Tesis sobre el tema "Pastures"

This thesis investigates how small disturbances influence community structure in three permanent pastures. Small disturbances play an important role in providing spatial heterogeneity that permits new recruits to enter populations in closed sward communities, thereby promoting diversity and species co-existence. The thesis has four components: the first two are based on observation and measurement of the occurrence of small disturbances, molehills and dung pats, in three pastures. Within pasture seasonal changes in disturbance regime were related to changes in patterns of species abundance by multidimensional contingency table analysis. Dactylis glomerata, Agropyron repens and Taraxacum officinale increased in highly disturbed plots, whereas Holcus lanatus and Trifolium repens decreased. Invasion of molehills and dung pats was usually by rhizomes or stolons from surrounding plants. Seedling recruitment was rare: Trifolium repens was the only species dependent on small gaps for sexual regeneration. Patterns of species replacement on and around the disturbances were non-random. The third part of the thesis investigated the effects of selective removal of Lolium perenne, Holcus lanatus and Trifolium repens from the oldest and youngest pastures. Strong responses to the removal of these species were found only in grasses in the youngest pasture. This is consistent with the hypothesis that competition decreases over time because of niche divergence, but may also reflect biological accommodation to grazing pressure. The fourth part of the thesis investigated changes in species composition in simulated swards in response to different regimes of mowing, fertilizer and small gap creation. Species composition was strongly influenced by mowing and fertilization but was unresponsive to small gap creation.
Science, Faculty of
Botany, Department of
Graduate

Treatment of endophyte-infected tall fescue [Lolium arundinaceum (Schreb.) Darbysh] with the broad leaf herbicide Chaparral® can mitigate fescue toxicosis and enhance forage quality by suppressing seedhead emergence. Applying the herbicide to fescue pastures also reduces forage mass and promotes severe spot grazing when pastures are continuously grazed. A grazing experiment was conducted with steers (2013) and heifers (2014) to evaluate animal and plant responses in fescue-bluegrass (Poa pratensis L.) mixtures treated with Chaparral to determine the effects of grazing management on pasture carrying capacity, nutritive values, botanical composition, and animal performance. Continuous and rotational (i.e., four subdivisions to provide a 7-d grazing period and a 21-d rest period) grazing treatments were assigned to six, 3.0-ha fescue-bluegrass pastures in a randomized complete block design with three replications. Each pasture had six tester animals, and stocking rates were varied using put-and-take animals. Pastures were grazed from 16 April to 8 July 2013 (Year 1) and 20 May to 12 Aug (Year 2) and cattle were blocked by body weight for allotment to pastures. Pasture carrying capacities were greater (P = 0.07) for rotational compared to continuous pastures across both years. Calves on rotationally grazed pastures had greater average daily gain (P = 0.03) and gain per acre (P = 0.05) than those on the continuous treatment across both years. Canopies of continuously grazed pastures contained less (P = 0.01) tall fescue than those in rotationally grazed pastures. Herbage in pre-grazed paddocks had less NDF and ADF than post-grazed paddocks and continuously grazed pastures in 2013 (P < 0.10), but did not differ in 2014 (P > 0.10). In vitro digestible dry matter was greater (P = 0.07) in pre-graze rotational pastures in 2013 compared with continuous and post-graze rotational, and IVDDM did not differ (P < 0.01) between pre-graze rotational and continuous in 2014, but was greater than post-graze rotational. Crude protein was lower (P = 0.06) in both years in post-graze rotational pasture than in continuous or pre-graze rotational pasture, which did not differ. In 2013, there was no difference (P = 0.60) in root WSC among treatments; however, in 2014, WSC levels were greater (P = 0.01) in rotationally grazed pastures compared with continuously grazed pastures. This grazing experiment indicated that rotational grazing of Chaparral treated fescue-bluegrass mixtures can improve both animal performance and the sustainability of pasture productivity.

Benefits of establishing legumes into permanent pastures have been well studied. Successful establishment of legumes in pastures can be challenging, however, and more information is needed about different seeding methods and variables that affect legume establishment. A pasture and a small plot experiment were conducted in Blacksburg, Va from 2009 to 2011to gain better understanding of how seeding method and management variables affected red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) establishment into permanent cool season grass pasture and sod. In the pasture experiment, seedling density was measured two months after sowing and grass, white clover, red clover, and weed biomass were periodically measured during the experiment. Broadcast seeding treatment had 93% more clover seedlings than drill treatment (P = 0.1087) two months after sowing. No difference (P > 0.10) for clover biomass was observed between sowing treatments in any year and clover establishment was considered successful (over 25% of pasture composition) in both treatments. In the drill treatment, clover seedling density was negatively affected by the residual grass biomass at sowing (P = 0.0196). In the broadcast treatment, a quadratic relationship between clover seedling density and residual grass biomass at sowing was found (P = 0.0516). Clover seedling density in April 2009 determined the amount of clover biomass in August 2009 (P = 0.0008) and the 2010 clover biomass mean (P = 0.0249). Further exploration of the influence fertilization with P and K, grass biomass at sowing, and defoliation frequency on clover establishment were studied in a split-split plot study. iii Fertilization with P and K was assigned to whole plots that were split in half and assigned a high or low grass biomass at sowing treatment, the subplots were split in and designated either a high or low cutting frequency. Prior to cutting, samples from each plot were sorted to grass, white clover, red clover, and weed. Plots with a low grass biomass at sowing (232 seedlings m-2) had a higher seedling density (P < 0.0001) compared with plots with a high grass biomass at sowing plots (111 seedlings m-2). Greater biomass of white and red clover depended both on having a low grass biomass at sowing and a high frequency of defoliation (P = 0.0026 and P < 0.0001, respectively). Red clover yield was also determined by interactions between fertilization and a high frequency of defoliation (P < 0.0001), as well as between fertilization and low grass biomass at sowing (P = 0.0026). Dry conditions resulted in low clover yields (6% of total herbage mass) with red clover producing four times the herbage mass of white clover. These data show that creating a favorable environment for seedlings to germinate and establish was more important than seeding method.
Master of Science

Pastures established using buffelgrass (Cenchrus ciliaris L.) have shown heterogeneous responses in terms of forage production and permanence. A good alternative for determining establishment sites and predict trends in buffelgrass conditions is the use of simulation models. The objectives of this research were to determine the factors that regulate successfulness in buffelgrass pastures and to develop a model to determine suitability in areas managed for buffelgrass pastures, based on environmental, ecological, and management variables. Above ground biomass production was considered to determine suitability in sites with buffelgrass. Eight ranches with different geographic locations, environmental situations, and management conditions were sampled as preliminary study sites to measure and model plant production. The resulting model was used to estimate plant production in the 37 sampling sites of the study areas. Results of the study indicate that basal area is a good modeling parameter to estimate production in buffelgrass plants. I also found that plant production in buffelgrass is negatively affected by population density. I concluded that there exist a positive correlation between pasture management and buffelgrass plant production. Correlation analyses demonstrate that there exist significant correlations between Pasture Condition Index (PCI) and mean annual temperatures, aspect, pasture age, nitrogen and sodium content. However, after performing stepwise regressions, only three variables were significant: pasture age (PA), nitrogen content (N2), and mean annual temperature (MAT); the last two, produce a negative response on PCI.

