| 1. |
- Jönsson Belyazid, Ulrika, et al.
(författare)
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A comparative study of two methods for determination of pH, exchangeable base cations, and aluminum
- 2002
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Ingår i: Communications in Soil Science and Plant Analysis. - 0010-3624. ; 33:19-20, s. 3809-3824
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Tidskriftsartikel (refereegranskat)abstract
- The ability to compare soil chemical data achieved by different chemical extraction methods is a necessity for an efficient long-term monitoring of soils and for comparisons of results from regional soil surveys with differing standard methods. This study compares two common, methods for analysis of soil chemical properties, the combination of soil extraction in 1.0 M NH4Cl and 1.0 M KCl and the single extraction method using 0.1 M BaCl2. Results show that the two methods do not differ in extraction capability with regard to pH and exchangeable calcium (Ca) and magnesium (Mg). However, there is less agreement in extraction capability with regard. to potassium (K), sodium (Na), and aluminum (Al). For these elements, BaCl2 is less efficient than NH4Cl and KCl. Despite the differences in extraction capability between BaCl2 and KCl/NH4Cl, regression analyses showed that the methods are well correlated (high regression coefficients for all, elements). Thus, transformation of data achieved by one method to estimated values of the other method are possible. Results from this study may be an important tool for comparisons of mineral soil data achieved by the two methods.
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| 2. |
- Jönsson Belyazid, Ulrika, et al.
(författare)
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Acidification-induced chemical changes in coniferous forest soils in southern Sweden 1988-1999
- 2003
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Ingår i: Environmental Pollution. - 0269-7491. ; 123:1, s. 75-83
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Tidskriftsartikel (refereegranskat)abstract
- Thirty-two Norway spruce [Picea abies (L.) Karst.] and Scots pine (Pinus sylvestris L.) stands in southern Sweden were studied for a period of 12 years to evaluate acidification-induced chemical changes in the soil. Soil, at 20-30 cm depth in the mineral layer, was sampled three times during this period (1988, 1993 and 1999). The results show that pH(BaCl2) in mineral soil decreased by, on average, 0.17 units between 1988 and 1999, accompanied by an increase in aluminium (Al) concentration and a decrease in base saturation in the soil. In 1999, the base saturation was below 5% in 58% of the 32 sites compared with 16% in 1988 and 7% in 1993. Concentrations of calcium (Ca), potassium (K) and magnesium (Mg) are low and decreasing. Based on C/N ratios in humus, 45% of the sites may be subjected to leaching of considerable amounts of nitrate. The results show that the acidification of coniferous forest soils in southern Sweden is continuing, and that the negative effects on the nutrient status in soil are extensive. The results are compared with reference values for productive, long-term sustainably managed boreal coniferous or mixed forest soils and implications for long-term sustainability are discussed.
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| 3. |
- Jönsson Belyazid, Ulrika, et al.
(författare)
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Can Phytophthora quercina have a negative impact on mature pedunculate oaks under field conditions?
- 2006
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Ingår i: Annals of Forest Science. - : EDP Sciences. - 1286-4560 .- 1297-966X. ; 63:7, s. 661-672
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Tidskriftsartikel (refereegranskat)abstract
- Ten oak stands in southern Sweden were investigated to evaluate the impact of the root pathogen Phytophthora quercina on mature oaks under field conditions. Phytophthora quercina was present in five of the stands, while the other five stands were used as controls to verify the effect of the pathogen. In each stand, a healthy, a moderately declining and a severely declining tree were sampled. Fine-root length and nutrient status of each tree were analyzed, and the chemistry of the soil surrounding each tree was determined. The results showed that P. quercina can cause substantial reductions in the fine-root length of mature trees under natural conditions. The impact of the pathogen varied depending on tree vitality and season, being most pronounced for declining trees after an unusually dry summer. Despite the significant reduction in live fine-root length of declining trees in Phytophthora-infested stands, no consistent effects were found on the nutrient status of trees. Based on the significant impact of the pathogen on the fine-root systems of declining trees, we suggest that P. quercina contribute to oak decline in southern Sweden at the sites where it is present. No explanation is currently available for the decline of trees in non-infested stands, but the lack of symptoms of root damage indicate, together with the extensive root growth of declining trees, that root pathogens are not involved in the decline at these sites.
