Poa Alpina Research Articles

Adaptation of Poa alpina to altitude and land use in the Swiss Alps

Current land use and climate change are prompting questions about the ability of plants to adapt to such environmental change. Therefore, we experimentally addressed plant performance and quantitative-genetic diversity of the common Alpine Meadow Grass Poa alpina. We asked how land use and altitude affect the occurrence of P. alpina in the field and whether its common-garden performance suggests adaptation to conditions at plant origin and differences in quantitative genetic diversity among plant origins. Among 216 candidate grassland sites of different land use and altitude from 12 villages in the Swiss Alps, P. alpina occurred preferentially in fertilized and grazed sites and at higher elevations. In a common garden at 1,500 m asl, we grew two plants of >600 genotypes representing 78 grassland sites. After 2 years, nearly 90% of all plants had reproduced. In agreement with adaptive advantages of vegetative reproduction at higher altitudes, only 23% of reproductive plants from lower altitudes reproduced via vegetative bulbils, but 55% of plants from higher altitudes. In agreement with adaptive advantages of reproduction in grazed sites, allocation to reproductive biomass was higher in plants from grazed grasslands than from mown ones. For 53 grasslands, we also investigated broad-sense heritability H2, which was significant for all studied traits and twice as high for grazed as for mown grasslands. Moreover, possibly associated with their higher landscape diversity, H2 was higher for sites of villages of Romanic cultural tradition than for those of Germanic and Walser traditions. We suggest promoting diverse land use regimes to conserve not only landscape and plant species diversity, but also adaptive genetic differentiation and heritable genetic variation.

Species Diversity, Community Structure, and Distribution Patterns in Western Himalayan Alpine Pastures of Kashmir, Pakistan

Western Himalayan alpine pastures are among the most diverse ecological locations on the globe. Four alpine pastures were investigated to study species distribution patterns, richness, similarity, and community structure in Bagh District, Azad Kashmir, Pakistan. Four communities, Poa–Primula–Sibbaldia, Primula–Caltha–Primula, Poa alpina–Poa pratensis–Scirpus, and Sibbaldia–Poa–Scirpus, were identified on the basis of an importance value index. The average value of species richness was 1.42; Simpson's and Shannon–Wiener's diversity values were 3.13 and 0.91, respectively; the degree of maturity index was 44.1; and species evenness was 0.901. Local alpine flora was dominated by a hemicriptophytic life form with microphyllous leaf spectra. The species–environment correlation was analyzed using canonical correspondence analysis. A negative correlation of both diversity and richness was revealed with altitudinal gradient. Anthropogenic disturbances showed a significant negative impact on distribution of medicinal and palatable species. Unpalatable species dominated the local flora, indicating the heavy grazing pressure in the area. Development and implementation of regional conservation strategies are recommended to protect the threatened Himalayan alpine biodiversity.

Volatile Constituents of Festuca nigrescens, Phleum alpinum and Poa alpina from N.W. Italian Alpine Pastures

The composition of the volatile fractions of three important grasses from sub-alpine N.W. Italian pastures, namely Festuca nigrescens Lam. non Gaudin (chewing fescue), Phleum alpinum L. (alpine timothy) and Poa alpina L. (alpine bluegrass) was investigated. The fresh aerial parts were collected at the flowering stage during the summer season. The volatile oils obtained from green tissues by steam distillation in a Clevenger-type apparatus, were analyzed by GC/FID and GC/MS. The oil yield was 0.04 +/- 0.01% weight/fresh weight bases for each of the investigated species. Several classes of compounds were found in the volatile fractions, including aldehydes, alcohols, acids, hydrocarbons, esters, ketones, terpenes, and phenolics. Qualitative and quantitative differences were observed.

