Selecting the trees to be harvested based on the relative value growth of the remaining trees     

Jari Vauhkonen  Timo Pukkala 《European Journal of Forest Research》2016,135(3):581-592

  相似文献   

Changes in soil fauna 10 years after forest harvestings: Comparison between clear felling and green-tree retention methods     

Anne Siira-Pietikäinen  Jari Haimi 《Forest Ecology and Management》2009

We studied the responses of soil decomposer animals to clear felling and alternative, green-tree retention harvesting methods (GRT) in Norway spruce forests in Finland. The study plots which were sampled for immediate treatment effects (up to three years) were resampled after 10 years. We hypothesized that responses of decomposers still depends on the level of GTR. The treatments, in addition to untreated controls (100% retained), were: (1) selection felling (70% dispersed tree retention), (2) and (3) gap felling with and without site preparation, respectively (three small gaps were felled in a 1-ha area and 50% of the stand volume was retained), (4) retention felling (10% of the stand volume was retained in three small tree groups) and (5) traditional clear felling (0% retention). Ten years after the treatments the strong increase of enchytraeids immediately after the harvestings was leveled out and the numbers on all treated plots were at the control level. Total numbers or community structure of soil dwelling collembolans were not affected either. The abundance of macroarthropods on the harvested plots, except selection felling, was ca. 50% lower compared to the control forest. Their community structure was also changed due to the harvestings. The most sensitive animal groups were herbivores, microbivores and some detritivores. After 10 years, predators (mainly spiders and certain coleopterans) were decreased only under retention tree groups, while microbidetritivores (dipteran and coleopteran larvae) were unaffected. Our study showed that dispersed tree retention, at least when only 30% of the stand volume was harvested, induced no significant changes in soil decomposer animal community in boreal coniferous forest. On the other hand, decomposer community in clear-felled areas (either large or small) and in small aggregated retention tree groups is still different from that in unfelled forest 10 years after the harvestings. Mesofauna living in the soil organic layer (humus) seem to be better buffered against environmental changes induced by the harvesting compared to animals dwelling close to or on the soil surface. These animals are affected long after harvestings.  相似文献   

Method for predicting tension capacity of sawn timber considering slope of grain around knots   总被引：1，自引：1，他引：0  

Kohsaku Mitsuhashi  Matti Poussa  Jari Puttonen 《Journal of Wood Science》2008,54(3):189-195

This study introduced a new parameter, the area reduction factor (ARF), to consider the effect of knots on the tension strength of timber. It is an improved version of the knot area ratio (KAR). ARF considers both the projected area of knots and the effect of the slope of grains around the knots. The tension capacity of a tested structural timber was predicted as a product of ARF, clear wood tension strength parallel to the grain, and the area of the cross section. ARF was determined as the minimum value obtained when a knot measurement window of 100 mm was slid along the plank. The prediction method was examined with 11 planks. The average ratio of the predicted capacity to the actual value was 1.11 with a coefficient of variation of 0.26. The average ratio obtained by using a KAR-based parameter, the clear wood area ratio (CWAR), was 2.15 with a coefficient of variation of 0.23. To study the reliability of ARF and CWAR as single parameters, the correlations of ARF and CWAR with the tension strength were determined for 57 planks. The coefficients of determination for ARF were slightly better than those for CWAR, although both of them seemed to be quite poor predictors of tension capacity when used alone. Therefore, a multiparameter model is preferred and should be a subject for further studies. The results of the structural tension tests conducted in this study have been presented in part at the 40th meeting of the International Council for Research and Innovation in Building and Construction: Working Commission W18 - Timber Structures (CIB-W18) in Bled, Slovenia, August 2007  相似文献   

Temperature sensitivity of soil organic matter decomposition in southern and northern areas of the boreal forest zone     

Pekka Vanhala  Kristiina Karhu  Mikko Tuomi  Katarina Björklöf  Hannu Fritze  Jari Liski 《Soil biology & biochemistry》2008,40(7):1758-1764

