Aivo Vares

Estonian University of Life Sciences, Dorpat, Tartu County, Estonia

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Publications (9)11.59 Total impact

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    ABSTRACT: We analysed the economics of hybrid aspen and silver birch which are both fast-growing hardwoods recommended for the establishment of plantations on abandoned agricultural lands in Northern Europe. If managed during one rotation period the internal rate of return (IRR) of hybrid aspen plantations was 4.4-7.3% and the IRR of silver birch plantations was 4.7-6.7%. The highest value of IRR of 8.1% was estimated for the two-rotation (26+26 years) hybrid aspen management scenario at excellent site conditions. Higher IRR values were reached in excellent quality sites whereas hybrid aspen was more sensitive to site quality. With land cost included in the analysis, 1.1-1.7% lower IRR values were obtained compared to the case where land cost was excluded from analysis, but the ranking of scenarios did not change. The financial maturity ages of one-rotation scenarios corresponding to maximum expected IRR values were 26 or 34 years for hybrid aspen in excellent or good to moderate sites respectively, whereas the maturity age did not change with the inclusion of land in analysis. The maturity ages for different silver birch scenarios varied in the range of 34-45 years. The land expectation values (LEV) remained positive in case of 1-5% discount rates. In case of 3% discount rate, LEVs of all scenarios were roughly comparable to the current median agricultural land price. We conclude that the establishment of plantations with both studied hardwoods can be a profitable investment in Northern Europe and to ensure greater profitability such plantations should be managed under shorter rotations than traditionally used for birch and aspen forests in the region.
    Baltic Forestry 01/2012; 18(2):288–298. · 0.38 Impact Factor
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    ABSTRACT: Limited nutrient acquisition from soil is a key process limiting productivity in boreal forest. We investigated short-root morphological adaptations and rhizosphere effect in relation to site conditions in interaction with tree mineral nutrition. We studied seven young (8- to 14-yearold) silver birch (Betula pendula Roth.) stands on abandoned agricultural land in Estonia. Soil pH varied from 3.8 to 7.0, and soil N % from 0.07 to 0.26%. Tree nutrient (NPK) status was expressed by leaf nutrient concentrations. Leaf N correlated negatively with short-root specific length and area. Summed activity (SA) and metabolic diversity of bacteria (by BIOLOG EcoplateTM), bacterial community diversity (by DGGE) and pHKCl were determined for rhizosphere (R) and bulk soil (S) to reveal the extent of the rhizosphere effect. Bacterial activity in rhizosphere was 1.4–4.7 times higher than in bulk soil. Ratio SAR/SAS indicating root support to the rhizosphere bacterial communities decreased with increasing bulk soil pH; however, when bulk soil pH was C5, the decrease in SAR/SAS was insignificant, i.e. the rhizosphere effect stayed at a stable level. Diversity of bacterial community was 6% higher in bulk soil than in rhizosphere. Rhizosphere acidification occurred in studied stands when bulk soil pHKCl C 5. Short-root N % correlated positively with SAR/SAS. We concluded that tree N-nutritional status was related to short-root morphological parameters but not to studied microbiological characteristics in the soil of young silver birch stands.
    European Journal of Forest Research 11/2011; 130(6):1055-1066. · 1.96 Impact Factor
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    ABSTRACT: Eight-year-old plantations (11) of silver birch were studied on abandoned agricultural land in Estonia. Trees were planted on uncovered soil and on polyethylene. After eight growing seasons, the height and diameter at breast height of the trees grown on polyethylene were significantly (P<0.001) larger than corresponding parameters of the trees grown on uncovered soil. The annual height increment of the birches grown on the polyethylene was significantly (P<0.05) larger during six growing seasons after planting compared to that of the trees grown on uncovered soil. However, annual height increments were not significantly different in the 7th and the 8th growing seasons. The use of polyethylene mulching had a statistically significant effect (P<0.001) on the height of the beginning of the live crown in 8-year-old plantations. The differences between the values of live crown ratio of the trees grown on polyethylene and the values of live crown ratio of the trees grown on uncovered soil decreased during six growing seasons. However, by the 7th and 8th growing seasons, there was no significant difference (P>0.05) between the values of the live crown ratio. The height growth of silver birch grown without mulching as well as with mulching was found to be more intensive on Glossic Podzoluvisol, Calcaric Cambisol, Calcaric Luvisol and Dystric Gleysol; however, the height growth was more intensive on mulched soil. The height growth of the birches was modelled on the single-tree and stand levels for five soil types. KeywordsSilver birch-Field soils-Polyethylene mulching-Height growth model-Crown characteristics
    European Journal of Forest Research 01/2010; 129(4):679-688. · 1.96 Impact Factor
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    ABSTRACT: The understorey vascular plant cover and its relations with the overstorey tree species and site properties in young silver birch and hybrid aspen plantations were studied. Understorey vegetation was similar in both plantation types in terms of species richness, diversity, sensitivity to human impact, life-span and habitat preference. Nevertheless, in denser silver birch plantations some signs indicated a faster vegetation development overall e.g. a higher share of shade tolerant plant species. The concentration of total N was higher in the humus layer of silver birch plantations consequently affecting the nutritional status of the understorey vegetation. The significant impact of the plantation type on the understorey vegetation was confirmed by the NMDS analysis. The hypothesis that semi-exotic hybrid aspen plantations may support the spread of alien species or may show a tendency towards smaller indigenous species richness was not confirmed. Irrespective of the overstorey tree species, a strong previous land use impact, i.e. disturbance history, on the ground vegetation was eminent.