ACCESSORY CHROMOSOMES IN THE ROOTS OF POA ALPINA

HereditasVolume 43, Issue 3-4 p. 583-588 Open Access ACCESSORY CHROMOSOMES IN THE ROOTS OF POA ALPINA VINKO MILINKOVIC, VINKO MILINKOVIC INSTITUTE OF PLANT BREEDING AND GENETICS, COLLEGE OF AGRICULTURE UNIVERSITY OF ZAGREB, YUGOSLAVIASearch for more papers by this author VINKO MILINKOVIC, VINKO MILINKOVIC INSTITUTE OF PLANT BREEDING AND GENETICS, COLLEGE OF AGRICULTURE UNIVERSITY OF ZAGREB, YUGOSLAVIASearch for more papers by this author First published: November 1957 https://doi.org/10.1111/j.1601-5223.1957.tb03461.xCitations: 1AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Literature Cited Häkansson, A. 1948. Embryology of Poa alpina plants with accessory chromosomes. Hereditas 34: 233– 247. Müntzing, A. 1946. Different chromosome numbers in root lips and pollen mother cells in a sexual strain of Poa alpina. Hereditas 32: 127– 129. Müntzing, A. 1948. Accessory chromosomes in Poa alpina. Heredity II: 49– 61. Citing Literature Volume43, Issue3-4November 1957Pages 583-588 ReferencesRelatedInformation

CYTOGENETIC STUDIES IN POA PRATENSIS AND ITS HYBRID WITH POA ALPINA

HereditasVolume 28, Issue 1-2 p. 1-126 Open Access CYTOGENETIC STUDIES IN POA PRATENSIS AND ITS HYBRID WITH POA ALPINA ERIK ÅKERBERG, ERIK ÅKERBERG UNDROM, SWEDENSearch for more papers by this author ERIK ÅKERBERG, ERIK ÅKERBERG UNDROM, SWEDENSearch for more papers by this author First published: January 1942 https://doi.org/10.1111/j.1601-5223.1942.tb03268.xCitations: 17AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume28, Issue1-2January 1942Pages 1-126 ReferencesRelatedInformation

Demographic Consequences of the Two Reproductive Modes in Poa alpina L. along a Primary Succession Gradient in the Central Alps

Poa alpina grass plays a predominant role across the entire range of primary succession on alpine glacier forelands. One demographic factor that reacts clearly to changing environmental conditions is reproduction. Using permanent plot data, the complete life cycle of Poa alpina was studied along a successional gradient of the Rotmoos glacier foreland (2300–2400 m a.s.l., Central Alps, Austria) over a period of three years. We used matrix modeling to study the importance of the generation of plantlets and seedlings along the successional gradient and their ability to form adult individuals, and we hypothesized that plantlets develop faster to adults than seedlings because they start already with 3–4 developed leaves.The study showed that plantlet and seedling fecundities of Poa alpina changed differently in the course of succession: seedling establishment was observed over the entire range of the successional stages, whereas plantlet establishment almost vanished with ongoing succession. In the pioneer stage, plantlets were more important than reproduction by seedlings. But we found neither a higher survival rate nor a significant advantage in development to adults for plantlets compared to seedlings. Opportunistic reproduction—plantlets under harsh abiotic conditions, seeds under increasing density—may therefore explain the fact that the species is ubiquitous along the whole glacier foreland.

Genetic diversity, phenotypic variation and local adaptation in the alpine landscape: case studies with alpine plant species

Plant survival in alpine landscapes is constantly challenged by the harsh and often unpredictable environmental conditions. Steep environmental gradients and patchy distribution of habitats lead to small size and spatial isolation of populations and restrict gene flow. Agricultural land use has further increased the diversity of habitats below and above the treeline. We studied the consequences of the highly structured alpine landscape for evolutionary processes in four study plants: Epilobium fleischeri, Geum reptans, Campanula thyrsoides and Poa alpina. The main questions were: (1) How is genetic diversity distributed within and among populations and is it affected by altitude, population size or land use? (2) Do reproductive traits such as allocation to sexual or vegetative reproduction vary with altitude or land use? Furthermore, we studied if seed weight increases with altitude. Within-population genetic diversity of the four species was high and mostly not related to altitude and population size. Nevertheless, genetic differentiation among populations was pronounced and strongly increasing with distance. In Poa alpina genetic diversity was affected by land use. Results suggest considerable genetic drift among populations of alpine plants. Reproductive allocation was affected by altitude and land use in Poa alpina and by succession in Geum reptans. Seed weight was usually higher in alpine species than in related lowland species. We conclude that the evolutionary potential to respond to global change is mostly intact in alpine plants, even at high altitude. Phenotypic variability is shaped by adaptive as well as by random evolutionary processes; moreover plastic responses to growth conditions seem to be crucial for survival of plants in the alpine landscape.

An Apomictic biotype of Poa alpina in the Koster islands of Sweden

An Apomictic biotype of Poa alpina in the Koster islands of Sweden

Pioneer vegetation on glacier forelands in southern Norway: emerging communities?

