Reproductive phenology in the leafy hepaticLophozia silvicolaBuch in southern Finland

Abstract

Reproductive phenology was described in the leafy dioecious hepatic Lophozia silvicola Buch during three successive growing seasons in an old-growth forest population in southern Finland. The sequence of phenological events was quantified by a maturity index M i , which was calculated on the basis of the rankings of the developmental stages and the numbers of individual shoots in each stage. The developmental cycle of antheridia was correlated with the temperature during the growing season, with maturation from July to August. Gametangia maturation from initials to gametangia dehiscence takes about 10 months including a probable pause during winter. Antheridia in early developmental stages were present in the population under study throughout the growing season. The timing of the developmental cycle of archegonia varied among years. Fertilization was estimated to occur in early to mid-summer on the basis of the presence of dehisced antheridia and the subsequent emergence of 'swollen venter' archegonia. Maturation of archegonia and the proportion of sporophyte-bearing shoots were correlated with mean rainfall and relative humidity during the week preceding each sampling. Total shoot number per sample, an indication of population density, was correlated with numbers and proportions of females and sporophyte-bearing shoots in the samples. The proportion of sex-expressing shoots in the population was on average 26%. The proportion of females was on average 8%, while the proportion of males was 17%, the difference between them being significant. The female to male sex ratio varied between the samples, with a mean of 0.61 indicating male-biased overall sex ratio in the population studied.

Comparison of gemma production among three Lophozia species during the growing season

“…This suggests that the total amount of produced gemmae alone is not the main reason why L. ascendens is a rare and endangered species in the Czech Republic. Day length, temperature (Duckett and Renzaglia, 1993;Hohe et al, 2002), air humidity, and precipitation (Laaka-Lindberg, 2005) were proven to influence the initiation of sex organs or sporophyte maturation in bryophytes. Likewise, vegetative growth can be influenced by day length and temperature (Furness and Grime, 1982;Schwabe and Nachmony-Bascomb, 1963).…”

Geographical range in liverworts: does sex really matter?

“…For example, sporophyte production is correlated with higher shoot mortality among females (Pohjamo & Laaka‐Lindberg, ), reduced size of vegetative offshoots, reduced branching (Rydgren & Okland, ) and reduced production of new reproductive organs (Bisang & Ehrlen, ). Sexual reproduction also requires specific habitat and climatic conditions, so that some species freely release spores in some areas, but not in others (Laaka‐Lindberg, ). This raises the question of whether lineages producing asexual propagules can also better partition their resources between vegetative and sexual reproduction than species only dispersing by spores, possibly influencing their fitness and hence, their ability to disperse over greater distances.…”

Phenology and survival of sporophytes in Dutch populations of Buxbaumia aphylla

“…Loeske (Busby et al 1978). Also, rainfall has been demonstrated to influence timing and speed of development in desert mosses (Stark 2002b) and in the boreal bryophyte Lophozia silvicola Buch (Laaka-Lindberg 2005). In the closely related Buxbaumia viridis (DC) Moug.…”

“…General stages in the life cycle of bryophytes include spore germination, gametophyte formation, development of gametangia and sporophyte formation (Forman 1965, During 1979. Phenological studies in bryophytes may explore the complete life cycle of multiple bryophyte species (van der Wijk 1960) or may more specifically aim at a single species or a single life cycle event (Laaka-Lindberg 2005). It is well established that species differ largely between each other in life strategy and reproductive timing (van der Wijk 1960, During 1979, Miles et al 1989 and that moss phenology depends on environmental factors such as temperature and precipitation (Busby et al 1978, Zehr 1979, Furness and Grime 1982, Laaka-Lindberg 2005, Stewart and Mallik 2006.…”