    Annales Botanici Fennici 08/2009; 46:353-364. · 0.66 Impact Factor
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    ABSTRACT: The early growth of the trees, foliar and soil properties, and floristic diversity were studied in 5-year-old hybrid aspen plantations in four sites: A1-levelled oil shale quarry spoil (Calcaric Regosol), A2-levelled quarry spoil covered with the mixture of removed former Calcaric Cambisol horizons, B1-former arable land on Calcaric Cambisol, Chromic Cambisol and Rendzic Leptosol, B2-former arable land on Mollic Planosol. In the quarry area trees had grown significantly faster in site A2. Overall fastest growth was observed on former arable land (B2). Significantly higher pH and lower values of P in the substrate and of foliar N and P were estimated in A1. TWINSPAN classifica- tion and DCA ordination showed substantial differences in vegetation composition between the sites. Vegetation of the quarry site A2 resembled more to B1 and B2 than to A1.
    Oil Shale 01/2008; 25(1). · 0.64 Impact Factor
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    ABSTRACT: Since 1999 hybrid aspen plantations have been established on former agricultural lands for production of pulpwood as a practice of short rotation plantation forestry in boreal Estonia. During the early growth period the dimensions of the trees have been highly variable. The main objective of the study was to explain the high variability in early growth speed of hybrid aspens by differences in physicochemical soil properties. A network of 51 experimental plots was created to study growth–soil interactions in 5-year-old plantations at various sites. The mean height of the trees was 2.7 ± 0.02 m, mean diameter at breast height was 1.9 ± 0.02 cm and mean current year height increment was 0.7 ± 0.01 m. Mean foliar concentrations of main mineral nutrients were estimated as follows: N 2.15%, P 0.20%, K 0.76%. Trees have grown faster on Arenosols, Albeluvisols and Planosols. Growth intensity has been poor on Luvisols, Cambisols and Gleysols. While evaluating site quality based on soil texture and drainage condition, we found, that in general, hydromorphic soils have been less favourable. At a young age, hybrid aspen grew faster on automorphic soils with loamy sand and on semihydromorphic soils with loam, silt loam and sandy loam texture. The study of height increment in 5-year-old hybrid aspen plantations allows us to predict that the modest growth rate during the first years after planting could improve at an older age. Preliminary impact hierarchy of site properties, especially soil moisture condition, may change during later growth stages, when light competition in the canopy layer of the stand and nutrient competition between the tree roots in the soil will become more decisive for the growth performance of the trees.
