33P translocation in the thallus of the mat-forming lichen Cladonia portentosa

The extent of vertical migration of ³³P in thalli of the heathland lichen Cladonia portentosa was investigated under field conditions. ³³P-labelled orthophosphate was introduced into the bottom 25 mm of podetia cut to a length of 50 mm from the apices. The distribution of label was scanned using a molecular imager immediately after incubation, and after growing for 8 wk and 6 months. Differences in the relative distribution of label between podetia harvested at the beginning and the end of the experiment showed that there had been a significant migration of ³³P upwards out of the labelled 25 mm stratum towards the apex. This was confirmed by statistically significant changes in the median (md) and the 90 percentile of total relative distribution of ³³P label. In a control treatment in which label was introduced into the apical 25 mm of podetia, which were then grown inverted (top down), no upward movement of label was detected. By contrast, a statistically significant reduction in the md of the distribution indicated migration downwards towards the thallus apex. The results are consistent with the hypothesis that P is recycled within podetia of mat-forming lichens, migrating from degrading basal regions upwards to the growing apices following a source–sink relationship.     

Die Variabilität vegetativer und generativer Flechtenstrukturen und ihre Bedeutung für die Systematik

Die Entstehung von Stützleisten in den Thalli von Cladonia chlorophaea und Cetraria islandica, sowie die Entwicklung sekundärer Soredien im Inneren der Podetien von Cladonia chlorophaea werden beschrieben. Gemeinsam mit anderen Entwicklungsvorgängen von Flechten zeigen die Beobachtungen eine sehr geringe Determination der Flechtengewebe. Die Struktur wird weitgehend durch die Funktion bestimmt, während gleichzeitig bestimmte ontogenetische Abläufe unveränderbar sind. Die Bedeutung dieser Erscheinungen für die Systematik wird diskutiert.     

Effects of Thallus Temperature and Hydration on Photosynthetic Parameters of Cetraria Islandica from Contrasting Habitats

Two methods of induced in vivo chlorophyll (Chl) fluorescence were used to investigate the effects of varying thallus temperature and hydration on the performance of photosynthetic apparatus of a foliar lichen Cetraria islandica: slow Chl fluorescence induction kinetic with the analysis of quenching mechanisms, and rapid irradiance response curves of photosynthesis derived from quantum yield of photochemical reactions of photosystem 2 (₂) recorded at increasing irradiances. We compared responses of photosynthetic apparatus in populations of C. islandica growing in lower altitude (LAP: 1 350 m a.s.l.) and in higher altitude (HAP: 2 000 m a.s.l.). At each altitude, the samples were collected both in fully irradiated sites (HI) and in shade (LI). Temperature optimum of photosynthetic processes was the same for LAP and HAP thalli of LI populations (18 °C), while it was significantly lower for HI HAP (14 °C). Gradual dehydration of fully hydrated thalli led to initial increase (up to 20 % of water saturation deficit, WSD) in F_V/F_M and ₂, no change at 20–50 % WSD, and a dramatic decrease of the parameters within 50–80 % of WSD. LI HAP of C. islandica was the best adapted population to low temperature having higher rates of photochemical processes of photosynthesis than HI HAP within temperature range of –5 to +5 °C. The differences between populations were apparent also in Chl content and thallus morphology.     

Translocation of 15N indicates nitrogen recycling in the mat-forming lichen Cladonia portentosa

Nitrogen translocation was measured in Cladonia portentosa during 2 yr growth in Scottish heathland. Translocation was predicted to occur if N is resorbed from senescent basal tissue and recycled within the thallus. (15)N was introduced into either the lower (TU thalli) or upper (TD thalli) 25 mm of 50-mm-long thalli as (15)N-NH(4) (+), (15)N-NO(3) (-) or (15)N-glycine. Labelled thalli were placed within intact lichen cushions, either upright (TU) or inverted (TD). Vertical distribution of label was quantified immediately following labelling and after 1 and 2 yr. Independently of the form of introduced label, (15)N migrated upwards in TU thalli, with new growth being a strong sink. Sink regions for (15)N during year 1 (including new growth) became sources of (15)N translocated to new growth in year 2. Upward migration into inverted bases was minimal in TD thalli, but was again marked in new growth that developed from inverted apices. Relocation of N to regions of growth could facilitate internal N recycling, a process postulated to explain the ecological success of mat-forming lichens.     

