Refine search
Results 81-90 of 98
Estimation of forest parameters using the non-parametric techniques and satellite images at compartment level
2010
Jonikavicius, D., Lithuanian Univ. of Agriculture, Akademija, Kauno reg. (Lithuania) | Mozgeris, G., Lithuanian Univ. of Agriculture, Akademija, Kauno reg. (Lithuania)
This paper discusses the use of medium resolution Landsat TM satellite images to support conventional approaches of Lithuanian forest inventory practices. Estimation accuracies achieved using just field measured sample plots, Landsat TM satellite images and two non-parametric k-nearest neighbour and most similar neighbour estimators were studied at a level of compartments. 19 mature forest areas, prepared for final felling with GPS measured borders and all trees callipered, were used for validation. Notably higher estimation accuracies were achieved using field sample plots distributed through the whole forest area studied than just ones located on mature forest stands. The root mean square deviations in estimating compartment-wise volume of growing stock per 1 ha was around 27-28% if the best variant of estimation approach was used. Possible influence of the accuracy in locating the borders of validation areas on the estimations is discussed in the paper, too.
Show more [+] Less [-]Testing the simultaneous use of laser scanning and aerial image data for estimation of tree crown density
2010
Bikuviene, I., Lithuanian Univ. of Agriculture, Akademija, Kauno reg. (Lithuania) | Mozgeris, G., Lithuanian Univ. of Agriculture, Akademija, Kauno reg. (Lithuania)
This paper introduces the first test results to use laser scanning and high resolution digital colour infrared aerial image data to estimate average tree crown density at a sample plot level. General methodological framework based on two-phase sampling schemes, non-parametric estimators and satellite images as the auxiliary data sets was adopted for the use with airborne data sources. More than 400 circular sample plots were established and measured in a special research forest area near Kaunas, the central part of Lithuania. The tree crown density was visually estimated for every coniferous tree belonging to the 500 square m plot together with other conventional forest parameters. Two variants of digital colour infrared aerial images (ground sampling density 15 and 40 cm), LiDAR point clouds, based on 1 point/square m scanning density and two phase sampling approach with non-parametric k-nearest neighbour and most similar neighbour estimators were used to test the accuracies of tree crown density estimation at a sample plot level. Reliable estimates were found to be possible on pure coniferous stands only. Average tree crown density was estimated with the root mean square error around 17.5-18% at a sample plot level, bearing in mind average crown density around 64% for the whole study area. The estimates were unbiased. Integration of laser scanning based variables with the ones available from digital aerial images resulted in lowest estimation root mean square errors. Laser scanning based variables used as the auxiliary data set independently resulted in better estimation errors than the variables available from digital colour infrared images.
Show more [+] Less [-]Impact of amelioration system renovation on the growth of mature forest stands
2010
Zalitis, T., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Libiete-Zalite, Z., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Both forestry theory and practice have proved that amelioration favours the growth of forest stands significantly. The growing stock increases even 10 times, if the amelioration system is well-functioning. Joint Stock Company Latvia State Forests that is managing half of forests in Latvia has started renovation of old amelioration systems aiming to improve the productivity of state owned forests in Latvia. In order to evaluate the impact of the renovation of the old amelioration systems, a tree ring width in 7 pine stands, 5 spruce stands and 3 birch stands was analysed. This study shows that the renovation itself has not affected the productivity of mature pine, spruce and birch significantly 3-4 years after the renovation. Authors have come to a conclusion that the reason for that could be too short observation period or particularities of a stand structure and age.
Show more [+] Less [-]Research on genetic aspects of Scots pine resistance to root rot
2010
Skipars, V., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Baumanis, I., Latvian State Forest Research Inst. Silava, Salaspils (Latvia) | Rungis, D., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Scots pine (Pinus sylvestris) is Latvia's most economically important tree species. It accounts for 38% of the total forest area of Latvia. One of diseases affecting P. sylvestris is root rot caused by the fungus Heterobasidion annosum, which causes large economic losses. There is some evidence of Scots pine trees with higher levels of resistance but no absolutely resistant tree clones have been described so far. Many genes encoding peptides and proteins with direct or indirect antifungal activity have been described in various plant species, but only few of them have been studied in conifers. In our study we have utilised various approaches to research genetic aspects of Scots pine resistance to H. annosum. Here we present our initial results. Initially, H. annosum infection was determined in 300 trees and in a subset of twenty seven trees representing fifteen families (progeny of one mother tree) infection levels were quantitatively characterised. Candidate-genes were selected based on previously published research. Gene copy number variation (CNV) analyses were performed on selected samples. Copy number variation polymorphism was detected for a gene encoding a thaumatinlike protein analogues of which are described as potent antifungal proteins in other plants. As increased gene copy number can lead to increased gene product amounts in cells it is possible that an increased copy number of thaumatin-like protein is beneficial to the pine tree in respect to resistance against H. annosum and other pathogens. Further experiments need to be performed to investigate this in more detail.
