| 1. |
- Alatalo, J. M., et al.
(författare)
-
Changes in plant composition and diversity in an alpine heath and meadow after 18 years of experimental warming
- 2022
-
Ingår i: Alpine Botany. - Basel : Springer Science and Business Media LLC. - 1664-2201 .- 1664-221X. ; 132, s. 181-193
-
Tidskriftsartikel (refereegranskat)abstract
- Global warming is expected to have large impacts on high alpine and Arctic ecosystems in the future. Here we report effects of 18 years of experimental warming on two contrasting high alpine plant communities in subarctic Sweden. Using open-top chambers, we analysed effects of long-term passive experimental warming on a heath and a meadow. We determined the impact on species composition, species diversity (at the level of rare, common and dominant species), and phylogenetic and functional diversity. Long-term warming drove differentiation in species composition in both communities; warmed plots, but not control plots, had distinctly different species composition in 2013 compared with 1995. Beta diversity increased in the meadow, while it decreased in the heath. Long-term warming had significant negative effects on the three orders of phylogenetic Hill diversity in the meadow. There was a similar tendency in the heath, but only phylogenetic diversity of dominant species was significantly affected. Long-term warming caused reductions in forbs in the heath, while evergreen shrubs increased. In the meadow, deciduous and evergreen shrubs showed increased abundance from 2001 to 2013 in warmed plots. Responses in species and phylogenetic diversity to experimental warming varied over both time (medium (7 years) vs long-term (18 years)) and space (between two neighbouring plant communities). The meadow community was more negatively affected in terms of species and phylogenetic diversity than the heath community. A potential driver for the changes in the meadow may be decreased soil moisture caused by long-term warming.
|
|
| 2. |
- Alatalo, J. M., et al.
(författare)
-
Impact of ambient temperature, precipitation and seven years of experimental warming and nutrient addition on fruit production in an alpine heath and meadow community
- 2022
-
Ingår i: Science of the Total Environment. - Amsterdam : Elsevier BV. - 0048-9697 .- 1879-1026. ; 836
-
Tidskriftsartikel (refereegranskat)abstract
- Alpine and polar regions are predicted to be among the most vulnerable to changes in temperature, precipitation, and nutrient availability. We carried out a seven-year factorial experiment with warming and nutrient addition in two alpine vegetation communities. We analyzed the relationship between fruit production and monthly mean, maximum, and min temperatures during the fall of the pre-fruiting year, the fruiting summer, and the whole fruit production period, and measured the effects of precipitation and growing and thawing degree days (GDD & TDD) on fruit production. Nutrient addition (heath: 27.88 +/- 3.19 fold change at the end of the experiment; meadow: 18.02 +/- 4.07) and combined nutrient addition and warming (heath: 20.63 +/- 29.34 fold change at the end of the experiment; meadow: 18.21 +/- 16.28) increased total fruit production and fruit production of graminoids. Fruit production of evergreen and deciduous shrubs fluctuated among the treatments and years in both the heath and meadow. Pre-maximum temperatures had a negative effect on fruit production in both communities, while current year maximum temperatures had a positive impact on fruit production in the meadow. Pre-minimum, pre-mean, current mean, total minimum, and total mean temperatures were all positively correlated with fruit production in the meadow. The current year and total precipitation had a negative effect on the fruit production of deciduous shrubs in the heath. GDD had a positive effect on fruit production in both communities, while TDD only impacted fruit production in the meadow. Increased nutrient availability increased fruit production over time in the high alpine plant communities, while experimental warming had either no effect or a negative effect. Deciduous shrubs were the most sensitive to climate parameters in both communities, and the meadow was more sensitive than the heath. The difference in importance of TDD for fruit production may be due to differences in snow cover in the two communities.
|
|
