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Význam ekologické stechiometrie pro vývoj půd. / Importance of ecological stoichiometry in soil development.Veselá, Hana January 2019 (has links)
Ecological stoichiometry is a useful tool for understanding of ecological dynamics and related processes. There are only rare informations about nutrient cycling and nutrient dynamics in plant- soil system in restoration areas after coal mining. Different plant species have developed own strategies and treat differently with nutrients which can influence nutrient cycling and consequent nutrient return to the soil. In thesis, I investigated ecological stoichiometry as one of key factors which controls soil development in post mining sites. In general introduction, known facts are summarized about e.g. plant traits, decomposition process, nutrient cycling and consequences for soil development and restoration practices. But still, relationship between leaves, plant litter, and soil is poorly understood in restoration areas. The results of a doctoral thesis are presented in five papers, out of which three have been published, one has been already submitted and one manuscript is prepared for publication in an international journal with impact factor. In the first presented publication, the influence of soil fauna was studied (especially earthworms) on soil development. Soil development differed significantly between sites afforested with different tree species and it is strongly influenced by the...
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Vegetation changes following fire in the pinyon-juniper type of west central UtahBarney, Milo Arnel 01 May 1972 (has links)
A total of 28 burn areas, that varied in age from 3-100+- years, were analyzed in a study of succession following fire, in the pin yon-juniper woodlands of west central Utah. Data were collected by means of the line-point and quadrat methods. These data were subjected to a multiple regression analysis. Canopy cover, basal area (sq. ft./acre) and density (trees/acre) of juniper were highly correlated with age of burn. Percentage dead sagebrush was found to be positively correlated with density of junipers. The stages of succession following fire began with weedy annuals, that reached a peak within 3-4 years. Juniper woodlands are well developed 85-90 years following fire. Intermediate stages of succession varied, but followed a general pattern of perennial grasses, perennial grasses-shrubs and perennial grasses-shrubs-trees. Tree height and stem diameter are positively correlated with age of Utah juniper. Thirty-three years is the average minimum age at which Utah juniper produce seed.
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Plant Successional Patterns at Sperry Glacier Foreland, Glacier National Park, MT, USASchulte, Ami Nichole 12 June 2023 (has links)
Regional and local changes in the climate have been driving rapid glacial retreat in many glaciers since the Little Ice Age. This retreat provides a unique opportunity to study succession across the chronosequences of glacier forelands. Patterns of plant colonization and succession on terrain exposed by retreating glaciers give insight into factors influencing alpine ecosystem change and recovery. Understanding these patterns and processes is important for conserving alpine landscapes and flora as glaciers disappear. This study sought to investigate how various biotic and abiotic factors influence plant successional patterns in the dynamic alpine environment of Sperry Glacier, a Little Ice Age, mid-latitude cirque glacier in Glacier National Park, Montana. Through field data collection, additional Geographic Information System (GIS) derived variables, and subsequent geostatistical analysis, I specifically assessed: (1.) vegetative trends (percent cover, species richness, Shannon's diversity, species evenness, composition, and species turnover) over a 170-year chronosequence, and (2.) vegetative trends over field and GIS-derived site conditions (e.g., surface fragmentation, concavity, flow accumulation, and solar irradiance). Sixty-one plots (each 8 square meters) were placed throughout the glacier foreland using a random sample stratified by terrain date. Percent cover, species richness, Shannon's diversity, and species evenness were calculated for each plot. All sampled vegetation was identified with taxonomic resolution down to species whenever possible. I assessed vegetative trends across terrain age ranges using Kruskal-Wallis and Dunn's tests. I used two models, generalized linear models (GLMs) and Classification and Regression Trees (CARTs), to assess field and GIS-derived biophysical correlates (e.g., surface fragmentation, concavity, terrain variables, and solar irradiance with vegetative trends), followed by Kruskal-Wallis tests, Dunn's tests, and scatterplots. Species richness and vegetation cover were greater on older terrain. Plant composition changed over terrain age, with Penstemon ellipticus favoring older terrain and Boechera lemmonii favoring moderately aged terrain. Moderate drainage and concave plots, which were important in the GLMs, explained increased species richness and Shannon's diversity across different site conditions. The CARTs were able to predict species richness, vegetation cover, Shannon's diversity, and species evenness with surface fragment sized from gravel to cobble, topographic position index, and flow accumulation. These findings show that both temporal and biophysical site conditions influence successional trends across the foreland, though different vegetation measures are most influenced differently. / Master of Science / Regional and local changes in the climate have been driving rapid glacial retreat in many glaciers since the Little Ice Age. This retreat provides a unique opportunity to study succession across glacier foreland terrain that has been uncovered for different lengths of time. Patterns of plant colonization and succession on terrain exposed by retreating glaciers give insight into factors influencing alpine ecosystem change and recovery. Understanding