This study presents the first annually-resolved chronology using Salix alaxensis (Anderss.) Cov from Victoria Island, Northwest Territories, Canada, an area well north of treeline. Forty-one samples were collected and examined for subsequent analysis. However, crossdating was difficult because of locally absent or missing rings and the narrowness of the rings, and ultimately thirteen stems were crossdated and used to evaluate their dendroclimatological potential. The chronology spans 74 years (1927-2000) and could potentially be extended further using subfossil wood. Precipitation data from December of the previous year to March of the current year were the most consistently and highly correlated with ring width. This suggests that the recharge of the soil moisture by early summer snowmelt is a key factor limiting growth of these shrubs.

The presence of competitors and predators as well as plant quality affect which plants an insect feed from. These factors affect food choice through the entire insect life cycle, and is especially important when it comes to nurturing larvae. Females oviposition choice sets the initial stage for larval growth and survival, and it is therefore predicted that there is a strong selection pressure to make them oviposit on the best plants possible. This study looks into the behavior of nutrient driven ovipositing and food choice in the beetles Phratora vitellinae and Lochmaea caprea by offering individuals ten leaves of Salix viminalis, one treated with extra nitrogen in order to increase the nutritional value, and four treated with extra carbon, which should lower the nutritional value. During the choice experiment, only two females of Phratora vitellinae oviposited, making it impossible to draw any conclusion regarding nutrient driven oviposition choice. However, data showed a preference for nitrogen treated leaves and an avoidance of untreated control leaves in almost every case when looking into the largest loss of area for leaves of each treatment. When analyzing the number of leaves of each treatment that is eaten per individual there was a slight preference for nitrogen treated leaves, even though the probability of nitrogen being ranked as most preferred in this case was almost zero. Carbon treated leaves and acetone treated control leaves were equally avoided. For Lochmaea caprea, females fed from a significantly larger numer of leaves than males did (t-test, t=1.86, p=0.0003). An ANOVA showed no significant difference in C:N ratio among leaf treatments (ANOVA, F=9.28E-07, p=0.99). Since plant C:N ratio most likely will increase continuously due to CO2 emissions, the effects an increased carbon concentration in plant tissues has on oviposition and food choice in herbivorous insects is something to look further into. More studies on this subject are therefore needed.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Extraction of mineral resources causes landscape degradation and the aim of reclamation efforts is to restore ecosystems. Our research was carried out on spoil heaps after brown coal mining near Sokolov (Czech Republic). We compared twenty years old spontaneously developed sites and reclaimed sites afforested by alders Alnus glutinosa and A. incana. Biomass and nutrient budget were evaluated for herbs and woody plants, separately for species Salix caprea, Populus tremula and Alnus glutionosa. Alder showed significantly higher concentrations of nitrogen and carbon compared to other tree species. The total amount of biomass, carbon and nitrogen was higher on reclaimed sites whereas phosphorus was more represented on spontaneously developed sites. Most of nitrogen was accumulated in the below-ground tree biomass and the largest amount of phosphorus was in the above-ground tree biomass. Woody plants of non-reclaimed sites produced more litter whilst litter of alder stands showed a higher concentration of nitrogen. Higher values of biomass, carbon and nitrogen of reclaimed sites were probably achieved through alder ability to fix atmospheric nitrogen.

