tab >>History and forest biodiversity of woodland key habitats in south boreal Sweden
Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:umu:diva-3816 (URN)
Available from: 2004-03-26 Created: 2004-03-26Bibliographically approved
5. Verifying an Extinction Debt among Lichens and Fungi in Northern Swedish Boreal Forests
Open this publication in new window or tab >>Verifying an Extinction Debt among Lichens and Fungi in Northern Swedish Boreal Forests
2005 (English)In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 19, no 2, 338-348 p.Article in journal (Refereed) Published
Abstract [en]

Destruction and fragmentation of natural habitats results in small species populations that face increased risk of extinction. A time delay may be involved in the regional extinction of species, and the number of species that eventually may go extinct in the future is called the “extinction debt.” In boreal Sweden, we examined whether the number of epiphytic crustose lichens and wood-inhabiting fungi in old-growth forest remnants diverges from species richness levels in forest patches that have been naturally isolated for millennia. An excess of species in forest remnants could indicate the presence of an extinction debt. Observed species richness in 32 old-growth forest remnants (also called woodland key habitats [WKHs]) was compared with predicted species richness. To predict species richness we used regression models based on data from 46 isolated old-growth forest patches in a forest-wetland matrix. The reference landscape is ancient and assumed to reflect the conditions of insular floras in dynamic equilibrium. Stand factors constituted predictive variables in the models. The observed number of lichen species was higher than expected (i.e., an extinction debt among lichens may exist). By contrast, there was no significant difference between observed and expected species richness among wood-inhabiting fungi. The species richness of wood-inhabiting fungi has adjusted to the changes in forest and landscape structure more rapidly than the species richness of lichens. Differences in substrate dynamics between epiphytes on living trees and species growing on decaying logs might explain the difference between species groups. The results also indicate that population densities of red-listed species were low, which may result in continuing extinctions of red-listed species. The importance of WKHs might be overvalued because species may be lost if conservation efforts consider only protection and preservation of WKHs.

Abstract [es]

La destrucción y fragmentación de hábitats naturales provoca que poblaciones de especies pequeñas enfrenten mayores riesgos de extinción. Puede haber retraso en la extinción regional de especies, y el número de especies que eventualmente podrán extinguirse en el futuro es denominado la “deuda de extinción.” Examinamos, en Suecia Boreal, si el número de líquenes epifitos y de hongos de la madera en remanentes de bosques maduros difiere de los niveles de riqueza de especies en parches de bosque que han estado naturalmente aislados por milenios. Un exceso de especies en los remanentes de bosque podría indicar la presencia de una deuda de extinción. La riqueza de especies observada en 32 remanentes de bosque maduro (también denominados hábitats boscosos clave [HBC]) fue comparada con la riqueza de especies predicha. Para predecir la riqueza de especies utilizamos modelos de regresión basados en datos de 46 parches aislados de bosque maduro en una matriz de bosques-humedales. El paisaje de referencia es antiguo y se asume que refleja las condiciones de floras insulares en equilibrio dinámico Atributos de los bosques fueron las variables predictivas en los modelos. El número observado de especies de líquenes fue más alto que el esperado (i. e. puede existir una deuda de extinción). En contraste, no hubo diferencia significativa entre la riqueza de especies de hongos de la madera observada y esperada. La riqueza de especies de hongos de la madera se ha ajustado más rápidamente a los cambios en la estructura del bosque y del paisaje que la riqueza de especies de líquenes. La diferencia entre grupos de especies se pude explicar por diferencias en la dinámica del sustrato entre epifitas sobre árboles vivos y especies que crecen en troncos en descomposición. Los resultados también indican que las densidades poblacionales de especies enlistadas fueron bajas, lo que puede resultar en extinciones de estas especies. La importancia de HBC se puede sobrevaluar porque se pueden perder especies si los esfuerzos de conservación sólo consideran la protección y preservación de los HBC.

Place, publisher, year, edition, pages
John Wiley & Sons, 2005
National Category
Biological Sciences
Identifiers
urn:nbn:se:umu:diva-3817 (URN)10.1111/j.1523-1739.2005.00550.x (DOI)
Note

Article first published online: 23 MAR 2005

Available from: 2004-03-26 Created: 2004-03-26 Last updated: 2012-05-15Bibliographically approved

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