The study was undertaken to evaluate the efficiency of selection on growth performance of Menz sheep under a community-based breeding program (CBBP) from the period of 2009 – 2017. A total of 3996 lamb records (ram lambs 2025/ ewe lambs 1971) were used to evaluate the phenotypic and genetic factors affecting the growth traits of Menz sheep. REML in Wombat and General linear model on SAS (version 9.0) were used to evaluate selection efficiency for growth of Menz sheep. The least squares means and standard errors on phenotypic growth weight for birth, weaning age, six month age and yearling age were 2.58±0.004, 8.99±0.02, 13.28±0.02 and 19.94±0.06 kg, respectively. The effect of sex was significant (p<0.001) only for birth weight and no significance effect (p>0.05) was observed for weaning, six month and yearling weights. All growth traits were not affected by fixed effect of parity and birth type in this particular study. However, birth season and birth year had a great influence (p<0.0001) on all growth traits. The genetic trend on estimated breeding values (EBV) was not consistent across years and varied between sexes. The highest EBV for weaning, six month and yearling were recorded for the year 2013 and the lowest in 2009 (at weaning and six month) and 2015 (at yearling).The female EBV (at weaning, six month and yearling) was higher than male for the current (2017) and base population (2009).The responses to selection as compared to base population (2009) for birth, weaning, six month and yearling weight were – 0.00446Kg, + 0.11Kg, + 0.54Kg and + 0.75Kg respectively. This study indicates that improvement in body weight for Menz sheep through CBBP is possible; however, the response to selection varied across years and its pattern was irregular for the implemented years due to the problem on selection of breeding rams (lower availability of breeding rams) and management effect.

The influence of non-genetic factors on lamb survivability at various ages up to 360 days was studied under village management condition in Jimma, Ethiopia. The overall least squares means of lamb survival rate was 89.0 at 0-60, 81.5 at 0-120 and 50.0 % up to 360 days. The survival rate of lambs up to weaning (120 days) was 81.5 %. Season of birth consistently exerted a significant effect (p<0.05)) on lamb survival. Lambs born during the post rain and dry periods showed a higher survival rate than lambs born during the wet season. Districts showed a significant effect (p<0.05)) on survival rates of lambs. Lambs born in land scarce areas (Dedo) had a low survival rate than lambs born in Seka (land available area). Type of birth did not exert an influence (p>0.05) on lamb survival. Sex had a significant effect (p<0.05) on survivability of lambs at later stages and the females showed higher survivability rate than males. Mortality tended to decrease with an increase with birth weight and decreased as parity increased. The birth weight showed a significant effect (p<0.05) on survival rate of lambs. The lambs with birth weight of 2 kg and above were showing higher survival rate. The lambs with 1.5 kg and lower birth weight showed high mortality rate. The study revealed that, adequate measures to be taken to curb mortality of lambs. The selection of heavier weight and larger litter at birth coupled with improved management could be a means to improve lamb productivity in the villages.

