Norway Spruce Monocultures Research Articles

Soil properties as a component of predisposition factors of Norway spruce forest decline in the Hanušovická highland mountain zone

Mature Norway spruce (Picea abies [L.] Karst.) stands affected by decline symptoms were selected in the northern part of the Hanušovická highland (Czech Republic) at Jeřáb Mt. foot and summit (1,003 m a.s.l.). Spruce stand (SS) 1 (700 m a.s.l.) was situated in conditions of the fir-beech forest altitudinal zone (FAZ). SS 2 (880–900 m a.s l.) was situated in conditions of the spruce-beech FAZ. Research plots (RPs) of the area 400 m<sup>2</sup> were selected in the stands according to the different level of damage and stand diversity. On the basis of the complex soil analysis it was proved that the soil environment could be a part of stress factors, influencing the predisposition of non-natural Norway spruce monocultures at mountain locations of the Krkonoše Mts.-Jeseníky Mts. elevation. High Al<sup>3+</sup> concentrations in soil mineral horizons were determined in a direct correlation with decline of stand enclaves on the selected RPs. The  concentrations of Al<sup>3+</sup> and limiting content Mg<sup>2+</sup> make root systems exist mainly in H-horizons or Ae/Ep-horizons. This causes stand predisposition to climatic drought and drought episodes.

Simulating the influence of initial stand structure on the development of young mixtures of Norway spruce and birch

The development of different stand structures, including Norway spruce ( Picea abies (L.) Karst.) and silver birch ( Betula pendula Roth), were simulated from the time of precommercial thinning until the dominant height of spruce reached 13 m. The aim was to find a combination of Norway spruce and silver birch that ensured a satisfactory development of spruce combined with a long-term admixture with birch. Empirical models were used to create initial stands and to estimate the growth of the individual trees. The initial number of stems was 2500 ha −1 and the proportion of birch was 0, 20, 40 and 60%. The initial average height of Norway spruce was set to 3 m and for birch the height was varied between 1–6 m. Conditions describing a medium fertility in southern Sweden was used in the simulations. In mixtures with the greatest initial birch height, the total volume after 15 years was similar to or greater than in a monoculture of Norway spruce with 2500 stems ha −1. The total volume was greater in mixtures compare to Norway spruce monocultures of the same density as the spruce component in the mixtures. The volume of Norway spruce decreased with increasing initial birch height if the average height of birch exceeded 2 m. The status of competitive birches at the time of first commercial thinning was identified by investigating variables describing vital birches in a survey study. Given the conditions used in this study, it was concluded that leaving birch with an average height slightly greater (0.5–1 m) than that of spruce after precommercial thinning will result in a large number of competitive birches at first commercial thinning. It was also indicated that the dimensions of the Norway spruce will be similar to a monoculture of Norway spruce with 2500 stems ha −1. When the initial average height of birch exceeded 4 m the increase in the number of competitive birches leveled off due to intra-species competition.

The influence of different overstory removal on planted spruce and several broadleaved tree species: Survival, growth and pine weevil damage during three years

The influence of different overstory removal on herbivory by the pine weevil to seedlings was studied in a field experiment. Four overstory treatments with middle aged Norway spruce in combination with or without insecticide treatments were applied. Seedlings of the following seven tree species were planted in each of the four blocks: Acer platanoides L., Fagus sylvatica L., Fraxinus excelsior L., Picea abies L. (Karst.), Prunus avium L., Quercus robur L. and Tilia cordata Mill. The seedlings were monitored through the 2001-2003 growing seasons. Highest survival was found among seedlings planted in the overstory treatments with 15 and 20% light in the understory, whereas best diameter growth in seedlings was found in the clearcut. Overstory trees of Norway spruce decreased herbivory from pine weevil considerably among underplanted seedlings, and the pine weevils fed significantly more on planted Norway spruce seedlings than on all broadleaved tree species. The following rough preference order was obtained: (1) Norway spruce >> (2) beech and oak > (3) ash, cherry, lime and maple. The influence from the insecticide treatment was minor. Therefore, during the conversion of Norway spruce monocultures into mixed species stands using overstories, the use of insecticides against pine weevil is not needed.