Show more [+] Less [-]Territorial organisation of game management in Latvia
2010
Baumanis, J., Latvia Univ. of Agriculture, Jelgava (Latvia) | Ozolins, J., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
The number of the most important game animals of artiodactyla species (moose, red deer, roe deer, wild boar) has been increasing in Latvia during the last 10 years. At the same time, the number of hunting districts where the census of these game animals is taken is also increasing, whereas the average area of the districts is diminishing. The studies show that at present the area of many hunting districts is notably smaller than the individual territory inhabited by these species. This particular study aims at establishing whether there is a relationship between the area of a hunting district on which a census is taken and the number of animals counted, as well as whether the number of animals is really increasing or the increase in the number is attributed to an increase in the census unit number. It was established that in respect of the four species there is a significant correlation between the area of the hunting district and the density of animals in the district. The number of moose and red deer may be assessed more objectively in the districts with an area exceeding 5,000 hectares. The census of roe deer and wild boars is notably influenced by the area of the territory where the census is taken, but the analysis does not explicitly show whether the number of roe deer and wild boars is under-assessed in large districts or over-assessed in the small ones.
Show more [+] Less [-]Participatory approaches to investigate breeding objectives of livestock keepers
2010
Duguma, G. | Mirkena, T. | Haile, Aynalem | Iñiguez, L. | Okeyo Mwai, Ally | Tibbo, Markos | Rischkowsky, Barbara A. | Sölkner, Johann | Wurzinger, Maria
There are distinct breeds suitable for diverse purposes in the different production environments or ecological zones. Farmers in different production systems have different trait preferences and the strategies followed by them are also as diverse as the agro-environments within which they operate. In order to design a viable breeding plan, farmers’ preferences for the different traits need to be investigated. In this paper available tools and methods for defining livestock breeding objective traits are described, discussed and comparisons among them are made. The reviewed tools were: participatory rural appraisal (PRA), choice experiments, ranking of animals from own flock/herd and ranking of others animals. Each methodology may be appropriate to specific situation; however, it is recommended that a combination of approaches be used to precisely capture the breeding objective traits of livestock producers. Elucidation of objective traits using the tools with active involvement of producers can result in appropriate livestock genetic improvement that is well grounded in practical reality and truly reflects owners’ preferences.
Show more [+] Less [-]Economic analysis of animal disease control inputs at farm level: the case of trypanocide use in villages under risk of drug resistance in West Africa
2010
Affognon, Hippolyte D. | Randolph, Thomas F. | Waibel, H.
This paper presents an economic analysis of the use of drugs (isometamidium and diminazene) in controlling African Animal Trypanosomosis (AAT), a serious disease of cattle and small ruminants in villages that exhibit resistance to isometamidium in Burkina Faso and Mali in West Africa. The study applies a production function framework integrating a damage control function to assess the short term productivity effect of trypanocide use under different epidemiological conditions. We found that the marginal value products of isometamidium in all epidemiological conditions, and the marginal value product of diminazene in high-prevalence-high-resistance conditions are positive and greater than one revealing an underuse of trypanocidal drugs in those conditions. The economical optimum level of isometamidium is far larger than the current use level. In a strict economic interpretation, this implies that in the short term cattle farmers could increase the profitability if they increase trypanocide input beyond current levels. On the other hand, if the use of trypanocide increases, cattle farmers will also be more likely to experience future losses from trypanocide resistance. In this paper we demonstrated the feasibility of applying the damage control framework for measuring the productivity of veterinary therapeutic drugs at farm level in poor African countries.
Show more [+] Less [-]Factors influencing the trade of local chickens in Kampala city markets
2010
Emuron, Nathan | Magala, Henry | Kyazze, Florence B.||Kugonza, Donald R.||Kyarisiima, Connie C. | Kyazze, Florence B. | Kugonza, Donald R. | Kyarisiima, Connie C.
