The ecosystem changes.
Changes made by man are in menu after this!
Pick out one of the subjects of ecology on the up there!
Pick up one special subject):
Changes in the function of ecosystems:
In the world of organisms nothing is permanent, but it’s not easy to notice slow or small changes.
The image of the balance of ecosystems same as manmade concepts of climax, over-aged forest or suicide spruce forest are ecologically illusions or at least one-sided.
Even though many northern organisms have had long evolution, many species and ecosystems are still seeking - especially in the limits of their environments - new possibilities to thrive.
In the extreme limits of tolerance there is the biggest struggle for existence.
Total destruction in the nature is quite rare, if the distance of observation is long enough.
For example in the fjeld area of Lapland is going today various changes in the ecosystems.
Often it is difficult to explain, if those changes are natural (among others competition between species),
or if the men have an effect to nature (for example the grazing or greenhouse effect).
After this picture the quantity of lichens in vegetation is reducing year after year but the amount
of mountain birch forests is increasing. Reason to decreasing of lichen vegetation is at least partly grazing of reindeers.
see also: Changes on coverage quantity of forest dwarf shrubs!
It existed quite big climate changes among others after the time of last ice age. Illustration (above)
describes situation in the time, when the last ice age was largest (about 20 000 vyears ago).
Here and there in Fennoscandia the ice cap was over 3 kilometers thick, and the sea level
was about 100 meters farther down of present sea level. See also: Northern climate!
In the time of last two million years has been several icetimes and warmer interglacial periods in Europe. Last big icetime so-called Veiksel-icetime started about 120 000 years ago and terminated about 11 500 years ago (after older opinion about 10 000 years ago). Between the icetimes existed some even thousands of years long warmer periods. At that times the vegetation was restored in several areas of Finland. Before Veiksel-icetime grow in Finland - perhaps - among others beechforests even on Oulu area.
(Above): Places, in which some organisms perhaps are overwintered of the time of glacial period
are so-called refugiums. Such places have been in the low-lying shores of Arctic Ocean and Atlantic
and partly non-ice high peaks (so-called nunataks). Shore areas have been uncovered from the sea,
since water-level was low in the time of glacial period. The ancient nunataks may recognize from the high
and sharp tops of montains, that are not round by icecap.
After regugium-theory a lot of fjeldplants - and maybe some fjeldanimals (birds, rodents?) - were "overwinter" over last icetimes in refugiums. This theory is not accepted by all scientists. More: sentric species!, lemming!
Left picture: Jään reunan peräytyessä oli Fennoskandiassa vielä iso jäätikkö Balttian jääjärven aikaan.
As well later on, in the time of Yoldiasea, ice and sea localized migration of organisms from south.
Right picture: The are some other plants whose history after last icetime is like that of Dryas octopetala.
On the southern border of the icecap stagnated the dispersion of some plantspecies that had overwintered on the area of Alps. When climate then get warmer (on th time of Yoldia sea), those from south to north aspiring species - at least some - not was able to move to north; becouse the forest vegetation - birch and pine - restrained the dispersion of fjeldplants. Like so for instance mountain avens (Dryas octopetala) became extinct at the isthmus of Karelia, at Denmark and at southern Sweden (see map of Dryas, above!). There was in the North as late as 9000 BC large mountain area without forests (perhaps tundra vegetation) among others on the Saariselkä area of Finnish Lapland (see the map 1, below).
After the dominance of birch forests (n. 8000 BC) began consist coniferous forest-islands at first on the mild shores of Arctic Ocean (among others on the area of Varangerfjorden, North Norway), see above map 2!). Pineforests existed widely in Lapland about 6000 - 4000 BC. Pines grew to the elevation 700 metre; there was few bare fells were at that time!
Pine retires in the north...
Afterwards - about 4000 years ago - when climate was cooling moved the northern border of pine to more south, approximately to the grade of distribution at present. The area of bare fells grew almost to the A Uusimaa-size. However some rather small pine forests continued on the shores of fjords and on dales of rivers. Trunks of pines are preserved in several small lakes of Lapland.
In the same times began the spruce (Picea abies) approach from east/south-east.
Norway spruce (Picea abies) came to Finland south-east and from east relatively late (about 5500 years ago) and fast, but it has not found as yet West-Norway (bicture above). More: coming of spruce!
The limited resources available in the north become apparent by examining, for example, the life of the mountain birch: born from the genetic material of the downy birch (Betula pubescens) and the dwarf birch (B. nana), but has not yet reached the characteristics of an independent species (= B. ssp. tortuosa).
The economy of the mountain birch weakened significantly at the end of the 1960's, perhaps because of the cold summers. This led to a weakened resistance toward the autumnal moth (moore about this butterfly! and the fluctuation of population!) which, in turn, was the main reason for the great birch destruction, the biggest ecocatastrophy in the history of Lapland. After the birches had been eaten (reindeer completed the wipe-out), the increased light and nutrients in the ground layer changed the vegetation in many ways. Even now 30 years after the destruction some areas that were destroyed have still not become re-established. The timber line in particular the survival limit of the trees can easily shift because of disturbance. When the timber line moves many forest organisms follow. The protection forest zone in Lapland has a great significance in terms of the ecology and conservation, especially when we keep in mind that human activity can also trigger the vicious circle.
A total destruction is rare in nature, when the time scale is long enough. In the long run, the effects of forest fires, pests or diseases are relatively short. During its lifespan of hundreds of years, a pine tree, even in Lapland, will get more offspring than any of us! Paludification or climate changes on the timber line may sometimes eventually lead to the change of a forest ecosystem into another.
There is a lot of genetic variation in the nature, even among the same species or population. Perhaps, this fact has more influence on the structure and operation of the system than we realise. It is very important on the viewpoint of adaptation that the populations in the northern areas will stay apart from the southern populations. This is realised by securing that the plant species flower later in the north than in the south. So, if the pollens from the south spread to the north with the wind, it will come to no effect since the flowers in the north will not be able to be fertilised at that point. However, occasionally the flowering takes place almost the same time in the north and in the south. Thus, the genetic material will be mixed. This is important to remember e.g. in thinking the effects of the warming of climate.
All structural and functional means used in adaptation in the harsh northern conditions are based on diversity. Plant species are genetically very variable even here in the periphery of their distribution. The diversity of nature is based on genetic variation, which sustains the possibilities of adaptation and survival through the years in the pressure of changing climatic conditions.
It is lots of genetical variation in the nature among the same species or population too. Perhaps this fact has more influence than we wise up. It is very important - on the viewpoint of adaptation -, that the populations for instance in the northern areas are restricted from the southern populations. This is assured such that the plant species are flowering later on in the north than in the south. So, if the pollens from the south fly to the north, the will came to no effect, because the flowers in the north are not able to be fertilized in that time. But sometimes flowers are open nearly in the same time in the north and in the south and so the genetic matter will be blend. This is important to remember e.g. thinking the effects of warming of climate.
One of the recent transformations in northern forests is the fragmentation of the original forest regions. This has significant effects not only on landscape but also on the stability of the populations.
Aikanaan on perinteinen maatalous luonut sopivia uusia (valoisia, puuttomia) elinympäristöja jopa n. 600 eläin- ja kasvilajille. Viime aikoina on tehomaatalous kuitenkin hävittänyt näistä lajeista melkoisen osan. Luonto elää ja muuttuu... Lisää: linnustomuutoksia pohjoisessa!
The greenhouse effect has been named as one of the greatest threats of our future. The scientists quite commonly consent that the greenhouse effect will have the most powerful consequences in northern latitudes.