The annual and seasonal water use efficiency of six pasture combinations were calculated from the ‘MaxClover’ Grazing Experiment at Lincoln University. Pastures have been established for six years and are grazed by best management practices for each combination. Measurements for this study are from individual plots of four replicates of ryegrass (RG)/white clover (Wc), cocksfoot (CF)/Wc; CF/balansa (Bal) clover; CF/Caucasian (Cc) clover; CF/subterranean (Sub) clover or lucerne. Water extraction measurements showed soils for all dryland pastures had a similar plant available water content of 280±19.8 mm. Dry matter measurements of yield, botanical composition and herbage quality were assessed from 1 July 2008 until 30 June 2009. Lucerne had the highest annual yield of 14260 kg DM/ha/y followed by the CF/Sub at 9390 kg DM/ha/y and the other grass based pastures at ≤ 6900 kg DM/ha/y. All pastures used about 670±24.4 mm/y of water for growth. Lucerne had the highest annual water use efficiency (WUE) of 21 kg DM/ha/mm/y of water used (total yield/total WU). The WUE of CF/Sub was the second highest at 15 kg DM/ha/mm/y, and the lowest was CF/Wc at 9 kg DM/ha/mm/y. The CF/Sub pastures had the highest total legume content of all grass based pastures at 21% and as a consequence had the highest annual nitrogen yield of 190 kg N/ha. This was lower than the monoculture of lucerne (470 kg N/ha). Ryegrass/white clover had the highest total weed component in all pastures of 61%. For dryland farmers spring is vital for animal production when soil temperatures are rising and moisture levels are high. The water use efficiency at this time is important to maximize pasture production. In spring lucerne produced 8730 kg DM/ha, which was the highest dry matter yield of all pastures. The CF/Sub produced the second highest yield of 6100 kg/DM/ha. When calculated against thermal time, CF/Sub grew 5.9 kg DM/ºCd compared with lucerne at 4.9 kg DM/ºCd. The higher DM yield from lucerne was from an extra 400 ºCd of growth. The highest seasonal WUE of all pastures occurred in the spring growing period. Linear regressions forced through the origin, showed lucerne (1/7/08-4/12/08) had a WUE of 30 kg DM/ha/mm (R2=0.98). Of the grass based pastures, CF/Sub produced 18 kg DM/ha/mm (R2=0.98) from 1/7 to 10/11/08 from 270 mm of water used. The lowest spring WUE was 13.5 kg DM/ha/mm by CF/Bal pastures which was comparable to the 14.3±1.42 kg DM/ha/mm WUE of CF/Wc, CF/Cc and RG/Wc pastures. During the spring, CF/Sub clover had the highest spring legume component of the grass based pastures at 42% and produced 120 kg N/ha. This was lower than the 288 kg N/ha from the monoculture of lucerne. Sub clover was the most successful clover which persisted with the cocksfoot. Based on the results from this study dryland farmers should be encouraged to maximize the potential of lucerne on farm, use cocksfoot as the main grass species for persistence, rather than perennial ryegrass, and use subterranean clover as the main legume species in cocksfoot based pastures. By increasing the proportion of legume grown the water use efficiency of a pasture can be improved. When pastures are nitrogen deficient the use of inorganic nitrogen may also improve pasture yields particularly in spring.

Cirsium arvense (L.) Scop. (Canada thistle) is a persistent perennial pasture weed in Eastern Canada. Single control measures such as cultural, chemical, and biological methods are not effective in long term reduction of the weed population. The objectives of this research project were to evaluate the efficacy of various traditional control methods and to attempt to integrate them.
The effectiveness of Urophora cardui L. as a biological control agent is limited due to a lack of synchrony between the agent and the weed. This can be improved through integration with herbicides or mowing in time or space. Other biological control agents such as Orellia ruficauda Fab., Cassida rubiginosa Muell., and Puccinia punctiformis (Str.) Rhol. resulted in limited suppression of the weed population. Mowing was not effective in sustaining weed reductions for longer than one year. Application of clopyralid or 2,4-D/dicamba effectively reduced the weed population. The application of 3.37 kg a.i. ha$ sp{-1}$ 2,4-D/dicamba or 0.3 kg a.i. ha$ sp{-1}$ clopyralid with the spring and summer mowings were the most effective mowing/herbicide combinations over the two-year period.

Spiny amaranth is a problematic weed of heavily grazed pastures in Kentucky and surrounding states. The first objective was to evaluate spiny amaranth control when herbicides are applied before and after emergence. Spiny amaranth seed collected in 2008 were seeded in rows in the fall (November) and the following spring (March) in fields located near Lexington and Princeton, KY. Treatments consisted of five application dates and five herbicides plus an untreated control arranged in a split-split plot design. The following parameters were measured: fresh weight, plant height and percent visual control. At both locations pendimethalin applied in November, March and April before spiny amaranth emergence gave the greatest control and significantly reduced fresh weight biomass compared to other treatments. June applications of 2,4-D reduced plant height and provided 80 control. Fresh weight biomass and height were also reduced with dicamba, aminopyralid and aminocyclopyrachlor applied in June compared to pendimethalin and the untreated control. A soybean bioassay was conducted to measure soil dissipation of aminopyralid, a common pasture herbicide active ingredient. Soil samples were collected from two sites in Lexington and Princeton. During a season of above average rainfall aminopyralid had dissipated from the soil within 16 weeks at Lexington and by 4 weeks at Princeton.

The evolutionary consequences of interactions between neighbouring plants of Trifolium repens and three selected grasses were studied in a series of different-aged pastures. Experiments were conducted at three different levels of interaction; between species, between populations, and between individuals. The primary objective was to examine under natural conditions the relevance of two revolutionary theories of species coexistence - niche differentiation and competitive equivalence. Additional studies focused on the differentiation of T. repens subpopulations in response to neighbouring grasses, on the presence of carry-over effects, and the validity of extrapolating the results of greenhouse studies to predictions of natural pasture processes. Plants collected from different pastures showed different patterns of growth in a common garden. These patterns appeared to be related to the age of the pasture from which the plants were originally collected. Occasionally, species which were poorer competitors in 3'ounger pastures became superior competitors in mixtures from older pastures. Plants grown under natural field conditions were affected by both competitive and non-competitive forces. Non-competitive factors such as grazing, disturbance, and/or abiotic conditions, killed more individuals and accounted for more variation in growth than did competitive factors. However, plant interactions were important, including both competitive effects on neighbours and competitive responses to neighbours. These competitive effects and responses were not symmetrical and each appeared to behave independently. The balance between the intensity of intra- and inter-specific competition was critical. Two pairs of species which were more adversely affected by interspecific competition showed evidence of increased niche separation in older compared to younger pastures. A third pair of species was more affected by intraspecific competition and showed a decrease in niche separation in older pastures. These results support the theory that competition leads to changes in the pattern of resource use. The ability to predict the growth of species under natural pasture conditions from either greenhouse or controlled garden conditions was poor. This lack of predictability, when coupled with the observed rapid evolution of a species' competitive ability, suggests that caution should be exercised in developing theories based upon greenhouse growth characteristics or on "species" characteristics. Unlike previous studies in a Welsh pasture, no evidence of long-term specialization of Trifolium repens to patches of neighbouring grasses was found. Differences in the age of the pastures, and the average patch size of the neighbouring grasses (environmental grain) may explain these differences.
Science, Faculty of
Botany, Department of
Graduate

Pathogenic microorganisms introduced by cattle may be transported to distant locations via watershed runoff. Escherichia coli, Enterococcus spp., and Streptococcus spp. are a few species present in runoff from land impacted by humans, cattle, and wildlife. Initial data reveals that E. coli concentrations in water are greater in areas impacted by cattle than by humans. And, wildlife contributes greater concentration fluctuations than either humans or cattle. When cattle are removed from a pasture, the bacterial concentrations rapidly decrease; however, slight variations in cattle herd size do not appear to significantly influence these counts. Amplified fragment length polymorphisms (AFLP) and repeated-sequence polymerase chain reactions (rep-PCR) are molecular techniques used in this study to assess the impact of several cattle pastures on one rural communities? watershed system. DNA fingerprints, along with data plots, reveal a direct link between cattle load and bacterial concentrations, as well as seasonal trends, possibly due to migratory wildlife.

Our objective was to identify the major barriers to natural regeneration of tree species in abandoned Panamanian pastures as a first step in formulating management strategies to facilitate forest recovery. We tested whether fire, seed dispersal, and the presence of an introduced grass, Saccharum spontaneum L., were barriers to forest regeneration. We examined growth, survival, and density of both experimentally-introduced and naturally-regenerating tree seedlings using a series of multifactorial experiments.
We found that seed dispersal limits forest regeneration. Large-seeded species have the highest performance in the Saccharum spontaneum, but were found in the lowest abundance in natural conditions. Small-seeded species were most frequently observed, but they have the lowest survival. We conclude that dispersal limitations preclude entry of the larger-seeded species. Distance from the forest limits dispersal of many small-seeded species. Fire is a major barrier to natural regeneration because it lowers species diversity.

