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- Dahlberg, C. Johan, et al.
(författare)
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Correlations between plant climate optima across different spatial scales
- 2020
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Ingår i: Environmental and Experimental Botany. - : Elsevier BV. - 0098-8472 .- 1873-7307. ; 170
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the factors determining the abundance and distribution of species is a fundamental question in ecology. One key issue is how similar the factors determining species' distributions across spatial scales are (here we focus especially on spatial extents). If the factors are similar across extents, then the large scale distribution pattern of a species may provide information about its local habitat requirements, and vice versa. We assessed the relationships between landscape and national optima as well as landscape and continental optima for growing degree days, maximum temperature and minimum temperature for 96 bryophytes and 50 vascular plants. For this set of species, we derived landscape optima from abundance weighted temperature data using species inventories in central Sweden and a fine-grained temperature model (50 m), national optima from niche centroid modelling based on GBIF data from Sweden and the same fine-grained climate model, and continental optima using the same method as for the national optima but from GBIF data from Europe and Worldclim temperatures (c. 1000 m). The landscape optima of all species were positively correlated with national as well as continental optima for maximum temperature (r = 0.45 and 0.46, respectively), weakly so for growing degree days (r = 0.30 and r = 0.28), but sometimes absent for minimum temperature (r = 0.26 and r = 0.04). The regression slopes of national or continental optima on local optima did not differ between vascular plants and bryophytes for GDD and Tmax. However, the relationship between the optima of Tmin differed between groups, being positive in vascular plants but absent in bryophytes. Our results suggest that positive correlations between optima at different spatial scales are present for some climatic variables but not for others. Moreover, our results for vascular plants and bryophytes suggest that correlations might differ between organism groups and depend on the ecology of the focal organisms. This implies that it is not possible to routinely up- or downscale distribution patterns based on environmental correlations, since drivers of distribution patterns might differ across spatial extents.
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| 2. |
- Christiansen, Ditte Marie, et al.
(författare)
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Changes in forest structure drive temperature preferences of boreal understorey plant communities
- 2022
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 110:3, s. 631-643
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Tidskriftsartikel (refereegranskat)abstract
- The local climate in forest understories can deviate substantially from ambient conditions. Moreover, forest microclimates are often characterized by cyclic changes driven by management activities such as clear-cutting and subsequent planting. To understand how and why understorey plant communities change, both ambient climate change and temporal variation in forest structure have to be considered.We used inventories from 11,436 productive forest sites in Sweden repeated every 10th year 1993–2017 to examine how variation in forest structure influences changes in the average value of minimum and maximum temperature preferences of all species in a community, that is, community temperature indices (CTIs). We then evaluated to what extent these changes were driven by local extinctions and colonizations, respectively, and to what extent the difference in CTI value between two inventories was related to changes in forest density and in macroclimate. Lastly, we tested whether effects on CTI change by these two drivers were modified by topography, soil moisture and tree species composition.CTI values of the understorey plant communities increased after clear-cutting, and decreased during periods when the forest grew denser. During the period immediately after clear-cutting, changes were predominately driven by colonizations of species with a preference for higher temperatures. During the forest regeneration phase, both colonizations by species preferring lower temperatures and local extinctions of species preferring higher temperatures increased. The change in understorey CTI over 10-year periods was explained more by changes in forest density, than by changes in macroclimate. Soil moisture, topography and forest tree species composition modified to some extent the effects of changes in forest density and in macroclimate on understorey CTI values.Synthesis. Via stand manipulation, forest management impacts the effects of regional climate on understorey plant communities. This implies that forest management by creating denser stands locally even can counterbalance the effects of regional changes in climate. Consequently, interpretations of changes in the mean temperature preference of species in forest understorey communities should take forest management regimes into account.
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| 3. |
- Christiansen, Ditte Marie, 1990-
(författare)
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Responses of boreal forest understory plant communities to climate and forestry
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A warming climate is altering species distributions and community compositions. To understand and predict changes in species distributions to climate change, we often use species occurrences together with large-scale regional climate data. This can be problematic for several reasons. Species living near the ground experience small-scale spatial variation in temperatures, i.e., microclimate, that are influenced by topography and vegetation and can therefore deviate a lot from regional temperatures. Further, climate often affects species indirectly via species interactions, and such interactions can also change with climate. And last, species may respond slower than climate changes. Ignoring these aspects can complicate our understanding of species-climate relationships.In this thesis, I examined how microclimate and changes in microclimate due to forest management impact performances, interactions, and distributions of plant species in boreal forest understory communities. First, I quantified the importance of microclimate for species performances and distributions. Specifically, I compared the effects of spring temperatures measured on local and regional scales on the population dynamics of a southern forest herb (I). I also tested how small-scale spatial microclimate variation contributed to the regional co-existence of northern and southern understory plant species (II). Second, I examined the role of species interactions in driving abundance patterns of two moss species with different temperature niches across their Swedish ranges by transplanting them separately and together across a climate gradient (III). Lastly, I investigated how understory plant communities respond to changes in microclimate caused by forest management (IV), and how past microclimates influence current patterns of species occurrence, abundance, and reproduction (II).I found that local spring temperatures had a significant effect on the population dynamics of the southern forest herb that could not be detected using regional spring temperatures (I). Spatial variation in microclimate explained the regional co-existence of two northern and two southern species, where the northern species were favoured by cold microclimates and the southern species by warm microclimates (II). In the transplant experiment (III), I found that climate-mediated competition can override the direct effects of climate and limit abundances across ranges. Lastly, I found that microclimate changes caused by forest management activities had a large effect on understory communities (IV), and that current abundances of northern and southern species were partly explained by past microclimate (II).Overall, I demonstrated that, to understand how species (particularly understory plants) respond to climate, we need to replace the standard use of regional climate data with locally measured climate data or down-scaled gridded climate data that account for variation in topography as well as vegetation. To predict how species will respond to climate change, we also need to include species interactions and how these interactions change with a changing climate. Finally, changes in microclimate following changes in forest structure have large effects on understory species. The last finding is important to consider when studying changes in understory communities in a climate context and could be used to mitigate climate effects on forest biodiversity.
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