Mugo Turra Research Articles

Structural and dendrochronological characterization of mountain pine persisten woodlands on the Monti del Sole - Dolomiti Bellunesi National Park

High-mountain ecosystems, located at the geographical distribution limit of the species, may provide valuable information about tree-growth responses to changes in climate conditions and land uses. In order to provide a first description of a mountain pine ecotone, at the alpine treeline, three plots were sampled along an altitudinal gradient in the Monti del Sole (Dolomiti Bellunesi National Park, Veneto, Italy) on a northwestern slope from 1850 to 2000 m a.s.l. In order to reconstruct recent dynamics of Pinus mugo Turra ssp. mugo (mountain pine) at this altitudinal range dendroecological methods were used,which allowed reconstructing the age structures of tree populations. Raw mean chronologies showed the long-term variability, related to non-climatic signals due to age, size and stand dynamics. The raw mean chronology of Plot 1 followed the typical exponential negative trend, while raw mean chronologies of Plot 2 and Plot 3 depicted an increasing growth trend, starting from early fifties of 20th century. There was a greater ring width in Plot 2,than the other two plots. These mountain pine scrublands belong the Sorbo chamaemespili - Pinetum mugi association and form persistent woodlands.

Nematode assemblages from Mountain Pine (Pinus mugo Turra) communities in Pirin Mountain, Bulgaria

Abstract The structural and functional diversity of nematode communities from Pinus mugo sites in Pirin Mountain was assessed. The sampling plots represent different levels of disturbance — next to and outside ski runs. Nematode assemblages from this habitat can be characterised with high diversity (in total, 104 taxa and richness ranging from 41 to 65 genera per site). In general, the trophic structure was dominated by omnivorous and bacterial feeders coupled with low proportion of plant feeding nematodes. The high values of Maturity indices and the results from faunal analysis indicate relatively stable environment and undisturbed conditions for all sites. No clear correlation between the nematode assemblages’ characteristics and the level of disturbance (position of the site in relation to ski runs) was revealed.

Seed quality in hybrid swarm populations of Pinus mugo Turra and P. sylvestris L.

Crop characteristics involving cone size, average number of seeds per cone, and seed germinability have been studied for three hybrid swarm populations of Pinus mugo and P. sylvestris, two pure P. mugo populations and one pure P. sylvestris population, in northern Slovakia. Generally, reproduction capability characteristics were significantly reduced in hybrid swarms in relation to the control populations. Although there were no consistent differences between hybrid swarms and control populations in the average number of seeds per cone or cone size, seed germination rates and full seed production in hybrid swarms were lower than for the control population of P. sylvestris and one of the pure populations of P. mugo. Based on these data a conclusion has been drawn postulating partial rather than full fertility of the hybrid swarm populations of P. mugo and P. sylvestris.

A new, isolated and endangered relict population of dwarf pine ( Pinus mugo Turra) in the northwestern Alps

Dwarf pines were discovered in 2004 during a paleoecological survey in the Mont Cenis massif (Savoy, France). These dwarf pines are the sole natural and spontaneous population in the NW French Alps of Pinus mugo Turra, ssp. mughus (Scop.) O. Schwarz. The population, fragile in light of the individual numbers, is currently isolated, but likely results from populations that would have covered larger areas during the Lateglacial or the early-Holocene, from the SW Alps (France) toward the Mont Cenis, throughout the Susa valley (Italy). With a fragmented distribution area of dwarf pine, the future of the Mont Cenis population seems altered due to important necroses observed on the topmost part of pine crowns, except for individuals that do not grow in the local ski station area. We stress the need for a conservation program to preserve this natural population, the sole known in the NW French Alps. To cite this article: C. Carcaillet et al., C. R. Biologies 332 (2009).

