THE DYNAMICS OF THE PLANT LACTUCA-SIBIRICA AND THE FREQUENCY OF ITS RUST PUCCINIA-MINUSSENSIS IN RIVER VALLEYS IN NORTHERN SWEDEN

Citation
A. Wennstrom et al., THE DYNAMICS OF THE PLANT LACTUCA-SIBIRICA AND THE FREQUENCY OF ITS RUST PUCCINIA-MINUSSENSIS IN RIVER VALLEYS IN NORTHERN SWEDEN, Oikos, 72(2), 1995, pp. 288-292
Citations number
17
Categorie Soggetti
Zoology,Ecology
Journal title
OikosACNP
ISSN journal
00301299
Volume
72
Issue
2
Year of publication
1995
Pages
288 - 292
Database
ISI
SICI code
0030-1299(1995)72:2<288:TDOTPL>2.0.ZU;2-D
Abstract
The population dynamics of the rust Puccinia minussensis and its host plant Lactuca sibirica were studied in four localities. Three of the l ocalities were subjected to different degrees of erosion and/or deposi tion (Kukkola, Aspliden and Hummelholm) during flooding, while one loc ality (Langed) was situated above the flood level. At Kukkola and Humm elholm both the densities of the host plant L. sibirica and the freque ncy of the rust P. minussensis varied markedly within transects. At th e other two localities, Langed which is not disturbed and Aspliden whi ch is dry and subjected to erosion, densities and disease frequencies remained constantly low between the years. There was a positive correl ation between host densities and frequency of aecia-producing shoots a t Hummelholm. However, it is suggested that this correlation is caused by similar responses to variation in environmental conditions and not by a response of the pathogen to host plant densities. Furthermore we found that systemically diseased shoots (aecia) at all localities die d before August, while uredial and telial stages did not cause death o f shoots. It is suggested that (1) the host densities are primarily re gulated by stochastic disturbances and (2) the direct and close fit in the response of the fungus is due to resource limitation.