FundaÃÃo de Amparo à Pesquisa do Estado do CearÃ
Objetivou-se com esse trabalho avaliar os efeitos da intensificaÃÃo da produÃÃo de leite, via nÃveis de intensificaÃÃo do sistema, em pastagens de capim-mombaÃa (Panicum maximum Jacq. cv. MombaÃa) no trÃpico Ãmido, durante o perÃodo das Ãguas. Os tratamentos consistiram de quatro nÃveis de intensificaÃÃo, determinados pela combinaÃÃo de nÃveis de adubaÃÃo e nÃvel de produÃÃo dos animais. Foram eles, na sequÃncia crescente de intensificaÃÃo: 1  adubaÃÃo com 400 kg de NÃha-1Ãano-1, com vacas de baixa produÃÃo; 2 adubaÃÃo com 800 kg de NÃha-1Ãano-1, com vacas de baixa produÃÃo; 3 adubaÃÃo com 400 kg de NÃha-1Ãano-1, com vacas de alta produÃÃo; 4 adubaÃÃo com 800 kg de NÃha-1Ãano-1, com vacas de alta produÃÃo. As vacas eram sem raÃas definidas, em mÃdia de terceira cria, com partos ocorridos em outubro/novembro de 2009. No inÃcio das avaliaÃÃes de produÃÃo de leite, encontravam-se com aproximadamente 110 dias de lactaÃÃo. O perÃodo experimental foi de 24 de dezembro de 2009 a 10 de maio de 2010. Para as medidas relacionadas à morfogÃnese e estrutura, foi utilizado o delineamento inteiramente casualizado, com medida repetida no tempo. Quatro tratamentos, com quatro ciclos e quatro repetiÃÃes (piquetes), avaliando a interaÃÃo entre tratamentos e ciclos. Para a avaliaÃÃo do comportamento dos animais, foi utilizado o delineamento inteiramente casualizado, com quatro tratamentos, oito perÃodos e quatro repetiÃÃes (animais), avaliando a interaÃÃo entre tratamentos e perÃodos. Na avaliaÃÃo da distribuiÃÃo de fezes, foi utilizada a anÃlise geoestatÃstica, com quatro tratamentos e trÃs repetiÃÃes (piquetes). Nas anÃlises de produÃÃo dos animais, foi utilizado delineamento inteiramente casualizado simples (placas de fezes, total de fezes, consumo de forragem e consumo total), com medidas repetidas no tempo (escore de condiÃÃo corporal e peso vivo) e com medidas repetidas no tempo, sendo o tempo medida de controle local (produÃÃo de leite por vaca, peso vivo, taxa de lotaÃÃo e produÃÃo de leite por hectare). O perÃodo de descanso utilizado foi o necessÃrio para que fosse possÃvel a expansÃo de 2,5 novas folhas e o resÃduo equivalente ao IAF residual 2,0. O maior fornecimento de nitrogÃnio nÃo proporcionou elevaÃÃo nas variÃveis TAlF, TAlH, TSFant e TSFpost. NÃo foram observadas diferenÃas entre tratamentos em funÃÃo dos tipos de animais. A TAlF segue, em parte, a disponibilidade de Ãgua oriunda da precipitaÃÃo. NÃo houve diferenÃa na TAlH em funÃÃo dos tratamentos. Esse efeito, sendo reflexo do perÃodo de descanso adotado (2,5 novas folhas à perfilho-1), reduziu o nÃvel de interceptaÃÃo da radiaÃÃo fotossinteticamente ativa para valores inferiores a 95%. A intensificaÃÃo apresenta pouco reflexo nas variÃveis estudadas (MSFT, MSFV, MSLV e MSCV). A altura prÃ-pastejo apresentou crescimento do primeiro para o segundo ciclo e posterior declÃnio atà o Ãltimo ciclo, sendo esse o que apresentou os menores valores, para todos os tratamentos. A elevaÃÃo da oferta de nitrogÃnio proporcionou maiores nÃveis de produÃÃo em determinados momentos, quando da oferta de Ãgua em nÃveis adequados. A disponibilidade de Ãgua influenciou a resposta da produÃÃo das pastagens ao longo dos ciclos. Houve relaÃÃo do teor de matÃria orgÃnica do solo e o desempenho produtivo das pastagens. Quanto ao comportamento dos animais, foi observado interaÃÃo entre os tratamentos e os perÃodos do dia, com exceÃÃo do âcomportamento urinandoâ que sà apresentou efeito de perÃodo. A adubaÃÃo influenciou positivamente no âcomportamento pastejandoâ, elevando o tempo gasto na expressÃo do mesmo. Para Outras atividades, o efeito foi negativo, diminuindo o tempo de deslocamento dos animais. A adubaÃÃo e a interaÃÃo a adubaÃÃo à suplemento proporcionaram maior tempo de utilizaÃÃo de sombra pelos animais. A utilizaÃÃo de alimento concentrado elevou o nÃmero de defecaÃÃes, com concentraÃÃo durante os perÃodos de maior permanÃncia no pasto. O perÃodo do dia influenciou o âcomportamento bebendoâ, causando maior consumo de Ãgua nos perÃodos de maiores temperaturas, assim como os tratamentos intermediÃrios apresentaram maiores consumos. No que se refere à distribuiÃÃo de fezes, os dados apresentaram coeficientes de assimetria positiva e de curtose platicÃrtica. Para o coeficiente de variaÃÃo verificou-se uma elevaÃÃo acentuada, com as Ãreas de descanso, apresentando maiores valores e piquetes com maior nÃvel de adubaÃÃo e menores valores. Os fatores climÃticos radiaÃÃo, temperatura e umidade relativa influenciaram significativamente na dispersÃo e localizaÃÃo das fezes. No que se refere ao grau de dependÃncia espacial (GDE), foi verificado classificaÃÃo, variando de moderado a forte. O alcance foi de 14,0 e 12,7 m para as Ãreas de descanso e piquetes, respectivamente. A adubaÃÃo e o fornecimento de concentrado influenciaram a deposiÃÃo e a perda de nitrogÃnio via fezes, elevando seus valores na medida em que se elevou o aporte nutricional. Observou-se heterogeneidade na deposiÃÃo das fezes, ocorrendo zonas de maior concentraÃÃo, como sombra, entrada de piquetes e malhadouro, mostrando picos de deposiÃÃo que chegaram a 1.051,2 kg de N à ha- à ano- e mÃdia variando de 148,8 a 210,7 kg de N à ha- à ano-Â. Houve crescimento das produÃÃes diÃrias e por Ãrea de leite, na medida em que intensificou o sistema. Com a intensificaÃÃo houve maior persistÃncia da lactaÃÃo, observado por meio da relaÃÃo obtida pela divisÃo do coeficiente angular pelo intercepto, resultando em percentual diÃrio de diminuiÃÃo da lactaÃÃo. A persistÃncia da produÃÃo dos animais respondeu diretamente à intensificaÃÃo do sistema, como reflexo da maior intensificaÃÃo (melhoria da dieta). A produÃÃo por Ãrea respondeu mais fortemente ao nÃvel de produÃÃo individual diÃria e segue comportamento quadrÃtico, de acordo com a distribuiÃÃo das chuvas. A produÃÃo fecal cresceu no sentido do maior nÃvel de intensificaÃÃo, resultando em maiores estimativas de consumo. O maior aporte de nutrientes (mais intensivo) possibilitou elevar os nÃveis de produtividade por animal, por Ãrea, em relaÃÃo à mÃo-de-obra e à produÃÃo total diÃria. A maior intensificaÃÃo possibilitou elevar as receitas, todavia elevou os custos totais mensais, apresentando melhor relaÃÃo nos nÃveis intermediÃrios de intensificaÃÃo. Na medida em que se elevou a Ãrea utilizada, o nÃvel menos intensivo apresentou margem bruta positiva. Os custos operacionais efetivos elevaram-se com a intensificaÃÃo dos sistemas. Jà os custos operacionais totais diminuÃram com a intensificaÃÃo, voltando a crescer no nÃvel mais intensivo. A alimentaÃÃo representou por volta de 70% dos custos operacionais efetivos. Os sistemas apresentaram-se inviÃveis no mÃdio-longo prazo, e no curto prazo, foram menos atrativos que o observado na amostra de produtores utilizada nesse estudo.
This study aimed at analyzing the intensification effects via different enhancement levels of the system of milk production in Mombasa grass pastures (Panicum maximum Jacq. cv. MombaÃa) in the humid tropics, during the water period. Treatments consisted of four enhancement levels, determined by combining fertilization levels and production level of the animals. Treatments were in increasing sequence of fertilization, as follow: 1Â Â fertilization with 400 kg of NÃha-1Ãyear-1, with low yield dairy cows; 2ÂÂ fertilization with 800 kg of NÃha-1Ãyear-1, with low yield dairy cows; 3ÂÂ fertilization with 400 kg of NÃha-1Ãyear-1, with high yield dairy cows; 4ÂÂ fertilization with 800 kg of NÃha-1Ãyear-1, with high yield dairy cows. It was used mixed breed cows, on average of third calving, and the births had occurred in October/November 2009. At the beginning of the evaluation of milk production, the cows had around 110 days of lactation. The experiment was conducted between December 24th, 2009 and May 10th, 2010. For the measures related to the morphogenesis and structure, we used a completely randomized design with repeated measurements over time. Four treatments, with four cycles, and four replicates (paddocks) were used to assess the interaction between treatments and cycles. To evaluate the behavior of the animals, we used a completely randomized design, with four treatments, eight periods and four replicates (animals) to evaluate the interaction between treatments and periods. In the evaluation of the distribution of feces, a geostatistical analysis was applied, with four treatments and three replicates (paddocks). In the analysis of animal production, a simple completely randomized design (feces patches, total feces, forage intake and total consumption), with repeated measures over time (body condition score and live weight) and with repeated measures over time; the time considered the measure of local control (milk yield per cow, live weight, stocking rate, and milk production per hectare). The rest period was the necessary to enable the expansion of 2.5 new leaves and the residue equivalent to the residual leaf area index 2.0 (residual LAI 2.0). The greater supply of nitrogen has not provided increase in the following variables: leaf elongation rate (TAlF), stem elongation rate (TAlH), anterior leaf senescence rate (TSFant) and posterior leaf senescence rate (TSFpost). There was no difference among treatments as a function of the type of animals. The TAlF partly had followed the availability of water from the rainfall. It was observed a variation in the organic matter content throughout the area, reflected in the ability to store water and nutrients, which influenced their availability to the pastures. No difference was detected in TAlH in function of treatments. This effect was a result of the rest period adopted (2.5 new leavesÃtiller-1), reducing the capture level of photosynthetically active radiation to values below 95%. The intensification has little consequence on studied variables (total forage dry mass, green forage dry mass, green leaf blade dry mass, and green stem dry mass). The pre-grazing height presented growth from the first to the second cycle and a subsequent decline until the last cycle, considering that this had the lowest values for all treatments. The increase in nitrogen availability promoted higher yield levels at certain moments, when water was supplied at suitable levels. Water availability influenced the yield response of pasture over the cycles. A relationship was verified between the soil organic matter content and yield performance of pastures. Regarding the animals behavior, it was registered interaction between treatments and day periods, except for urinating behavior that was only affected by the period. The fertilization had positive influence on the grazing behavior, increasing the time spent to expressing it. For the other activities the effect was negative, reducing the displacement time of animals. The fertilization and the interaction fertilization x supplement provided a longer use of shading by the animals. The use of concentrate feed increased the number of defecations, especially during the periods of longer permanence in the pasture. Day period influenced the drinking behavior, leading to a higher consumption of water in the periods with higher temperatures, as well as intermediate treatments presented higher consumption. In relation to the feces distribution, the data had coefficients of positive skewness and platicÃrtica kurtosis. For the coefficient of variation, we verified a great variation, with the rest areas presenting higher values, and paddocks with higher fertilization level presenting the lowest values. Climatic factors radiation, temperature and relative humidity have significantly influenced the dispersal and location of the feces. Regarding the degree of spatial dependence (GDE) it was verified classification ranging from moderate to strong, with higher proportion of GDE. The range was between 14.0 and 12.7m for rest areas and paddocks, respectively. The fertilization and supply of concentrate influenced the deposition and loss of nitrogen via feces, increasing its values to the extent that it increased the nutrient input. We observed heterogeneity in deposition of feces, with areas of higher concentration, as shadow, entrance of paddocks, and rest area, presenting peaks of deposition reaching 1,051.2kg NÃha-ÂÃyear-Â, and average varying between 148.8 and 210.7 NÃha-ÂÃyear-Â. There was increase in milk daily production and per area, as it intensified the system, via enhancement. With the intensification there was a greater persistence of lactation, observed through the relationship obtained by dividing the slope per intercept, resulting in a daily percentage of decrease in lactations. The persistence of animalsâ production responded directly to the system intensification, as a consequence of higher enhancement (improved diet). The production per area responded more strongly to the level of individual daily production and followed a quadratic trend, accompanying the rainfall distribution. The fecal production increased towards the highest level of enhancement, resulting in higher estimates of consumption. The greater input of nutrients (more intensive) allowed elevating the productivity levels per animal, per area, in relation to the labor and total daily production. The increase in area used for production improves the investment/production ratio, decreasing as enlarges the area. The greater enhancement enabled raising the revenues, but also raised the total monthly costs, presenting better relationship the intermediate levels of enhancement. To the extent that it has increased the area used, the lowest intensive level had a positive gross margin. The actual operating costs increased as the systems had been intensified. But the total operating costs decreased with the intensification, increasing again at the most intensive level. The feed represented around 70% of actual operating costs. Systems were unfeasible at medium-long terms, and at short term they were less attractive than observed in the sample of producers used in this study.