Spontaneous Hybridization between Pinus sylvestris L. and P. mugo Turra in Slovakia

Abstract Molecular evidence for spontaneous hybridization between Pinus sylvestris L. and P. mugo Turra in the putative hybrid swarm populations of the species in Slovakia was provided based on PCR-RFLP analysis of the cpDNA trnV-trnH region. Species-specific restriction profiles generated by Hinf I digests of the cpDNA products reliably identified P. sylvestris and P. mugo haplotypes of the embryos from open pollination. Simultaneous analysis of the respective cpDNA region in megagametophytes and embryos of individual seeds along with needles of a given maternal tree has enabled to score either the P. sylvestris or P. mugo haplotypes in the embryos illustrating hybridization patterns between the two species. Data obtained in this way indicate a relatively extensive hybridization which takes place between P. sylvestris and P. mugo. The extent of hybridization varied among populations as evidenced by the 41.1-58.7% proportion of hybrid embryos registered on the locality Habovka, and by the 8.3% and 2.7% proportions of hybrid embryos on the localities Tisovnica and Sucha Hora, respectively. The approach itself is recommended as a convenient method for monitoring the hybridization patterns in sympatric zones of the studied pine species.

Organic matter accumulation following Pinus mugo Turra establishment in subalpine pastures

Background: Livestock reduction or abandonment has been common on the subalpine pastures of the Northern Calcareous Alps in Austria and Germany since the mid-nineteenth century. The mosaic of Pinus mugo scrub and grassland is being increasingly recolonised by P. mugo. Aims: In this study we focus on the accumulation rate of the organic layer associated with establishment and development of Pinus mugo in non-forest plant communities. Methods: Age determination of P. mugo is used in combination with soil and existing climatic data to describe the site-dependent accumulation rates of the organic layer by using generalised linear models. Results: Mean increase of the organic layer is 12.5cm during the first 100 years. Decomposition of fresh litter is retarded in the first 30–50 years after P. mugo establishment. The residual variation of the age–depth relationship can be explained satisfactorily by using climate and habitat descriptors. Temperature, site water balance, and the presence of a clayey soil are significantly related to the depth of the organic layer. Conclusions: Organic layer accumulation after P. mugo establishment in former pastures is a long-term process exceeding the investigated period of 100–150 years. Increased needle litter input as the prime factor, together with soil properties and particular microclimatic conditions under the P. mugo canopy all contribute to controlling accumulation rates.

Long-term development of above- and below-ground carbon stocks following land-use change in subalpine ecosystems of the Swiss National Park

Vegetation changes following agricultural land abandonment at high elevation — which is frequent in Europe — could have a major impact on carbon (C) sequestration. However, most information on the effects of vegetation changes on ecosystem C stocks originates from low-elevation studies on reforestation or early successional forests, and little is known about how these stocks change during long-term secondary forest succession and at high elevation. We assessed aboveground, belowground, and ecosystem organic matter and C stocks in high-elevation ecosystems that represent the long-term development (centuries) following land abandonment: short- and tall-grass pastures, Swiss mountain pine (Pinus mugo Turra), mixed-conifer, and Swiss stone pine ( Pinus cembra L.) – European larch ( Larix decidua P. Mill.) forests. Aboveground C stocks were lowest in the short-grass pastures (0.1 Mg C·ha–1) and reached a maximum in the mixed-conifer and stone pine – larch forests (166 Mg C·ha–1). Belowground C stocks did not differ among the ecosystems studied. We only detected ecosystem C sequestration during reforestation; whereas no significant differences in ecosystem C stocks were found during long-term secondary forest development. Our calculations showed that only an additional 1733–3032 Mg C·year–1 would be sequestered owing to natural reforestation in high-elevation Switzerland, which likely can be considered negligible compared with total annual C sequestration calculated for Swiss forests in other studies.

Conifer Dispersion on Subalpine Pastures in Northeastern Spain: Characteristics and Implications for Rangeland Management

