Forest Competence Center

Riga, Latvia

Forest Competence Center

Riga, Latvia
SEARCH FILTERS
Time filter
Source Type

Jansons A.,LSFRI Silava | Matisons R.,LSFRI Silava | Zadina M.,LSFRI Silava | Sisenis L.,Akademijas str. 11 | Jansons J.,Forest Competence Center
Silva Fennica | Year: 2015

Height growth of trees is a crucial parameter that influences the composition and productivity of forest stands and quality of timber; however, the relationships between annual height increment (HI) and climatic factors have been poorly studied. In this study, the effect of monthly mean temperature and precipitation sums on the HI of Scots pine in two sites in Latvia have been determined using dendrochronological techniques. Correlation and response function analyses were conducted for entire chronologies of HI and for 50-year intervals within them. Climatic factors significantly affected the HI of Scots pine; however, not only did the suite of significant factors differ between the sites, but the influence of these factors changed during the 20th century. In the site in western Latvia where climate is milder, temperature in the preceding summer was the main climatic determinant of HI. The effect of temperature in the dormant period and spring was significant during the first part of the 20th century, while the effect of temperature in the previous September and November has become significant since the second half of the 20th century. In the site in eastern Latvia where summers are hotter, HI has been affected by both temperature and water deficit related factors in the summer. However, since the later part of the 20th century, the effect of temperature in the previous October has intensified and become the main climatic determinant of HI. © 2015 Finnish Society of Forest Science. All rights reserved.


Zadina M.,Latvian State Forest Research Institute Silava | Zadina M.,Latvia University of Agriculture | Donis J.,Forest Competence Center | Jansons A.,Latvian State Forest Research Institute Silava
Research for Rural Development | Year: 2015

Fire is a frequent disturbance in hemiboreal forests that in Latvia affects mostly Scots pine (Pinus Sylvestris L.) stands. Increased forest fire risk is predicted in future as a result of climatic changes. Therefore the aim of our studywas to assess Scots pine regeneration after forest fire in different forest types and with different regeneration methods. Tree height was measured and browsing damage assessed seven years after the forest fire in six different forest types, where planting and natural regeneration (in a clearcut and without management) occurred in compartments randomlyselected from a list of stands severely affected by forest fire. The height of Scots pine was significantly affectedboth by forest type and regeneration method. Notable advantages of planting based on tree height were found in wetmineral soils and peat soils. Trees on poor (dry, wet, peat) soils were higher in natural regeneration after clearcutthan in natural regeneration without clearcut. The density of Scots pine trees was significantly affected by the foresttype but not by regeneration method (planting, natural regeneration, natural regeneration after the clearcut). Themost abundant tree species in natural regeneration after clearcut in all forest types was silver birch (Betula pendulaRoth.). The height of silver birch exceeded that of Scots pine in all analyzed soils in clearcut areas except Vaccinososphagnosaforest type, emphasizing the importance of thinning to ensure a successful development of Scots pinestands.


Purina L.,Forest Competence Center | Purina L.,Latvian State Forest Research Institute Silava | Straupe I.,Latvia University of Agriculture | Liepa L.,Latvia University of Agriculture | And 2 more authors.
Research for Rural Development | Year: 2015

Wind is an important natural disturbance factor in a forest ecosystem. It creates gaps in a forest canopy, providing microenvironmental conditions, suitable for forest regeneration and affects the species composition of ground vegetation. Most of the studies analysing consequences of wind-storm have addressed short-term changes or influence the stand structure, but the aim of our study is to analyse ground-vegetation long time after windstorm in hemiboral forests. Data on ground vegetation cover have been collected in areas affected by the storm of 1967, where due to salvage-logging 200-400 m wide clearcuts were created. Sample plots (1×1 m) were placed in different distance from the edge of former clearcuts and projective cover of ground vegetation assessed using Braun-Blanquet method in Myrtillosa mel. forest type on 5 sites in north-western part of Latvia. Results reveal that in all sites species belonging to boreal, boreal-temperate and temperate biome were present, but their proportions varied between sites. In total 82 species of vascular plants were found, most frequent among them Maianthemum bifolium (L.) F.W. Schmidt (species characteristic to Norway spruce forests), Vaccinium myrtillus L. and Vaccinium vitis-idaea L. (associated with Scots pine forests) as well as Molinia caerulea (L.) Moench and Deschampsia caespitosa (L.) P. Beauv. (both characteristic to wet soils). Results suggest, that even 47 years after the storm microenvironmental conditions in the sites are not stable. Ellenberg's indicator values reveal, that most of the sites are in semi-shade, cool and moist conditions, placed on acidic, nitrogen-poor (in few sites - also nitrogen rich) soils.