A series of four trials over the grazing season were conducted to evaluate the nutritional status of beef cows grazing reclaimed strip-mined pastures in southwestern, Virginia. Blood samples, esophageal fistula forage samples and hand plucked forage samples were taken in each trial. An external marker, Ytterbium, and an internal marker, indigestible neutral detergent fiber (INDF) were used to estimate organic matter intake, fecal output and digestibility. In addition to samples taken during the trials, blood samples and hand plucked forage samples were taken monthly for 11 mo prior to the trial period. In late summer esophageal masticate samples had a low fiber fraction (ADF and NDF), high crude protein and total nonstructural carbohydrates (TNC) which contributed to a high organic matter digestibility. Hand plucked forage samples had higher TNC than esophageal masticate samples. Organic matter digestibility predicted by the internal marker was highest in late summer 61.6%, similar in spring and late fall, and lowest in mid-summer, 52.6% (p < .01). Fecal output was highest in mid-summer and lowest in spring (p < .05). Estimated intake was not significantly different in any of the trials. Although data was variable, forage quality was higher in May, June, October and November samplings, as indicated by highest CP, TNC, and lower NDF and ADF values, compared with July and August data when forage quality was lowest. Packed cell volume, BUN and serum P and Mg concentrations fell within normal ranges for beef cattle. Low BUN values were observed in spring and late fall which corresponded to low crude protein values observed in the esophageal masticate samples for the same trials. Serum Cu was on the low end of normal values in the late spring and decreased to .6 ppm by late fall. Serum K levels were above the expected values for beef cattle. Serum Na concentrations were lower than normal with lowest values observed throughout spring and summer months.
M.S.

The Pastures of Heaven is John Steinbeck’s second published literary work. It was released in 1932 when only few knew the writer’s name: in fact, only seven years later he would become the well-known author of The Grapes of Wrath, one of the greatest American novels. The Pastures of Heaven belongs in the genre of the short story cycle, although the writer himself referred to these individual portraits as “tiny novels”. Primarily, what these stories have in common is the underlying unity of place and the recurring presence of the Munroe family, together with various thematic threads such as the clash between domestic tragedies and the idea of an idyllic life among the pastures. The detailed descriptions of the valley allow the reader to create a virtual map of the place: they are polished and evocative, almost naturalistic. Furthermore, in the stories each character inhabiting this thriving setting is depicted with a distinctive coloring and at times with bitter irony, but these individual frameworks are not independent and self-contained. As a matter of fact, meaning is added when these portraits are read in relationship to one another, forming “an emerging community of co-protagonists” . The following research stems from this premise, as recent works in the field of literary theory have provided new tools to interpret the relationship between the characters and the setting. Studies on description by Mieke Bal and Patricia Hampl, and in-depth analysis on characterization by Ralf Schneider and Uri Margolin have outlined new frameworks for literary analysis that allow a new reading of The Pastures of Heaven. In the first place, this work will gather previous studies on Steinbeck’s text that will facilitate the contextualization of the piece both in its time and in its genre’s guidelines. In fact, Steinbeck’s formal choice for the genre of this literary work cannot pass unnoticed. Short story cycles developed in the context of literary modernism and were also dubbed as “narratives of community” by English Professor Sandra A. Zagarell. Later on, in light of the aforementioned new literary theories, this study will explain how description works as an amplification of characterization and how characters’ hopes and expectations are linked to the setting. Moreover, considering Steinbeck’s interests for early ecology encouraged by his friend Ed Rickett, particular relevance will be given to how he was able to re-create houses and domestic spaces that act as places of synthesis between the characters’ interiority and the land. In conclusion, the aim will be to point out the literary devices that allow the text’s polyphony and the ways in which characters and territory enter one single harmony chorally.

