Browsing by Subject "SCOTS PINE STANDS"

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  • Nieminen, M.; Hökkä, H.; Laiho, R.; Juutinen, A.; Ahtikoski, A.; Pearson, M.; Kojola, S.; Sarkkola, S.; Launiainen, S.; Valkonen, S.; Penttilä, T.; Lohila, A.; Saarinen, M.; Haahti, K.; Makipää, R.; Miettinen, J.; Ollikainen, M. (2018)
    Environmental and economic performance of forestry on drained peatlands was reviewed to consider whether continuous cover forestry (CCF) could be a feasible alternative to even-aged management (EM). CCF was regarded feasible particularly because continuously maintaining a tree stand with significant transpiration and interception capacity would decrease the need for ditch network maintenance. Managing CCF forests in such a way that the ground water levels are lower than in clear-cut EM forests but higher than in mature EM forests could decrease greenhouse gas emissions and negative water quality impacts caused both by anoxic redox reactions and oxidation and mineralization of deep peat layers. Regeneration studies indicated potential for satisfactory natural regeneration under CCF on drained peatlands. An economic advantage in CCF over EM is that fewer investments are needed to establish the forest stand and sustain its growth. Thus, even if the growth of trees in CCF forests were lower than in EM forests, CCF could at least in some peatland sites turn out to be a more profitable forest management regime. An advantage of CCF from the viewpoint of socially optimal forest management is that it plausibly reduces the negative externalities of management compared to EM. We propose that future research in drained peatland forests should focus on assessing the economic and environmental feasibility of CCF.
  • Ding, Yiyang; Leppälammi-Kujansuu, Jaana; Helmisaari, Heljä-Sisko (2019)
    Abstract 1. Fine root turnover plays a critical role in carbon and nutrient cycling in forest ecosystems. In this study, we focused on the most abundant deciduous species in Nordic countries, silver birch (Betula pendula Roth) and its fine root dynamics, including the amount of litter produced by fine roots as well as by aboveground vegetation. 2. The minirhizotron method was used to quantify fine root longevity of silver birch and understory fine roots and rhizomes in northern Finland. Fine root biomass per basal area and ectomycorrhizal short root numbers per mg were also quantified. The fine root litter production was estimated by fine root biomass and longevity, and then compared with the aboveground litter collected with litter traps. 3. Birch fine root biomass was 1.4-fold higher than that of understory fine roots and rhizomes (234 ± 22, 171 ± 19 g m−2 respectively). Fine root longevity of birch (372 days) was significantly (P < 0.05) shorter than that of understory vegetation (643 days). The birch fine root longevity was positively related to root diameter and soil depth. Hazard analysis showed that thicker roots, long roots, roots produced late in the growing season, and roots growing deeper in the soil had relatively lower mortality hazard compared to the reference data. The total annual soil C input, including both birch and understory, was 283 g C m−2 yr−1. The proportion of understory annual C input was 35% of the total. Total annual belowground C input was 1.4-fold greater than that of aboveground. 4. Our study indicated that the total annual belowground litter production was greater than that of the aboveground litter in a boreal deciduous forest stand. Therefore, more emphasis should be put to quantify the C cycling of both above- and belowground parts of different tree species as well as understory in boreal forests.
  • Leppälammi-Kujansuu, Jaana; Aro, Lasse; Salemaa, Maija; Hansson, Karna; Kleja, Dan Berggren; Helmisaari, Heljä-Sisko (2014)
  • Kaarakka, Lilli Matilda; Vaittinen, Janne; Marjanen, Mikael; Hellsten, Sofie; Kukkola, Mikko; Saarsalmi, Anna; Palviainen, Marjo Maarit; Helmisaari, Heljä-Sisko Marketta (2018)
    Finland has a long tradition of utilizing forest-based biomass for energy and industry purposes and the use has steadily increased in the past decade due to changes in international and regional energy policies. Intensive harvesting practices, in which a larger proportion of the woody biomass is removed from the forest stand, are becoming more common. The objectives of this study were (i) to evaluate the spatial and temporal extent of soil surface disturbance caused by stump-root system harvesting and (ii) to quantify how much biomass and nitrogen is removed from the stand in stump and coarse root removal. The extent of surface disturbance was assessed in three clear-cut Norway spruce (Picea abies, (L.) Karst.) stands in southern and central Finland, differing in time since harvest. To determine the biomass distribution of the stump-root system, stumps and coarse roots were excavated at one of the experimental stands. Across all age classes (time since harvest) less soil surface had remained undisturbed at the stump harvesting sites (48%) than at the sites where only mechanical site preparation (72%) had been carried out. Thus, the findings of this study indicate that soil disturbance caused by stump harvesting can exist on forest soil surface for more than a decade following harvest. The total biomass of the stump-root system in the stand was estimated to 39.3 Mg ha-1 and 79% of this biomass was removed during stump harvesting and consequently, 8.3 Mg ha-1 of stump-root biomass remained in soil. The stump-root system accounted for 17% of the whole-tree biomass, and coarse roots and fine coarse roots represented a significant portion of it (73%). Thus, the stump-root system represents a large biomass component in boreal forest stands. However, forest management utilizing stumps may result in carbon losses from the stand.