A study was conducted to determine the factors influencing the supply of live indigenous (local) chickens in Kampala city markets in December 2008. A total of fifty local chicken traders were randomly selected from five markets to respond to a structured questionnaire. Chicken trade was generally informal. Local chickens were mainly marketed alive in Kampala markets and the main customers were piecemeal consumers. The majority of the traders (52.9%) obtained local chickens from Eastern Uganda. Chickens were transported to markets in passenger vehicles, on motorcycles and on lorry trucks that were carrying cattle and other agricultural produce. This mode of transport sometimes caused injuries and bird mortality. Fifty percent of the traders obtained the chickens from middlemen while 46% of the traders personally bought the birds from rural farm households. Chicken trade was the major source of household income to 72.7% of the chicken traders and many of the traders had secondary sources of income. During peak seasons, the traders could sell an average of 120 birds per week per person. Local chicken marketing involved traders of varying levels of education (with a mean of 9.5 years of formal education). The number of local chickens traded per week was positively correlated (P<0.01) with the level of education of the traders. The demand for these chickens was highest in the festive months of December and April; and lowest in February and March. The cost of local chickens was more than twice as much as that of exotic chickens. Most traders (56.7%) perceived taste to be the basis for consumers’ preferential demand for local chickens in preference to exotic chickens. The major constraints in the marketing of local chickens in Kampala city markets were identified as high mortality rates/chicken diseases (43.5%), costly transport (22.4%), and irregular demand (15.3%). The study revealed that there was a high potential for the development of local chicken trade in Uganda. Designing solutions for the constraints of local chicken marketing would act as a tool for poverty alleviation not only to the rural chicken farmers but also the traders.
Show more [+] Less [-]Role of traditional enclosures on the diversity of herbaceous vegetation in a semi-arid rangeland, southern Ethiopia
2010
Angassa, A. | Oba, G. | Treydte, A.C. | Weladji, R.B.
Grazing management and seasonality strongly influence the recovery potential of herbaceous vegetation in semi-arid rangelands of southern Ethiopia after history of heavy grazing. We investigated effects of management (enclosures versus grazed landscapes), age of enclosures and seasonality related to rainfall (i.e., independent variables) on herbaceous biomass, grass basal cover, herbaceous species abundance, species richness and diversity in a savanna rangeland of southern Ethiopia. We further assessed the relationship between the herbaceous biomass and species richness. Management significantly affected most of the herbaceous response variables (i.e., comparing enclosures and open grazed). Herbaceous biomass, grass basal cover, herbaceous species richness and diversity were greater in enclosures than in grazed areas. Rainfall was also influential on herbaceous biomass, grass basal cover, abundance of herbaceous species, herbaceous species richness and diversity. Herbaceous biomass, abundance and diversity did not however vary with the age of enclosures, while herbaceous species richness appeared to decrease as the age of enclosures advanced. Grass basal cover initially decreased and later on increased with the age of enclosures, so that the older enclosures disclosed improvement of grass basal cover.
Show more [+] Less [-]Rangeland dynamics in South Omo Zone of Southern Ethiopia: Assessment of rangeland condition in relation to altitude and Grazing types
2010
Terefe, A. | Ebro, A. | Tessema, Z.K.
A study was undertaken in Hamer and Benna-Tsemay districts of the Southern Ethiopia with the objective to determine the condition of the rangelands for grazing animals as influenced by altitude and grazing types. The rangelands in each of the study districts were stratified based on altitude and grazing types. In the study districts, a total of 32, 3, 2, 7 and 29 species of grasses, legumes, sedges, other herbaceous plants and woody species were identified, respectively. The common and/or dominant grass species in the enclosures was Cenchrus ciliaris while in the communal grazing areas they were Cynodon dactylon and Tetrapogon tennulis. In riverside grazing areas, the common and/or dominant grass species was Cynodon dactylon. The total grass biomass of communal, riverside and enclosure areas found in the different altitude categories of the study districts ranged from 398-503; 98-626, and 1,132 – 1,209 kg/ha, respectively. The common and/or dominant woody species in the communal grazing areas were highly palatable species of Acacia tortilis and Grewia bicolor and less palatable Solanum species. In riverside grazing areas, the common and/or dominant woody plants were species of Acacia tortilis, Grewia bicolor, and Solanum species while in the enclosures; Acacia brevispica and Acacia tortilis were found. The woody vegetation density per hectare of communal, riverside and enclosure areas in the different altitude categories of the study districts ranged from 2,501-3,021; 2251-3,021, and 201-700,wd/ha respectively which showed that the communal and riverside grazing areas were bush encroached. The range condition scores ranged from 17.87-20.38 (communal), 22-27 (riverside), 31.05-31.2 (enclosures) which were poor, fair and good condition classes, respectively. Similarly, with regard to the same variable the scored varied from 22-32.87, 19.73-31.43, 17.97-31.44 and 17.87-31.28% in altitudes >1550m, 1250-1550m, 900-1250m, and 550-900m, respectively. The result indicated the need for rangeland improvement measures in communal and riverside grazing areas, in order to attain sustainable livestock production from these areas. Establishment of community based enclosures was found to be one of the ways to improve the condition of the rangelands. The result indicated the need for rangeland improvement measures in communal and riverside grazing areas, in order to attain sustainable livestock production from these areas. Establishment of community based enclosures was found to be one of the ways to improve the condition of the rangelands
Show more [+] Less [-]