Should planting of broad-leaved species be encouraged at the expense of spruce? An economic approach to a current southern Swedish forestry issue

Non-timber values of the forest have been subject to much attention in Sweden during the last decades. Of special interest in this respect are the diminishing and species rich broad-leaved forests in southern Sweden. During the late 1900s many of these forests were converted to monocultures of Norway spruce (Picea abies L. Karst.) and other conifers at a high and accelerating pace. While the consequences of this change on biodiversity are currently studied on a broad scale, recreational values, although recognized, have only been subject to a limited number of scientific studies.In the current study, we focused on timber values and recreational values of coniferous and broad-leaved forests in southern Sweden. The first objective was to model the timber value of different management alternatives including spruce or beech (Fagus sylvatica L.) at a typical southern Swedish forest site. The site expectation value for spruce was considerably higher than for beech. The second objective was to include recreational values in monetary terms in the model. The estimated required level of marginal willingness-to-pay for an increase in the area of beech forest in the county of Skåne was very low, indicating that regeneration of beech may be superior to spruce from a socio-economic point of view.

Industrial Round-Wood or Fuel-Chips in Medium-Aged Norway Spruce

Close-to-nature forestry may contribute to fulfil the objective of sustainable forestry. In western Denmark conversion of even-aged monocultures of Norway spruce to more stable stands has high priority, and must be done before close-to-nature forest management systems such as selection management can be implemented. Shelterwood regeneration in medium-aged Norway spruce stands seems to be the most promising method for conversion. Time consumption and damages were studied on the different harvesting methods in the establishment of the shelterwood. The traditional cut-to-length system gave higher net income than the fuel chip harvesting systems, but changes in price relations or lower stand quality might reverse this. The damage rate of remaining trees seems to be negatively correlated with the productivity of the logging/chipping operation.

Recovery from acidification in central Europe—observed and predicted changes of soil and streamwater chemistry in the Lysina catchment, Czech Republic

The geochemical model MAGIC was applied to estimate streamwater and soil chemistry between 1851 and 2030 at the Lysina catchment, an acid-sensitive granitic catchment covered by planted Norway spruce monoculture in the western Czech Republic. The total deposition of sulfur to the catchment was 164 meq m−2 in 1991, but had declined to 52 meq m−2 by 2000. Although SO2 emissions in the region declined by 90% compared to the 1980s, acidification recovery was small within the period 1990–2000. Stream pH increased only slightly (from 3.92 to 4.07), although SO4 concentration declined sharply from 568 μeq l−1 (1990) to 232 μeq l−1 (2000). Organic acids played an important role in streamwater buffering. According to the MAGIC prediction using deposition measured in 1999–2000, streamwater pH will increase to 4.3 and soil base saturation will increase to 6.2% by 2030 (from 5.7% in 2002). Pre-industrial pH was estimated to be 5.5 and soil base saturation 24.7%. The loss of base cations (Ca, Mg, Na, K) was caused predominantly by atmospheric acidity, but intensive forestry was responsible for approximately one third of the net base cation loss via accumulation in harvested biomass. Severely damaged sites, under continued pressure from forestry, will not return to a good environmental status in the near future (if ever) when the acid deposition input is only partially reduced.

Evaporation and transpiration from forests in Central Europe ? relevance of patch-level studies for spatial scaling

Spatial scaling from patch to the landscape level requires knowledge on the effects of vegetation structure on maximum surface conductances and evaporation rates. The following paper summarizes results on atmospheric, edaphic, and structural controls on forest evaporation and transpiration observed in stands of Norway spruce (Picea abies), Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica). Forest canopy transpiration (E c ) was determined by tree sapflow measurements scaled to the stand level. Estimates of understory transpiration and forest floor evaporation were derived from lysimeter and chamber measurements. Strong reduction of E c due to soil drought was only observed at a Scots pine stand when scil water content dropped below 16% v/v. Although relative responses of E c on atmospheric conditions were similar, daily maximum rates of E z (E cmax ) could differ more than 100% between forest patches of different structure (1.5-3.0mmd -1 and 2.6-6.4 mmd -1 for spruce and beech, respectively). A significant decrease of E cmax per leaf area index (E cmax /LAI) with increasing stand age was found for monocultures of Norway spruce, whereas no pronounced changes in E cmax /LAI were observed for beech stands. It is concluded that structural effects on E cmax can be specified and must be considered for spatial scaling from forest stands to landscapes. Hereby, in conjunction with LAI, age-related structural parameters are important for Norway spruce stands. Although compensating effects of tree canopy layers and understory on total evaporation of forests were observed, more information is needed to quantify structure-function relationships in forests of heterogenous structure.

