Category: Research article
article id 107, category Research article
Machine planting of Norway spruce by Bracke and Ecoplanter: an evaluation of soil preparation, planting method and seedling performance. Silva Fennica vol. 45 no. 3 article id 107. https://doi.org/10.14214/sf.107
We evaluated the effects of planting date and planting machine (Bracke: three machines, 69 regeneration areas in three years; Ecoplanter: six areas, two years) on the quality and field performance one and three years after planting of Norway spruce (Picea abies (L.) Karst.) seedlings in central Finland. Both machine types planted on average 1800 seedlings per hectare, and after three years approximately 1600 (Bracke) and 1200 (Ecoplanter) were still alive. This study suggests that planting with a Bracke machine can achieve better regeneration rates than those observed in privately-owned Finnish forests. We characterized the quality of mounding and planting with the Bracke machine as excellent and that of the Ecoplanter as good. The soil preparation method of the Ecoplanter produced humus-rich mounds where seedlings were susceptible to pine weevils and consequently suffered higher mortality. Different machines were used in different regional areas and each machine was operated by different driver/s which may have influenced the results. No negative effects of planting date were observed. Seedling growth decreased if they were tall in relation to their root plug volume, grown too densely in the nursery, and if stored in the field for several months prior to planting. We conclude that mechanized planting is successful when the soil preparation method produces mounds covered by purely mineral soil. Planting from May to the end of September is suitable for seedlings intended for use during this period.
article id 157, category Research article
The effect of quality management on forest regeneration activities in privately-owned forests in southern Finland. Silva Fennica vol. 44 no. 2 article id 157. https://doi.org/10.14214/sf.157
This study describes the effect of quality management on forest regeneration activities in privately-owned forests in southern Finland. The study material consists of two mail surveys conducted in 2006 and 2007. The questionnaires were sent to forestry professionals in Forest Owners’ Associations (FOAs), who had either participated (participants) or not (non-participants) in the forest regeneration quality management interventions in years 2000–2006. Quality management interventions of the FOAs included field inventories, feedback meetings, and education sessions about quality techniques. The activities of participant and non-participant FOAs were compared in terms of the available resources, the actions taken, and the aspirations for improvement. In the FOAs, which had participated in quality management, the number of excavator contractors had increased by 16% more than in the non-participant FOAs. The contractors had acquired 23% more soil preparation equipment under the supervision of the participant forestry professionals. The soil preparation method used in conjunction with Norway spruce that had most increased in use was patch mounding. Seedlings that were 1.5 years and older were used by participant forestry professionals in the planting of Norway spruce 11% more than by non-participants. The planting workers had attended 14% more educational sessions, while the use of self-control measurements in soil preparation and planting density had been adopted 10% more frequently under the supervision of the forestry professionals participating in the quality management. A greater interest in obtaining feedback by using quality control inventories was also found among forestry professionals who participated in quality management.
article id 175, category Research article
Late termination of freezer storage increases the risk of autumn frost damage to Norway spruce seedlings. Silva Fennica vol. 43 no. 5 article id 175. https://doi.org/10.14214/sf.175
Over the last few years it has become increasingly common in artificial forest regeneration to extend the planting period by using freezer-stored seedlings for early summer plantings. Developmentally, however, planted freezer-stored seedlings lag behind seedlings planted earlier in the spring. As freezer-stored seedlings also start hardening later, they are more susceptible to early autumn frosts, especially in years when the thermal growing season ends and the first autumn frosts come earlier than usual. By means of computer simulations with a simple temperature sum model and long-term air-temperature data from three locations in Finland, we examined the effect of the freezer-storage termination date on the risk of autumn frost damage to the seedlings. The long-term simulations revealed a drastic effect of year-to-year variation in the thermal conditions during the growing season on the occurrence of autumn frost damage. Such results provide crucial information complementary to those obtained in field experiments, which are always restricted to a relatively short time period. Together with earlier field data, the present results suggest that at an average regeneration site in central Finland, the planting of seedlings whose storage has terminated on 15 June and 22 June involve autumn frost damage every tenth and every fifth year, respectively. The sensitivity analysis revealed that the temperature sum requirement of maturation has a great effect on the risk of autumn frost damage, thus pinpointing the need for experimental studies addressing this ecophysiological trait of the seedlings.