<p>The great difference in the level of chloroplast variation and its geographic structure among the three main species studied here demonstrates that forest species do not form a homogeneous group. Hazel shows a genetic structure similar to many other thermophilous species and this structure, in combination with fossil evidence, indicates that the post-glacial colonisation of most of Europe originated in a refugium in western France while the Balkan and Italy were colonised from a south-eastern refugium.</p><p>In sallow and silver birch the chloroplast DNA variation and its structure does not fit with a scenario of glacial restriction to southern refugia and survival at intermediate latitudes is suggested for both species. The chloroplast DNA variation in silver birch suggests the presence of one western and one eastern European post-glacial colonisation route and limited contribution of southern populations in the colonisation of the rest of Europe. Unique haplotypes by the Ural Mountains indicates the possibility of a separate glacial origin of these populations.</p><p>The study of chloroplast DNA in species closely related to sallow and silver birch indicate that extensive hybridisation and cytoplasmic gene flow occurs within both the Salix and Betula genera in Europe. The nuclear and chloroplast phylogenies of 14 Betula species were not in complete agreement with each other or with the classical division of the Betula genus into subgenera or sections. The phylogenetic structure implies that hybridisation has played a role in the evolution of the Betula genus.</p><p>This thesis focuses on the chloroplast DNA variation in three forest tree genera: Corylus, Betula and Salix. Chloroplast PCR-RFLP is used to evaluate the post-glacial history of hazel, Corylus avellana, silver birch, Betula pendula and sallow, Salix caprea and to explore the possibility of introgression in the Salix and Betula genera. In addition, the chloroplast matK gene, its flanking regions and the nuclear ADH gene were used to study the phylogenetic relationships within the Betula genus.</p>

<p>The aim of the study was to quantify the extent of inorganic chemical pollution of the Franschhoek River and draw relationships between contaminants in water, sediment and plants. The invasive Acacia mearnsii and Salix babylonica and indigenous Brabejum stellatifolium species were chosen as biomonitors due to their wide spread distribution along the river and their apparent ability to accumulate heavy metals. The sites chosen allowed for comparison of the river quality upstream with that of the river further down stream as it meandered through residential, agricultural and recreational areas, until it joined with the Berg River further downstream. The general aim of the study was to assess the degree of inorganic pollution in the Franschhoek River to evaluate its contribution to pollution of the Berg River, of which it is an important tributary. Also understanding the sources of the pollution would contribute to the ability to reduce pollution.</p>

The great difference in the level of chloroplast variation and its geographic structure among the three main species studied here demonstrates that forest species do not form a homogeneous group. Hazel shows a genetic structure similar to many other thermophilous species and this structure, in combination with fossil evidence, indicates that the post-glacial colonisation of most of Europe originated in a refugium in western France while the Balkan and Italy were colonised from a south-eastern refugium. In sallow and silver birch the chloroplast DNA variation and its structure does not fit with a scenario of glacial restriction to southern refugia and survival at intermediate latitudes is suggested for both species. The chloroplast DNA variation in silver birch suggests the presence of one western and one eastern European post-glacial colonisation route and limited contribution of southern populations in the colonisation of the rest of Europe. Unique haplotypes by the Ural Mountains indicates the possibility of a separate glacial origin of these populations. The study of chloroplast DNA in species closely related to sallow and silver birch indicate that extensive hybridisation and cytoplasmic gene flow occurs within both the Salix and Betula genera in Europe. The nuclear and chloroplast phylogenies of 14 Betula species were not in complete agreement with each other or with the classical division of the Betula genus into subgenera or sections. The phylogenetic structure implies that hybridisation has played a role in the evolution of the Betula genus. This thesis focuses on the chloroplast DNA variation in three forest tree genera: Corylus, Betula and Salix. Chloroplast PCR-RFLP is used to evaluate the post-glacial history of hazel, Corylus avellana, silver birch, Betula pendula and sallow, Salix caprea and to explore the possibility of introgression in the Salix and Betula genera. In addition, the chloroplast matK gene, its flanking regions and the nuclear ADH gene were used to study the phylogenetic relationships within the Betula genus.

