The subalpine vegetation of Mt. Vysokaya, central Sikhote-Alin

The subalpine vegetation structure of Mt. Vysokaya, the Central Sikhote-Alin, is described. This vegetation consists mainly of subalpine spruce-fir forest, a complex of subalpine meadows, shrubs, groves of Betula lanata (B. ermanii s.l.), krummholz of Pinus pumila and alpine tundras. Significant disturbances in the vegetation structure were noted, especially in the forest-tundra ecotone accompanying a sharp reduction of the belts of Betula lanata and Pinus pumila. The altitudinal level of the upper timberline reaches 1600 m a.s.l. which is 250 m less than the expected altitude calculated by Kira's warmth index. An undergrowth of scattered trees of Picea and Betula are growing up to the mountain top. Based on these data and a review of the literature, we concluded that a catastrophic lowering of the timberline and devastation of the subalpine vegetation belt occurred several centuries ago, probably as result of fires.     

Airborne‐pollen pool and mating pattern in a hybrid zone between Pinus pumila and P. parviflora var. pentaphylla

The reproductive isolation barriers and the mating patterns among Pinus pumila, P. parviflora var. pentaphylla and their hybrids were examined by flowering phenology and genetic assays of three life stages: airborne‐pollen grains, adults and seeds, in a hybrid zone on Mount Apoi, Hokkaido, Japan. Chloroplast DNA composition of the airborne‐pollen was determined by single‐pollen polymerase chain reaction. Mating patterns were analysed by estimating the molecular hybrid index of the seed parent, their seed embryos and pollen parents. The observation of flowering phenology showed that the flowering of P. pumila precedes that of P. parviflora var. pentaphylla by about 6 to 10 days within the same altitudinal ranges. Although this prezygotic isolation barrier is effective, the genetic assay of airborne‐pollen showed that the two pine species, particularly P. pumila, still have chances to form F₁ hybrid seeds. Both parental species showed a strong assortative mating pattern; F₁ seeds were found in only 1.4% of seeds from P. pumila mother trees and not at all in P. parviflora var. pentaphylla. The assortative mating was concluded as the combined result of flowering time differentiation and cross‐incompatibility. In contrast to the parental species, hybrids were fertilized evenly by the two parental species and themselves. The breakdown of prezygotic barriers (intermediate flowering phenology) and cross‐incompatibility may account for the unselective mating. It is suggested that introgression is ongoing on Mount Apoi through backcrossing between hybrids and parental species, despite strong isolation barriers between the parental species.     

Effects of wind and thermal conditions on timberline formation in central Japan: a lattice model

The upper distribution limit of tall tree species Abies mariesii is the timberline in central Japan, and dwarf pine Pinus pumila dominates above the timberline to near the summit. My previous studies suggested that the main cause of the timberline formation is the increase in mortality due to strong wind in winter rather than low growth due to low summer temperature. This study evaluated how wind velocity affects timberline formation and if the altitude of timberline moves upward due to high thermal conditions, by using a lattice model. Increase in wind velocity throughout the altitude lowered the altitudes of upper distribution limits of the two species. On the contrary, prolonged growth period due to high thermal conditions increased the upper distribution limit of P. pumila, and the upper distribution limit of A. mariesii was hardly affected by the change of growth period. However, the upward shift of the upper distribution limit of P. pumila due to the prolonged growth period in the model would not be realistic because P. pumila had already distributed up to near the summit. This study concludes that A. mariesii is a superior competitor to P. pumila at low altitudes with low wind velocity, but dwarf pine P. pumila can dominate at higher altitudes because A. mariesii suffers severe mechanical damage due to strong wind in winter, and that the altitude of the timberline does not move upward even under high thermal conditions due to global warming.     