AbstractQuestion: How variable is the pioneer plant community on glacier forelands in southern Norway, both in terms of species composition and geographical distribution?Location: The Jotunheim and Jostedalsbreen regions of southern Norway (61°‐62°N, 6°‐9°E).Methods: The relative frequencies of vascular plant species were recorded in the pioneer zones of 43 glacier forelands, with an altitudinal range of 80‐1860 m (boreal to high alpine) and an east‐west range of 100 km. Classification and ordination techniques were used to search for evidence of consistently recurring communities, variability along a continuum or stochasticity.Results: Mean variability in species composition between all glacier forelands sampled was 65% (Sørensen dissimilarity). Poa alpina, Oxyria digyna, Deschampsia alpina and Festuca ovina had the highest frequency, occurring on over 80% of forelands. Non‐metric multidimensional scaling did not reveal clear divisions between groups of sites, but cluster analysis, multi‐response permutation procedures and indicator species analysis suggested two sub‐communities: the Saxifraga cespitosa‐Trisetum spicatum sub‐community is restricted to forelands above 1100 m in the Jotunheim region; whereas the D. alpina‐O. digyna sub‐community has a wider altitudinal range of 80‐1780 m. Variance partitioning indicated that altitude alone accounts for 24%, distance east for 18%, and the component shared by altitude and distance east for 17% of the variance in species composition.Conclusions: At the broadest scale, pioneer vegetation on the glacier forelands can be viewed as a single P. alpina‐O. digyna community of predominantly wind‐ and water‐dispersed perennials. However, this community shows a high degree of variability, with dominant species missing from a number of sites, and is poorly structured, suggesting a degree of stochasticity. Furthermore, the pioneer vegetation can be dissected within a continuum of variation to produce two emerging sub‐communities, reflecting the influence of environmental factors and, possibly, early successional development within the pioneer zone. Variance partitioning indicates that altitudinal and continentality gradients are important in accounting for a significant proportion of the variability within this dataset.

Changes in reproductive investment with altitude in an alpine plant

In perennial species, the allocation of resources to reproduction results in a reduction of allocation to vegetative growth and, therefore, impacts future reproductive success. As a consequence, variation in this trade-off is among the most important driving forces in the life-history evolution of perennial plants and can lead to locally adapted genotypes. In addition to genetic variation, phenotypic plasticity might also contribute to local adaptation of plants to local conditions by mediating changes in reproductive allocation. Knowledge on the importance of genetic and environmental effects on the trade-off between reproduction and vegetative growth is therefore essential to understand how plants may respond to environmental changes. We conducted a transplant experiment along an altitudinal gradient from 425 to 1 921 m in the front range of the Western Alps of Switzerland to assess the influence of both altitudinal origin of populations and altitude of growing site on growth, reproductive investment and local adaptation in Poa alpina. In our study, the investment in reproduction increased with plant size. Plant growth and the relative importance of reproductive investment decreased in populations originating from higher altitudes compared to populations originating from lower altitudes. The changes in reproductive investment were mainly explained by differences in plant size. In contrast to genetic effects, phenotypic plasticity of all traits measured was low and not related to altitude. As a result, the population from the lowest altitude of origin performed best at all sites. Our results indicate that in P. alpina genetic differences in growth and reproductive investment are related to local conditions affecting growth, i.e. interspecific competition and soil moisture content.

Population dynamics along a primary succession gradient: do alpine species fit into demographic succession theory?

Understanding processes and mechanisms governing changes in plant species along primary successions has been of major importance in ecology. However, to date hardly any studies have focused on the complete life cycle of species along a successional gradient, comparing pioneer, early and late-successional species. In this study it is hypothesized that pioneer species should initially have a population growth rate, lambda, greater than one with high fecundity rates, and declining growth rates when they are replaced by late-successional species. Populations of late-successional species should also start, at the mid-successional stage (when pioneer species are declining), with growth rates greater than one and arrive at rates equal to one at the late successional stage, mainly due to higher survival rates that allow these species to persist for a long time. The demography of pioneer- (Saxifraga aizoides), early (Artemisia genipi) and late-successional species (Anthyllis vulneraria ssp. alpicola) was investigated together with that of a ubiquitous species (Poa alpina) along the Rotmoos glacier foreland (2300-2400 m a.s.l., Central Alps, Austria) over 3 years. A matrix modelling approach was used to compare the main demographic parameters. Elasticity values were plotted in a demographic triangle using fecundity, individual growth and survival as vital rates contributing to the population growth rates. The results largely confirmed the predictions for population growth rates during succession. However, high survival rates of larger adults characterized all species, regardless of where they were growing along the succession. At the pioneer site, high mortality rates of seedlings, plantlets and young individuals were recorded. Fecundity was found to be of minor relevance everywhere, but it was nevertheless sufficient to increase or maintain the population sizes. Demographically, all the species over all sites behaved like late-successional or climax species in secondary successions, mainly relying on survival of adult individuals. Survival serves as a buffer against temporal variation right from the beginning of the primary succession, indicating a major difference between primary and secondary succession.