Much effort has been made to improve understanding of factors controlling the temperature dependence of soil organic matter (SOM) decomposition. The question of how soils formed in different geographical locations and conditions respond to temperature changes is still open. In addition to climate, residence times of soil organic matter are controlled by its decomposability and microbial community. In this work we hypothesized that the decomposition of SOM is adapted to the prevailing SOM quality and climatic conditions. This should result in different temperature vs. decomposition curves for northern and southern soils. We studied short-term temperature dependence of SOM decomposition near the northern and southern borders of the boreal forest zone using a Gaussian model. As carbon mineralization rate is driven by microbial activity, we focused on organic carbon fractions available to microbes and the size, composition and functioning of microbial communities in the soil. Despite differences in microbial community structure and behavior, similar amounts and qualities of the microbially available carbon led to similar temperature dependences of carbon mineralization in the north and south. The overall soil respiration rate level was higher in spruce forest sites than in pine forest sites irrespective of climate conditions. Our results do not mean that there is no risk of carbon losses from northern soils due to warming climate conditions. As temperature sensitivity of the decomposition increases with decreasing temperature regime, the proportional increase in the decomposition rate in northern latitudes might lead to significant carbon losses from the soils.  相似文献   

Temperature sensitivity of young and old soil carbon – Same soil,slight differences in 13C natural abundance method,inconsistent results     

Franz Conen  Kristiina Karhu  Jens Leifeld  Barbara Seth  Pekka Vanhala  Jari Liski  Christine Alewell 《Soil biology & biochemistry》2008,40(10):2703-2705

Predictions of future climate change critically depend on the temperature sensitivity of soil organic carbon decomposition. One question of debate is whether temperature sensitivity differs between young or labile and old or more stable carbon pools. We re-analysed soil that has previously led to the conclusion that old soil carbon is more temperature sensitive. The re-analysis gave different results compared to the earlier study, most likely due to small differences in an otherwise very similar experimental approach. This study illustrates how conclusions may depend upon details of the experimental setting.  相似文献   

Price integration for domestic and imported sawlogs and pulpwood in Finland: an update     

Jari Kuuluvainen  Jaana Korhonen  Danyun Xu  Anne Toppinen 《Scandinavian Journal of Forest Research》2018,33(1):71-80

This paper provides an analysis on the integration of prices for imported coniferous pulpwood and sawlogs, and respective domestic stumpage prices in the Finnish wood market. Eight real price series were investigated during 2002–2014 using monthly observations. The bounds testing approach by Pesaran et al. [(2001) Bounds testing approaches to the analysis of level relationships. J Appl Econom. 16: 289–326. doi:10.1002/jae.616], indicates there are long-run relationships between prices of domestic and imported wood. For more detailed information, the vector error correction model (VECM) approach was used. Estimation of a system with all eight prices with interpretable results did not succeed; therefore, we estimated models for prices of sawlogs and for pulpwood separately. For sawlogs, two co-integrating vectors, one for pine and one for spruce, were found. For pulpwood prices, one co-integrating vector was identified. The estimated VECMs confirm the results of bounds testing approach, suggesting that causation in the Finnish wood market runs from domestic prices to prices of imported wood. We conclude that prices of domestic and imported coniferous logs and pulpwood are closely connected. The question of full integration remains open, as border prices and stumpage prices by definition differ, at least, by logging and transportation costs.  相似文献   

Reconstructing forest canopy from the 3D triangulations of airborne laser scanning point data for the visualization and planning of forested landscapes     

Jari Vauhkonen  Roope Ruotsalainen 《Annals of Forest Science》2017,74(1):9

  相似文献   

Optimizing the joint production of timber and bilberries     

Jari Miina  Timo Pukkala  Juha-Pekka Hotanen  Kauko Salo 《Forest Ecology and Management》2010