In the Italian Alps, summer pastures are still managed in traditional ways, which maintain important grassland habitats of many species, although the number of pastures has declined drastically over the past few decades. Research on alpine pastures is important in many respects. From the aspect of nature protection, pastures represent a habitat for numerous plant and animal species; and, through their diversity, contribute greatly to the biodiversity and scenic value of the area. From the economic standpoint, grasslands are a source of feed for stock, a habitat for medicinal and melliferous plants. They are also capable of supporting particular dairy products, high added value, because fodder obtained from natural with unique qualities and not reproducible, capable of giving products derived valuable characteristics and identification. Land use changes constitute a threat to the persistence of these grassland ecosystems Therefore, it is very important to understand the mechanisms leading to the organization and distribution of these communities to preserve plant diversity and to develop effective agri-environment schemes, which can maintain and enhance biodiversity. Phytosociological investigation is important to understand some aspects of the study of grasslands. As in the forestry sector, also in grasslands sector have arisen in recent years some efforts to characterize, according to a typological approach, pasture vegetation. A purpose of this research was to realize an interpretative classification of pastures of Province of Trento. Since the pastures of the study area have not been systematically investigated for a long time, the pasture vegetation of the Province of Trento was classified using numerical methods, then the results were compared with the traditional syntaxonomic system, and finally were examined the influence of ecological factors on variation in grassland vegetation. Further aim of the research was assessed the relationship between topography, distance from the farm centre, altitude, bedrock, grazing intensity, species richness and vegetation composition across two spatial scales (within and between summer farms). A stratified random sampling design was used to collect 157 vegetation relevés along an elevation gradient. It was hypothesized that plant diversity varies in response to topography due to the highly variable alpine environment and it depends strongly not only on grazing spatial gradient from the centres of the farms to the surrounding vegetation, but also on spatial distribution of the management practices within the study region The patterns of species richness and species composition found in alpine pastures result from the interaction of different environmental and management factors operating at different spatial scales. The results indicate that at small scales (within farms) species richness is mainly determined by slope, while specie composition is controlled by distance from the farm centre as well as slope. At large scale (between farms), was observed a key role of grazing intensity and bedrock types on species diversity patterns. The results indicate that the identification of appropriate stocking rates appears to be the most promising approach to conserve the high biodiversity of alpine pastures, as both intensification and abandonment changed species composition and reduced plant species diversity. Finally, to gain insight into the processes that may affect species diversity and functional diversity in alpine pastures, the observed local patterns of additive species diversity components (α-, β-, γ-) were analysed with respect to altitude, landscape, topographic hetereogeneity, bedrock type and grazing intensity. Additive diversity partitioning approach facilitated a quantification and comparison of the relative contributions of α- and β-diversity components to total regional diversity along an elevation gradient. Based on the results, I conclude that the observed patterns of plant species diversity appeared to be influenced by processes at multiple spatial scales. The results indicate that the maintenance of a large variety of grassland utilisation systems along with heterogeneous abiotic environmental conditions appears to be a promising tool for the conservation of species richness and functional diversity due to enhanced β-diversity among pastures parcels.
Nelle Alpi italiane, gli alpeggi sono ancora gestiti in maniera tradizionale, conservando importanti habitat e specie vegetali, sebbene il numero delle malghe monticate sia diminuito drasticamente negli ultimi decenni. La ricerca sui pascoli alpini è importante sotto molti aspetti. Dal punto di vista della protezione della natura, i pascoli rappresentano l'habitat di numerose specie vegetali ed animali e attraverso la loro ricchezza di specie, contribuiscono notevolmente alla biodiversità ed al valore paesaggistico delle Alpi. Dal punto di vista economico, i pascoli sono una fonte di alimentazione per gli animali, ed habitat per piante officinali e mellifere. Sono anche in grado di supportare prodotti lattiero-casearii particolari, ad alto valore aggiunto, perché ottenuti da foraggi naturali con caratteristiche uniche e non riproducibili, in grado di dare prodotti derivati di qualità. I cambiamenti di uso del suolo costituiscono una minaccia per la persistenza di questi ecosistemi. Pertanto, è molto importante comprendere i meccanismi che controllano l'organizzazione e la distribuzione di queste comunità, per preservare la diversità delle piante e di sviluppare efficaci schemi agro-ambientali, in grado di mantenere e migliorare la biodiversità. L’analisi fitosociologia è importante per comprendere alcuni aspetti dello studio delle praterie. Come nel settore forestale, anche in quello pastorale sono iniziati negli ultimi anni alcuni progetti per caratterizzare, secondo un approccio tipologico, le vegetazioni pascolive. Uno degli obiettivi di questa ricerca era quello di realizzare una classificazione interpretativa dei pascoli della Provincia di Trento. Poiché i pascoli della zona oggetto di studio non sono mai stati studiati in modo sistematico, la vegetazione dei pascoli della Provincia di Trento è stata classificata utilizzando metodi numerici; i risultati sono stati confrontati con il sistema tradizionale sintassonomico e, infine, è stata analizzata l'influenza dei fattori ecologici sulla variazione della composizione floristica dei pascoli. Un successivo obiettivo della ricerca era quello di valutare la relazione tra la topografia, la distanza dal centro aziendale, l'altitudine, il tipo di substrato geologico, l’intensità di pascolamento, la ricchezza di specie e la composizione della vegetazione attraverso due scale spaziali (all'interno e tra le malghe campionate). Un disegno sperimentale stratificato è stato utilizzato per campionare i 157 rilievi vegetazionali lungo un gradiente altitudinale. E’ stato ipotizzato che la diversità vegetale varia in risposta della topografia legata all'ampia variabilità ambientale degli ambienti alpini, e dipende in modo consistente non solo dal gradiente spaziale di pascolamento dal centro della malga alle vegetazioni marginali, ma anche dalla distribuzione spaziale delle pratiche gestionali impiegate nell’area di studio. I modelli di distribuzione della ricchezza di specie e della composizione riscontrati nei pascoli alpini derivano dall'interazione di diversi fattori ambientali e gestionali che operano a diverse scale spaziali. I risultati indicano che su piccola scala (all’interno delle malghe), la ricchezza di specie è principalmente controllata dalla pendenza, mentre la composizione vegetazionale è determinata dalla distanza dal centro della malga, e dalla pendenza. Su larga scala (tra le malghe), è stato osservato un ruolo chiave dell’intensità di pascolamento e del tipo di substrato geologico sulla ricchezza di specie. I risultati indicano che l'individuazione di appropriati indici di carico animale sembra essere l'approccio più promettente per la conservazione della biodiversità dei pascoli alpini, poiché, sia l’intensificazione gestionale che l’abbandono cambiano composizione delle specie e riducono la diversità delle specie vegetali. Infine, al fine di conoscere i processi che possono influenzare la diversità delle specie e, la diversità funzionale nei pascoli alpini, i diversi componenti additivi della biodiversità (diversità -α, -β e -γ) sono stati analizzati in relazione all'altitudine, alle variabili del paesaggio, dell’eterogeneità topografica, del tipo di substrato geologico e l'intensità di pascolamento. L’approccio della partizione additiva della diversità facilita la quantificazione ed il confronto tra i contributi relativi delle componenti -α-e –β della diversità rispetto al totale delle diversità regionale lungo un gradiente altitudinale. Sulla base dei risultati ottenuti, è stato osservato che la diversità vegetale sembra essere influenzato dai processi operanti a differenti scale spaziali. I risultati indicano che il mantenimento di una grande varietà di tipi gestionali, insieme alle condizioni ambientali eterogenee delle zone alpine sembra essere uno degli strumenti più favorevoli per la conservazione delle ricchezza di specie e della diversità funzionale, contribuendo ad aumentare la diversità β tra i pascoli.

Thesis (M.S.)--West Virginia University, 1999.
Title from document title page. Document formatted into pages; contains v, 44 p. Vita. Includes abstract. Includes bibliographical references (p. 30-35).

This study aimed to contribute to the understanding of the morphogenesis and structure of signal grass (Brachiaria decumbens Stapf.) pastures, and how they are affected by the environment and cattle defoliation. A diagrammatic model was adopted to identify and relate the major morphogenetic and structural characteristics at different levels of organisation of the sward: phytomer, tiller, plant and population. The morphogenetic characteristics studied were leaf elongation rate (LER) and internode elongation rate (IER) at the phytomer and tiller level, leaf senescence rate (LSR) and leaf appearance rate (LAR) at the tiller level, and tiller birth rate (TBR) and tiller death rate (TDR) at the plant and population level. The structural characteristics analysed were length of phytomer components (blade, sheath and internode), number of phytomers per tiller, total length and number of live blades per tiller, number and size-age distributions of tillers per plant, and number and size distribution of plants and tillers per area. Experiments to analyse the effects of temperature, nitrogen application, season and defoliation intensity on sward structural and morphogenetic variables were performed under controlled and field conditions, and using destructive and non-destructive measurements. An initial experiment under controlled environments showed highest LAR, LER and IER values at 30°C, and strong mutual regulations between morphogenetic and structural characteristics at the phytomer and tiller levels. The effects of cattle grazing and nitrogen fertilisation on the dynamics of signal grass morphology, and the patterns of defoliation were monitored during one year in long established pastures in Santa Cruz, Bolivia. Plant population demography were mainly defined by the season: high number of seedlings and new vegetative tillers at the beginning of summer; new vegetative tillers, plant fragmentation, and flowering during summer (wet season); and low tiller and plant densities with low proportions of live leaf towards the following winter. Defoliation affected only the phytomer level of organisation.