article id 217, category Research article
Variation in the results of Norway spruce planting and Scots pine direct seeding in privately-owned forests in southern Finland. Silva Fennica vol. 43 no. 1 article id 217. https://doi.org/10.14214/sf.217
This study describes the variation in the planting results for 3-year-old Norway spruce (Picea abies (L.) Karst.) and 4-year-old Scots pine (Pinus sylvestris L.) using direct seeding in privately-owned regeneration areas in southern Finland. The study material consists of operative forest regeneration quality management inventory areas from the years 2000–2006. The effect of both the regional and the administrative levels as well as ecological factors was modelled on the basis of the hierarchy structure forestry centre, Forest Owners’ Association (= FOA), forestry professional, regeneration area and sample plot. The major part of the variation occurred at the sample plot and regeneration area level. Particular attention was paid to observation of the clustered spatial distribution of Scots pine seedlings. The FOA and forestry professional levels explained 5% of the variation in Norway spruce planting and 11% of the variation in Scots pine direct seeding. Applied forest regeneration operations, site and soil characteristics were included in the fixed effects. In the planting of Norway spruce the most important factor explaining the regeneration result was soil preparation. Mounding produced better results than patching and disc trenching. The site and soil characteristics were other important factors in the operations. The selection of direct seeding of Scots pine on too fertile, fine textured or moist sites yielded poor results.
article id 342, category Research article
Field performance of hybrid aspen clones planted in summer. Silva Fennica vol. 40 no. 2 article id 342. https://doi.org/10.14214/sf.342
We investigated the possibility to plant clonal hybrid aspen (Populus tremula x tremuloides) during the summer of propagation when the plants are 20–25 cm tall and only a few months old. In four experiments carried out in years 1998–2001, survival of summer-planted hybrid aspens was at least as high as that of hybrid aspen planted in autumn and spring. In all experiments, compared to planting in September or the following May, height growth was greater with planting in July and early August. Root egress of hybrid aspens planted in July and August was also greater than that of aspens planted in autumn or the following spring. Summer planting was thus possible both with plants produced by micropropagation and with those produced from root cuttings.
article id 361, category Research article
Extending the planting period of dormant and growing Norway spruce container seedlings to early summer. Silva Fennica vol. 39 no. 4 article id 361. https://doi.org/10.14214/sf.361
In order to make mechanized planting economically viable, the present spring planting period for Norway spruce (Picea abies (L.) Karst.) seedlings in Scandinavia needs to be extended. To evaluate the possibilities to extend the planting period, six field experiments were established in four years during which frozen-stored, dormant seedlings and actively growing seedlings targeted for spring planting were planted regularly from mid-May to mid-July or the end of August. The survival of actively growing seedlings did not differ between planting dates from mid-May to mid-July. For dormant seedlings, however, the later in summer they were planted the lower was the survival. Oversized seedlings grown in the nursery in containers of too small volume, which were usually planted after mid-June, resulted in reduced growth of seedlings after planting. Root egress (growth of roots from root plugs into the surrounding soil) was most rapid in July and early August and slowest in May and September. Results showed that with dormant seedlings the planting period can be extended from May to mid-June without increasing mortality or reducing growth. The planting period for seedlings stored outdoors and those seedlings that were already growing in June for the purpose of spring plantings can be extended even longer, but it must be kept in mind that the risk of mechanical damage and reduced growth increase due to brittleness of the shoot and increased height. Further research is needed to evaluate the risks in practical scale plantings and with seedlings that are specially targeted for planting after mid-June.