The objective of this study was to estimate genetic parameters of reproduction traits of pure Fogera cattle at Metekel Ranch. Metekel cattle Breeding and Improvement Ranch has so far been engaged in maintenance of Fogera cattle population outside their adapted environment (ex-situ conservation). The breeding program has two components: selection and crossbreeding. The establishment of the pure breed unit is meant for the improvement of the Fogera breed and for providing heifers to cross- breed to exotic dairy sires (by Artificial insemination). In cross breeding program; crossbred animals are produced through artificial insemination of Fogera cows with Friesian semen. Around three to six months of pregnancy, the F1 cross heifers are sold to farmers for milk production (Melaku et al., 2011a, b). Very recently the ranch started to distribute non pregnant F1 cross heifers. WOMBAT software was used to estimate genetic parameters. The variance components and heritability were estimated using a Uni-variate animal model using four models which fitted direct additive, dam genetic and permanent environmental effect as a random effect and the fixed effects (year, season, sex and parity). Parameter of age at first calving (AFC) were estimated using Model 1 (Y= Xb + Z1a + e), Model2 (Y= Xb + Z1a + Z3c + e), Model3 (Y= Xb + Z1a + Z2m + e (cova, m = 0), and Model4 (Y= Xb + Z1a + Z2m + Z3c + e (cova, m = 0) whereas parameters of reproductive traits including gestation length (GL), calving interval (CI) and days open (DO) were estimated using model 2 and 4 which fit permanent environmental effect due to repeated records per cow. Correlations (genetic and phenotypic) among the different traits were estimated from bi--variate analysis by using model 1 for growth traits and AFC and model 2 to estimate the correlation between CI, GL and DO and birth weight (BWT) and GL. Correlation between birth weight and gestation length were estimated by treating gestation length as a trait of calf. Due to record limitation correlation between AFC with other reproductive traits were not estimated. Estimates of direct heritability of reproductive performance traits from the best model were 0.003 ± 0.05 for AFC, 0.00 ± 0.03 for GL and CI and 0.013 ± 0.03 for DO. The phenotypic correlations between reproductive traits were 0.003 ± 0.034 for CI and GL, 0.37 ± 0.041 for CI and DO and 0.167 ± 0.036 for DO and GL and the genetic correlation between reproductive traits ranged from -0.94 ± 0.2 for DO and GL to 0.83 ± 0.579 for CI and DO. Genetic correlation between growth and AFC ranged from 0.77 ± 0.24 for BWT and AFC to 0.87 ± 0.03 for pre-weaning average daily gain (PADG) and AFC. The phenotypic and genetic correlations between BWT and GL were 0.03 ± 0.05 and -0.84 ± 0.013 respectively. The results of genetic correlation between considered traits was ranged from moderate to high and it indicates that selection for one trait would have a significant effect on the other traits not considered however selection must be done with caution. The heritability estimates confirmed the presence of high environmental effect among the study population and it masks the individual animal genetic difference. Given the low heritability estimates obtained, effective improvement in reproduction performance of Fogera cattle could be achieved by improving the production conditions and through crossbreeding.

Icing notably increases the mass of a tree crown, causing damage to the tree. So far, a very limited number of studies have assessed the icing influence on coniferous trees, none of them in Latvia. The aim of the study was to assess the influence of tree parameters and recent thinning on the proportion of damaged trees and the type of damage in Scots pine stands. The study sites were located in the eastern part of Latvia, damaged in December 2012. In total, 98 pine dominated stands of different age were selected randomly. Eight (mean) plots per stand were established; in each plot, all trees larger than 2.1 cm were measured and the type of damage assessed. The above-ground biomass from 12 randomly selected stands (57 dominant trees) of different age was weighted with and without icing. The biomass of pine with icing exceeded that without 1.5 ± 0.27 times. The mean proportion of damaged trees in pine dominated stands was 26%; the proportion of broken trees peaked in the middle-aged stands (41 – 70 years old), but the largest proportion of pooled bent and uprooted trees was found in the young (11 – 20 years old) stands. The proportion of damaged dominant trees was affected by the slenderness coefficient – a higher proportion of such trees was found among more slender trees. The results suggest that the risk of icing damage could be reduced by silvicultural measures boosting individual tree stability.

Climatic changes are shifting the potential tree distribution limits of many tree species northwards. One of such species is Fagus sylvatica, currently represented in Latvia only by a few stands. In order to increase knowledge on its potential use in the forest management, the aim of our study was to characterize the growth of beech in a young stand in the central part of Latvia. The stand of beech and spruce, mixed in rows with an initial spacing of 2.5 x 2.5 m in Oxalidosa forest type was assessed. Survival of European beech in clear cutting was similar to that observed for the native Norway spruce (73% and 79%, respectively), but both height and diameter were notably and significantly superior for wildlings at the mean age of 15 ± 2 years, reaching on average 7.4 ± 0.30 m and 8.9 ± 0.69 cm, respectively. Increasing ring width with increasing tree age for both tree species was observed until the last four years, when large and increasing superiority of beech over spruce, coinciding with reduction of ring width of spruce, was noted. It was most likely caused by intensified competition due to very wide crowns formed by young beech trees in the plantation with wide spacing: average crown radius reached 2.4 ± 0.16 m, for few trees exceeding even 4 m.

