wise use of mires and peatlands - Peatland Ecology Research Group

66 VALUES AND FUCTIONS OF MIRES AND PEATLANDScultivation. The principal uses arevegetable production and pastureland.Cranberries are produced in BritishColumbia, wild rice is grown in Manitobaand peatlands in Newfoundland are usedto grow forage crops 120 . Over 230 000hectares of fen peatlands are cultivated inthe Florida Everglades, including largeareas of sugar cane and rice. Other cropsproduced in the U.S.A. include vegetables,grass sods for use in lawns andcranberries 121 .The commercial production of cranberrieson peatlands in North America 122 is - with aproduction of 6 million barrels 123 - a majorbusiness enterprise 124 . This form of monocroppinginvolving removal of wetlandvegetation, re-profiling and periodic floodharvesting,is very different from the wildberry collection from intact mires describedin §3.4.1(ca) above. With the industry’sintensive use of water and the applicationof fertilisers and pesticides in a wetenvironment, impacts on streams and lakescan be more direct than for otheragricultural operations 125 . Theconsumption of cranberries is promoted fortheir medicinal values 126 . Expansion ofcranberry cultivation on peatlands in otherareas of the world 127 is currently beingexplored.(eb) Forestry on mires and peatlands 128Intensity levels of utilisation: There are threeintensity levels of the utilisation of mires forforestry (Table 3/12):●In some parts of the world wood harvestingis practised on pristine peatlands. Thistype of utilisation is called ‘exploitation’ 129but is referred to here as transitorycollection forestry. As a consequence thetree growth and regeneration possibilitiesmay be hampered due to a rise in thegroundwater level after tree harvesting,leading to decreasing yields. At the same●●time, however, the functioning of the mireecosystem may continue.Conserving management forestry(‘sustainable forest management’) aims atmaintaining the forest resource by applyingproper natural regeneration of the treestands on the sites which have beenharvested.Progressive management forestry aims atincreasing the forest resource byameliorating the growing conditions in thesite by drainage and fertilisation and bytaking good care of the tree stand by propersilvicultural measures. This man-madedisturbance in the peatland ecosystem hasto be maintained if the increased levels ofwood production on the site are to bemaintained 130 .The forms of peatland utilisation for forestryvary from country to country depending onsuch factors as demand for raw wood,silvicultural management practice andtradition and infrastructure of thecountryside. In some countries peatlandforestry may still be at the ‘transitorycollection forestry’ stage although theimportance of ‘conserving managementforestry’ is generally admitted. In countrieslike Finland the approach to the utilisation ofpeatlands for forestry has for decades beennot only ‘conserving’ but ‘progressivemanagement forestry‘, minimising harmfuleffects on the site and on stream water.Forest on pristine mires: On pristine miresseveral factors (climate, excessive water,deficiency of nutrients) may restrict theproductivity of tree species. However, someforested mire sites support commercial-sizetree stands. In a typical pristine-mire treestand the number of stems is high in smalldiameter classes and decreases abruptly withincreasing diameter. The result is that onpristine mires the tree stands have an unevenage structure. There is also some variation inthe density of the tree stands.