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Vliv změn klimatických podmínek během roku na mléčnou užitkovost dojnic / Impacts of climate changes on milk production efficiency in dairy cattle during a calendar yearUHEROVÁ, Jaroslava January 2015 (has links)
Negative effects of high temperatures on cattle milk production is a specific problem. Dairy-cows, who produce much more heat than cows that are not milked, are more susceptible to high temperatures of the surrounding environment than other cattle. Changes in temperatures and atmospheric pressure were monitored throughout a year and then its influence on the milk production of cattle has been evaluated. It has been discovered that low temperatures do not have any significant influence on dairy-cows. However, at high temperatures dairy-cows suffer from heat stress and it leads to lower volumes of the daily milk production. The Holstein breed showed a higher sensitivity to temperature fluctuations than the Czech spotted breed; however, the Holstein breed milk production is better balanced in a long run (a year period).
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The Intervention of Human Modifications on Plant and Tree Species in the Landscape of the LBJ National GrasslandsLang, Brett M. 05 1900 (has links)
An analysis utilizing both ArcGIS and ethnographic interviews from private land owners and environmental professionals examined how man-made landscape changes affected plant and tree species in the LBJ National Grasslands in Wise County, Texas north of Decatur. From the late 1800s to the Dust Bowl Era the land was used for crop production and cattle grazing resulting in erosion and loss of soil nutrients. The research indicated by 2001 that cattle grazing and population increase resulted in land disturbance within the administrative boundary of the national grasslands. Participants expressed concern over the population increase and expansion of 5 to 10 acre ranchettes for cattle grazing common in modern times. Recommendations for the future included utilizing and expanding the resources already existing with environmental professionals to continue controlling erosion.
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Cattle Grazing in the National Parks: Historical Development and History of Management in Three Southern Arizona ParksPinto, Robin Lothrop January 2014 (has links)
This dissertation traces the history of cattle grazing at Saguaro NP, Organ Pipe Cactus NM and Fort Bowie NHS in southern Arizona. This collection of studies examines the factors affecting that use, the ranchers who made their living from the landscape, and the federal land managers responsible for sustaining the natural and cultural resources. A dominant industry on arid public lands since the Civil War, grazing was altered by a variety of influences: environmental and human-derived. Ranching communities developed from homesteading settlements. Success was determined by climate, topography, and natural resources; social and cultural pressures; economic events and political legislation; and later federal regulations and decisions. The first agency to oversee grazing, USFS was under constant pressure to maximize short-term human benefits. The NPS Organic Act of 1916 mandated conservation of natural resources "by such means as will leave them unimpaired for future generations" and yet approved cattle grazing, an extractive use, under USFS management. Park managers were frustrated by grazing practices not under their control. Parks were at a cultural and social disadvantage. Residents and politicians often expressed displeasure at park reservations; communities feared that parks would interfere with local industries. Park employees supervised visitors and developed recreation infrastructure; they came with little experience to manage livestock. Lack of funding for research, limited manpower, and political and administrative interference allowed cattle grazing to continue unregulated for decades altering vegetation and enhancing erosion. In the 1960s, changing values from the environmental movement, the waning power of the livestock industry, and the rise of activist scientists impelled NPS to act. Without monitoring data, NPS turned to legal opinions to terminate grazing. Now grazing is regulated and carefully monitored. NPS is mandated to incorporate research results into management decisions. Older grazing permits are being retired, but land acquisitions for park additions add new management challenges. Purchasing permits offers a new but financially limited opportunity to protect sensitive lands. Grazing has ended at all three parks, yet ecological changes and historic structures remain. As cultural and administrative legacies, those remnants offer opportunities to interpret a significant regional tradition and an untold controversy.
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A SUCESSÃO SECUNDÁRIA NA FLORESTA ESTACIONAL SUBTROPICAL DO RIO GRANDE DO SUL, BRASIL / SECONDARY SUCCESSION IN SUBTROPICAL SEASONAL FOREST IN RIO GRANDE DO SUL, BRAZILKilca, Ricardo de Vargas 28 February 2014 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The subtropical seasonal forests located on the brazilian southern plateau (BSP) of Rio
Grande do Sul state (Brazil) represent an extension from the Misiones province flora,
considered one of the most threatened ecosystems in the world. BSP represents the largest
forested areas of the state, most of the them are secondary forests, originate from agricultural
abandonment areas. In many cases, these forests are source of shelter and food for livestock.