these patterns and processes is important for conserving alpine landscapes and flora as glaciers disappear. This study sought to investigate how various biotic and abiotic factors influence plant successional patterns in the dynamic alpine environment of Sperry Glacier, a Little Ice Age, mid-latitude glacier in Glacier National Park, Montana. Through field data collection, additional Geographic Information System (GIS) derived variables, and subsequent geostatistical analysis, I specifically assessed: (1.) vegetative trends (percent cover, species richness, Shannon's diversity, species evenness, composition, and species turnover) over terrain uncovered between zero and 170-year, and (2.) vegetative trends over field and GIS-derived site conditions (e.g., surface fragmentation, concavity, flow accumulation, and solar irradiance). Sixty-one plots (each 8 square meters) were randomly placed within each terrain age range throughout the glacier foreland. Percent cover, species richness, Shannon's diversity, and species evenness were calculated for each plot. Shannon's diversity is a measurement of a community's diversity and uses both species richness and evenness to calculate diversity. All sampled vegetation was identified with taxonomic resolution down to species whenever possible. I assessed vegetative trends across terrain age using several statistical comparison tests. I used two types of statistical models to assess field and GIS-derived biophysical correlates (e.g., surface fragmentation, concavity, terrain variables, and solar irradiance with vegetative trends), followed by comparison tests and scatterplots. Species richness and vegetation cover were greater on older terrain. Plant composition changed over terrain age, with the species Penstemon ellipticus (rocky ledge penstemon) favoring older terrain and Boechera lemmonii (Lemmon's rockcress) favoring moderately aged terrain. Moderate drainage and concave plots explained increased species richness and Shannon's diversity across different site conditions. Species richness, vegetation cover, Shannon's diversity, and species evenness could be predicted with surface fragments sized from gravel to cobble, topographic position index, and flow accumulation. These findings show that both temporal and biophysical site conditions influence successional trends across the foreland, though different vegetation measures are most influenced differently.
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Mycorrhizal fungi and their relationship to plant succession in subalpine habitatsCazares, Efren 15 January 1992 (has links)
Graduation date: 1992
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Forest vegetation and fuel dynamics following stand-replacing wildfire, re-burn, and postfire management in the Siskiyou Mountains, Oregon /Donato, Daniel C. January 1900 (has links)
Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 172-187). Also available on the World Wide Web.
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The assessment of variable buffer zones to manage rocky ridges in Johannesburg, Gauteng / I.M.R. GarrattGarratt, Iain Michael Ronald January 2006 (has links)
Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2007.
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Ecosystem response to dam removalLejon, Anna G.C. January 2012 (has links)
This thesis aims to improve our understanding of how riverine ecosystems respond to dam removal. Riverine and particularly riparian ecosystems are among the most variable and important features of all landscapes. They connect landscape elements both longitudinally and laterally, and are governed by processes such as flooding, erosion and deposition that create dynamic, diverse and heterogeneous habitats. In fact, riparian zones are among the world’s most species-rich habitats. Worldwide there are millions of dams that fragment stream and river systems, regulate flows and degrade ecosystems. Dams impact freshwater, marine and terrestrial ecosystems and threaten biodiversity by disrupting organism movements and energy flows in the landscape. An important upstream effect of dams is inundation of habitats and development of new shorelines around impounded areas. Effects downstream of dams are mainly caused by changed hydrological regimes and retention of organic and inorganic materials in reservoirs, leading to reduced transport and dispersal of for example seeds to reaches downstream. The removal of dams create expectations that biota will eventually recover. We have studied a number of dam removal projects in Sweden. Our experimental results showed that following dam removal, newly exposed soils in former impoundments were rapidly colonized by pre-removal species. Their species richness increased slightly with time and their species composition indicated a slow change towards that in the reference site. In addition, the vegetation in formerly impounded areas showed a direction of change from lentic riparian plants (high proportion of aquatics) towards lotic ones, consisting of native perennials typical of free-flowing streams. We also found that the apprehensions that former impoundments would turn into pools of mud did not come true; in fact, a process towards more pristine channel morphology was observed. After removal there was erosion and downstream transport of sediment. We found only minor effects on macroinvertebrate communities. For example, a few species decreased over the years, suggesting that dam removal in itself might cause a temporary disturbance. This highlights the importance of long-term studies after dam removal, and also the importance of comparisons with pre-removal conditions and stretches unaffected by dams. Thorough documentation of executed dam removal projects and distribution of the results and experiences are tremendously important in the planning process of future decommissioning projects. Also, our experiences have taught us that in order to attain a successful dam removal it is important to involve stakeholders such as non-governmental organizations and local inhabitants in the process.