Thesis (Ph.D.)--University of Melbourne, School of Agriculture and Food Systems,Institute of Land and Food Resources, 2004.
Typescript (photocopy). Includes bibliographical references (leaves 249-282).

Two glasshouse experiments were conducted to; (i) investigate the effects of soil mechanical impedance (MI) on individually grown plants of Lolium perenne, Trifolium repens (sown pasture species) and Agrostis capillaris (indigenous species); and (ii) investigate the effects of MI on the growth of L. perenne and A. capillaris grown in swards comprising pure stands and mixtures. The individually grown plants showed a significant (P0.05) reduction in dry matter accumulation in an impeding treatment (2.3 MPa PR) compared to a control (0.25 MPa) for all species. Each species showed significant (P0.01) correlations between root and shoot dry weight indicating that the root to shoot ratio was maintained across the different MI treatments. This suggested that MI caused some form of root to shoot communication which kept root and shoot growth in synchrony. L. perenne also shows significant reductions and delays in shoot development. This effect was less pronounced in the other two species showing that L. perenne was more sensitive to MI. MI also significantly (P0.05) reduced root length and axis numbers for both L. perenne and A. capillaris in both pure and mixed stands. Only in pure swards of L. perenne was there significantly (P0.05) less root dry weight in the impeding treatment (1.8 MPa) compared to the control (0.2 MPa). MI had no significant effect on any aspect of shoot growth of either species grown in pure swards. However, L. perenne grown in mixture with A. capillaris had significantly less shoot dry weight in the 1.8 MPa treatment compared to the control. These results reinforced the findings from the individually grown plants which also showed that L. perenne was more sensitive to MI than A. capillaris. From the evidence of the glasshouse experiments, it was concluded that the PR measured at the field sites, would have affected the growth of the sward species. It is also suggested that the greater MI at one of the sites would have played a role in the more rapid replacement of L. perenne by A. capillaris observed at that site. This is due to the greater sensitivity of L. perenne to MI compared to A. capillaris, reducing its competitive advantage.

Problem. More than ever, some of the biggest challenges to society involve governance of natural resources. From large-scale resource systems such as the rain forest and oceans to small-scale systems such as lakes or alpine pastures, cooperative efforts are required to ensure sustainable and yet productive use of natural resources. In Switzerland, the management of alpine pastures has for centuries been predominantly organized by local governance institutions, avoiding an overuse of the scarce resources. During the past decade, the use and maintenance of common property pastures (CPP) is declining, leading to land abandonment and forest regrowth. However, CPP provide significant services to the mountain regions, such as additional grazing grounds, assets for the tourism industry, protection from soil erosion, water run-off and landslides, and high biodiversity. These services are currently threatened by reduced use and maintenance of the CPP. Research Aims. The research presented herein aims for a better understanding of social-ecological interactions driving the use of CPP to provide policy recommendations for the sustainable governance of CPP. Methods. To generate a holistic understanding of the variables driving CPP use, this research used multiple methods to investigate CPP use in Grindelwald, Switzerland as a social-ecological system (SES). The research was structured in 4 modules. First, qualitative methods were applied to analyze institutional change in the governance of CPP. Second, regression models were built from survey data to better understand farmers’ land-use decision. Third, an analysis of the ecological system was conducted bases on land-cover statistics. Forth, a systems dynamics model of the local SES was built and combined with formative scenario analysis to investigate potential future developments of CPP use. Results. The outcomes of the different modules suggest that: First, local governance systems originally designed to prevent overuse of CPP are able to adapt to problems of declining use and maintenance of CPP by altering a set of rules. Second, farmers’ use of CPP depend on personal attributes, including farm size, norms, and dependence on the resource. Furthermore, the analysis suggests that high local demand and prices for alpine cheese are a central factor in the sustainable use of CPP. Third, the land-cover analysis showed that afforestation occurs in Grindelwald at a relatively moderate pace and defines the area most prone to afforestation and bush encroachment. Fourth, the simulation model allows for the display of complex social-ecological interactions, showing that afforestation tendencies are likely to continue, although at different pace depending on the scenario setting. Conclusion. This research provides a better understanding of CPP use through the analysis of the subsystem characterizing the SES. It showed how the general framework for analyzing social-ecological systems can be operationalized using a broad set of methods. It thereby contributed and advanced central themes within the study of the commons such as institutional analysis, users’ behavior in cooperative dilemmas, and modeling of SES. The integration of the findings from different modules into a simulation provided insights about the effects of different policies on the sustainability of the SES, and thereby demonstrated why particular policy blueprints will rather accelerate than counteract the problem of CPP abandonment.

A series of experiments were conducted to compare nine new sainfoin populations developed to persist in mixtures with alfalfa under a multiple-cut management. In trials at Lethbridge under rain-fed and irrigated conditions, new sainfoin populations produced higher (P<0.05) dry matter yields as compared to Nova sainfoin. New cultivars persisted for three production years in mixed stands with alfalfa accounting for >20% DM at each harvest. Condensed tannin concentrations in sainfoin were highest at the bud stage. One new sainfoin population, LRC-3519 seeded in alternate rows with alfalfa caused a reduction (p<0.001) in bloat incidence by 98% as compared to Nova-alfalfa stands. Average daily gains (>1.0 kg d-1) of steers on alfalfa-sainfoin mixed pastures were similar (p>0.05). Seeding of these new sainfoin populations in mixed stands with alfalfa could prove to be a means of taking advantage of the productivity of mixed forage legume pastures while preventing bloat in grazing ruminants.

Bermudagrass (Cynodon dactylon L.) is a perennial warm-season grass that is very responsive to nitrogen (N) fertilization. Excessive N applications have negative environmental consequences and make maintaining mixed swards difficult. This study determined the effects of enhanced efficiency (EE) N fertilizers and fertilizer rate on bermudagrass yields, nutritive values, and white clover persistence. Nitrogen sources included urea, urea formulated with Agrotain® (U+A), urea with Agrotain® and dicyandiamide (SuperU), a polymer-coated urea (ESN), ESN+urea (75% ESN, 25% urea), and methylene urea (MU). In the urea formulation trial, SuperU and U+A maximized forage yields at lower N rates. The dicyandiamide in SuperU did not increase yields over U+A. Highest production efficiency was achieved at lower N rates. ESN had the lowest relative stimulate growth, which may increase clover persistence. In the clover persistence trial, the addition of N fertilizer began decreasing clover populations after 112 kg N/ha. Slow-release fertilizers (ESN, ESN+urea, MU) had higher clover percentage at the final harvest. Crude protein and in vitro digestible dry matter increased, while neutral detergent fiber and acid detergent fiber decreased with the addition of white clover. SuperU and U+A were more efficient and ESN had lower relative stimulated growth beneficial for mixed pastures.

La diminution de la biodiversité compte parmi les problèmes les plus préoccupants de notre époque. En terme de conservation, il est aujourd’hui primordial de mieux comprendre les mécanismes qui créent et maintiennent la biodiversité dans les écosystèmes naturels ou anthropiques. Cette étude a pour objectif d’améliorer cette compréhension dans un écosystème complexe, riche en espèces et à forte valeur patrimoniale, les pâturages boisés jurassiens. Elle vise à explorer des patrons spatiaux de biodiversité végétale et à tester de façon empirique des hypothèses théoriques ou issues de simulation concernant le lien entre structure spatiale du paysage et biodiversité, dans un contexte multi-échelle, pour différentes mesures de biodiversité (richesse et composition en espèces). Les données de terrain ont été collectées selon un plan d’échantillonnage hiérarchique novateur et combinées à des données lidar. Leur analyse statistique à l’aide de techniques récentes a montré que : - la richesse spécifique augmente généralement avec l’hétérogénéité de l’environnement - la structure spatiale de la composition en espèces végétales est principalement liée à la topographie et à la disponibilité en lumière, respectivement aux échelles grossières et fines. La fraction non-environnementale de cette structure spatiale est liée à plusieurs traits d’espèces. - les relations deux à deux entre diversités alpha, beta et gamma, fortement dépendantes de l’échelle spatiale, ne suivent pas toujours les tendances attendues. Cette étude souligne donc le rôle essentiel joué par la structure spatiale dans la détermination de la biodiversité et l’importance de prendre en compte plusieurs échelles spatiales
The world-wide loss of biodiversity at all scales has become a matter of urgent concern, and improving our understanding of local drivers of biodiversity in natural and anthropogenic ecosystems is now crucial for conservation. The main objective of this study was to further our comprehension of the driving forces controlling biodiversity patterns in a complex and diverse ecosystem of high conservation value, wooded pastures. We tested several hypotheses relating spatial pattern scale and biodiversity and explored spatial patterns of biodiversity in a multi-scale context and using different measures of biodiversity (species richness and composition), with field data. Data were collected using an innovative hierarchical sampling design and combined with remotely-sensed lidar data. Their analysis using recent statistical tools showed that: - species richness generally increased with environmental heterogeneity. - the spatial structure of plant species composition was related to topography at the coarsest scales and insolation at finer scales. The non-environmental fraction of the spatial variation in species composition had a complex relationship with several species traits, suggesting a scale-dependent link to biological processes. - the pairwise relationships between alpha, beta and gamma diversity were strongly scale-dependent and did not follow the expected patterns, at least at certain scales. Thus, our results highlight the crucial role of spatial structure for all components of biodiversity. They also emphasize the importance of considering multiple spatial scales and multiple scale components when studying species diversity