Berries and mushrooms are increasingly appreciated products of Finnish forests. Therefore, there is a need to integrate them in silvicultural planning. Bilberry (Vaccinium myrtillus L.) is an economically important wild berry that is widely collected for household consumption and sale in North Karelia, Finland. In this study, bilberry yield models developed recently were included in a stand growth simulator and the joint production of timber and bilberry was optimized by maximizing soil expectation value (SEV) with 3% discounting rate, assuming that 75% of the bilberry yield is harvested. The effect of bilberry production on the optimal stand management increased with increasing bilberry price. With high bilberry prices (4–8 € kg⁻¹) it was optimal to manage the mixed stand of Scots pine, Norway spruce and birch, and the pure stand of Norway spruce so as to promote bilberry production. In the Scots pine stand, where bilberry yields are higher, bilberry production affected optimal stand management already with a price of 2 € kg⁻¹. Compared to timber production, joint production led to longer rotation lengths, higher thinning intensities, more frequent thinnings, and higher share of Scots pine in the mixed stand. The contribution of bilberries to the total SEV increased with increasing bilberry price and discounting rate. In the mixed stand and pine stand the SEV of bilberry production, calculated with 3% discounting rate, exceeded the SEV of timber production when bilberry price was 4 € kg⁻¹.With 4% discounting rate this happened already with bilberry price of 2 € kg⁻¹. It was concluded that forest management which promotes bilberry yields is the most profitable in pine stands where the potential bilberry yields are high.  相似文献   

Variability of Peronospora Sparsa (syn. P. rubi) in Finland as Measured by Amplified Fragment Length Polymorphism     

Hannele Lindqvist-Kreuze  Hilkka Koponen  Jari P.T. Valkonen 《European journal of plant pathology / European Foundation for Plant Pathology》2002,108(4):327-335

Downy mildew caused by Peronospora sparsa (syn. P. rubi) is a serious threat to commercial cultivation of arctic bramble (Rubus arcticus subsp. arcticus) in Finland. P. sparsa is distributed throughout the country in cultivated and wild arctic bramble and in cloudberry (R. chamaemorus). A total of 36 isolates of P. sparsa collected from these hosts was analysed for amplified fragment length polymorphism (AFLP). Of the 226 markers scored, 223 were polymorphic and all isolates of P. sparsa had unique AFLP fingerprints, which indicated high levels of genetic variability. An UPGMA clustering analysis of the isolates did not reveal any genetically distinguishable strains. The isolates were grouped neither according to the geographic origin nor the host from which they were isolated. Isolates of P. sparsa obtained from wild arctic bramble and one from cloudberry readily infected the leaves of the cultivated arctic bramble (cultivar Pima). Also, P. sparsa isolated from cultivated arctic bramble infected the leaves of wild arctic bramble. These data suggest that P. sparsa may be disseminated from wild arctic bramble and cloudberry to cultivated arctic bramble in the field.  相似文献   

Effects of organic carbon and clay contents on structure-related properties of arable soils with high clay content     

Helena Soinne  Riikka Keskinen  Mika Tähtikarhu  Jukka Kuva  Jari Hyväluoma 《European Journal of Soil Science》2023,74(5):e13424

Understanding of factors governing soil structural features is necessary for managing key processes affecting crop productivity and environmental impacts of agriculture, for example, soil water balance, aeration, and root penetration. Organic matter is known to act as a major binding agent in soil aggregation and thus constitutes a central pillar in soil structure formation. However, knowledge of the structural role of organic matter or carbon (OC) in soils highly rich in clay-sized particles (<0.002 mm) is limited. In this study, the effects of clay and OC contents on aggregate stability, water holding capacity, near-saturated hydraulic conductivity, total porosity, and pore size distribution were assessed in cultivated fields with high clay content located in private crop production farms in southern Finland. Significant positive correlations were found between OC content and proportion of water stable aggregates and specific pore sizes from the range of 30 μm up to 1 mm diameter determined by image analysis. Porosities on a smaller size range derived from water retention measurements likewise showed a positive correlation with OC in <0.2 μm sizes. On the range of 0.2–1 μm, a negative relationship was observed, which induced a negative effect of OC on soil plant available water reserves. In line with the positive correlation between OC and larger soil pores, free water, representing the amount of water that can be drained by gravity, exhibited a positive relationship with OC suggesting that OC content can enhance aeration of soils with high clay content. Compared to OC, clay content tended to have an adverse effect on soil structural properties. Clay correlated negatively with pores larger than 30 μm, free water content, and extrapolated field saturated hydraulic conductivity. Further, our imaging results showed how saturated hydraulic conductivity was controlled by pore morphology, and there was a power law relationship between the conductivity and critical pore diameter. $K\propto d_c^2$ in agreement with the percolation theory. Overall, the structural impacts and hydrological implications of OC and clay in heavy clay soils vary by pore size ranges and their emergent practical impacts are thus not straightforward.  相似文献