Effects of fertilization on understorey vegetation in a Norwegian Pinus sylvestris forest

Abstract. Boreal coniferous forests have been impacted by long distance airborne pollutant deposition for most of the 20th century. Changes in forest understorey vegetation attributable to N‐deposition have been observed in southern Sweden, but not so far in southern Norway. We recorded the quantity of all species of vascular plants, bryophytes and lichens in 144 plots in a fertilization experiment in a 35‐yr old Pinus sylvestris forest in Aust Agder County, southernNorway initiated 6 yr before our study. Each plot represented a combination of three levels of nitrogen, two levels of magnesium and two levels of phosphorus addition. Effects of fertilization on species quantity were tested by Kruskal‐Wallis one‐way analysis by ranks. For vascular plants, only small and hardly significant differences were found between treatments and control. Significant negative effects of N‐fertilization were found on both mosses and lichens. To some extent, these effects could be attributed to direct effects of application of the fertilizer, but were more likely to be due to a negative feedback response to the faster growth of pine trees in fertilized stands, reducing throughfall precipitation and increasing litter fall. Significant differences between Mg‐ and P‐fertilized sites and respective controls were found for too few species to be likely to represent an overall trend.     

南极乔治王岛菲尔德斯半岛和阿德雷岛地衣研究 Ⅱ.石蕊属(Cladonia)(英文)

本文第一作者在参加南极长城站地区科学考察中在乔治王岛菲尔德斯半岛和阿德雷岛采集了大量地衣标本。从形态与化学相结合研究了该地区大型地衣中种类最多的石蕊属,共计12个分类单位,多于国际上有关学者在该地区报道的石蕊属地衣种类。其中,Cl．deformis,Cl．carneola,和Cl．weymouthii等3个种是南设特兰群岛的新记录;Cl.chlorophaea是乔治王岛和阿德雷岛的新记录。Cl．cornuta,Cl．pyxidata和Cl．squamosa等3个种是阿德雷岛的新记录。其余5个分类单位即Cl.borealis,Cl．fimbriata,Cl．gracilissubsp．elongata,Cl．novochlorophaea和Cl．sarmentosa是该地区过去的已知种。记叙和讨论了每个种与邻近种之间的异同,地衣化学和在南极地区的分布。在本研究地区没有发现石蕊科地衣中的其它属。     

黑龙江省五大连池枝状地衣多样性

报道了五大连池地区枝状地衣4属32种,其中圆鳞石蕊(Cladonia trassii Ahti)为中国新记录种,裸柄石蕊(Cladonia gymnopoda Vain.)为中国大陆新记录种,7种为黑龙江省新记录种。对32种地衣地理成分进行了分析,分属于6个地理成分:环北极成分(50%),广布成分(25%),东亚成分(9%),欧亚成分(6%),泛热带成分(6%),中国特有成分(3%);并对32种地衣的基物及分布特点进行了简要分析。     

中国石蕊属地衣的地理学分析

将中国92种石蕊属地衣划分为8个地理成分：广布成分19种,占总种数的21％,环北极成分32种（35％）,泛热带成分8种（9％）,欧亚成分5种（5％）,东亚-北美成分7种（8％）,东亚成分13种（14％）,中国喜马拉雅成分1种（1％）,中国特有成分7种（7％）。对中国石蕊属地衣所属的主要地理成分的形成进行了初步讨论,提出东亚特有种云南石蕊（Cladoniayunnana）和北美特有种拟胀石蕊（C.transcendens）为一对地理替代种;比蒙氏石蕊（C．Beaumontii）,圆筒石蕊（C.cylindrica）,丛杯石蕊（C.mateocyatha）和大翅石蕊（C.macroptera）等4种为东亚-北美间断分布种。指出中国喜马拉雅成分戴氏石蕊（C.delavayi）及欧亚成分中的细枝石蕊（C.corymbescens）在中国分布的北界是秦岭山脉。