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| 4. |
- Jönsson Belyazid, Ulrika, et al.
(författare)
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Pathogenicity of Swedish isolates of Phytophthora quercina to Quercus robur in two different soils
- 2003
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 158:2, s. 355-364
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have demonstrated the involvement of soil-borne Phytophthora species, especially Phytophthora quercina , in European oak decline. However, knowledge about the pathogenicity of P. quercina in natural forest soils is limited. The short-term effects of two south-Swedish isolates of P. quercina on root vitality of Quercus robur seedlings grown in two different soils, one high pH, nutrient-rich peat-sand mixture and one acid, nitrogen-rich but otherwise nutrient-poor forest soil are described. Pathogenicity of P. quercina was tested using a soil infestation method under a restricted mesic water regime without prolonged flooding of the seedlings. There was a significant difference in dead fine-root length between control seedlings and seedlings grown in soil infested with P. quercina . Trends were similar for both soil types and isolates, but there was a higher percentage of fine-root die-back and more severe damage on coarse roots in the acid forest soil. No effects on above-ground growth or leaf nutrient concentration between control seedlings and infected seedlings were found. The results confirm the pathogenicity of south-Swedish isolates of P. quercina in acid forest soils under restricted water availability. Stress-induced susceptibility of the seedlings and/or increased aggressiveness of the pathogen in the forest soil are discussed as key factors to explain the difference in root die-back between soil types.
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| 5. |
- Jönsson Belyazid, Ulrika, et al.
(författare)
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Relationships between health of Quercus robur, occurrence of Phytophthora species and site conditions in southern Sweden
- 2005
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Ingår i: Plant Pathology. - : Wiley. - 1365-3059 .- 0032-0862. ; 54:4, s. 502-511
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Tidskriftsartikel (refereegranskat)abstract
- The effect of Phytophthora species, soil chemistry, precipitation and temperature on the vitality of oak was evaluated in 32 oak stands in southern Sweden. In addition, the relationship between the occurrence of Phytophthora species and soil conditions was determined. The results showed that there was a weak association between the presence of P. quercina, the most frequently recovered Phytophthora species in southern Sweden, and the vitality of the oak stands (determined from estimates of crown defoliation of individual trees). The pathogens occurred more frequently in clayey and loamy soils that were less acidic and which had higher base saturation. However, they were found in all but the most acidic soils (pH < 3.5). In stands where Phytophthora species were not present, positive correlations between the average crown defoliation and proportion of damaged trees with average summer precipitation and average annual precipitation were found. There were no significant differences in soil chemistry between healthy and declining stands included in this study, and no significant correlations were found between any soil parameter and crown vitality. Based on the results from these 32 oak stands, it is likely that the decline of oaks in southern Sweden can be attributed to several different site-specific factors, such as infection by P. quercina or unusual weather events, which interact with a number of biotic and abiotic factors, leading to oak decline.
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| 6. |
- Rosengren, Ulrika, et al.
(författare)
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Functional Biodiversity Aspects on the Nutrient Sustainability in Forests–: Importance of Root Distribution
- 2006
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Ingår i: Journal of Sustainable Forestry. - 1054-9811. ; 21:2-3, s. 75-98
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Nutrient availability is of major importance for plant productivity. When estimating long-term sustainability from a nutrient perspective it is therefore interesting to focus on long-term changes in the soil nutrient pools when comparing different forest types. Here, we have highlighted some factors of importance for long term nutrient sustainability (e.g., several forest rotations) and pointed out some important features that differ between forest tree species and also between monocultures and mixed species stands. Using computer models like PROFILE reveals tree rooting depth to be a crucial factor when assessing long-term nutrient sustainability. Literature studies show that soil type and other soil conditions have a strong effect on root distribution. However, Norway spruce is generally a very shallow rooted species, with approximately 80% of it fine roots in the top 20-25 cm, whereas for pendiculate oak, generally 80% of the roots are found down to 60 cm soil depth. Rooting depth of Scots pine and beech seem to be intermediate with 80% of the roots down to approximately 25-30 cm and 30-35 cm, respectively. Importance of mycorrhiza for nutrient uptake in a sustainability perspective is discussed in the paper.
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