Zeps M.,Latvian State Forest Institute Silava | Sisenis L.,Latvia University of Agriculture | Luguza S.,Latvia University of Agriculture | Purins M.,Latvia University of Agriculture | And 2 more authors.
Agronomy Research | Year: 2015

Annual increment of hybrid aspen exceeds that of other tree species (including common aspen) in Baltic States. Notable (several-fold) differences in productivity between clones have been detected and therefore tree breeding programs are established to select the best genotypes (clones) for large-scale propagation. In order to aid the selection as well as understand the potential changes in growth of hybrid aspen as a result of climatic changes, it is important to analyse the intra-annual growth dynamics. Therefore aim of our study was to assess height growth intensity of hybrid aspen and factors affecting it. Weekly measurements of height increment were carried out through the third growing season of trees in two plantations, consisting of 19 clones (10 ramets per clone), on abandoned agricultural land in western (Mazirbe, 56° 36´ N, 24° 30´ E) and central (Vecumnieki, 57° 40´ N, 22° 19´ E) part of Latvia. Mean height growth period of hybrid aspen ranged from 119 ± 8.9 days for late flushing clones to 137 ± 8.6 days for early flushing and was tightly (r = 0.69) linked to total length of height increment. Mean height growth intensity during this period for respective groups of clones ranged from 7.7 ± 3.04 mm day-1 to 11.7 ± 2.93 mm day-1. Growth intensity (and height increment) was significantly affected by genotype (clone) and in both sites tightly (r = 0.57…0.84) linked with daily mean temperature, but not with precipitation. Increasing temperature in future might boost the productivity of hybrid aspen plantations, especially with early flushing clones. © 2015, Eesti Pollumajandusulikool. All rights reserved.


Smilga J.,Forest Competence Center | Zeps M.,Latvian State Forest Institute Silava | Sisenis L.,Latvia University of Agriculture | Kalnins J.,Latvian State Forest Institute Silava | And 2 more authors.
Agronomy Research | Year: 2015

Hybrid aspen (Populus tremuloides × P. tremula) has fast growth in climatic conditions of Northern Europe and relatively high wood quality. Therefore, breeding of it has been carried out in a number of Baltic Sea Region countries. Breeding requires notable financial investment; therefore, the aim of our study was to estimate the profitability of hybrid aspen breeding in Latvia and the factors affecting it. Financial analysis was based on the differential approach, that is, only the costs and benefits that differ between two compared alternatives – planting of hybrid aspen and natural regeneration of silver birch or common aspen – were compared. Differential gain in this case included additional monetary value of the above-ground parts of trees in planted hybrid aspen stands (values obtained from trials in Latvia); differential costs were the costs of tree breeding, plants, planting, cleaning and protection against browsing damages (repeated use of browser repellents or fencing). Profitability of hybrid aspen breeding was significantly affected by the size of the area planted annually, soil fertility (site index) and length of rotation period. The differential gain from investments in tree breeding and establishment and management of plantations (r = 3%), assuming that selected clones would be used for 15 years and 500 ha are planted annually, in comparison to natural regeneration of common aspen and to silver birch, was 662 EUR ha-1 and 1136 EUR ha-1, respectively. In contrast, if only 50 ha are planted annually, the respective figures were 588 and 756 EUR ha-1. If fencing was used for protection of the hybrid aspen plantation against browsing, the differential gain was positive only on the most fertile soils (site index Ia). © 2015, Eesti Pollumajandusulikool. All rights reserved.


Neimane U.,Latvian State Forest Institute Silava | Zadina M.,Latvian State Forest Institute Silava | Sisenis L.,Latvia University of Agriculture | Dzerina B.,Latvian State Forest Institute Silava | Pobiarzens A.,Forest Competence Center
Agronomy Research | Year: 2015

The Norway spruce is widely spread in Eastern Europe and it is managed mainly for the production of sawlogs, though its logging residues are now increasingly used for the production of wood chips for bioenergy. The growth of the Norway spruce is and will be affected by climatic changes; one of the possible effects might be an increase in the frequency of trees with lammas shoots. Therefore, the aim of this study was to assess the influence of lammas shoots on the length of height increment of young Norway spruce in Latvia. Tree height and height increment was repeatedly measured and the presence of lammas shoots, bud flushing grades and frost injuries were assessed in two young (8–13 years) open-pollinated progeny tests in the central part of Latvia (56°46´N, 24°48´E). The mean portion of trees with lammas shoots in one experiment was 6% at the end of 8th growing season. In another experiment, it was 8.7%, 26.9% and 8.1% at the end of 10th, 11th and 13th growing seasons, respectively; 32.3% of trees had lammas shoots at least in one of three seasons. Faster growing and earlier flushing trees had a significantly higher frequency of lammas shoots. Lammas shoots increased the length of annual height increment by 10 to 14 cm, resulting in a 14–20% taller tree height at the age of 13 years. The reduction of height increment as a result of frost damages for very early flushing trees was less pronounced for trees with lammas shoots than without them. © 2015, Eesti Pollumajandusulikool. All rights reserved.


Jansons A.,LSFRI Silava | Matisons R.,LSFRI Silava | Purina L.,LSFRI Silava | Neimane U.,LSFRI Silava | Jansons J.,Forest Competence Center
Silva Fennica | Year: 2015

Relationships between climatic variables and tree-ring width (TRW) of dominant European larch (Larix decidua Mill.) and European beech (Fagus sylvatica L.) trees growing outside of their natural distribution area in western Latvia were studied. Chronologies of TRW, which covered the periods 1949–2012 and 1911–2012, were produced for beech and larch, respectively. Common signatures in TRW between both species were observed, but their amplitude differed. Correlation analysis showed that variation of TRW of both species was affected by drought related climatic variables. Tree-ring width of beech was affected by temperature in the previous July and August and the effect of spring and autumn temperature was observed. Since the 1980s, the effect of July precipitation has become significant. Summer precipitation was significant for larch in the mid-part of the previous century; however, temperature in the previous September has become a limiting factor since 1970s. The limiting effect of winter and spring temperature apparently lost its significance around the 1950s. © 2015, Finnish Society of Forest Science. All rights reserved.

Loading Forest Competence Center collaborators
Loading Forest Competence Center collaborators