Pastures in the Intermountain Western United States mainly consist of cool-season grasses which lack production without supplemental nitrogen. Legumes provide nitrogen at reduced cost compared to nitrogen fertilizer. There is a need for proven methods of inter-seeding legumes into existing cool-season grass pastures as well as knowledge of how animals prefer legumes to grasses and how the nutritive value of forages change throughout the growing season. This research provides a resource for effective integration of legumes into pastures of the Intermountain West. Alfalfa, birdsfoot trefoil, and cicer milkvetch were inter-seeded into existing cool-season grass pastures following pretreatments of light tillage, mowing and glyphosate. Early spring and fall inter-seeding was unsuccessful, while late spring was moderately successful with overall alfalfa frequency of 30% after a year. Summer inter-seeding was the most successful with birdsfoot trefoil, alfalfa, and cicer milkvetch frequency of 42, 32, and 22%, respectively. In the animal preference study, when compared to tall fescue, birdsfoot trefoil was always utilized more.In most observations birdsfoot trefoil utilization was higher than orchard grass. While in all comparisons with meadow bromegrass there was no difference in utilization. During early growth, perennial ryegrass utilization was higher than birdsfoot trefoil utilization, but no difference in utilization was detected in later observations. Overall, birdsfoot trefoil was utilized 73% overall while grass utilization was 74, 67, 64, and 53% for perennial ryegrass, meadow bromegrass, orchardgrass and tall fescue, respectively. The interaction of growth stage and time of season on the nutritive value of alfalfa, birdsfoot trefoil, cicer milkvetch, orchardgrass, perennial ryegrass and tall fescue was determined. In the spring to early summer, legume nutritive value decreased rapidly with maturity, in midsummer the nutritive value decreased slowly with maturity, while in late summer the nutritive value remained stable. In the spring, grass nutritive value decreased rapidly, while in mid to late summer all grass regrowth was vegetative and the nutritive value remained stable. By inter-seeding in the summer, effectively managing mixed pastures, and utilizing forage at its highest nutritive value, legumes can benefit the pastures of the Intermountain West.

Tall fescue is the one of most common grasses in irrigated pastures throughout the Intermountain West. Two limitations of tall fescue are a decrease in productivity during hot summer months and the need for supplemental nitrogen (N). The objective of this research was to compare tall fescue-alfalfa (TF+ALF), tall fescue-birdsfoot trefoil (TF+BFT), tall fescue-nitrogen fertilizer (TF+N), and tall fescue without nitrogen fertilizer (TF-N) on forage yield, nutritional quality, and livestock performance. Research plots were established at the Utah State University Pasture Research Facility in Lewiston, UT in 2010 and grazed in 2012 and 2013. Treatments were arranged in a randomized complete block design with four replications and divided into four paddocks per replication. Three Angus crossbred steers with an average starting weight of 380 kg were placed on each treatment and rotated to a new paddock every 7 days. A put-and-take method was used throughout the growing season such that each paddock received 80% utilization. Four forage samples were collected from each paddock just prior to grazing using a 0.5 m2 quadrat for determination of dry matter (DM) and nutrient content. ADF, NDF, IVTD, and TDN were used to estimate nutrient content and steers were weighed every 28 days to determine livestock performance. Forage yield was highest (P<0.05) in TF+N (5164 kg ha-1), followed by the TF+BFT (4721 kg ha-1) and TF+ALF (4463 kg ha-1) treatments, whereas, the TF-N treatment had the lowest yield (2920 kg ha-1). In this study, TF+BFT (593 g kg-1) and TF+ALF (593 g kg-1) had a better (P≤ 0.05) season-long average TDN value than TF+N (558 g kg-1), which in turn was higher (P≤ 0.05) than TF-N (550 g kg-1). Steer average daily gains (ADG) were different (P<0.05) in every treatment with TF+BFT (0.73 kg d-1) being the highest, followed by TF+ALF (0.67 kg d-1), then TF+N (0.61 kg d-1), and similar to forage yield, TF-N had the lowest ADG (0.40 kg d-1). Tall fescue greatly benefits from added N whether via fertilizer or N transfer by legumes and this study showed that BFT and ALF mixed with TF increases plant and animal performance while reducing fertilizer costs and helps maintain a more environmentally sustainable pasture.

This thesis seeks to understand the development and implementation of the community-based pasture management policy in Kyrgyzstan, which transferred the responsibility for pasture-use planning from state administrative organs to local community-based organizations. Using document analysis, this thesis contextualizes the emergence and evolution of the policy’s key premises, including the advantages of community-based management compared to state-centered management. Using interviews and observations, this thesis draws out individual experiences of herders, forestry service officials and the members of pasture committees with the implementation of the policy in the Kadamzhai district of Kyrgyzstan. Findings suggest that historical continuities in pasture governance play an important role in the functioning of such policies. On the national level, the reliance of the state on the Soviet administrative and territorial division has reinforced pasture-use fragmentation, where different institutional actors struggle for authority over pastures. These struggles can be observed on the local level, where the implementation of policy is often challenged by forestry officials believing in the advantages of the Soviet fortress conservation, rather than community-based management. Second, the local outcomes of policy depend on the compliant or resistant subject positions of individuals involved in pasture use. Policy implementation succeeded in the recruitment of compliant pasture committee chairmen, who claim to be interested in bringing good to the communities through steering the use of pastures. However, the procedures for the establishment of committees contributed to their top-down functioning, where herders often consider the committees as a state agency and find different strategies to avoid their imposed payments.

Herbicide sod suppression during pasture renovation by legume sod-seeding often results in the loss of potentially usable forage, weed encroachment, and inadequate glass-legume ratios. A study was conducted to investigate the viability of sod suppression by sheep grazing or mowing, as alternatives to herbicide, during pasture renovation with no-till seeding of red clover (Trifolium pratense L.) or white clover (Trifolium pratense L.). Sod suppression methods evaluated were: strategically timed mowing or sheep grazing to 5 or 10 cm at seeding and during legume establishment, or similarly managed mowing or sheep grazing with an additional defoliation to 5 cm the previous fall. Additional treatments included suppression by herbicide and, unsuppressed and unseeded controls. Treatments were evaluated by determining clover plant population, botanical composition, forage yield and quality. Physical (mowing or grazing) and herbicide sod suppression resulted in similar clover plant populations; clover yields tended to be higher with herbicide suppression. However, increasing the intensity of physical suppression increased clover yields. Forage quality was increased only with sod suppression by grazing or herbicide when compared with the unimproved control. Although, for grazing this was attributed to a more frequent defoliation regime and not to the renovation itself. Unlike suppression with herbicide, physical suppression did not decrease total seasonal forage yields in the renovation year when compared with controls.