The impact of climatic and genetic factors on needle cast damage, as well as relationship between the degree of damage and survival and growth of trees was evaluated in the study. The analysis was done in two series of experiments, both established in two locations in Latvia (central and eastern part). Needle cast damage (in 5 grade scale) as well as the height and height increment, diameter of root collar and survival of trees were assessed. Results suggest that the degree of needle cast damage was influenced by the genetic, as well as climatic factors, and also their interaction. The average degree of needle cast damage in experiment of open-pollinated families was 4.7 ± 0.01 in central and 4.6 ± 0.03 in eastern Latvia; in the experiment of control-crossed families it was 4.6 ± 0.02 in central and 3.4 ± 0.04 in eastern Latvia. The impact of genetics on the needle cast damage degree was statistically significant (p is less than 0.05), and this effect was observed when any of growth traits (diameter, height or height increment) was used as a covariate in analysis. Results suggest the potential to select more resistant families, since the genetic correlation of grade of the damage between locations was significant (r = 0.40 - 0.72) and therefore improve also the growth of trees, since the grade of the damage had a negative correlation with growth traits both at provenance and family mean level (r = -0.69 and r = -0.42; p is less than 0.01).

Fast-growing hybrid aspen clones are recommended for establishment of plantation on abandoned agriculture land in Northern Europe. In this study we assessed the productivity, quality and assortment structure of hybrid aspen clones at final felling. Data were collected during the hybrid aspen clonal experiment conducted in the central part of Latvia. Large variation in the productivity level between different clones was affected by growth and survival. From the compared 5 most and least productive clones, based on the yield m**3 haE-1, the faster growing clones have about 17% better survival rate at age 10. Also, the mean annual increment (MAI) differed notably and significantly (p is less than 0.05, α = 0.05) between hybrid aspen clones at the age of 18 years ranging from 7 to 34 m**3 haE-1 yearE-1. Theoretical assortment structure of hybrid aspen at the age of 18 years was the following: 43 ± 4.86% of small dimension saw logs (SDS logs), 21 ± 4.86% high quality saw logs (HQS logs), 18 ± 4.33% pulpwood, 4 ± 0.77% firewood and 13 ± 0.08% of logging residues (tops). The outcome of HQS logs on average is more than 30% from the 5 best clones and further increase can be predicted with age. Stem volume (H2 = 0.32), height (H2 = 0.47) and quality parameters (stem straightness - H2 = 0.73, branch angle - H2 = 0.60) had a high heritability and large differences between clones, indicating notable possibilities to improve the productivity of plantations via selection of the best-growing genetic material.

Wood based ash can be used as a liming material and fertilizer in forest, thus providing a solution for utilization of wood ash and formation of additional increment of trees, especially on organic soils, where lack of potassium and phosphorus is a well-known factor limiting the growth of trees. Yet, many studies have been made with adverse results mostly because of different soil types and species investigated. However, by now the best results on fertilization with wood ash have been found on drained peatlands, where some nutrient deficiencies have emerged. The aim of this study was to find out the growth response of Norway spruce on drained organic soils after spreading of potassium sulphate (K2SO4) and wood ash (WA). The experiment was carried out in three middle aged Norway spruce (Picea abies) stands on drained mineral and peat soil. Experiment consisted of three replications of each treatment in each stand including WA, K2SO4 and the control on 400 square meter sub-sample plots each. The diameter and height of trees were measured. The samples of increment cores were collected 4 years after fertilization to determine the additional volume increment, which varied from 8.5 m**3 haE-1 in WA plots and from 9.7 m**3 ha-1 to 17.2 m**3 haE-1 on K2SO4 plots. Both - the wood ash and potassium application - significantly increased the increment of Norway spruce on drained mineral and peat soil, although no significant differences were found between the treatments (p = 0.82, α = 0.05).

Impact of a variety of forestry machine types on soil compaction is evaluated in this study according to the measurement of soil penetration resistance at 0 to 80 cm depth. It is concluded in the study that soils with poor bearing capacity (PBC), comparably small penetration resistance and organic layer thicker than 5 cm are less vulnerable to soil compaction. The use of small-size forwarder Vimek 610 allows to reduce soil compaction to an insignificant level in comparison to the control sites, and most or ruts disappear within a few days in PBC conditions. Whereas John Deere 810E, which belongs to the middle-size class of forwarders, significantly compacts soil through the whole measured depth in similar conditions. Rottne F10B and John Deere 810E forwarders represent the same weight category, and soil compaction due to the use of these machines on soils with moderate bearing capacity (MBC) is similar too; however, on soils with weak (WBC) and good (GBC) conditions results are different, mostly due to a different amount of extracted roundwood in both trials. Tracked forwarder was used only in GBC conditions and the results demonstrated significant compaction only down to 22 cm depth. The trials confirm that the depth of the intensity of impact depends on the weight of the machine and amount of material extracted; however, additional measurement data are necessary to characterize the impact quantitatively in different conditions.