Response of Photosynthesis to Radiation and Intercellular CO<sub>2</sub> Concentration in Sun and Shade Shoots of Norway Spruce

Functional differentiation of assimilation activity of sun versus shade foliage was analysed in a Norway spruce monoculture stand (age 15 years). The investigated stand density (leaf area index 8.6) and crown structure led to variation in the photosynthetically active photon flux density (PPFD) within the crowns of the sampled trees. At the saturating PPFD, the maximum rate of CO2 uptake (P Nmax) of exposed shoots (E-shoots) was 1.7 times that of the shaded shoots (S-shoots). The apparent quantum yield (α) of E-shoots was 0.9 times that of the S-shoots. A lower ability to use excess energy at high PPFD in photosynthesis was observed in the S-layer. The CO2- and PPFD-saturated rate of CO2 uptake (P Nsat) of the E-shoots was 1.12 times and the carboxylation efficiency (τ) 1.6 times that of the S-shoots. The CO2-saturated rate of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) carboxylation (VCmax) and of actual electron transport (Jamax) in the S-needles amounted to 89 and 95 % of VCmax and Jamax in the E-needles. Thus, in addition to the irradiation conditions and thus limitation by low Ja, the important limitation of photosynthesis in shade needles is due to carboxylation. This limitation of photosynthesis is accompanied by lower stomatal conductance.

Changes caused by Norway spruce in an ochreous brown earth, assessed by the isoquartz method

SUMMARYPrevious investigations had shown that about 80 years of Norway spruce monoculture on an ochreous brown earth of the Belgian Ardennes were sufficient to accentuate the weak podzolization process already present in the climax beechwood soil and to increase the weathering of several minerals, e.g. 2:2 clay minerals. In order to evaluate more accurately mineral weathering and spruce‐induced losses of nutrient elements, an isoquartz assessment method has been applied to a pair of soil profiles, one developed under beech, the other under spruce.Results show a clear decrease of several weatherable minerals in the soil of the spruce stand which was more marked than in the beechwood, especially for chloritic minerals: losses reach about 30% of the initial chlorite content in the cambic horizon and regularly increase up to 70% in the humic layer. There were severe spruce‐induced losses of Mg and Na: 27% of the initial Mg reserve was removed from the whole soil and the losses reached 60% in the upper 20 cm.It is concluded that 86 years of Norway spruce monoculture have appreciably increased weathering processes and removal of elements.

Nesting Habitats and Nest Predation in Sympatric Populations of Capercaillie and Black Grouse

During 1979-85, 196 capercaillie (Tetrao urogallus) and 90 black grouse (T. tetrix) nests were studied at Varaldskogen in southeast Norway. Both species nested in all available habitat types and in a wide range of forest tree-stocking density and nesting cover. Both species preferred to nest in the habitat types to which they are generally adapted, capercaillie in mature, mixed coniferous forest and black grouse in forested bogs. Black grouse used denser nest cover than capercaillie. Individually marked capercaillie females changed successive nesting habitats 12 of 19 (63%) possible times. Nest loss was unrelated to habitat type, forest density, or nest cover. Capercaillie suffered higher nest loss than black grouse in all comparable habitats. Depredated eggs of both species composed about 10% of the food demands of predators. Because nests survived equally well in all habitats and no single predator depended on grouse eggs for food, there may be no selection for rigid nest-site characteristics. High nest predation in recent years cannot be ascribed to direct effects of modern forestry on nesting habitats. J. WILDL. MANAGE. 51(1):167-172 Capercaillie and black grouse are lekking species. The cryptically colored females nest solitarily on the ground at varying distances from the lek (Bernard 1982, Wegge et al. 1982a, Kolstad et al. 1985), and the 2 species differ in general habitat selection. Most of the year, black grouse use younger forest successional stages and open moorland habitats, whereas capercaillie select mature climax forests (Seiskari 1962, Borset and Krafft 1973, Wegge et al. 1982b, Angelstam 1983). Boreal forests in Norway are exploited for commercial logging, which since the 1950's has been characterized by clearcuts of 6-20 ha, subsequently replanted to monocultures of Norway spruce (Picea abies) or Scotch pine (Pinus sylvestris). Nest losses, particularly in capercaillie, seem to have increased in recent years, estimated at 64-83% in the area of this investigation (Storaas and Wegge 1985). The nesting habitats of black grouse have been studied by Bernard (1982) in the French Alps. However, except for some superficial notes (H6glund 1953, Siivonen 1953, Semenow-TjanSanskij 1960) and observations in Scottish plantations (Jones 1985), no systematic study has been published on the nesting habitats of capercaillie. The aim of this paper is to compare the nest sites of sympatric populations of caperca llie and black grouse, to relate the fate of nests to habitat types, habitat density, and nest cover, and to discuss the factors affecting nest site selection. The study was financed by the Norwegian Dir. Nat. Conserv. and the T. Gotaas Fund. O. Bakken, I. Gjerde, A. Haugland, L. Kastdalen, B. B. Larsen, M. Ribsskog, and J. Rolstad assisted in the field. F. C. Zwickel and B. W. O'Gara gave valuable comments on the manu-