Pinus sylvestris L. and Pinus mugo Turra originating from two plantations established during the 1960s are invading subalpine heathlands higher than 1 500 m above sea level in Montseny Natural Park (northeast Spain). Both species are native at a regional scale but may not have been present in the park’s subalpine vegetation previously. In addition, Abies alba P. Mill., which is in regression in many areas in Europe, is also colonizing the area from a neighboring natural forest. This invasion appears to be stimulated by a combination of natural and human factors, including differences between vegetation components, climate (i.e., drought periods), changes in land use due to conservation policies (i.e., suppressing fire or grazing practices), the creation of the plantations, and probably the nurse role played by accompanying dwarf shrubs ( Calluna vulgaris [L.] Hull and Juniperus communis subsp. nana [Willd.] Syme). We examined the effects of this process in terms of the spatial dispersion and characteristics of the established conifers and deduce implications for the conservation of isolated subalpine pastures in Mediterranean Basin mountains. P. sylvestris was the most successful invading species in this area. The P. mugo invasion is distributed mainly near the plantation. The only native conifer species, A. alba, appears to be colonizing only the eastern slope. The invasion process is related to the diversity and species richness recorded on each slope. Conserving valuable subalpine heathlands at the latitude of the Montseny mountain range implies suppressing propagule pressures from the plantations. The option of removing conifers that are nonnative, at a local scale, must be considered. However, in the case of the native A. alba this option leads to a management conflict between conserving former pastureland and the dispersion of A. alba. Las especies Pinus sylvestris L. y Pinus mugo Turra, procedentes de dos plantaciones establecidas durante la decada 1960–1970, están invadiendo los páramos subalpinos superiores a los 1 500 m sobre el nivel del mar (snm) en el Parque Natural del Montseny (NE España). Ambas especies son nativas a escalas regionales, pero puede que no hayan estado presentes en la vegetación subalpina del Parque con anterioridad. Además, la especie Abies alba P. Mill., que se encuentra en regresión en muchas zonas de Europa, también está colonizando la zona desde un bosque natural colindante. Esta invasión parece ser estimulada por una combinación de factores naturales y humanos, incluyendo diferencias entre componentes vegetacionales, clima (p.e. períodos de sequía), cambios en el uso de la tierra debido a las políticas de conservación (p.e. supresión de fuegos o prácticas de pastoreo), creación de plantaciones y probablemente el papel nodriza desempeñado por los arbustos enanos ( Calluna vulgaris [L.] Hull y de Juniperus communis subsp. nana [Willd.] Syme). Hemos examinado los efectos de este proceso en términos de la dispersión espacial y las características de las coníferas establecidas y deducimos las implicaciones para la conservación de los pastizales subalpinos aislados en las montañas del Mediterráneo. P. sylvestris fue la especie invasora más éxitosa en este área. La invasión de P. mugo se distribuye principalmente cerca de la plantación. La única especie nativa de coníferas, A. alba, parece està colonizando sólo la pendiente este. El proceso de invasión está relacionado con la diversidad y con la riqueza de especies encontradas en cada pendiente. La conservación de valiosos páramos subalpinos en la latitud de la sierra del Montseny implica suprimir las presiones de los propágulos de las plantaciones. La opción de eliminar las coníferas que no son nativas, a escalas locales, debe ser considerada. Sin embargo, en el caso de la nativa A. alba esta opción conduce a un conflicto de manejo entre la conservación de antiguos pastizales y la dispersión de A. alba.

Contribution to the taxonomy of Pinus uncinata (Pinaceae) based on cone characters

Eight natural populations of Pinus uncinata Ramond from the Spanish Pyrenees, five of P. mugo Turra from the Carpathians, the Sudethians and Abruzzian Apennines, three of P. sylvestris L. from the Central-European Lowland and the Iberian Peninsula and one of P. uliginosa Neumann from SW Poland have been compared biometrically in 16 cone characters. P. uncinata appears the most distant from all other taxa, differing by having the largest and most asymmetric cones and the thickest apophyses with the most prominent umbo. In cone characters, P. mugo is more similar to P. sylvestris than to P. uncinata. Nevertheless, P. mugo and P. sylvestris remain distant from each other in a number of morphological characters examined. P. uliginosa has cones intermediate between the other three taxa and is moreover very variable. The locality of P. uliginosa in the Silesian Lowland may be of a relict character and conserve genes from P. uncinata.

Growth of mountain pine (Pinus mugo Turra) in relation to the use of other tree species

In summit parts of the Orlické hory Mts., massive dieback of forests occurred during an air pollution/ecological disaster in the 70s to the 80s of the 20<sup>th</sup> century. Destroyed stands were cut down and deforested areas were planted by more resistant species including mountain pine (Pinus mugo Turra). The aim of the paper was to assess effects of mountain pine on the prosperity of other tree species. Four localities with mountain pine stands were selected at altitudes from 1,000 to 1,115 m. In 2003–2005, growth analyses of shrubs were carried out there and basic parameters of stands were determined such as: height; cover of mountain pine, other tree species and herbs; radiation transmittance and temperature gradients. Results show the importance of the height of mountain pine stands in mitigating climatic changes in the ground layer of air, identification of the light compensation point for the mountain pine prosperity, the dependence of a growth type on outer and inner conditions of mountain pine including partly its age. Under given conditions, the present stands of mountain pine on top parts of the Orlické hory Mts. show their justification because they create a good protection for young seedlings, self-seeding and newly planted tree species. If forest spreads there, the markedly heliophilous mountain pine will recede similarly as in case of more than hundred-year-old mountain pine in the Sowie gory Mts. in Poland.