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The assessment of variable buffer zones to manage rocky ridges in Johannesburg, Gauteng / Iain Michael Ronald GarrattGarratt, Iain Michael Ronald January 2006 (has links)
In the pursuit of sustainable development, Environmental Impact Assessments (EIA) are
acknowledged globally as a tool designed to assist governing authorities by providing
the information required to make an informed decision regarding development
proposals. South Africa has entrenched this EIA requirement in the presiding
environmental legislation: the National Environmental Management Act (Act 107 of
1 998).
In the effort to manage the negative impact of development on the rocky ridges of
Johannesburg, the Gauteng Department of Agriculture, conservation, Environment and
Land Affairs (GDACEL) has introduced a buffer zone requirement in the procedure of
the EIA. The Red Data Plant Policy for Environmental Impact Evaluations for GDACEL
described a buffer zone as a collar of land that filters out inappropriate influences from
surrounding activities.
As a tool in the EIA, a buffer zone is a worthwhile concept. However, the determination
of the dimension of the buffer zone on rocky ridges, is non-discriminatory between sites,
and thus, presents potential contention between decision-making authorities and
developers. There is a need for further research to establish a scientifically acceptable
method of determining site-specific buffer zones for individual EIA applications.
The key objective of this paper is to suggest the possibility of determining a buffer zone
that accommodates the unique environmental aspects of each site. This is achieved by
determining the distance between the edge of existing developments and the point at which the successional climax community within the adjacent natural vegetation is
established.
Three suitable study sites, consisting of developed residential estates on ridges
adjacent to nature reserves, were identified within the greater Johannesburg metropolis.
The three study sites identified for this assessment include Kloofendal (west), Morning
Hill (east) and Kliprivier (south). Within each study site field surveys were conducted
along transects starting 5m from the development edge and ending 75m within the
nature reserve adjacent to each site. Quantitative (species density) and qualitative
(Braun-Blanquet cover-abundance values) data analysis was employed to describe and
evaluate the identified plant communities.
The data in this study provides clear indication that a 25-35m buffer zone would suffice
for these specific plant communities to maintain a climax successional status if impacted
on by residential development. This paper thus makes a case for permitting the
determining of variable buffers zones, based on a gradient analysis of a plant
community, as a potential panacea to the problem of resistance and reluctance to
accept present standard buffer zones. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2007.
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Förändring av våtmarkers areal och ekosystemtjänster i Byringe, Strängnäs kommun : En landskapsanalys på över 250 årRingborg, Evelina January 2014 (has links)
Wetlands have been considered throughout millenniums as valuable assets due to the ecosystem services they provide for humans. However, previous research has shown that the value of wetlands has declined over the last 150 years, in parallel to the growth of agriculture. Today, society has realized the value of ecosystem services, through increased knowledge and awareness.This study focuses on the area of Byringe, 20 km southwest of Strängnäs. The aim of this study was to identify changes of wetland areas, wetland classes and ecosystem services over time. This study compared four maps covering the area, between the years 1714 to 2013. The results show that the wetland areas have increased from their initial coverage of 6.5% up to 24.4% today. This 17.9% increase corresponds to 115.3 ha. A closer examination of this 300-year transformation showed variation among the wetland classes. Marshlands showed the largest increase of 44.3ha, followed by fen with 33.5ha and bog 7.6ha. In some areas fen had been converted to bog, which is a change in carbon storage and thus climate regulation. The lakes had developed into marshland, which has caused the disappearance of fish stocks, negatively affecting the generation of food supply. The increased marshland area has also resulted in increased carbon storage and provisioning services such as fiber material from plants and bioenergy production from trees. Furthermore, the recent transformation of agricultural land into fen has generated a loss in food production services such as crops. Instead, other services have appeared in terms of climate regulation, flood protection, increased protection against erosion, water purification and support of biodiversity.
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The effect of sun and shade on the leaves of four coastal tree species.Kemp, Lynley Claire. January 1992 (has links)
Mimusops caffra, Euclea netetensis, Olea woodiana and Peddiea
africana are tree species associated with different successional stages in a
coastal dune forest. Saplings of these tree species were established in four
different light intensities. These were full sun, 40% shade, 70% shade and
90% shade. The hypothesis proposed that the species from different
successional stages are preadapted for a particular light environment and are
disadvantaged in other light environments. Growth, morphological,
biochemical and physiological aspects of the four species in the four light
environments were determined.
Growth rates showed no consistent pattern with respect to light intensity.
However, most species, irrespective of their successional status, had the
best growth response in either 40% or 70% shade treatments. All the
species showed typical sun and shade responses for morphological,
anatomical and some biochemical characteristics. Photosynthetic responses
were complex and showed no relationship between the successional status
of the species and the light conditions in which they were grown.
There appears to be very little relationship between the growth responses,
the measured biochemical and morphological aspects, assimilation rates and
the successional status of the species.
Light intensity is therefore not the sole driving force of forest succession but
one of the many factors that contribute to the
overall process. / Thesis - (M.Sc.)-University of Natal, Durban, 1992.
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