Artikkelit kirjoittajalta Pekka Pietiläinen

Neulasanalyysi on vakiintunut menetelmä määrittää puiden ravinnetila ja lannoitustarve. Käytännön metsänhoito-ohjeissa neulasnäytteet suositetaan otettavaksi puiden talvilevon aikana, jolloin puut ovat jäässä ja niiden aineenvaihdunta pysähdyksissä. Ravinneanalyysin tulkinta ja puutostiloja osoittavien pitoisuuksien raja-arvot pohjautuvat niin ikään talvella kerätyistä neulasnäytteistä tehtyihin ravinnemäärityksiin. Tässä tutkimuksessa selvitettiin metsäojitusalueella kasvavien mäntyjen ravinnetilassa syksyn aikana tapahtuvia muutoksia. Keskeinen tavoite oli vastata kysymykseen, voidaanko puiden ravinnetila määrittää luotettavasti jo syys–lokakuussa ennen puiden talvilepoa kerätyistä neulasnäytteistä. Tutkimusaineisto (216 neulasnäytettä) kerättiin kuudesta ojitusaluemänniköstä Keski- ja Pohjois-Suomesta. Aineistoon sisältyi neulasnäytepuita sekä lannoittamattomista että 2–4 vuotta aiemmin PK-lannoitetuista metsiköistä. Ravinnepitoisuuksien erot samoista puista otettujen syys- ja talvinäytteiden välillä olivat suhteellisen vähäiset. Vain lannoitettujen metsiköiden männynneulasten Cu- ja K-pitoisuudet olivat syyskuussa merkitsevästi korkeammat kuin lokakuussa tai seuraavana talvena. Lannoittamattomilla koealoilla neulasten K-pitoisuus oli lähes sama eri ajankohtina. Ca- ja Mn-pitoisuudet puolestaan hiukan kohosivat syyskuun ja sitä seuranneen talvikauden välisenä aikana. Lokakuun ja talvikauden välillä ei puiden ravinnepitoisuuksissa esiintynyt mainittavia eroja. Tulokset osoittavat, että neulasnäytteet voidaan luotettavia ravinneanalyysejä varten kerätä männyistä lokakuun alun ja maaliskuun lopun välisenä aikana.

• Moilanen, Sähköposti: ei.tietoa@nn.oo
• Pietiläinen, Sähköposti: ei.tietoa@nn.oo

The total peat nitrogen (N) concentration is an important factor when determining stand heights and volumes in areas of poor climate conditions. This study explores the effect of peat nitrogen on the height and volume of Scots pine (Pinus sylvestris L.) stands in drained peatland sites in three temperature sum regions (Susivaara 909, Hepokangas 930, and Haapua 987 dd) in northern Finland. The peat nitrogen concentration ranged from 0.7% to 3.0%. In all experimental fields, the concentrations of foliar nutrients (nitrogen (N), potassium (K), phosphorus (P), and boron (B)) were analyzed. A total of 550 peat samples, 440 foliar samples, and 1687 sample trees were measured. We found nitrogen deficiencies in the foliar samples of all experimental fields. At Haapua, the stands were the highest, about 140 dm, when the peat N-concentration was at its maximum (3.0%). In the areas of Susivaara and Hepokangas, the stand heights were lower than in Haapua, about 90 dm, when N-concentrations of peat were at their maximum (2.5% and 2.8%). The stand volumes were largest at Haapua (about 190 m3/ha, N = 3.0%). At Susivaara (80 m3/ha, N = 2.5%) and Hepokangas (70 m3/ha, N = 2.8%), lower stand volumes were measured. We found a strong positive relationship between peat N-concentration and stand height as well as stand volume at Hepokangas and Haapua. At Susivaara, however, this relationship was weak. The results show that the total peat nitrogen concentration strongly affects stand height and volume on drained peatlands. The information of this study can be utilized, for example, when assessing the feasibility of forest management practices, such as the profitability of ditch network maintenance and fertilizations on peatlands.

• Korkalainen, University of Joensuu, Department of Geography, P.O. Box 111, 80101 Joensuu, Finland Sähköposti: ei.tietoa@nn.oo
• Pietiläinen, Sähköposti: ei.tietoa@nn.oo
• Colpaert, Sähköposti: ei.tietoa@nn.oo

Phosphorus and potassium deficiencies are common in Scots pine stands growing on drained peatlands. In this study, the foliar nutrient concentrations and stand growth were monitored after the application of phosphorus and potassium fertilisers of different solubility in four experiments on thick-peated drained peatlands in northern central Finland. The studied stands involved three fertilisation treatments: (i) unfertilised control, (ii) rock phosphate and potassium chloride, and (iii) apatite and biotite. The growth of stands was monitored 20–25 years after the fertilisation. Needles were sampled four times: 4–9, 11–14, 16–19 and 21–24 years after the fertilisation. According to foliar analyses, the trees on the control plots suffered from severe phosphorus and potassium deficiencies. Rock phosphate and apatite fertilisation increased the foliar phosphorus concentrations above the deficiency limit, and the effect was still noticeable 21–24 years after the application. Both potassium sources, that is, the slowly soluble biotite and the water-soluble potassium chloride increased the foliar potassium concentration to an adequate level. Potassium chloride increased the concentrations faster and stronger than biotite during the first years (4–9) after the applications. The situation was reversed when 11–14 years or more had passed from the fertilisation: the biotite fertilised stands had higher potassium concentrations. The fertilisation treatments decreased the foliar nitrogen, zinc, manganese, copper and boron concentrations. The fertiliser applications increased the stand volume growth considerably. Raw phosphate and potassium chloride increased the volume growth significantly already during the first five-year period. The effect of the apatite and biotite treatment was weaker during the first 10 years, but became stronger with time. During the period 19–24 years after the fertilisation, the stand growth on the biotite plots was equal to that of the plots fertilised with potassium chloride. However, during the whole study period the differences between the treatments remained insignificant. The results showed that slowly soluble apatite and biotite are suitable sources of phosphorus and potassium for pines on drained peatlands. However, to avoid boron deficiency, also boron should be added simultaneously.