Incendies et peuplements à Pinus mugo Turra dans les Alpes occidentales (Val de Suse, Italie) durant la transition Tardiglaciaire–Holocène : une zone refuge évidente

In western Italian Alps, small distinct populations of Pinus mugo Turra raise some questions concerning its ecological status and dynamics in the occidental Alps. This note present new palaeobotanical data based on cone imprints of Pinus mugo, identified in travertine systems located in the Val di Susa and dated back to the Late Dryas ( 11 506 ± 66 BP ) and the Early Holocene ( 10 145 ± 225 et 9475 ± 670 BP ). Heliophilous species and charcoal fragments were also identified, testifying to the oldness of wildfires in this region. The data support the hypothesis that this zone was a refuge area of this pine during the last glaciation. Here we discuss about the postglacial dynamics of the Pinus mugo in the occidental Alps. To cite this article: A.A. Ali et al., C. R. Biologies 329 (2006).

The host spectrum of Dothistroma needle blight Mycosphaerella pini E. Rostrup - new hosts of Dothistroma needle blight observed in theCzech Republic

Dothistroma needle blight Mycosphaerella pini E. Rostrup and its anamorphic stage Dothistroma septospora (Dorog.) Morelet was detected for the first time in the territory of the Czech Republic in a consignment of imported plants of Austrian pine Pinus nigra Arnold in 1999. In 2000, it was also found on Pinus nigra in an open planting in a plantation of Christmas trees by the village of Jedovnice near Brno in South Moravia. In the Czech Republic, Dothi-stroma needle blight was identified on 13 species of pine. Pinus nigra Arnold and Pinus mugo Turra are the most frequent hosts. In addition to these species, Dothistroma needle blight was observed on Pinus ponderosa Douglas ex Lawson, Pinus jeffreyi Grev. et Balf, Pinus banksiana Lamb., Pinus contorta Douglas, Pinus rotundata Link, Pinus leucodermis Ant. and Pinus sylvestris L. Finds on Pinus aristata Engelm., Pinus rigida Mill., Pinus heldreichii H. Christ. and Pinus cembra L. var. sibirica (Du Tour) G. Don. are a certain rarity. These species are not mentioned anywhere as potential hosts of Dothistroma needle blight. As for the species of other genera Picea pungens Engelm., Picea abies L. Karst. and last but not least Picea schrenkiana Fisch. & C. A. Mey were also observed as hosts. The host range of Dothistroma needle blight recorded in papers is noted as well.

Effectiveness of neutral RAPD markers to detect genetic divergence between the subspecies uncinata and mugo of Pinus mugo Turra

Fifteen populations of Pinus mugo subsp. mugo (shrub) and Pinus mugo subsp. uncinata (erect), located in the Alps, were investigated through genetic variation scored at 64 polymorphic RAPD loci. In addition, morphological traits of the female cones were analysed. According to AMOVA most of the genetic variation was found within populations (83.39%), and only 1.25% of it between subspecies. Populations differed in terms of their internal genetic variation, with Nei’s gene diversity ranging from 0.227 to 0.397. Morphological data showed differences between subspecies, although none of the populations showed full accordance with expectations. Significant correlation was found between matrices for geographical and morphological distances, while genetic distances were not correlated with any other aspect. The efficacy of morphological and RAPD markers in discriminating between subspecies, and the contribution of the results in relation to the preservation of biodiversity, are discussed.