Mode of propagation and chromosomal peculiarities in Scotch material of Poa alpina

In Great Britain Poa alpina L. is usually viviparous, but among specimens received from Scotland there was also a seed-producing plant. In the seminiferous offspring from this individual, there was a high degree of sexual reproduction but also the occurrence of total or partial apomictic seed formation. Root tips of 55 plants were examined with regard to chromosome number and chromosome morphology. There was a very pronounced variation in somatic chromosome number between plants, ranging from 2n=32 to about 70. There was also a frequent occurrence of intra-plant variation in chromosome number. This variation was largely caused by a variable number of dot-like minute chromosomes. Comparison between the Scotch material and diploid and sexual strains of Poa alpina from central Europe carrying B chromosomes, indicates that also the minute chromosomes in the Scotch material are B chromosomes or derivatives from such chromosomes.

The Association Drepanoclado Uncinati-Heliospermetum Pusilli (Arabidetalia Caeruleae, Thlaspietea Rotundifolii) in the Trnovski Gozd Plateau (Slovenia, NW Dinaric Mts)

The AssociationDrepanoclado Uncinati-Heliospermetum Pusilli (Arabidetalia Caeruleae, Thlaspietea Rotundifolii)in the Trnovski Gozd Plateau (Slovenia, NW Dinaric Mts)The phytosociology and ecology ofHeliosperma pusillumin freezing ravines of the Trnovski gozd plateau (Slovenia, NW Dinaric Mts) are discussed. The species thrive on shadowy, moist, cold and stable screes of boulders with long-lasting snow cover. The stands belonged to the associationDrepanoclado uncinati-Heliospermetum pusilli (Salicion retusae, Arabidetalia caeruleae, Thlaspietea rotundifolii). Due to close proximity to the Julian Alps, the stands host a significant number of SE - Alpine and N-Illyrian species. Therefore, a new geographical variantPaederota luteais described. Differential species for the geographical variant arePhyteuma scheuchzerissp.columnae, Valeriana saxatilis, Rhodothamnus chamaecistus, andSaxifraga cuneifolia.For less stable screes with smaller rocky particles a new subassociationsalicetosum retusaeis described, and the differential species for the subassociation areSalix retusaandPoa alpina.Stands of the associationDrepanoclado-Heliospermetumvar. geogr.Paederota luteafrom the Trnovski gozd plateau are on the north-westernmost part of the distribution area of the Dinaric allianceSalicion retusae.

Ice Propagation in Dehardened Alpine Plant Species Studied by Infrared Differential Thermal Analysis (IDTA)

Infrared differential thermal analysis (IDTA) was used to study ice propagation and whole plant freezing patterns in dehardened intact individuals of various alpine plant species, including a shrub (Rhododendron ferrugineum), a herbaceous plant (Senecio incanus), a cushion plant (Silene acaulis), and two graminoids (Poa alpina and Juncus trifidus). Freezing patterns differed markedly among species and reflected peculiarities of the shoot structure and the vascular system. In graminoids, each single leaf required a separate ice nucleation event, as the polystele prevents ice propagation between leaves via the stem. Additionally, enhanced supercooling resulted in a temperature range of whole plant freezing of up to 10°C, which corroborates the high summer frost resistance of graminoids. This could have ecological significance for frost survival. In contrast, in dicotyledonous species one nucleation event was usually sufficient for whole plant freezing. Controlled ice-seeding experiments on leaves with droplets of water and bacterial water suspension (Pseudomonas syringae) showed that ice propagation into the leaf tissue from the surface was inhibited as long as the leaves were undamaged. The rate of ice propagation in veins was significantly higher at lower temperatures and reached up to 24 cm s−1 in J. trifidus, which is much higher than reported in earlier findings. Ice propagation in graminoids was much faster, which may indicate that ice propagates within the protoxylem lacunae of large vessels.

