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Jääksoode korrastamine AS Nurme Turvas näitel

Koit, Madis (2018) Jääksoode korrastamine AS Nurme Turvas näitel. [thesis] [en] Rehabilitation of Cut-over Peatland on the Example of AS Nurme Turvas.

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Abstract

Eesti soode pindala on vähenenud viimase 60 aasta jooksul ligikaudu 60%, mille on põhjustanud soode kasutamine põllumajandusmaana, metsanduses, infrastruktuuri arendamine, põlevkivi kaevandamine ja turbatööstus. Turba kaevandamine on sellest 8,5%. Enne 1950. aastat kaevandati turvast väikestes kogustes ja pätsidena raba servadest, mis jättis looduslikuks taimestumiseks head tingimused. Peale 1950. aastat võeti turbatootmises kasutusele freestehnoloogia, mille tulemusel rabad kuivendati, eemaldati taimestik ning rajati suured tasase pinnaga ja kraavivõrgustikuga turbaväljad. 2009. aastal läbi viidud uuringu põhjal on Eestis 9371 ha jääksoosid ning praeguseks hetkeks arvatakse olevat juba kahekordne. Jääksoodega kaasnevad mitmed olulised keskkonna probleemid nagu lagugaaside eraldumine, suur tuleohtlikkus, mõju naabruskonna veerežiimile. AS Nurme Turvasel on ette nähtud ammendunud freesväljade taastamine metsastamise näol. Selleks on ettevõtte loonud rekultiveerimisfondi, kuhu raha iga aastaselt eraldatakse. Ettevõtte juhtkond on veendunud, et neile määratud taastamisviis antud tingimustes pole sobiv. Töö koostamise käigus tutvuti Eestis varasemalt kasutatud taastamisviisidega, neid alalüüsides ning märkides üle tingimused, mis peavad olema täidetud, et oleks võimalik tagada parim tulemus nii keskkonnale kui ettevõtjale. Töö käigus peeti nõu spetsialistidega ning varasemalt teemaga kokku puutunud inimestega. Autor leiab, et metsastamine ei sobi analüüsitud alale peamiselt selle tõttu, et kolmandikust suvest puhub rabaväljadel ligi 12-20 m/s tuul. Jääksoodesse soovitatakse peamiselt istutada kaskesid, mändisid ning kuuski, mis on aga kõige tormihellemad puuliigid, seetõttu oleks antud rabaväljadel nende liikide kasvama jäämine raskendatud. Autori hinnangul on üheks parimaks võimalikuks lahenduseks jääksoo taastamisel AS Nurme Turvase territooriumil marjakasvatuse rajamine. Kraavivõrgustikuga aladel on võimalik muuta veerežiimi marjakasvatuse jaoks sobilikuks. Samuti ei sega marjakasvatus kaevandustegevust ümberkaudsetel rabaväljadel. Tegemist oleks taastamisviisiga, mille õnnestumise tõenäosus on kõige suurem

Abstract [en]

The surface area of Estonian peatland has decreased by nearly 60% over the past 60 years, caused by the use of peatlands in agriculture, forestry, infrastructure development, oil shale extraction, and peat industry. Peat extraction makes up about 8.5% of this. Before 1950, peat was extracted in small quantities, and as cakes around the edges of the peatland, which ensured good conditions for natural vegetation. After 1950, the milling method was introduced in peat production. As a result, peatlands were drained, vegetation was removed, and large and flat peat fields with networks of dikes were established. According to a study from 2009, there is 9,371 ha of cut-over peatland. Presently, this number is believed to be 20,000 ha. Cut-over peatland is accompanied by a number of significant environmental issues such as degradation gases, high flammability, and impact on the hydrological regime of the neighbourhood. Attempts to restore cut-over peatlands have been made across the world as well as Estonia. While there have been attempts to restore milled peatlands for recreational and economic objectives in Estonia, a common understanding and good practice do not yet excist, and restoration of peatland using a prescribed method is required from businesses that have leased land for mining from the state and acquired a mining licence. This is done without ensuring that the method is suitable in the first place. Objectives of the thesis: • To describe the environmental problems related to cut-over peatland. • To investigate which methods of rehabilitation have been used for cut-over peatland in the past, and highlight their pros and cons as well as the conditions for their functioning. • To analyse the intended rehabilitation methods of AS Nurme Turvas and suggest the most suitable method. AS Nurme Turvas is expected restore the milled fields by afforestation. To do this, the company has created a land restoration fund, into which money is allocated each year. The management of the company is convinced that the intended rehabilitation method is not suitable for the present conditions. During the course of preparing the theses, previously used restoration methods were examined and analysed, highlighting the conditions that have to be met in order to ensure the best results for both the environment and the company. Specialists and individuals with prior contact with cut-over peatland were consulted. The author finds that afforestation is not suitable there due to the fact that for one third of the summer, winds of nearly 12l–20 m/s blow on the peatlands. Mainly birches, pines and spruces are suggested for planting on cut-over peatlands. These tree species are also most sensitive to storms and their growth on the peatlands would be difficult due to strong and consistent winds. As one of the best possible solution for restoring cut-over peatland on the territory of AS Nurme Turvas, the author suggests the introduction of berry cultivation. It is easy to convert hydrological regimes on areas with networks of dikes to be suitable for berry cultivation. Additionally, growing berries does not interfere with the mining activities on the surrounding peatlands. In conclusion, it can be said that it would be a method of restoration with the highest probability of success.

Item Type: thesis
Advisor: Oliver Kalda
Subjects: Technoecology > Environmental Protection > Hydrogeology and Estonian Geology
Technoecology > Environmental Protection > Estonian Biota and Biocenosis
Technoecology
Divisions: Institute of Circular Economy and Technology > Environmental Technology and Management
Depositing User: Madis Koit
Date Deposited: 05 Jun 2018 13:24
Last Modified: 30 Aug 2019 07:30
URI: http://eprints.tktk.ee/id/eprint/3602

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