Susceptibility to low-temperature photoinhibition in three conifers differing in successional status

Susceptibility to photoinhibition of the evergreen conifers Abies alba Mill., Picea abies (L.) Karst. and Pinus mugo Turra was investigated in an unheated greenhouse during winter and spring 2003. Photosynthetic performance of the seedlings was assessed by chlorophyll a fluorescence and analyses of chlorophyll and total carotenoid concentrations in needles. During winter months, maximum quantum yield of PSII photochemistry (ratio of variable to maximum fluorescence, Fv/Fm) was significantly greater in A. alba than in P. abies and P. mugo. Abies alba also sustained higher maximum apparent electron transport rate (ETRmax) than P. abies and P. mugo. Total concentrations of chlorophyll and carotenoids in needles decreased during the winter in P. mugo and P. abies, but remained stable in A. alba. For all species, Fv/Fm decreased from December until February and then increased to a maximum in April. Photoinhibition was greatest (Fv/Fm < 0.80) in all seedlings in February, the month with the lowest mean temperature. Saturating photosynthetic photon flux (PPFsat) and ETRmax were positively related to air temperature. All species had lower values of ETRmax and PPFsat in winter than in spring. Non-photochemical quenching of chlorophyll fluorescence (NPQ) was highest at low air temperatures. Differences among species in susceptibility to winter photoinhibition resulted from their specific light preferences and led to different mechanisms to cope with photoinhibitory stress. The more shade-tolerant A. alba sustained a higher photosynthetic capacity in winter than P. abies and P. mugo. Winter photoinhibition in P. abies, P. mugo and, to a lesser extent, in A. alba may reflect adaptive photoprotection of the photosynthetic apparatus in winter.

Allozyme variation, differentiation, and inbreeding in populations ofPinus mugoin Bulgaria

Genetic variation of 17 populations of Pinus mugo Turra was studied using 10 polymorphic allozyme loci. Polymorphism and gene diversity in these populations were comparable to mean values for gymnosperm species, but slightly lower than in pines with large and continuous ranges. We did not find significant interpopulation differentiation (FST= 0.041) or isolation by distance, suggesting that gene flow might be extensive or that the time elapsed since the species range became fragmented has been too short for genetic differentiation to arise via genetic drift. We detected moderate and statistically significant levels of inbreeding (mean FIS= 0.252) for all loci in all populations. Although there are many possible explanations for this nonequilibrium population structure, we propose that the main reasons for its ubiquity are the peculiar growth form and reproductive biology of P. mugo, which promote excessive near-neighbor pollinations. Populations in Vitosha Mountain and western Stara Planina had the highest levels of inbreeding and the lowest observed heterozygosities. All populations in these mountains are small and isolated, but none of them is under a special regime of protection. Thus, the conservation status of P. mugo populations in Vitosha Mountain and western Stara Planina may deserve reevaluation. Future gene conservation efforts should focus on obtaining information on the genetic variation of adaptive traits in P. mugo.

Dothistroma needle blight Mycosphaerella pini E. Rostrup, a new quarantine pathogen of pines in the CR

Dothistroma needle blight caused by Mycosphaerella pini E. Rostrup was observed for the first time in the Czech Republic on an imported Pinus nigra Arnold in 1999. In 2000, it was also found in the open planting. During three years, it became an important pathogen of pines in the Czech Republic. Its occurrence was noticed in more than 50 localities, above all in the region of Moravia and Silesia and eastern Bohemia. In total, it was found on 10 species of pine (P. nigra Arnold, P.&amp;nbsp;banksiana Lamb., &lt;br /&gt;P. contorta Loudon, P. mugo Turra, P.&amp;nbsp;leucodermis Ant., P. sylvestris L., P. cembra L., P. aristata Engelm., P.&amp;nbsp;ponderosa P. et C.&amp;nbsp;Lawson and P. jeffreyi Grev. et Balf.). Also Picea pungens &amp;nbsp;Engelm. was noticed as a host species. In the Czech Republic, Pinus nigra is the most frequent host species of M. pini (80% localities) followed by Pinus mugo (27% localities). On Scots pine P. sylvestris, M. pini was noticed at two localities. The critical period for infection is in the Czech Republic from the second half of May until the end of June. The incubation period lasts about 2&amp;ndash;4 months depending on climatic conditions. The first symptoms on the needles infected in the current year appear in August being clearly expressed from September to November.In the CR, Dothistroma needle blight spread probably with infected planting stock obtained from import at the end of the 80s and at the beginning of the 90s.

The essential oil composition of Pinus mugo Turra from Serbia

AbstractThe chemical composition of the essential oil of the needles and twigs of dwarf pine (Pinus mugo Turra) growing wild in Serbia was investigated. The oil was analysed by GC/MS and the major constituents found were δ‐3‐carene (23.9%), α‐pinene (17.9%), β‐pinene (7.8%) and β‐phellandrene (7.2%). Copyright © 2004 John Wiley &amp; Sons, Ltd.

