Land use, genetic differentiation and population dynamics in plants
Johan Ehrlén (project leader)
Summary of results with list of publications from Stockholm University.
Email: ehrlen@botan.su.se
Preservation of biodiversity involves not only preservation of the biodiversity of species but also the maintenance of genetic variation within species. The changes in land use have resulted in considerable changes in the vegetation structure and species composition of agricultural landscapes. What is less well known is to what extent this affects the genetic composition of individual plant populations and the interactions between species.
In this project a study is made of the herb Primula farinosa, the distribution of which is strongly coupled to grazing which has greatly diminished in Sweden in recent years. The results of the project have contributed to an understanding of the factors which make the population viable and the way the risk of extinction is influenced by land use and large scale environmental variations in climate.
How are plant communities dominated by ericaceous dwarf-shrub species influenced by large scale environmental changes?
Lars Ericson (project leader)
Summary of results with list of publications from Umeå University.
Email: lars.ericson@emg.umu.se
Mankind has in many ways radically changed the global nitrogen cycle, which means that nitrogen which used to be a resource in short supply in most ecosystems is now occurring at considerably higher levels than before. This has resulted in dramatic changes in vegetation. The increased nitrogen deposition is therefore a serious threat to biodiversity. Measures are now needed to limit nitrogen deposition. One tool has been to investigate critical loads, i.e. the deposition levels which the ecosystem can tolerate without significant harmful effects. However, most of the studies that have been made have shortcomings.
The field studies which have now been conducted cover large areas over a long period, since different ecosystems respond at different rates to nitrogen treatment, and the nitrogen that accumulates in nature can result in lower nitrogen treatment doses, which can, however, give rise after a number of years to vegetation changes similar to those caused by higher doses.
Effects of stress induced by soil chemistry on the genetic diversity of plants
Pernilla Göransson
"Genetic adaptation to soil acidification in four grasses", doctoral thesis 2007 from Department of Ecology, Lund University.
Email: Stefan.andersson@ekol.lu.se
Human activities give rise to large changes in the environment of plants and animals through airborne pollution and the deposition of nitrogen and sulphur which acidifies soil. Species diversity among plants diminishes as the acidity of soil increases, and appears to be lower on soils affected by acid rain than on naturally acid soils. One important question is whether acidification also affects other types of diversity, i.e. genetic variation within species, and whether there is a linkage between the genetic variation of species and their ability to cope with acid stress. Genetic variation is an essential condition for the ability of species to adapt to changes in the environment, especially for plants since they cannot move.
In the project, four tussock-forming forest grasses have been studied in solution experiments with varying pH. The results show that genetic variation and adaptation do not appear to have such a great role for the ability to broaden the pH amplitude and to tolerate soil acidification which occurs naturally or due to air pollution. This was somewhat surprising since grass is usually good at adapting to its growth site. One possible explanation may be that individual plants can alter their physiology or morphology in such a way that they escape the harmful effects of a low soil pH. Shoots with elongated roots able to "grow past" soil horizons that are too acidic.
Loss of functional pollinator groups – effects in plants with generalised and specialised flowers
Anna Jakobsson (project leader)
Summary of results with list of publications from IMEDEA.
Email: anna.jakobsson@botan.su.se
The local abundance and density of plant species diminish when their natural habitat disappears or changes. This can give rise to indirect effects on the reproductive capacity of the plants since reductions in flower density influence the behaviour of pollinators and therefore seed production in plants pollinated by insects. Knowledge of such changes is essential since there is also a global decrease in pollinator populations.
The density of the flowers of the species may have a beneficial effect on pollination through the availability of suitable pollen and because pollinators preferably visit areas with a lot of flower resources. But it may also have an adverse effect if the high flower number gives rise to competition. The density of other species may also affect pollination since the wrong kind of pollen may be transferred if pollinators often change between species. Few studies have however been made to find how this influences pollen limitation.
In this study, an investigation was made to find how the local floral neighbourhood is influenced in thrift (Armeria maritima) and meadow buttercup (Ranunculus acris) – two species which are self-incompatible and are therefore wholly dependent on visits by insects to be able to produce seed. The results demonstrate the importance of investigating pollination limitation at different scales, both to have a deeper understanding of how the underlying processes function, and to ensure that the results are not only an effect of the scale at which the floral neighbourhood has been investigated. The study also shows that it is not only conspecific flowers that can influence pollination success.
Mosses as a component on green roofs: establishment, specific technical properties and diversity
Nils Cronberg (project leader)
Parts of the results have been published in the scientific journal Science. Summary of results from Department of Ecology, Lund University.
Email: Nils.Cronberg@ekol.lu.se
The value of mosses and lichens.
Extensive green roofs with moss/Sedum cultures have attracted attention as a possible means of increasing green spaces in the urban environment. In previous research priority was given to vascular plants, while mosses were regarded less interesting and even a problem. The fact that mosses and vascular plants function in completely different ways was overlooked. One of the primary goals of this project has therefore been to investigate experimentally how biological differences between vascular plants and mosses influence technical properties and long term development.
The investigations confirm the picture that mosses perform an important function as a supplement to vascular plants as components on green roofs. Mosses take up and release water quickly from the air and therefore account for a large proportion of the short term water circulation on the roof. Potentially, this has great significance for the local urban climate. Growth mainly takes place during moist periods in the summer months, but both too much and too little rain reduce growth.
In the long term, the rate of decomposition appears to be comparable between mosses and Sedum, but the mosses have a good capacity to take up heavy metals and other compounds from rain and dust particles. The results also show that mosses have a propensity to absorb microparticles from the air. These are considered to be one of the most serious air quality problems in modern cities. Changes in the composition of moss vegetation occur slowly, mostly because of dispersal problems. The establishment of mosses can to some extent be manipulated by the choice of different substrates.
The ecophysiology of lichens
Kristin Palmqvist (project leader)
Summary of results with list of publications from Umeå University.
Email: kristin.palmqvist@emg.umu.se
Lichens are symbiotic organisms between a fungus (mycobiont) and an alga or cyanobacterium (photobiont). The photobiont supplies the fungus with energy and building blocks in the form of carbohydrates from photosynthesis, but we still know very little of how lichen symbiosis functions and how it is optimised in relation to the environment.
In previous projects, methods were developed to study the growth pattern of lichens in relation to precipitation pattern, the availability of light and nitrogen, and the potential for growth that they have. In this project, a study has been made of how lichens maintain an optimum energy balance by tracing the path of carbon from photosynthesis by the photobiont to the carbon investments and energy needs they have. Parallel with the carbon flow studies, the distribution of nitrogen in lichens was observed. The results show that lichens can balance resources between photobiont and mycobiont in a surprisingly rapid and dynamic way.
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