Vegetatiivse liikuvuse mõju kahe hüpoteetilise taimeliigi kooseksisteerimisele
Laen...
Kuupäev
2012
Kättesaadav alates
ainult raamatukogus, only in library
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Antud töö eesmärgiks oli uurida seda, kuidas liikidevaheline erinevus vegetatiivses
liikuvuses mõjutab liikide kooseksisteerimist. Täpsemalt vaadeldi kahe hüpoteetilise
liigi ruumi hõivamist, kui nende vegetatiivne liikuvus varieerus 10 mm ja 100 mm
vahel. Seda tehti stohhastilise matemaatilise mudeli abil.
Mudeli sisendandmeteks olid järgmised statistilised suurused mõlema liigi kohta:
• Rameti keskmine eluiga aastates
• Rameti keskmise eluea standardhälve
• Vegetatiivne liikuvus (ehk risoomi juurdekasv aastas)
• Vegetatiivse liikuvuse standardhälve
• Järglaste arv ühe rameti kohta aastas
• Järglaste arvu standardhälve
Kogu modelleeritava ala asustustiheduseks määrati 5000 rametit ühe liigi kohta.
Eelnimetatud parameetrid olid kõikide katsete vältel konstantsed, välja arvatud
vegetatiivne liikuvus ja selle standardhälve. Rameti keskmiseks elueaks määrati 1
aasta, ning selle standardhälveks 0. Järglaste arv ühe rameti kohta aastas oli 2,5 ning
selle standardhälve 1. Vegetatiivne liikuvus varieerus 10 mm 100 mm-ni, ning
vegetatiivse liikuvuse standardhälve oli alati pool liikuvusest.
Mudeli simulatsioonis arvutati välja liikide arvukus erinevatel aastatel. Liigi käekäiku
igas simulatsioonis hinnati tema arvukuse muutuse tõsu kaudu. Tõus arvutati 6.–20.
katseaasta arvukuste põhjal. Kahe testliigi arvukuse tõusude erinevust testiti
ühefaktorilise dispersioonanalüüsiga kasutades iga parameetrite väärtuste
kombinatsiooniga tehtud kolme simulatsiooni kui statistilisi kordusi.
Töö peamised tulemused on järgmised:
• Vegetatiivne liikumine mõjutab liikide kooseksisteerimist.
• Üldjuhul on parem ruumi hõivaja suurema liikuvusega liik ning väiksema
liikuvusega liik jääb ruumi hõivamises alla. Seetõttu võib teatud aja möödudes
väiksema liikuvusega liik kooslusest ära kaduda ning selle tagajärjel koosluse
liigirikkus väheneda.
• Kõige paremini suudavad koosluses eksisteerima jääda sarnase liikuvusega
liigid, mis võib tähendada, et sarnaste liikide koosluses on suurem liigirikkus.
• Alates teatud suurusega vegetatiivsest liikuvusest (40–50 mm) ei ole
liikidevaheline erinevus vegetatiivses liikuvuses enam oluline. Kui mõlema
liigi liikuvus ületab seda piirväärtust, jäävad mõlemad liigid kooslusesse alles.
The aim of this paper was to study the effect of difference between species in vegetative mobility on the co-existence of species. The focus was on how two hypothetical species would cover the space in case where their vegetative mobility varies from 10 to 100 mm. The experiment was carried out using stochastic mathematical model. The species behaviour in the model was described with following parameters: • Average life span of a ramet in years • Standard deviation of the average life span of a ramet • Vegetative mobility (annual increase in the rhizome length) • The standard deviation of vegetative mobility • The number of offspring per ramet per year • The standard deviation of successors rate • The density of species for the whole modelled area was defined as 5000 ramets per species. Parameters mentioned above were constant during the experiment, except vegetative mobility and its standard deviation. Average life span of a ramet was set to one year (standard deviation = 0). The number of offspring was 2,5 per year (standard deviation = 1). Vegetative mobility varied form 10 to 100 m whereas its standard deviation was always half of the mobility. The abundance of species in different years for each combination of species' mobility was calculated in three simulations. Success of species was assessed by the slope of the ramet number dynamics. The slope was calculated according to data from 6th to 20th year of experiment. The difference in slope of the two hypothetical species was tested by one-way analysis of variance. The three simulations of every combination of mobilites were used as empirical repetitions. The results of this experiment were: • Vegetative mobility affects the co-existence of species • In general species with larger mobility are better in covering the space. Therefore the species with smaller mobility could be outcompeted and lost from the community. As a result the biological diversity decreases. • The coexistence of the two species is most probable when the species have similar mobility. This implies that in the community of similar species the biological diversity could be greater. • If the vegetative mobility exceeds a threshold level (40-50 mm) it's further increase ceases to have an effect on the dynamics of species. Species can coexist in the community if the species’ mobility exceeds that threshold.
The aim of this paper was to study the effect of difference between species in vegetative mobility on the co-existence of species. The focus was on how two hypothetical species would cover the space in case where their vegetative mobility varies from 10 to 100 mm. The experiment was carried out using stochastic mathematical model. The species behaviour in the model was described with following parameters: • Average life span of a ramet in years • Standard deviation of the average life span of a ramet • Vegetative mobility (annual increase in the rhizome length) • The standard deviation of vegetative mobility • The number of offspring per ramet per year • The standard deviation of successors rate • The density of species for the whole modelled area was defined as 5000 ramets per species. Parameters mentioned above were constant during the experiment, except vegetative mobility and its standard deviation. Average life span of a ramet was set to one year (standard deviation = 0). The number of offspring was 2,5 per year (standard deviation = 1). Vegetative mobility varied form 10 to 100 m whereas its standard deviation was always half of the mobility. The abundance of species in different years for each combination of species' mobility was calculated in three simulations. Success of species was assessed by the slope of the ramet number dynamics. The slope was calculated according to data from 6th to 20th year of experiment. The difference in slope of the two hypothetical species was tested by one-way analysis of variance. The three simulations of every combination of mobilites were used as empirical repetitions. The results of this experiment were: • Vegetative mobility affects the co-existence of species • In general species with larger mobility are better in covering the space. Therefore the species with smaller mobility could be outcompeted and lost from the community. As a result the biological diversity decreases. • The coexistence of the two species is most probable when the species have similar mobility. This implies that in the community of similar species the biological diversity could be greater. • If the vegetative mobility exceeds a threshold level (40-50 mm) it's further increase ceases to have an effect on the dynamics of species. Species can coexist in the community if the species’ mobility exceeds that threshold.
Kirjeldus
Märksõnad
liikidevahelised erinevused, vegetatiivne liikumine, kooseksisteerimine, mudel, bakalaureusetööd