Säilikpuude sobivus kalakotka (Pandion haliaetus) pesapuudeks
Laen...
Kuupäev
2013
Kättesaadav alates
ainult raamatukogus, only in library
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Tänapäeval on kalakotkastele suurimaks ohuks pesapuude puudus ja ebasobivatele puudele ehitatud pesade varisemine. Bakalaureusetöö eesmärgiks oli uurida, kas ja kui palju on Riigimetsa Majandamise Keskuse (RMK) poolt raielankidele jäetud selliseid säilikpuid, mis kalakotkale pesapuuks sobiksid.
Uurimuse käigus inventeeriti 1-2 aastaseid säilikpuudega RMK männi raielanke kalakotkale sobivaimates piirkondades. Otsiti lamendunud ladvaga männipuid. Teiseks andmestikuks olid 10-aastased raiesmikud. Sobilikud säilikpuud mõõdeti.
Töö tulemusena selgus, et kuigi raielankidele on jäetud säilikpuid vastavalt nõuetele, siis selliseid puid, mis vastaksid kalakotka pesapuu tingimustele, oli raiesmikel väga vähe. Uuriti ligikaudu 200 raielanki, kuid nende peale kokku leidus ainult 26 sobivat puud. Kokku võiks pesapuudeks sobida 1,5 % männi säilikpuudest.
Nii potentsiaalsete kui tegelike kalakotka pesapuude vanus oli keskmiselt 150 aastat, kuid säilikpuude keskmine vanus pisut üle 100 aasta. Murdunud ladvaga pesapuud olid keskmise vanusega 100 aastat. Pesapuude keskmine diameeter oli üle 50 cm, potentsiaalsete pesapuude läbimõõt oli 38 cm ja ülejäänud säilikpuudel 32 cm.
Tavapärase männi raievanuse juures ei ole kalakotka pesapuuks sobilikud omadused veel välja kujunenud. Säilikpuude valikul tasuks säilitada kõik sobiliku lamendunud ladvaga männid ja ka kõrgemad murdunud ladvaga puud.
Novadays the biggest threat to the Osprey is the lack of suitable nesting trees and the collapsing of the nests built on unsuitable treetops. In this Bachelor Thesis the objective was to examine how many retention trees does the Riigimetsa Majandamise Keskus (RMK) leave on clear cuttings areas, which could be used by Osprey as nest trees. Fieldwork required the examination of 1-2 year old RMK pine clear cuttings with retention trees on them. The objective was to find flat-topped pine trees. The second database contained 10-year old cuttings where the suitable retention trees were measured. The result of the study showed that, retention trees are left to the clear cutting areas according to the regulations. Trees which would have met the demands, to be an Osprey nest tree, were only a few. Around 200 clear cuttings were studied, but only 26 potential nesting trees were found, which means only 1,5% pine retention trees of all the retention trees could be taken as a potential nest tree for the Osprey. Age of the potential nest trees and the actual nest trees that are already inhabited were an average of 150 years. The unsuitable retention trees average age was just a little over 100 years, trees with a broken top had an average age of 100. Trees with a nest on them had an average diameter of 50 cm, potential nest trees had 38 cm and all the other retention trees had an anverage diameter of 32 cm. It comes out due to the usual cutting age of the pine, the tree usually hasn’t developed the necessary properties needed for a Osprey nest tree. In the selection of retention trees it’s worth to preserve all the flat-topped pines and taller trees with a broken top.
Novadays the biggest threat to the Osprey is the lack of suitable nesting trees and the collapsing of the nests built on unsuitable treetops. In this Bachelor Thesis the objective was to examine how many retention trees does the Riigimetsa Majandamise Keskus (RMK) leave on clear cuttings areas, which could be used by Osprey as nest trees. Fieldwork required the examination of 1-2 year old RMK pine clear cuttings with retention trees on them. The objective was to find flat-topped pine trees. The second database contained 10-year old cuttings where the suitable retention trees were measured. The result of the study showed that, retention trees are left to the clear cutting areas according to the regulations. Trees which would have met the demands, to be an Osprey nest tree, were only a few. Around 200 clear cuttings were studied, but only 26 potential nesting trees were found, which means only 1,5% pine retention trees of all the retention trees could be taken as a potential nest tree for the Osprey. Age of the potential nest trees and the actual nest trees that are already inhabited were an average of 150 years. The unsuitable retention trees average age was just a little over 100 years, trees with a broken top had an average age of 100. Trees with a nest on them had an average diameter of 50 cm, potential nest trees had 38 cm and all the other retention trees had an anverage diameter of 32 cm. It comes out due to the usual cutting age of the pine, the tree usually hasn’t developed the necessary properties needed for a Osprey nest tree. In the selection of retention trees it’s worth to preserve all the flat-topped pines and taller trees with a broken top.
Kirjeldus
Märksõnad
kalakotkas, säilikpuud, lageraie, bakalaureusetööd