    Forest Ecology and Management 01/2007; 245:118-129. · 2.77 Impact Factor
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    ABSTRACT: During the last decade, more than 400 000 ha of agricultural land was abandoned in Estonia. Such areas are often characterized by rapid natural afforestation with silver birch, which has led to an increase both in the woodland area and in the area of silver birch stands. However, many bioenergetic aspects related to birch stands growing on arable land are still poorly understood. The main aim of the present study was to investigate the above-ground biomass production, nutrient (NPK) accumulation, and foliar characteristics of young silver birch stands on abandoned agricultural land. Five 8-year-old stands of silver birch growing on different soil types were included in the study.The density of the studied stands varied from 3060 to 36 200 trees per ha and their above-ground biomass varied from 6.0 to 22.9 t DM ha−1. The largest share in the above-ground biomass of the birches (59–80%) was from the stems. The mean stem mass of the birches ranged from 0.29 to 1.79 kg, and the mean total above-ground biomass ranged from 0.36 to 3.03 kg. The leaf area index for the studied stands varied from 1.21 to 4.64 m2 m−2, being the highest for the stand of medium density. Mean single leaf area varied from 9.4±0.2 to 15.4±0.3 cm2, leaf weight per area varied from 61.1±0.4 to 77.5±0.5 g m2, and specific leaf area varied from 13.2±0.1 to 16.8±0.1 m2 kg−1. However, no significant differences were found between stand density and the foliar characteristics. There was a strong positive correlation between soil nitrogen concentration and leaf nitrogen concentration (R=0.92); regarding phosphorus concentration, the corresponding correlation was weak (R=0.52) and regarding potassium concentration, no significant correlation was found. The amount of nitrogen accumulated in the above-ground part of the silver birch stands varied between 42.4 and 145.8 kg ha−1, the amount of phosphorus, between 5.9 and 27.9 kg ha−1, and the amount of potassium, between 7.2 and 78.6 kg ha−1. The N:P:K ratios for the foliage were comparable. It is evident that the proportion of nitrogen and phosphorus are close to optimum, while the N:K ratio was lower than optimum value in all cases.
    Biomass and Bioenergy. 01/2007;
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    ABSTRACT: Grey alder (Alnus incana) and black alder (Alnus glutinosa) stands on forest land, abandoned agricultural, and reclaimed oil-shale mining areas were investigated with the aim of analysing the functional diversity and activity of microbial communities in the soil–root interface and in the bulk soil in relation to fine-root parameters, alder species, and soil type. Biolog Ecoplates were used to determine community-level physiological profiles (CLPP) of culturable bacteria in soil–root interface and bulk soil samples. CLPP were summarized as AWCD (average well color development, OD 48h−1) and by Shannon diversity index, which varied between 4.3 and 4.6 for soil–root interface. The soil–root interface/bulk soil ratio of AWCD was estimated. Substrate-induced respiration (SIR) and basal respiration (BAS) of bulk soil samples were measured and metabolic quotient (Q = BAS/SIR) was calculated. SIR and Q varied from 0.24 to 2.89mgCg−1 and from 0.12 to 0.51, respectively. Short-root morphological studies were carried out by WinRHIZOTM Pro 2003b; mean specific root area (SRA) varied for grey alder and black alder from 69 to 103 and from 54 to 155m2kg−1, respectively. The greatest differences between AWCD values of culturable bacterial communities in soil–root interface and bulk soil were found for the young alder stands on oil-shale mining spoil and on abandoned agricultural land. Soil–root interface/bulk soil AWCD ratio, ratio for Shannon diversity indices, and SRA were positively correlated. Foliar assimilation efficiency (FOE) was negatively correlated with soil–root interface/bulk soil AWCD ratio. The impact of soil and alder species on short-root morphology was significant; short-root tip volume and mass were greater for black alder than grey alder. For the investigated microbiological characteristics, no alder-species-related differences were revealed.
    Plant and Soil 04/2006; 283(1):1-10. · 3.24 Impact Factor
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    ABSTRACT: Lõhmus, K.1, Ivask, M.2, Tamm, Ü.3, Vares, A.4, Tamm, U.4 2000. The caloric value of stem of silver birch (Betula pendula Roth.), downy birch (Betula pubescens Ehrh.), black alder (Alnus glutinosa (L.) Gaertn.) and aspen (Populus tremula L.) in Estonia. - Metsanduslikud uurimused XXXII, 113-120. ISSN 1406-9954. Abstract. The aims of this study were (i) to estimate the caloric values of the stemwood and stembark of silver birch (Betula pendula Roth.), downy birch (Betula pubescens Ehrh.), black alder (Alnus glutinosa (L.) Gaertn.) and aspen (Populus tremula L.) in Estonia, (ii) to analyse the variability of caloric value of stemwood and stembark depending on tree species, social position of tree in the stand, and vertical location of the sample in stem. To characterize the caloricity of stemwood and stembark the caloric values (kJ g-1) were measured. The results demonstrated statistically significantly higher mean caloric values of stembark compared with stemwood for all investigated species. Social status of tree and relative height of the sample had no significant effect on the caloricity of stemwood or stembark.