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'Make the first step - let the nature do the rest' ANNA ORCZEWSKA
University of Silesia, Faculty of Biology and Environmental Protection, |
Description popularizing the research project
When a man gives up his fields, meadows and pastures after decades of farming, the nature steps in and takes them over. Several decades later there will be no trace of human activities there. Year after year the front of trees moves forward ignoring man-made boundaries. Common weeds go first as the vanguard followed closely by bushes and tree seedlings. The forest will not withdraw unless the history makes a full circle and a man decides to start farming there again.
In today's world it does not seem probable. On the contrary, the European Union's requirements state that a regenerating forest should not be cut down and a post-agricultural land should be planted with the species which had grown there before a man changed it with his saws and axes. The tree-killing tools cleared the abundant riverside alder groves which had been regularly watered and fertilized with organic sediments by rivers. Today there are no such mysterious groves where tufts raise from water at the foot of alders. The fields which were farmed by a man are gone too. Only wastelands spread there.
It is not easy to reconstruct alder groves. Simply it is not enough to plant several thousand seedlings of black alder to create such a forest. It is not in a man's power to form characteristic tufts, to plant species so characteristic for the forest: marigolds, irises and peat moss. Moreover no genius at hydrology will able to establish a unique equilibrium in once regulated river valleys.
In the western part of Silesia natural and man-made alder forests grow side by side. They have their own characters and specific inhabitants. Researches conducted on the forests will help the natural ones survive unchanged and the latter, resemble the original better.
Abstract
Although in recent years some scientific literature describing the development of herb layer vegetation in new plantations adjacent to ancient woodlands has been published, so far no data on the rates of migration of ancient woodland flora into alder plantations, the tree species most commonly planted on the wettest post-agricultural woodland sites, have been available.
The aim of the project is to investigate the process of colonisation of the herb layer of alder woods, planted on abandoned meadows, by forest plant species and to relate the findings to different habitat factors (soil and water conditions).
The preliminary results of the research show that there is a great difference in the species composition and their abundance between the herb layer of ancient woodlands and those planted on former agricultural land, regardless of the habitat type. Both, ancient and recent forests have a group of species displaying an affinity to such types of communities. The herb layer of ancient forests consists of stenotopic woodland flora, which can be regarded as ancient woodland indicators as such species cannot exist outside a forest habitat and their presence in recent woods is very limited. On the other hand the herb layer of recent forests is dominated by non-woodland species, mainly of meadow, ruderal and nitrophilous habitats. The lowest rate of renaturalisation of the herb layer in post-agricultural, alder plantations has been recorded in oak-hornbeam forest habitats, whereas the highest one has been observed in case of alder carr habitats. These findings confirm the assumption that the development of the herb layer is faster on more fertile and moist sites than in poorer and drier habitat conditions.
Knowledge of different trends present in the process of colonizing of alder plantations by typical woodland flora will be useful in planning future afforestation on former agricultural sites. The pressure to plant new forests in such locations is likely to increase following recent Polish initiatives and in response to the EU agricultural reforms and land use strategy. This new ecological knowledge should also assist in the development of a forest management policy, which should be in accordance with the resolution accepted by the EU countries in Lisbon in 1998, stating that the EU countries are obliged to maintain, conserve and enhance biological diversity in forest ecosystems.