Mesophyll freezing and effects of freeze dehydration visualized by simultaneous measurement of IDTA and differential imaging chlorophyll fluorescence

Infrared differential thermal analysis (IDTA) and differential imaging chlorophyll fluorescence (DIF) were employed simultaneously to study the two-dimensional pattern of ice propagation in leaves and mesophyll freeze dehydration as detected by a significant increase of basic chlorophyll fluorescence (F(0)). IDTA and DIF technique gave different insights into the freezing process of leaves that was highly species-specific. IDTA clearly visualized the freezing process consisting of an initial fast spread of ice throughout the vascular system followed by mesophyll freezing. While mesophyll freezing was homogeneously in Poa alpina, Rhododendron ferrugineum and Senecio incanus as determined by IDTA, DIF showed a distinct pattern only in S. incanus, with the leaf tips being affected earlier. In Cinnamomum camphora, a mottled freezing pattern of small mesophyll compartments was observed by both methods. In IDTA images, a random pattern predominated, while in DIF images, compartments closer to lower order veins were affected earlier. The increase of F(0) following mesophyll freezing started after a species-specific time lag of up to 26 min. The start of the F(0) increase and its slope were significantly enhanced at lower temperatures, which suggest a higher strain on mesophyll protoplasts when freezing occurs at lower temperatures.

Agricultural Land Use and Biodiversity in the Alps

Alpine grasslands are ecosystems with a great diversity of plant species. However, little is known about other levels of biodiversity, such as landscape diversity, diversity of biological interactions of plants with herbivores or fungal pathogens, and genetic diversity. We therefore explored natural and anthropogenic determinants of grassland biodiversity at several levels of biological integration, from the genetic to the landscape level in the Swiss Alps. Differences between cultural traditions (Romanic, Germanic, and Walser) turned out to still affect land use diversity and thus landscape diversity. Increasing land use diversity, in turn, increased plant species diversity per village. However, recent land use changes have reduced this diversity. Within grassland parcels, plant species diversity was higher on unfertilized mown grasslands than on fertilized or grazed ones. Most individual plants were affected by herbivores and fungal leaf pathogens, reflecting that parcels harbored a great diversity of herbivores and pathogens. However, as plant damage by herbivores and pathogens was not severe, conserving these biological interactions among plants is hardly compromising agricultural goals. A common-garden experiment revealed genetic differentiation of the important fodder grass Poa alpina between mown and grazed sites, suggesting adaptation. Pervillage genetic diversity of Poa alpina was greater in villages with higher land use diversity, analogous to the higher plant species diversity there. Overall, landscape diversity and biodiversity within grassland parcels are currently declining. As this contradicts the intention of Swiss law and international agreements, financial incentives need to be re-allocated and should focus on promoting high biodiversity at the local and the landscape level. At the same time, this will benefit landscape attractiveness for tourists and help preserve a precious cultural heritage in the Swiss Alps.

Species‐specific responses of an alpine plant community under simulated environmental change

AbstractQuestion:How will warming and increased nutrient availability affect individual alpine plant species abundances (non‐vascular and vascular) and community composition?Location:Dryas octopetala heath at alpine Finse, southern Norway.Methods:Four years with experimental warming (open top chambers) and nutrient addition. Detrended Correspondence Analysis and Redundancy Analysis were used to examine changes in community composition. GLM‐ANOVA was used to examine treatment effects on individual species.Results:Warming alone decreased the abundance of some Carex and bryophyte species, but did not affect community composition. Nutrient addition and warming combined with nutrient addition increased the abundance of high stature species, such as grasses (Festuca spp., Poa alpina) and some forbs (e.g. Cerastium alpinum, Potentilla crantzii). Low stature forbs (e.g. Tofieldia pusilla), a lycophyte (Selaginella selaginoides) and most bryophytes and lichens decreased in abundance. After four years of warming combined with nutrient addition 57% of the mosses, 57% of the liverworts and 44% of the lichens had completely disappeared. Community composition changed significantly, with the largest shift when warming and nutrient addition was combined.Conclusions:Tall species may expand at the expense of low stature species in the alpine region if temperature and soil nutrient content increase. Contrasting responses between grasses and sedges, and species‐specific responses within forbs, sedges and shrubs, within and across alpine and arctic sites, suggest that the use of functional types in environmental change research may mask important information on individual species responses. The response of one species within a functional type cannot predict the response of another.

