Habitat Quality and Population Size as Determinants of Performance of Two Endangered Hemiparasites

2010 ◽  
Vol 47 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Roosa Leimu
2010 ◽  
Vol 20 (2) ◽  
pp. 214-214 ◽  
Author(s):  
PAUL F. DONALD ◽  
GRAEME M. BUCHANAN ◽  
NIGEL J. COLLAR ◽  
YILMA DELLELEGN ABEBE ◽  
MERID N. GABREMICHAEL ◽  
...  

Oecologia ◽  
2008 ◽  
Vol 159 (1) ◽  
pp. 59-68 ◽  
Author(s):  
Natasha de Vere ◽  
Eelke Jongejans ◽  
Amy Plowman ◽  
Eirene Williams

2012 ◽  
Vol 17 (3) ◽  
pp. 537-547 ◽  
Author(s):  
Noémi Örvössy ◽  
Ádám Kőrösi ◽  
Péter Batáry ◽  
Ágnes Vozár ◽  
László Peregovits

2011 ◽  
Vol 75 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Lucyna Mróz

The frequency distribution and density of three life stages as well as fitness components of the perennial plant <em>Colchicum autumnale</em> growing in the unmanaged road verges and in the extensive mown and grazed meadows in the Sudeten Mts. were studied. Furthermore, investigated were the effects of population size and plant size (measured as number of flowers) on reproductive success and explored if variation in reproductive and vegetative traits of adults could be associated with soil characteristics. The t-test indicated that proportions of subadults and reproductive adults were significantly lower in verge than in meadow populations, and of vegetative adults significantly higher. The plant density of reproductive adults and the reproductive adults to all adults ratio were significantly lower in verge populations compared to meadow populations. Although habitat type accounted for significant variation in stage structure, no significant difference was found between vegetative and reproductive traits in adult plants, except for the number of flowers. In verge populations the number of flowers was significantly lower as compared to meadow populations. The traits related to reproduction were not significantly influenced by population size. However, the proportion of flowers setting fruit decreased significantly with increasing number of flowers. The stepwise multiple regression revealed significant relationships between soil characteristics and number of fruits per plant, fruit set, number seeds per plant and number of leaves in vegetative adults. The results suggest that the creation of the low and relatively open vegetation cover could increase the chance of persistence of <em>C. autumnale</em> living in verge habitats by promoting of seed germination, seedling establishment and flowering, and they also show that the reproductive success and vegetative components of fitness are most likely influenced by habitat quality.


2003 ◽  
Vol 91 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Philippine Vergeer ◽  
Ramses Rengelink ◽  
Annemieke Copal ◽  
N. Joop Ouborg

2000 ◽  
Vol 14 (5) ◽  
pp. 1413-1421 ◽  
Author(s):  
Anna-Kaija Eisto ◽  
Markku Kuitunen ◽  
Antti Lammi ◽  
Veli Saari ◽  
Jukka Suhonen ◽  
...  

Web Ecology ◽  
2001 ◽  
Vol 2 (1) ◽  
pp. 57-64 ◽  
Author(s):  
K. Ulbrich ◽  
K. Seidelmann

Abstract. To understand associations between habitat, individual behaviour, and population development of solitary bees we developed an individual-based model. This model is based on field observations of Osmia rufa (L) (Apoideae: Megachilidae) and describes population dynamics of solitary bees. Model rules are focused on maternal investment, in particular on the female’s individual decisions about sex and size of progeny. In the present paper, we address the effect of habitat quality on population size and sex ratio. We examine how food availability and the risk of parasitism influence long-term population development. It can be shown how population properties result from individual maternal investment which is described as a functional response to fluctuations of environmental conditions. We found that habitat quality can be expressed in terms of cell construction time. This interface factor influences the rate of open cell parasitism as the risk for a brood cell to be parasitized is positively correlated with the time of its construction. Under conditions of scarce food and under resulting long provision times even low parasitism rates lead to a high extinction risk of the population, whereas in rich habitats probabilities of extinction are low even for high rates of parasitism. For a given level of food and parasitism there is an optimum time for cell construction which minimizes the extinction risk of the population. Model results demonstrate that under fluctuating environmental conditions, decreasing habitat quality leads to a decrease in population size but also to rapid shifts in sex ratio.


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