Skogsstatistisk årsbok 2003.pdf - Skogsstyrelsen

SUMMARYstrong influence on soil and water quality. Sulphurdioxide (SO 2 ) and Nitrous Oxides (NO x) areresponsible for the acidification of soils (figure 5.5and 5.7).Emission of carbon dioxide (CO 2 ) contributesto global warming. Figure 5.6 shows differentsources of CO 2 emissions. Vegetation assimilatesCO 2 , generating carbon reservoirs. Forests canbecome carbon sinks when biomass volumesincrease (table 5.23).Felling strongly influences biological biodiversity.Environmental care during felling aremeasured and presented in tables 5.18 to 5.22.Chapter 6 SilvicultureInventories performed in 2000–2002 showed that planting was used as a method ofregeneration on 61 percent of the land affected by final felling. The areas studied wereSouthern Sweden (1994–1996) and Northern Sweden (1992–1994). Natural regenerationwas used on 36 percent of the land, sowing on one percent and three percent was left withoutactive regeneration measures. About 84 percent of planted areas met the Forestry Act’sregeneration standards. Corresponding calculations for natural regeneration and non-activeregeneration were 67 and 20 percent respectively.Some 20,600 hectares of forest were fertilised.In 2002 protective ditching notifications to the Forestry Administration covered1,700 hectares.The following statistics are from 2001:Ground preparation was carried out on 148,000 hectares, and 133,000 hectares wereplanted.Pre-commercial thinning increased to cover 254,000 hectares.Forest owners notified that natural regeneration was to be implemented on 21 percent of theland affected by felling.Approximately 301 million plants were delivered by plant distributors for use in Sweden.Most information on annual silvicultural activityis assessed through two questionnaires. One issent to companies, corporations and major forestowners (large-scale forestry), and the other is sentto private forest owners and selected public owners(small scale forestry). The survey of large-scaleforestry covers all owners, while the survey ofsmall-scale forest owners is sample based. TheNational Board of Forestry is responsible for thesurveys. Result accuracy from the survey of largescaleowners is good even after breakdown ofresults at regional level. Results from the survey ofsmall-scale owners are uncertain. The samplingerrors for single year results on a national levelhave been estimated at five to eight percent formost variables. The sampling error on a regionallevel is higher and suggests that averages forseveral years (usually three year averages) are used(tables 6.1, 6.2, 6.3, 6.5, 6.9 and 6.12).NFI results are used to express the timing ofsilvicultural activities. Results are affected by samplingerrors. NFI methodology (Chapter 1) isimportant to consider and the results differ fromother surveys (figures 6.1, 6.2 and 6.3).Forest plant statistics are compiled based on aquestionnaire sent to plant distributors. The NationalBoard of Forestry is responsible for thisquestionnaire (table 6.4).302