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

Wood production capacity on drained peatlands depends on the site type and temperature sum. Site type is closely related to the peat total nitrogen concentration. This study aims at clarifying the effect of peat nitrogen, fertilization and refertilization on the foliar nitrogen concentration of Scots pine in different temperature sum conditions (850, 950 and 1080 d.d.) on peatland sites with a wide peat nitrogen gradient (0.79- 2.80% in the 0-10 cm layer). In the coldest region, regardless of the peat total nitrogen concentrations in the 0-10 cm surface peat layer and PK- fertilization or PK-refertilization (37 and 26 years earlier respectively), the needle nitrogen concentrations were mostly below the severe deficiency limit (N = 1.2%) and also the arginine concentrations revealed a nitrogen shortage (<0.5 mg g-1). In the middle region the mean nitrogen concentrations in the needles were clearly higher and in the PK- fertilization and PK-refertilizations (32 and 22 years earlier respectively) surpassed the slight nitrogen deficiency limit (N = 1.3%). Also the arginine concentrations surpassed the deficiency limit (0.5 mg g-1 ) in both fertilization treatments although the mean arginine concentrations were near or under the deficiency limit. In the warmest region 25-26 years after the spot fertilization the mean nitrogen concentration was 1.84% and the arginine concentration was 3.04 mg g-1 revealing a surplus of nitrogen caused by phosphorus and potassium deficiencies. The PK-fertilization given 10 years later decreased the nitrogen concentration to 1.56% and the arginine concentration to 0.58 mg g-1. In the more favourable conditions the nitrogen and arginine in the needles increased when the nitrogen in the peat increased. In conclusion, tree growth in the middle and the warmest temperature sum region would respond to PK-refertilisation above a certain total peat nitrogen level but in the coldest temperature sum region tree growth would not respond to PK-refertilization in any of the studied peat total nitrogen conditions because of nitrogen deficiency.

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

The purpose of the study was to determine the usability of infra red imagery in evaluating the need for ditch network maintenance on nutrient-poor Scots pine mires. After interpreting a total of 75 tree stands in six peatland areas from the IR imagery, the stands were inventoried in the field. Site type, growing stock and ditch condition were determined. In addition, possible silvicultural treatments were suggested. Sphagnum fuscum, reddish-brown in the imagery indicated ditching areas unsuitable for ditch cleaning or complementary ditching. The estimated mean volumes of the tree stands were -37-+11% of the mean ground inventory values. The true proportions of tree species were in good agreement with the estimations based on the TR imagery. All in all, it was concluded that IR imagery is suitable in evaluating the need for ditch network maintenance on nutrient-poor mires. However, the validity of the method depended on the quality of the imagery and the skill of the interpreter. Keywords: forest drainage, ditch cleaning, complementary ditching, IR imagery, decision making system, environmental protection, biodiversity

• Lauhanen, The Finnish Forest Research Institute, Kannus Research Station,FIN-69101 Kannus, Finland Sähköposti: ei.tietoa@nn.oo
• Pietiläinen, Sähköposti: ei.tietoa@nn.oo
• Saarinen, Sähköposti: ei.tietoa@nn.oo
• Heikkinen, Sähköposti: ei.tietoa@nn.oo

Different kinds of boron and copper fertilizers were applied to pine seedlings planted in a flark (see table 1). Three growth periods after the fertilization copper oxide, fertilizer boron, fritted boron, micro-nutrient mixture and bark ash gave better height growth than the control (NPK, Ca). Poorest results were achieved with the following micronutrients; solubor, copper sulfate, copper chelate and PK with Cu and B. The height growth in years 1978 and 1979 of only those seedlings that were fertilized with solubor was poorer than that of the control. The height growtht of fritted boron and bark ash fertilized seedlings was statisticaly significantly better than that of the control. The best result was achieved with copper oxide (Table 2). The comparison between the copper fertilizers revealed that copper oxide was the best copper compound for pine seedlings in a flark (Fig. 1). Fritted boron appeared to be the best boron fertilizer (Fig. 2). Bark ash was best of the nutrient mixtures studied (Fig. 3). The experiment showed a positive trend in favor of slowly dissolving micronutrient compounds, including bark ash, on pine seedling growth in a flark. It is also evident, that the commercial micronutrient fertilizers are by no means biologically the most effective compounds for pine seedling fertilization on peatland. In forestry and research commonly used coppersulfate and fertilizer boron seemed to be rather questionable as peatland fertilizers.

• Pietiläinen, Sähköposti: ei.tietoa@nn.oo
• Veijalainen, Sähköposti: ei.tietoa@nn.oo