| 1. |
- Liu, Daijun, et al.
(författare)
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Delayed and altered post-fire recovery pathways of Mediterranean shrubland under 20-year drought manipulation
- 2022
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127. ; 506
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Tidskriftsartikel (refereegranskat)abstract
- Increasing water deficits and severe droughts are expected to alter the dynamics of vegetation post-disturbance recovery by decreasing new recruitment and limiting growth in semi-arid Mediterranean ecosystems in future. However, which vegetation metrics will be shifted and how they respond over time are not clear, and the experimental evidence is still limited. Here we assessed the impacts of a long-term (20 years) experimental drought (−30% rainfall) on the pathways of vegetation metrics related to species richness, community composition and abundance dynamics for an early-successional Mediterranean shrubland. The results indicate that the pathways of vegetation metrics were differently affected by experimental drought. The abundance of Globularia alypum follows pathway 1 (altered mature state). Simpson diversity and abundance of Erica multiflora follow pathway 2 (delayed succession) while species richness, community abundance and shrub abundance follow pathway 3 (alternative stable state). There were no significances for the resilience to extremely dry years (the ratio between the performance after and before severe events) between control and drought treatment for all vegetation metric. But, their resilience for the metrics (except Simpson diversity) to extremely dry years in 2016–17 were significantly lower than that of 2001 and of 2006–07, possibly caused by the severe water deficits in 2016–17 at mature successional stage. Principal component analysis (PCA) shows that the first two principal components explained 72.3 % of the variance in vegetation metrics. The first axis was mainly related to the changes in community abundance, shrub abundance and species richness while the second axis was related to Simpson diversity and abundance of G. alypum and E. multiflora. Principal component scores along PC1 between control and drought treatment were significantly decreased by long-term experimental drought, but the scores along PC2 were not affected. Further research should focus on successional pathways in more water-deficit conditions in Mediterranean ecosystems and the consequences of changes in vegetation recovery pathways on ecosystem functions such as biomass accumulation and soil properties.
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| 2. |
- Liu, Lei, et al.
(författare)
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Drought legacies on soil respiration and microbial community in a Mediterranean forest soil under different soil moisture and carbon inputs
- 2022
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061. ; 405
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Tidskriftsartikel (refereegranskat)abstract
- Soil moisture can strongly affect the fate of soil organic carbon (C) during microbial decomposition, but the characterisation and prediction of the effects remain challenging, especially the long-term effects of drought history and its interaction with current levels of soil moisture. We investigated the legacy effects of drought on soil activity and microbial community composition and its interaction with actual soil moisture and C addition. Soils from a long-term drought field experiment in a forest were incubated for 80 days under two levels of soil moisture after the addition of 13C-labelled glucose or cellulose. The drought legacy manifested as significantly higher soil CO2 efflux in wet soils from the long-term drought plots than in soils from all other treatments, including the historical control plots, as well as by a higher respiration in the dry treatment, but not in the wet one when cellulose was added. The supply of glucose primed the decomposition of SOM during the whole incubation whereas the supply of cellulose caused a negative priming at the very early stage but had an overall positive priming effect. The composition of the bacterial community varied with soil moisture, but the fungal community was more resistant to water stress and acquired labile C more efficiently under low moisture levels. Fungi dominated cellulose decomposition and bacteria dominated glucose decomposition. These results suggest a key role of fungi in SOM decomposition in the often water-stressed Mediterranean ecosystems. The legacy effects of long-term drought may increase soil respiration during the periods when soils are wet, although the effect may vary with the type of the C inputs.
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