Microsatellite Diversity of the Agriculturally Important Alpine Grass Poa alpina in Relation to Land Use and Natural Environment

The Alpine Meadow Grass Poa alpina is common in subalpine and alpine natural sites and agriculturally used land, where it is an important fodder grass. Natural factors and human land use are supposed to have been shaping its genetic diversity for hundreds of years. The species comprises sexually and vegetatively reproducing plants. The aim of this study was to investigate the effects of agricultural land use, environmental factors and the mode of reproduction on the distribution of its microsatellite diversity within and among populations and to analyse whether its genetic diversity is correlated with plant species diversity in grassland parcels. Genetic diversity of P. alpina was assessed with five microsatellite markers for 569 plants originating from 20 natural sites and from 54 grassland parcels of different cultural tradition, land use and altitude in the Swiss Alps. Due to polyploidy and frequent aneuploidy of the species, data analyses were based on the presence of microsatellite bands. A low but significant differentiation was found in microsatellite bands among natural sites and agriculturally used parcels, while their microsatellite band diversity within populations did not differ. An increased differentiation was found in microsatellite bands with increasing geographic distance among parcels, and a differentiation among grazed and mown parcels, and among sexually and vegetatively reproducing populations. Band richness of sampled plants per village was higher for villages where parcels represented more different land-use types. Within populations, microsatellite band diversity was higher in grazed than in mown parcels. The diversity of human land use in the Alps was associated with genetic diversity of P. alpina. Therefore, the ongoing socio-economically motivated land-use changes, which reduce the number of different land-use types, will affect the genetic diversity of P. alpina negatively.

Effects of temperature and light on the formation of chloroplast protrusions in leaf mesophyll cells of high alpine plants

Chloroplasts of many alpine plants have the ability to form marked, stroma-filled protrusions that do not contain thylakoids. Effects of temperature and light intensity on the frequency of chloroplasts with such protrusions in leaf mesophyll cells of nine different alpine plant species (Carex curvula All., Leontodon helveticus Merat., Oxyria digyna (L.) Hill., Poa alpina L. ssp. vivipara, Polygonum viviparum L., Ranunculus glacialis L., Ranunculus alpestris L., Silene acaulis L. and Soldanella pusilla Baumg.) covering seven different families were studied. Leaves were exposed to either darkness and a stepwise increase in temperature (10-38 degrees C) or to different light intensities (500 and 2000 micromol photons m(-2) s(-1)) and a constant temperature of 10 or 30 degrees C in a special temperature-regulated chamber. A chloroplast protrusions index characterising the relative proportion of chloroplasts with protrusions was defined. Seven of the nine species showed a significant increase in chloroplast protrusions when temperature was elevated to over 20 degrees C. In contrast, the light level did not generally affect the abundance of chloroplasts with protrusions. Chloroplast protrusions lead to a dynamic enlargement of the chloroplast surface area. They do not appear to be directly connected to a distinct photosystem II (PSII) (F(v)/F(m)) status and thus seem to be involved in secondary, not primary, photosynthetic processes.

Changes in chloroplast ultrastructure in some high-alpine plants: adaptation to metabolic demands and climate?

The cytology of leaf cells from five different high-alpine plants was studied and compared with structures in chloroplasts from the typical high-alpine plant Ranunculus glacialis previously described as having frequent envelope plus stroma protrusions. The plants under investigation ranged from subalpine/alpine Geum montanum through alpine Geum reptans, Poa alpina var. vivipara, and Oxyria digyna to nival Cerastium uniflorum and R. glacialis. The general leaf structure (by light microscopy) and leaf mesophyll cell ultrastructure (by transmission electron microscopy [TEM]) did not show any specialized structures unique to these mountain species. However, chloroplast protrusion formation could be found in G. reptans and, to a greater extent, in O. digyna. The other species exhibited only a low percentage of such chloroplast structural changes. Occurrence of protrusions in samples of G. montanum and O. digyna growing in a mild climate at about 50 m above sea level was drastically reduced. Serial TEM sections of O. digyna cells showed that the protrusions can appear as rather broad and long appendices of plastids, often forming pocketlike structures where mitochondria and microbodies are in close vicinity to the plastid and to each other. It is suggested that some high-alpine plants may form such protrusions to facilitate fast exchange of molecules between cytoplasm and plastid as an adaptation to the short, often unfavorable vegetation period in the Alps, while other species may have developed different types of adaptation that are not expressed in ultrastructural changes of the plastids.