Kase, kuuse, männi- ja haavapuude rinnasdiameetri sesoonne kasv dendromeetrite andmeil
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Kuupäev
2016
Kättesaadav alates
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Dendromeetriga puu kasvu mõõtmine on tähtis teadlastele, kes uurivad ja koostavad
metsamudeleid. Probleemne on, et dendromeetrid ei näita puu reaalset kasvu. Käesoleva
magistritöö eesmärgiks oli uurida dendromeetrite mõõtmisnäite ja ilmastiku mõju sellelele.
Töös olid kasutusel dendromeetrite andmed, mis oli kogutud 20 puult viielt erinevalt
proovitükilt. Samadelt puudelt võeti ka juurdekasvupuuriga puursüdamike proovid, millelt
mõõdeti aastarõnga laiused. Ilmastiku andmed saadi Järvselja ilmastikuseire punktist.
Koostati viis mudelit dendromeetri näitude ja ilmastiku vahelise seose tõestamiseks. AIC
statistiku abil uuriti mudelite headuse erinevust.
Töö tulemustest selgus, et dendromeetri näidud olid jämedatel puudel hüplikud,
peenematel puudel hüplikkust ei olnud. Kuna puu ei saa hüplikult kasvada, pidi olema
tegemist muu protsessiga, mida selgitati loodud mudelite abil. Modelleerimisel osutus
mõjukaks arvutuslik muutuja "vesisus", mille eelduseks oli, et päevased sademed tekitavad
hüplikkust dendromeetri näitudes. Saadud mudel jäljendas üsna täpselt dendromeetri
näiduseeriat, mis tõestas hüpoteesi. Võis järeldada, et tegemist on puu pundumisega, mille
käigus puu imeb niiskust sisse. Kuivadel päevadel tõmbub puu uuesti kokku. Pundumist
tõestas ka AIC statistik, mis andis kõige parema seose võrreldes teiste mudelitega.
Mudeliga M40 saadi puude tegelik kasv (ilma pundumiseta).
Ka teistes sarnastes töödes on olnud analoogseid probleeme, kus reaalset kasvu pole aru
saada, sest dendromeetri näidud on hüplikud. Samuti on varem täheldatud, et päevasel ajal
puu pundub ja tõmbub uuesti kokku ning seega ei ole tegu kasvuga. Kuna andmeseeriaid
oli vähe, oleks dendromeetritega töö jätkamine vajalik.
Measuring tree growth with dendrometer is important for scientists who study and compose forest models. Problematic is the fact that dendrometers do not show the real growth of the tree. The aim of the present Master's thesis was to analyze dendrometers’ data and the impact of weather on the data. Dendrometer data from 5 sample plots total of 20 trees were used in this study. Core samples were taken from the same trees with a increment borer. From the samples widths of the tree rings were measured. Weather data was gathered from Järvselja weather monitoring point. Five models were generated to prove the relationship between dendrometer readings and weather data. Difference between models compared was proved with AIC statistics. The results of this thesis showed that dendrometer readings from thick trees were not linear but jumping, this did not occur in thinner trees. As tree growth cannot be not jumpy, these results indicate another process, which was explained by developed models. For creating model M4, a new variable "watery" was calculated. For "watery" the assumption was that diurnal precipitation was responsible for the jumping in dendrometer readings. This assumption was proved by the fact that the M4 model imitated accurately dendrometer readings. It could be concluded that the tree absorbed water and swelled. On dry days, the tree would shrink. Swelling was also proved by the AIC statistics which gave better correlation compared to other models. With the model M40 real growth of the trees was found (without the swelling). Problems with understanding the real growth of the tree due to jumping dendrometer readings has also published in other studies. It has also been observed before that during daytime the tree swells and shrinks, therefore it is not real growth. Whereas there were few data series, it would be necessary to continue to work with dendrometers.
Measuring tree growth with dendrometer is important for scientists who study and compose forest models. Problematic is the fact that dendrometers do not show the real growth of the tree. The aim of the present Master's thesis was to analyze dendrometers’ data and the impact of weather on the data. Dendrometer data from 5 sample plots total of 20 trees were used in this study. Core samples were taken from the same trees with a increment borer. From the samples widths of the tree rings were measured. Weather data was gathered from Järvselja weather monitoring point. Five models were generated to prove the relationship between dendrometer readings and weather data. Difference between models compared was proved with AIC statistics. The results of this thesis showed that dendrometer readings from thick trees were not linear but jumping, this did not occur in thinner trees. As tree growth cannot be not jumpy, these results indicate another process, which was explained by developed models. For creating model M4, a new variable "watery" was calculated. For "watery" the assumption was that diurnal precipitation was responsible for the jumping in dendrometer readings. This assumption was proved by the fact that the M4 model imitated accurately dendrometer readings. It could be concluded that the tree absorbed water and swelled. On dry days, the tree would shrink. Swelling was also proved by the AIC statistics which gave better correlation compared to other models. With the model M40 real growth of the trees was found (without the swelling). Problems with understanding the real growth of the tree due to jumping dendrometer readings has also published in other studies. It has also been observed before that during daytime the tree swells and shrinks, therefore it is not real growth. Whereas there were few data series, it would be necessary to continue to work with dendrometers.
Kirjeldus
Märksõnad
puud (bot.), mõõtmine, dendromeetrid, ilmastik, magistritööd