2004 – 2005 m. Alytaus AB „Vilda“ gamybinėse gluosnių ir karklų plantacijose įrengtose lauko kolekcijose buvo atlikta gluosnio žilvičio (S. viminalis L.) ir kai kurių jo kultivarų bei hibridų klonų (S. viminalis kl. 04116, S. viminalis `Americana` žaliažievė forma kl. 9972, S. viminalis `Americana` kl. 9976, S. viminalis `Tordis`, S. purpurea x S. viminalis kl. 9714 ir kl. 04141) morfobiologiniai ir produktyvumo tyrimai. Nustatyta, kad I – II auginimo metais tirtųjų taksonų krūmai skiriasi pagal jų aukštį, atžalinių ūglių ir stiebų skaičių krūme, atžalinių ūglių vidutinį ilgį bei jų skersmenį ir nulaibėjimo pobūdį, lapų formą ir dydį, medienos ir šerdies plotį ūglio skerspjūvyje. Daugiausiai atžalinių ūglių (vytelių) antraisiais auginimo metais išaugino S. viminalis `Americana` žaliažievė forma kl. 9972 (649,8 tūkst.vnt./ha) ir S. purpurea x S. viminalis kl. 9714 (609,9 tūkst.vnt./ha). Intensyviausiu atžalinių ūglių krūmų augimu I-II-aisiais auginimo metais išsiskyrė S. viminalis `Tordis`, S. viminalis `Americana` kl. 9976 ir S. viminalis `Americana` žaliažievė forma kl. 9972. Didžiausią krūmo atžalinių ūglių masę I-II-aisiais auginimo metais išaugino S. viminalis `Americana` žaliažievė forma kl. 9972 (2004 m. – 17,1 t/ha,2005 m. – 44,4 t/ha), S. viminalis `Americana` kl. 9976 (2004 m. – 14,6 t/ha, 2005 m. – 48,9 t/ha), S. viminalis `Tordis` (2004 m. – 13,5 t/ha, 2005 m. – 34,8 t/ha). Didžiausią vieno krūmo vidutinė dvimečių... [toliau žr. visą tekstą] / In 2004 – 2006, in plantation of Alytus join stock company “Vilda”, there were researched and valued morphological characteristics and productivity of basket willow (Salix viminalis L.), some of its cultivares and clones of hybrids (S. viminalis cl. 04116, S. viminalis `Americana` green bark form cl. 9972, S. viminalis `Americana` cl. 9976, S. viminalis `Tordis`, S. purpurea x S. viminalis cl. 9714 and cl. 04141). It has been proved some differences between S. viminalis L., its cultivares and clones of hybrids in number and mass of sprouts and stems on a bush, the height of bushes, their diametre lenght and yield of twigs. The most valuable taxa of clones regarding productivity are S. viminalis `Americana` cl. 9972 (649,8 thou.unit/ha) and S. purpurea x S. viminalis cl. 9714 (609,9 thou.unit/ha). S. viminalis `Tordis`, S. viminalis `Americana` cl. 9972, S. viminalis `Americana` cl.9976 are the most intensively growing bushes and have the longest sprouts. In the field collections the highest mass of regrowth sprouts and stems are found by the clone 9976 of S. viminalis `Americana`(1828,9 gram) and S. viminalis `Tordis` (1774,9 gram). It has been discovered that within the period of 3 years taxa of S. viminalis L. reach the stated mass of dry stems per one ha: S. viminalis cl. 04116 – 35,5 t/ha, S. viminalis `Americana` žaliažievė forma cl. 9972 – 44,2 t/ha, S. viminalis `Americana` cl. 9976 – 50,1 t/ha, S. viminalis `Tordis` – 49,6 t/ha.

No description available.

<p>The aim of the study was to quantify the extent of inorganic chemical pollution of the Franschhoek River and draw relationships between contaminants in water, sediment and plants. The invasive Acacia mearnsii and Salix babylonica and indigenous Brabejum stellatifolium species were chosen as biomonitors due to their wide spread distribution along the river and their apparent ability to accumulate heavy metals. The sites chosen allowed for comparison of the river quality upstream with that of the river further down stream as it meandered through residential, agricultural and recreational areas, until it joined with the Berg River further downstream. The general aim of the study was to assess the degree of inorganic pollution in the Franschhoek River to evaluate its contribution to pollution of the Berg River, of which it is an important tributary. Also understanding the sources of the pollution would contribute to the ability to reduce pollution.</p>