Current issue: 53(3)

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Articles containing the keyword 'gradient'.

Category: Research article

article id 326, category Research article
Xuejiang Zhang, Helena Korpelainen, Chunyang Li. (2006). Microsatellite variation of Quercus aquifolioides populations at varying altitudes in the Wolong Natural Reserve of China. Silva Fennica vol. 40 no. 3 article id 326. https://doi.org/10.14214/sf.326
Genetic variation and differentiation were investigated among five natural populations of Quercus aquifolioides occurring along an altitudinal gradient that varied from 2000 to 3600 m above sea level in the Wolong Natural Reserve of China, by analyzing variation at six microsatellite loci. The results showed that the populations were characterized by relatively high intra-population variation with the average number of alleles equaling 11.33 per locus and the average expected heterozygosity (HE) being 0.779. The amount of genetic variation varied only little among populations, which suggests that the influence of altitude factors on microsatellite variation is limited. However, there is a significantly positive correlation between altitude and the number of low-frequency alleles (R2 = 0.97, P < 0.01), which indicates that Q. aquifolioides from high altitudes has more unique variation, possibly enabling adaptation to severe conditions. F statistics showed the presence of a slight deficiency of heterozygosity (FIS = 0.136) and a low level of differentiation among populations (FST = 0.066). The result of the cluster analysis demonstrated that the grouping of populations does not correspond to the altitude of the populations. Based on the available data, it is likely that the selective forces related to altitude are not strong enough to significantly differentiate the populations of Q. aquifolioides in terms of microsatellite variation.
  • Zhang, Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, P. R. China; Graduate School of the Chinese Academy of Sciences, Beijing 100039, P. R. China ORCID ID:E-mail:
  • Korpelainen, Department of Applied Biology, P.O. Box 27, FI-00014 University of Helsinki, Finland ORCID ID:E-mail:
  • Li, Chengdu Institute of Biology, Chinese Academy of Sciences, P.O. Box 416, Chengdu 610041, P. R. China ORCID ID:E-mail: licy@cib.ac.cn
article id 533, category Research article
Anna Liisa Ruotsalainen, Juha Tuomi, Henry Väre. (2002). A model for optimal mycorrhizal colonization along altitudinal gradients. Silva Fennica vol. 36 no. 3 article id 533. https://doi.org/10.14214/sf.533
Mycorrhizal associations are generally favourable for vascular plants in nutrient-poor conditions. Still, non-mycorrhizal plants are common in high arctic and alpine areas, which are often poor in nitrogen and phosphorus. The relative proportion of mycorrhizal plants has been found to decrease along with increasing altitude, suggesting that the advantage of the mycorrhizal symbiosis may change along an altitudinal gradient. This may be related to the environmental factors that possibly constrain the amount of photosynthesized carbon to be shared with mycorrhizal fungi. We propose a simple optimization model for root colonization by fungal symbionts and analyze the advantages of mycorrhizas in relation to the nutrient use efficiency of photosynthesis (PNUE), the kinetics of nutrient uptake and the soil nutrient levels. Our model suggests that mycorrhizas are not usually favoured at low PNUE values. At low nutrient levels, mycorrhizas may be advantageous if they have a lower threshold concentration of nutrient uptake (xmin) compared to non-mycorrhizal roots. If mycorrhizal roots have a higher maximum capacity of nutrient uptake (Vmax), mycorrhizas can be favourable for the host plant even at relatively low nutrient concentrations and at relatively low PNUE. Consequently, the possible patterns along altitudinal gradients essentially depend on PNUE. If the soil nutrient concentration is constant and PNUE decreases, the advantage of mycorrhizal symbiosis declines independently of the nutrient uptake kinetics. If PNUE remains constant and the soil nutrient concentration decreases along with increasing altitude, the emerging colonization pattern (either increasing, decreasing or intermediate) depends on the nutrient uptake kinetics. Additionally, if both PNUE and the soil nutrient concentration decrease, several patterns may emerge, depending on the nutrient uptake kinetics.
  • Ruotsalainen, Department of Biology, Botanical Museum, Box 3000, FIN-90014 University of Oulu, Finland ORCID ID:E-mail: annu.ruotsalainen@oulu.fi (email)
  • Tuomi, Department of Biology, Box 3000, FIN-90014 University of Oulu, Finland ORCID ID:E-mail:
  • Väre, Botanical Museum, Finnish Museum of Natural History, Box 7, FIN-00014 University of Helsinki, Finland ORCID ID:E-mail:

Category: Article

article id 7229, category Article
O. J. Lukkala. (1929). Über die Dicke der Torfschicht und die Neigungsverhältnisse der Mooroberfläche auf verschiedenen Moortypen. Acta Forestalia Fennica vol. 34 no. 16 article id 7229. https://doi.org/10.14214/aff.7229
English title: The thickness of peat bed and gradients of peatland surface on different peatland types.

The type of the peatland and its classification as forest site (height-over-age-classification) are important information when the drainage potential of a peatland is defined. The gradient and thickness of peat bed are also significant.

The observations for the study have been collected in state owned forests in middle-Finland. The thickness and gradient variations have no clear differences between different types of peatlands. The results show that from the view of drainage for afforestation, the peatlands that are good or suitable for afforestation are flatter and more even that those less suitable. The more suitable peatlands also have thinner peat bed and bigger gradient.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

 

  • Lukkala, ORCID ID:E-mail:
article id 5606, category Article
Pekka E. Kauppi, Pekka Hänninen, Helena M Henttonen, Antti Ihalainen, Eino Lappalainen, Maximilian Posch, Michael Starr, Pekka Tamminen. (1997). Carbon reservoirs in peatlands and forests in the boreal regions of Finland. Silva Fennica vol. 31 no. 1 article id 5606. https://doi.org/10.14214/sf.a8507

The carbon reservoir of ecosystems was estimated based on field measurements for forests and peatlands on an area in Finland covering 263,000 km2 and extending about 900 km across the boreal zone from south to north. More than two thirds of the reservoir was in peat, and less than ten per cent in trees. Forest ecosystems growing on mineral soils covering 144,000 km2 contained 10–11 kg C m-2 on an average, including both vegetation (3.4 kg C m-2) and soil (uppermost 75 cm; 7.2 kg C m-2). Mire ecosystems covering 65,000 km2 contained an average of 72 kg C m-2 as peat. For the landscape consisting of peatlands, closed and open forests, and inland water, excluding arable and built-up land, a reservoir of 24.6 kg C m-2 was observed. This includes the peat, forest soil and tree biomass. This is an underestimate of the true total reservoir, because there are additional unknown reservoirs in deep soil, lake sediments, woody debris, and ground vegetation. Geographic distributions of the reservoirs were described, analysed and discussed. The highest reservoir, 35–40 kg C m-2, was observed in sub-regions in central western and north western Finland. Many estimates given for the boreal carbon reservoirs have been higher than those of ours. Either the Finnish environment contains less carbon per unit area than the rest of the boreal zone, or the global boreal reservoir has earlier been overestimated. In order to reduce uncertainties of the global estimates, statistically representative measurements are needed especially on Russian and Canadian peatlands.

  • Kauppi, ORCID ID:E-mail:
  • Hänninen, ORCID ID:E-mail:
  • Henttonen, ORCID ID:E-mail:
  • Ihalainen, ORCID ID:E-mail:
  • Lappalainen, ORCID ID:E-mail:
  • Posch, ORCID ID:E-mail:
  • Starr, ORCID ID:E-mail:
  • Tamminen, ORCID ID:E-mail:

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