Given the importance of the BSP for biodiversity conservation and maintenance of ecological
services is little knowledge how these forests regenerate after impact. This doctoral thesis has
been organized into four chapters, the first three describe and evaluate the secondary
succession in soils and forest vegetation after abandonment of agricultural activities. Thirtyfive
preserved forests at different ages (5 to> 100 years) with low environmental variability
were sampled with standardized inventory methodology, for analyzes of the soil and
vegetation attributes. Specifically, the questions that this study sought to answer were: 1) how
soil attributes to change (11 chemical and three texture) along a forest succession and what
are the best indicators of change, 2) are linear floristic changes along succession and what
floristic similaririty between ages, chronosequence, successional stages and stages of
development of the forests? 3) how structural attributes of vegetation (13 attributes) changes
along a chronosequences and what the best indicators of changes? The results showed that the
chemical properties of soil and structure vegetation changed significantly and not predictable
for a single attribute along chronosequences forests. Only discriminant analysis aproach was
possible to characterize the ages of forest using a group of soil and structure attibutes. The
floristic composition also varied substantially where few species can be listed as indicators of
a particular stage of development. Floristic patterns emerged only when pooled data from
aged forests. The last chapter evaluated the effect of cattle grazing in 35 forests with different
ages (5 to > 100 years) and three levels of impact (forests with current impact of cattle
grazing, forests excluding grazing 10 years ago and forests without cattle grazing).
Standardized inventory in all these forests were employed for analysis of soil and vegetation
in order to compare and evaluate the effect and magnitude of the impact of grazing on forest
ecosystem. The most adverse effect ocurred in the soil (chemical and texture) than in the
floristic composition and structure of vegetation. However, the impact of grazing on soil and
tree component can be recovered in 10 years after sttoped the activity in forest ecosystems.
These results are important to impact monitoring, restoration and sustainable management
projects in the largest and most endangered ecological corridor in Rio Grande do Sul State. / As florestas estacionais subtropicais localizadas na região do rebordo do Planalto Meridional
(RPM) do Rio Grande do Sul representam uma extensão da flora proveniente da província
Misiones (Argentina), essa considerada um dos ecossistemas mais ameaçados do mundo. O
RPM comporta a maior área de floresta do estado que são principalmente compostas de
florestas secundárias originadas do abandono de áreas agrícolas. Em muitos casos, as florestas
remanescentes são utilizadas como fonte de abrigo e alimento para o gado. Dado a
importância das florestas do RPM para conservação da biodiversidade e para a manutenção
dos serviços ecológicos, sabe-se pouco como essas florestas se regeneram após o impacto. A
presente tese de doutorado foi organizada em quatro capítulos, os três primeiros buscaram
descrever e avaliar a sucessão secundária nos solos e da vegetação florestal após o abandono
da atividade agrícola. Foram amostradas 35 florestas preservadas em diferentes idades (5 a
>100 anos) com inventários padronizados, e em menor variação ambiental possível, para
análises das características do solo e da vegetação. De forma específica, o estudo procurou
responder as seguintes questões: 1) como muda os atributos do solo (11 variáveis químicas e
três físicas) ao longo da sucessão florestal e quais os melhores indicadores dessa mudança; 2)
existe mudanças florísticas lineares ao longo da sucessão e qual a similaridade florística entre
idades, cronossequências, estágios sucessionais e nas fases de desenvolvimento da floresta? 3)
como mudam os atributos estruturais da vegetação (13 atributos) ao longo da sucessão e quais
os melhores indicadores dessas mudanças? Os resultados demonstraram que os atributos
químicos do solo e da estrutura da vegetação mudaram significativamente nas florestas ao
longo da sucessão, no entanto, as mudanças não foram lineares ou previsíveis, o que não
permitiu elencar um único atributo eficiente para caracterizar uma idade de floresta. Somente
com o emprego da análise discriminante foi possível identificar grupos de variáveis do solo e
da estrutura da vegetação eficientes para classificar as diferentes idades de florestas. A
composição florística também variou e algumas poucas espécies podem ser elencadas como
indicadoras de uma determinada fase de desenvolvimento. O último capítulo avaliou o efeito
do pastoreio bovino em 35 florestas com diferentes idades (5 a > 100 anos) e níveis de
impacto (florestas com impacto atual de pastoreio bovino, florestas com exclusão do pastoreio
a 10 anos e florestas sem pastoreio bovino). Foram realizados inventários padronizados em
todas essas florestas para análise do solo e vegetação com objetivo de comparar e avaliar o
efeito e a magnitude do impacto do pastoreio no ecossistema florestal. O impacto do pastoreio
foi mais significativo no solo (química e textura) do que na composição florística e estrutura
da vegetação, sendo possível elencar maior número de indicadores ambientais no primeiro
caso. No entanto, o impacto do pastoreio no solo e no componente arbóreo pode ser
recuperado em 10 anos de abandono da atividade nos ecossistemas florestais. Os resultados
apresentados fornecem importantes subsídios para programas de monitoramento de impacto,
recuperação de ecossistemas degradados e manejo de espécies silvícolas nesse que é o maior e
mais ameaçado corredor ecológico do estado do Rio Grande do Sul.
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