Modelling climate change‐driven treeline shifts: relative effects of temperature increase, dispersal and invasibility

1 Global warming will probably shift treelines upslope in alpine areas and towards the pole in arctic environments. However, responses of regional treelines to climatic trends over the last century do not show any clear trends. We hypothesize that these equivocal responses may partly be caused by limitation of dispersal and/or recruitment that is species-specific to particular trees with potentially expanding ranges. 2 To test this hypothesis, we established and parameterized a temporally and spatially explicit model of plant spread and analysed its sensitivity to: (a) variation in predicted climatic trends; (b) the spatial distribution of recruits around a seed source; and (c) variation in the resistance of resident non-woody vegetation to invasion. We used data from a high mountain landscape of the Northern Calcareous Alps in Austria where the treeline is dominated by Pinus mugo Turra, a shrubby pine. 3 Low growth rates and long generation times, together with considerable dispersal and recruitment limitation, resulted in an overall slow range expansion under various climate-warming scenarios. 4 Running the model for 1000 years predicted that the area covered by pines will increase from 10% to between 24% and 59% of the study landscape. 5 The shape of the dispersal curve and spatial patterns of competitively controlled recruitment suppression affect range size dynamics at least as severely as does variation in assumed future mean annual temperature (between 0 °C and 2 °C above the current mean). Moreover, invasibility and shape of the dispersal curve interact with each other due to the spatial patterns of vegetation cover in the region. 6 Ambiguous transient responses of individual treeline systems may thus originate not only from variation in regional climatic trends but also from differences in species’ dispersal and recruitment behaviour and in the intensity and pattern of resistance of resident alpine vegetation to invasion.

First Report of Arceuthobium vaginatum subsp. cryptopodum on Pinus mugo.

Southwestern dwarf mistletoe (Arceuthobium vaginatum (Willd.) Presl subsp. cryptopodum (Engelm.) Hawksw. & Wiens, family Viscaceae) is a serious and common pathogen of ponderosa pine (Pinus ponderosa Douglas ex Lawson & C. Lawson) in Colorado, Utah, Arizona, New Mexico, and northern Mexico (1). In July 2002, this dwarf mistletoe was observed parasitizing a 1.4-m tall mugo pine (P. mugo Turra) in the Black Forest north of Colorado Springs, CO (39°02.118'N, 104°36.028'W, elevation 2,250 m). The infected mugo pine was planted as an ornamental approximately 6 m from a ponderosa pine infected with A vaginatum subsp. cryptopodum. Dwarf mistletoe shoots were produced on the only infected branch observed but this was sufficient for a positive identification of the dwarf mistletoe. Although J. Weir successfully inoculated mugo pine with western dwarf mistletoe (A. campylopodum Engelm.) and lodgepole pine dwarf mistletoe (A. americanum Nutt. ex Engelm.) (2), to our knowledge, this is the first report of a dwarf mistletoe occurring naturally on P. mugo, as well as the first report of A vaginatum subsp. cryptopodum on P. mugo (1). Specimens of A vaginatum subsp. cryptopodum from P. mugo have been deposited in the Deaver Herbarium, Northern Arizona University, Flagstaff (Accession No. 73761).

Patterns of Shrub Invasion into High Mountain Grasslands of the Northern Calcareous Alps, Austria

Both land use and expected climate change will probably cause range shifts of tree and shrub species in the European Alps. Attempts to predict the magnitude and direction of these processes will produce reliable results only if they consider both abiotic habitat conditions and biotic interactions. In this study we analyze recruitment patterns of Pinus mugo Turra in different grassland communities of the Northern Calcareous Alps, Austria. Pinus mugo is the most important invader of abandoned subalpine pastures in the area and the predominant woody plant at the current timberline. Results indicate strong dependence of colonization success on propagule pressure and differential invasibility of grassland types but only a marginal impact of local-scale site conditions, at least within the species’ current altitudinal distribution limits. Because the grassland matrix at and above the current treeline is dominated by a particularly invasible grassland type, a possible climate change–driven upward movement of Pinus mugo shrublands may take place quite rapidly. In contrast, encroachment on abandoned subalpine pastures is frequently delayed by competition with vigorous grassland canopies.