Artikkelit jotka sisältää sanan 'needle analysis'

The low availability of usable phosphorus (P), as well as the scarcity of potassium (K), are often limiting tree growth on peatlands. Approximately one third of the 5.5 million ha of peatlands drained for forestry in Finland has been fertilized during the last 50 years. The aim of this study was to determine the long-term effect of PK fertilization on the nutrient status of Scots pine on different site types of drained peatlands. Changes in nutrient concentrations (N, P, K) and dry mass of current needles was used for examining the effect of fertilization. The material included 82 fertilization experimental stands comprising a total of 892 needle samples; 434 from PK-fertilized and 458 from unfertilized control stands. The needles were collected and analyzed between 1980 and 2002. Depending on the experiment, a time period of 1–35 years had elapsed between fertilization and needle sampling. More than half (54%) of the control stands had P concentration below the defi ciency limit 1.3 mg g–1, and correspondingly, 48% had K concentration below 4.0 mg g–1. Fertilization increased considerably the needle dry mass and foliar P and K concentration raised above the deficiency limits. The lower the concentrations of foliar P and K and the higher the concentration of N were in control trees, the more pronounced the effect of PK fertilization was. Compared to control, the needle P concentration was still noticeably higher on the fertilized stands after 21–35 years of the fertilization. However, K concentration had decreased and was at the same level as in the control trees. The effect of fertilization was strongest on sites which had been treeless or sparsely forested before drainage and which had severe nutrient shortages or imbalances. The response to fertilization was very similar regardless of the temperature sum of the year the needles first appeared. The results of this study show that the P status of Scots pine could be improved for over 30 years with single fertilization. On the other hand, ensuring the K status will require 1–2 refertilization treatments during the rotation period.

• Silfverberg, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa Sähköposti: ei.tietoa@nn.oo
• Moilanen, Sähköposti: ei.tietoa@nn.oo

The effects of potassium (K) fertilisation on the nutrient status and growth of Scots pine (Pinus sylvestris L.) stands on drained peatlands were studied on three field experiments in northern central Finland. The Scots pine stands were at a sapling or pole stage with a dominant height of 3–8 m when the experiments were set up. The stands differed from each other in their nutritional status, for example, the foliar K concentration varied considerably between the experiments. The experiments were fertilised with potassium chloride, rock phosphate (P 42kg ha-1) and urea (N 46kg ha-1) between 1979 and 1980. The potassium doses in terms of elemental K, were 50, 100, 200 and 400kg ha-1. The foliar samples were taken three times during the study period: 7–9 years, 14–15 years and 19–20 years after fertilisation. The stand measurements were done 19–22 years after the fertilisation. The rate and magnitude of stand response due to fertilisation depended essentially on the nutritional status of the trees. The strongest effect of PK-fertilisation was obtained on a nitrogen-rich peatland, where the stands suffered from severe phosphorus and potassium deficiencies (foliar P concentration < 1.2 mg g-1, K concentration < 3.5 mg g-1). During the study period, the annual stand volume growth on fertilised plots ranged from 3.9 to 5.4 m3 ha-1 a-1, and that of the unfertilised plots was 0.78 m3 ha-1 a-1. In other sites, where the lack of phosphorus and potassium was not so drastic, nor did the trees suffer from shortage of nitrogen, the effect of PK-treatment on tree growth was weak or almost non-existent. The foliar K concentrations rose with the amount of potassium chloride applied. The fertilisation effect of the dose of 100kg K ha-1 lasted 15–20 years, after which the foliar K concentration dropped close to the deficiency limit. The effect of the larger doses (200–400kg K ha-1) on the needle K concentration was more pronounced and still visible at the end of the study period. However, the stand growth responses gained with larger potassium applications were not essentially greater than those with the 100 kg ha-1 dose.

• Pietiläinen, Finnish Forest Research Institute, Muhos Research Station, Kirkkosaarentie 7, FIN-91500 Muhos, Finland Sähköposti: ei.tietoa@nn.oo
• Moilanen, Sähköposti: ei.tietoa@nn.oo
• Vesala, Sähköposti: ei.tietoa@nn.oo

Variation in nutrient concentrations in Scots pine needles in relation to crown position and needle age was examined at two drained peatland fertilization experiments. Samples were taken from plots which had received NPK fertilizer and from sites which had received only P fertilizer and are now suffering from potassium and phosphorus deficiency. In the NPK fertilized plots, potassium concentrations were the lowest in the needles of the uppermost branchlet and increased down the crown. On plots showing potassium deficiency the situation was the opposite. In both experiments phophorus, magnesium, iron, zinc, and boron concentrations decreased and calcium concentrations increased down the crown but in potassium and phosphorus deficient trees calcium and manganese concentrations decreased down the crown. In both experiments phosphorus, potassium, magnesium and boron concentrations decreased with needle age while calcium, iron and manganese concentrations increased. Zinc concentrations increased in NPK fertilized trees but decreased in potassium and phosphorus deficiency trees. Keywords: Crown position, needle analysis, nutrient variation, Pinus sylvestris

• Kolari, The Finnish Forest Research Institute, Box 18, FIN-0I301 Vantaa Sähköposti: ei.tietoa@nn.oo

A granular calcium and wood ash mixture (Fyto-2H-fertilizer) increased foliar, K and B and decreased Zn after two growing periods in Pinus silvestris stands. It had also a positive effect on needle mass (d. m.), but not as pronounced one as the PK-fertilizer for peatland forests. It was concluded that Fyto-2H-product can increase the nutrient contents, which have been observed to be essential for the state of health in peatland forests. Further it contains slowly soluble portions of Ca and Mg, which have been proved to be very often the growth limiting factors e.g. in disturbed forests in Central Europe. Keywords: Fertilizer, liming, needle analysis, Pinus silvestris, wood ash

• Veijalainen, Department of Forest Ecology, The Finnish Forest Research Institute P.O. Box 18, FIN-01301, Vantaa Sähköposti: ei.tietoa@nn.oo

The study was made in four experimental fields on drained peatland in western Finland (63-66°N). One of the experiments was laid out in 1972; the others in 1978-1979. Treatments included different kinds of wood ash and PK-fertilizer, an ash-imitating mixture and apatite+biotite. Needle analyses and growth measurements were carried out in 1983— 1986. The concentrations of Mg and Mn generally decreased after fertilization. A rise in the foliar P, foliar K and foliar weight correlated with the growth response. Best growth increment was achieved with the ash-imitating mixture and PK-fertilizer, while apatite+biotite did not increase growth. In the first years after fertilization, growth on the ash plots was weaker, but later stronger or equal to growth on PK- and ash-imitating plots. The correlation between initial tree height and post-fertilization growth was similar on the different treatments. The poor growth increment on some ash treatments was probably due to the insufficient amount of nutrients in the ashes used. Key words: Ash fertilization, Finland, growth, needle analysis, peat, Scots pine

• Silfverberg, The Finnish Forest Research Institute, P.O. Box 18, SF-0I301 Vantaa, Finland Sähköposti: ei.tietoa@nn.oo