wise use of mires and peatlands - Peatland Ecology Research Group

68 VALUES AND FUCTIONS OF MIRES AND PEATLANDSthat intermediate (“thinning”) cuttings andtending of young stands are seldompractised. However, Canadian forestry isgradually changing from ‘transitorycollection forestry’ towards a plannedutilisation of forest resources (‘conservingmanagement forestry’) 138 .Tropical forestry: The natural vegetation oftropical peatlands is mainly forest. InSoutheast Asia tropical forest coversextensive tracts of peatlands, mainly betweencoastal mangroves and the terrestrial rainforest. Most of the tree families of lowlandrainforest are found in peatland forests butwith fewer species. Peatland forest has alower and more open tree canopy thanterrestrial rainforest. It consists of aconnected series of forest types whichreplace each other from the peatlandperimeter to its centre 139 . It includessubstantial quantities of commercial treespecies and yields some of the most valuabletropical timbers. Ramin (Gonystylusbancanus) and agathis (Agathis dammara),for example, contribute almost 10% ofIndonesia’s exports of forest products 140 .Although peat swamp forests produce asmaller number of large trees per hectarecompared to other lowland forests, severalcommercially important timber species, suchas ramin and some meranti (Shorea spp.), arerestricted to this forest type 141 . Peatland forestis exploited in much the same way asterrestrial forest, but allowing for the lowerbearing capacity of the soil. There are twotypes of exploitation – transitory collection(even destructive) forestry; and conservingmanagement forestry 142 .The most frequent destructive loggingoperations have been concentrated inpeatland forests earmarked for agriculture 143 .In other areas such forest has been damagedby logging concessions issued withoutdetailed environmental assessmentsconducted in advance, and by illegal logging.A conserving management forestry form ofselective timber extraction is carried out usingminimal mechanisation under assumptions asto the regeneration cycle of commercialspecies. An example of such cropping is inSarawak. Oldgrowth peatland forest isworked on a harvesting period of 45 years.Each group of permanent forest areasconstitutes a unit managed under a RegionalManagement Plan. An annual cut isprescribed for each area. Logging is carriedout manually. Damage to land is minimised.Silvicultural treatments are carried out afterlogging. While the felling cycle is set at 45years the time of subsequent cuts isdependent on the rate of re-growth of theforest 144 .Forest drainage: On a global scale theproportion of the total terrestrial wetland(including peatland) area drained for forestryis about 3%. The area under forest utilisationwithout drainage has not been estimated. Thecurrent practice and extent of drainage(‘progressive management forestry‘) indifferent countries varies considerablydepending on the potential wetland area, thestructure of land ownership, the demand forraw wood and national economicconsiderations 145 (Table 3/13).In maritime climates such as those of theBritish Isles, drainage and afforestation withlodgepole pine (Pinus contorta) and Sitkaspruce (Picea sitchensis) is a commonpractice on treeless mires. The long-termprospects for forests on drained peatlandsare reported to be good. Yields from thesecond rotation seem to be even higher thanfrom the first 146 . In Fennoscandia peatlandafforestation is nowadays restricted to cutawaypeatlands and abandoned farmland onpeat soil 147 . Drainage of new areas in Russiahas practically stopped 148 .Most of the drainage in Fennoscandia, Russiaand the Baltic states has been of naturallytree-covered mires. The profitability of