Australia is amongst the more efficient milk producers in the world.Milk production in the region of south-western Victoria relies mainly on rainfed white clover/perennial ryegrass pastures.As the demand for efficient and competitive milk production increases, the value of N2 fixation must be maximised. The objective of this thesis was to assess N2 fixation in grazed dairy pastures in south-western Victoria. Several tests and experiments were conducted and results noted. Studies revealed low white clover yields to be the major factor limiting N2 fixation in the region. For N2 fixation to have a significant impact on pasture quality and production, problems associated with legume persistence need to be addressed. Strategies may include the breeding of white clover cultivars with greater tolerance to water stress, improved winter production and increased competitiveness with companion species. Alternatively, the introduction of different legume species, better suited to the environment, may be appropriate. Where N2 fixation is unlikely to satisfy N demands, it may be necessary to introduce the strategic use of supplementary feeds or nitrogenous fertilisers. However, this would need to be carefully considered to ensure high input costs did not jeopardise the competitive advantage of low input pasture-based systems
Masters Thesis

Australia is amongst the more efficient milk producers in the world.Milk production in the region of south-western Victoria relies mainly on rainfed white clover/perennial ryegrass pastures.As the demand for efficient and competitive milk production increases, the value of N2 fixation must be maximised. The objective of this thesis was to assess N2 fixation in grazed dairy pastures in south-western Victoria. Several tests and experiments were conducted and results noted. Studies revealed low white clover yields to be the major factor limiting N2 fixation in the region. For N2 fixation to have a significant impact on pasture quality and production, problems associated with legume persistence need to be addressed. Strategies may include the breeding of white clover cultivars with greater tolerance to water stress, improved winter production and increased competitiveness with companion species. Alternatively, the introduction of different legume species, better suited to the environment, may be appropriate. Where N2 fixation is unlikely to satisfy N demands, it may be necessary to introduce the strategic use of supplementary feeds or nitrogenous fertilisers. However, this would need to be carefully considered to ensure high input costs did not jeopardise the competitive advantage of low input pasture-based systems

Over the past thirty years, price relativities and technological development have motivated an increase in the area of land allocated to cropping, as opposed to pasture production, throughout the central wheat belt of Western Australia. Nevertheless, reducing the proportion of pasture in these rotations has challenged the future productivity of farming systems in this area. First, the frequent application of selective herbicides for weed control in extended cropping rotations has promoted the development of herbicide resistance in a number of major agricultural weeds. Second, the primary use of annual plants has promoted the development of soil salinisation by allowing a significant proportion of rainfall to recharge saline water tables. The inclusion of perennial pasture phases between extended periods of cropping may mitigate or delay these constraints to production through (a) allowing the use of costeffective forms of non-selective weed control, and (b) through creating a buffer of dry soil that absorbs leakage occurring beneath subsequent crops. This study consequently explores the value of including perennial pasture phases in dryland agricultural systems in the eastern-central wheat belt of Western Australia, accounting for benefits related to herbicide resistance and water table management. A novel computational algorithm for the solution of multiple-phase optimal control problems is developed and used to conduct a conceptual analysis of the value of lucerne (Medicago sativa L.) pasture for managing annual ryegrass (Lolium rigidum Gaudin), the primary weed in wheat belt cropping systems. The competitiveness and fecundity of annual ryegrass provide strong economic incentives to maintain a low weed population, irrespective of herbicide-resistance status. Consequently, the ineffectiveness of selective herbicides primarily reduces the profitability of cropping by motivating the adoption of more costly non-selective forms of weed control. The inclusion of lucerne in land-use rotations is only optimal in the presence of severe herbicide resistance given (a) the low efficiency of alternative weed-management practices available during the pasture phase, relative to selective-herbicide application; (b) the significant cost of establishing this perennial pasture; and (c) the high relative profitability of cereal production in the absence of resistance. The value of lucerne, relative to annual pastures, for weed management is explored in greater detail through the use of compressed annealing to optimise a sophisticated simulation model. The profitability of candidate rotations is also manipulated to account for the long-term production losses accruing to the recharge of saline groundwaters that occurs beneath them. Sequences incorporating lucerne are only more profitable than those that include annual pasture at the standard set of parameter values if (a) annual ryegrass is resistant to all selective herbicides, (b) the water table is so shallow (approximately less than 3.5 m deep) that frequent rotation with perennials is required to avert soil salinisation, or (c) sheep production is highly profitable. The value of perennial pasture is sufficient under these circumstances to overcome its high establishment cost. Consistent with intuition, these benefits are reinforced by lower discount rates and higher rates of leakage occurring beneath annual-based systems. Formulation of an effective communication strategy to report these results to producers is justified given the complexity involved in determining the true magnitude of these intertemporal benefits through alternative means, such as field trials.

This study has provided fundamental information on the fate of urine nitrogen (N) when applied to pasture soils. In this work the three pasture soils used were a Bruntwood silt loam (BW), an old well-developed (lime and fertilizer incorporated and farmed for more than 20 years) peat soil (OP) and a young peat (YP) which was less developed (farmed for about 10 years). Initial soil chemical and physical measurements revealed that the peat soils were acidic, had higher cation exchange capacities, had greater carbon:nitrogen ratios and were better buffered against changes in soil pH than the BW soil. However, the BW soil was more fertile with a higher pH. The peat soils had lower bulk densities and higher porosities. Four experiments were performed. In the first experiment ¹⁵N-labelled urine was applied at 500 kg N ha⁻¹ to intact soil cores of the three soils. Treatments imposed were the presence and absence of a water table at two temperatures, 8°C or 23° C, over 11-14 weeks. ¹⁵N budgets were determined. This first experiment showed that the nitrification rate was faster in the BW soil and was retarded with a water table present. Significant leaching of nitrate occurred at 8°C in the BW soil without a water table. This was reduced when a water table was present. Leaching losses of urine-N were lower in the peat soils than in the BW soil. Apparent denitrification losses (i.e. calculated on a total-N recovery basis) ranged from 18 to 48 % of the ¹⁵N-applied with the greatest losses occurring in the peat soils. The second experiment examined denitrification losses, over 30 days, following the application of synthetic urine-N at 420 kg N ha⁻¹ to small soil cores situated in growth cabinets. The effects of temperature (8°C or 18°C) and synthetic urine (presence or absence) were measured on the BW and OP soils. Nitrous oxide (N₂0) measurements were taken from all soil cores and a sub-set of soil cores, at 18°C, had ¹⁵N-labelled synthetic urine-N applied so that ¹⁵N-labelled nitrogen gases could be monitored. This experiment showed that the application of synthetic urine and increased soil temperature enhanced denitrification losses from both soils. Denitrification losses, at 18°C, as ¹⁵N-labelled nitrogen gases accounted for 24 to 39 % of the nitrogen applied. Nitrous oxide comprised less than half of this denitrification loss. Losses of N₂0 in leachate samples from the soil cores accounted for less than 0.1 % of the nitrogen applied. A third experiment, using Iysimeters, was performed over a 150 day period in the field. The six treatments consisted of the 3 soils with applied synthetic urine, with or without a simulated water table; each replicated three times. Lysimeters were installed in the field at ground level and ¹⁵N-labelled synthetic urine-N was applied (500 kg N ha⁻¹) on June 4 1992 (day 1). Nitrification rates differed between the soils following the trend noticed in the first experiment. As in the first experiment, nitrate was only detected in the leachate from the BW soil and the inclusion of a water table reduced the concentration of nitrate. In the BW soil, the leachate nitrate concentrations exceeded the World Health Organisation's recommended limit (< 10 mg N L-1) regardless of water table treatment. No nitrate was detected in the leachates from the peat soils but there was some leaching of organic-N (< 5 % of N added) in all the peat soil treatments. Denitrification losses were monitored for the first 100 days of the experiment. In the BW soil without a water table, N₂0 production peaked at approximately day 20 and accounted for 3 % of the nitrogen applied. In the peat soils the measured denitrification losses accounted for less than 1 % of the nitrogen applied. Apparent denitrification losses in the peats were, however, calculated to be approximately 50 % of the ¹⁵N-labelled synthetic urine-N applied. It is postulated that the difference between apparent denitrification losses and those measured could have been due to; loss of dinitrogen in leachate, protracted production of dinitrogen below detectable limits, production of denitrification gases after measurements ceased (i.e. days 100 to 150) and entrapment of dinitrogen in soil cores. Due to the apparent denitrification losses being so high, further research into this nitrogen loss pathway was performed. The fourth and final experiment measured denitrification directly using highly enriched (50 atom %) ¹⁵N-labelled synthetic urine-N. It was performed in a growth cabinet held initially at 8°C. The ¹⁵N-labelled synthetic urine was applied at 500 kg N ha⁻¹ to small soil cores of each soil type. Fluxes of N₂0 and ¹⁵N-labelled gases were measured daily for 59 days. On day 42 the temperature of the growth cabinet was increased to 12°C in an attempt to simulate the mean soil temperature at the end of the field experiment. Up to this time, production of nitrogenous gases from the YP soil had been very low. Interpretation of gaseous nitrogen loss in the YP soil was difficult due to the possibility of chemodenitrification occurring. However, in the OP and BW soils, gaseous losses of nitrogen (determined as ¹⁵N-labelled gas) represented 16 and 7 % of the nitrogen applied respectively. Nitrous oxide comprised approximately half of this gaseous nitrogen loss, in both the OP and BW soils. This work implies that urine-N applied to the mineral soil (BW) could potentially threaten the quality of ground water due to nitrate contamination through leaching. In contrast, denitrification appears to be the major loss mechanism from the peat soils, with the production of nitrous oxide being the primary focus for any environmental concern. Future work should examine the fate of the nitrate leached from the BW soil and the potential for dilution, plant uptake or denitrification below a 30 cm soil depth. A better understanding of the denitrification mechanisms could help reduce denitrification and thereby improve the efficiency of nitrogen use and reduce the output of nitrous oxide.