article id 431, category Research article
Reduced simple ratio better than NDVI for estimating LAI in Finnish pine and spruce stands. Silva Fennica vol. 38 no. 1 article id 431. https://doi.org/10.14214/sf.431
Estimation of leaf area index (LAI) using spectral vegetation indices (SVIs) was studied based on data from 683 plots on two Scots pine and Norway spruce dominated sites in Finland. The SVIs studied included the normalised difference vegetation index (NDVI), the simple ratio (SR), and the reduced simple ratio (RSR), and were calculated from Landsat ETM images of the two sites. Regular grids of size 1 km2 with gridpoints placed at 50 m intervals were established at the sites and measurements of LAI using the LAI-2000 instrument were taken at the gridpoints. SVI-LAI relationships were examined at plot scale, where the plots were defined as circular areas of radius 70 m around each gridpoint. Plotwise mean LAI was computed as a weighted average of LAI readings taken around the gridpoints belonging to the plot. Mean LAI for the plots ranged from 0.36 to 3.72 (hemisurface area). All of the studied SVIs showed fair positive correlation with LAI but RSR responded more dynamically to LAI than did SR or NDVI. Especially NDVI showed poor sensitivity to changes in LAI. RSR explained 63% of the variation in LAI when all plots were included (n = 683) and the coefficient of determination rose to 75% when data was restricted to homogeneous plots (n = 381). Maps of estimated LAI using RSR showed good agreement with maps of measured LAI for the two sites.
article id 5414, category Article
Typpipitoisuuden vaikutus männyn neulasten fotosynteesiin ja verson itsevarjostukseen. Silva Fennica vol. 24 no. 1 article id 5414. https://doi.org/10.14214/sf.a15566
English title: (1990). The effect of nitrogen concentration on needle photosynthesis and within shoot shading in Scots pine.
A close relationship between photosynthetic capacity and nitrogen concentration of leaves is known to exist. In conifers, nitrogen also affects the pattern of mutual shading within a shoot, which is a basic unit used in studying photosynthesis of coniferous trees. These effects of needle nitrogen concentration on photosynthetic capacity and mutual shading of needles were analysed for Scots pine (Pinus sylvestris L.) shoots taken from five young stands growing on sites of different fertility. The effect of nitrogen concentration on needle photosynthesis was studied based on measurements of the photosynthetic radiation response of shoots from which two thirds of the needles were removed in order to eliminate the effect of within shading.
An increase of one percentage unit in nitrogen concentration of needles increased the photosynthetic capacity of needles by 25 mg CO2 dm-2h-1. The effect of nitrogen on within-shoot shading was quantified in terms of the silhouette area to total needle area ratio of a shoot (STAR), which determines the relative interception rate per unit of needle area on the shoot. Although nitrogen promoted needle growth, an increase in nitrogen concentration decreased the within-shoot shading. This effect resulted from a decrease in needle density on the shoot and an increased needle angle with increasing nitrogen content.
The PDF includes an abstract in Finnish.
article id 5210, category Article
The interactive effect of water stress and temperature on the CO2 response of photosynthesis in Salix. Silva Fennica vol. 18 no. 2 article id 5210. https://doi.org/10.14214/sf.a15389
The interactive effects of water stress and temperature on the CO2 response of photosynthesis was studied in Salix sp. cv. Aquatica using the closed IRGA system. A semi-empirical model was used to describe the CO2 response of photosynthesis. The interactive effect of water stress and temperature was divided into two components: the change in CO2 conductance and the change in the photosynthetic capacity. The CO2 conductance was not dependent on the temperature when the willow plant was well watered, but during water stress it decreased as the temperature increased. The photosynthetic capacity of the willow plant increased along with an increase in temperature when well-watered, but during water stress temperature had quite opposite effect.
The PDF includes a summary in Finnish.
article id 5019, category Article
An automatic system for measurements of gas exchange and environmental factors in a forest stand, with special reference to measuring principles. Silva Fennica vol. 13 no. 1 article id 5019. https://doi.org/10.14214/sf.a14873
A system for measuring the net photosynthesis, transpiration and environmental factors within the canopy and ground cover vegetation is described. The system operates continuously throughout the growing season in a young Scots pine (Pinus sylvestris L.) stand. A data-logging unit controls the system and carries out the measurements on the readings of the sensors of photosynthesis, transpiration, light intensity outside the canopy, light climate inside the assimilation chambers, and dry and wet temperatures from selected points. These measurements are shown digitally and automatically punched onto paper tape.
The PDF includes a summary in Finnish.
article id 4940, category Article
Männyn kaasunvaihdon elpyminen talvilevon keskeytyessä. Silva Fennica vol. 10 no. 2 article id 4940. https://doi.org/10.14214/sf.a14786
English title: (1976). Increase in gas exchange rate in Scots pine by terminating the winter rest period.
The activation of CO2 exchange was monitored in two Scots pine (Pinus sylvestris L.) seedlings transferred from the field to the laboratory in December. Gas exchange was monitored by an URAS I infrared gas analyser in a so-called open IRGA-system with trap type chambers. Transpiration was also measured at the same time by weighing the potted seedlings twice a day. The measuring period lasted eleven days. During the period, the level of both transpiration and net photosynthesis increased about ten times. Furthermore, it was found that the level of photosynthesis at high temperatures was relatively lower at the beginning than at the end of the measuring period.
The PDF includes a summary in English.
article id 7634, category Article
Measurement of fluctuating irradiance in field studies of photosynthesis. Acta Forestalia Fennica no. 187 article id 7634. https://doi.org/10.14214/aff.7634
The problems caused by the temporal and spatial microvariation in irradiance during field measurements of photosynthesis are studied. It is concluded on the basis of variation analyses based on irradiance data measured in a Scots pine (Pinus sylvestris L.) stand that the microvariation should be measured by integrating it over the measurement time and space.
However, the curvlinearity of the light response of photosynthesis results in biased estimates when linear integration (mean irradiance) is used. The significance of the bias is examined using a simulation technique on irradiance material. Whether the actual integral of photosynthesis can be approximated with mathematical method is next studied. The method gave satisfactory results only for a low curvature response, but the latter method was applicable also to the high curvature response. However, both methods presuppose that the mean and variance are known. Measurement of the variance is based on integration of the second power.
A new method, where the nonlinearity problem is avoided, is presented to measure fluctuation of the irradiance. The method enables the shoot geometry to be taken into account and it is also applicable to transpiration studies.
The PDF includes a summary in Finnish.
article id 7595, category Article
Effect of planting shock on the transpiration, photosynthesis, and height increment of Scots pine seedlings. Acta Forestalia Fennica no. 161 article id 7595. https://doi.org/10.14214/aff.7595
In the experiment Scots pine (Pinus sylvestris L.) seedlings were transplanted out in the field. The effect of the treatments on gas metabolism and daily height increment were examined. The seedlings were 5-year old Scots pine plants growing in clay pots, covered with plastic bags. Transpiration and photosynthetic rates were monitored with open IRGA measuring system for a few days before being subjected to the treatments and for one month after. In addition, the daily amounts of transpired water and daily height increments were measured. A model for the potential rate of each metabolic process was constructed.
Planting and additional exposure had a strong and rather permanent effect on the self-regulation of the processes. This effect is very similar to that caused by water deficit. Exposure makes the disturbance more pronounced. Transpiration of the transplanted seedlings decreased in a few days after planting to less than half of the potential value and that of the exposed ones decreased to a quarter of the potential value. The daily amounts of photosynthesis decreased to half of the potential value. There was no recovery in photosynthesis during the whole monitoring period of four weeks. There was a slight recovery in transpiration about five weeks after transplanting.
Thus, the treatment probably generated stress conditions throughout the whole growing period, which is characterized by strong self-regulation of photosynthesis and transpiration, thus causing an essential decrease in the total amount of CO2 fixed. The photosynthesis was depressed especially at elevated temperatures after planting, as during water deficit. Planting and additional exposure did not produce any detectable changes in the dependence of the growth rate on temperature or in the effect of self-regulation on height growth. On the other hand, the level of growth was decreased as a result of planting out.
The PDF includes a summary in Finnish.