How the scrub height of dwarf pine Pinus pumila decreases at the treeline

Plant height decreases much within narrow altitudinal spans near treelines. We compared the stem age, stem inclination and shoot elongation rates of alpine dwarf pine Pinus pumila between the upper distribution limit (treeline, 2,850 m a.s.l.) and the lower distribution limit (2,500 m a.s.l.) on Mount Norikura in central Japan, to examine how the growth traits of P. pumila change with altitude. The mean stem height at the upper distribution limit (49 cm) was about a quarter of that at the lower distribution limit (187 cm). The mean ratio of stem height to length was lower at the upper distribution limit than at the lower distribution limit, indicating that P. pumila stems inclined more at the higher altitude. The mean stem age at the upper distribution limit (48 years) was less than a half of that at the lower distribution limit (109 years). Although the shoot elongation rate positively correlated with stem length at the two altitudes, the shoot elongation rate at a given stem length was lower at the upper distribution limit than at the lower distribution limit. Thus, less developed scrub at the upper distribution limit than at the lower distribution limit was due to shorter stem age, more creeping stems and lower shoot elongation rates. Generally, wind velocity is greater in higher altitudes. Probably, strong wind reduces the growth and mean stem age of P. pumila stems at the upper distribution limit. Therefore, this study concludes that the scrub height of P. pumila is controlled not only by temperature, but also by strong wind.     

How the timberline formed: altitudinal changes in stand structure and dynamics around the timberline in central Japan

Background and Aims

Altitudinal timberlines are thought to move upward by global warming, a crucial topic in ecology. Tall tree species (the conifer Abies mariesii and the deciduous broad-leaved Betula ermanii) dominate the sub-alpine zone between 1600 and 2500 m a.s.l., the timberline, on Mount Norikura in central Japan. Dwarf pine Pinus pumila dominates above the timberline to near the summit (3026 m a.s.l.). This study evaluated how the timberline formed on Mount Norikura by examining altitudinal changes in stand structure and dynamics around the timberline.

Methods

One hundred and twenty-five plots of 10 m × 10 m were established around the timberline (2350–2600 m a.s.l.). Trunk diameter growth rate during 6 years was examined for A. mariesii, B. ermanii and P. pumila. Mortality during this period and mechanical damage scars on the trunks and branches due to strong wind and snow were examined for A. mariesii only.

Key Results

The density, maximum trunk height and diameter of A. mariesii in plots decreased with altitude. The maximum trunk height of B. ermanii decreased with altitude, but density and maximum trunk diameter did not decrease. In contrast, the density of P. pumila abruptly increased from around the timberline. A strong negative correlation was found between the densities of P. pumila and tall tree species, indicating their interspecific competition. Trunk diameter growth rates of A. mariesii and B. ermanii did not decrease with altitude, suggesting that these two tall tree species can grow at the timberline. The ratio of trees with mechanical damage scars increased with altitude for A. mariesii, a tendency more conspicuous for larger trees. The mortality of larger A. mariesii was also greater at higher altitude. Tall tree species may not increase their trunk height and survive around the timberline because of mechanical damage.

Conclusions

This study suggests that the altitudinal location of the timberline is mainly affected by mechanical damage due to strong wind and snow rather than by growth limitation due to low temperature. Therefore, the timberline would not move upward even under global warming if these growth and mortality characteristics do not change for a long time.     

Genetic structures of allopatric and sympatric populations in Pseudorasbora pumila pumila and Pseudorasbora parva

Pseudorasbora pumila pumila was collected to investigate its genetic relationships from 11 localities in Hokkaido and eastern Honshu of Japan with Pseudorasbora parva from 6 localities in Hokkaido, eastern Honshu, and Polovynka River (a tributary of the Amur River in eastern Russia) in 1996–1998. In Hokkaido and Akita prefectures (Honshu), three P. pumila pumila populations were distributed with P. parva sympatrically. Samples of P. pumila pumila and P. parva were analyzed based on 27 allozyme loci. Genetic differentiation between P. pumila pumila and P. parva (D = 0.522–0.622, average 0.601) was almost equal to or greater than that between other congeneric fish species previously reported. In the three sympatric populations of two species, which had arisen from artificial transplantation of the latter into localities of the former, the individual frequency composition of genetic types (P. pumila pumila, P. parva, F₁ hybrid, and later filial generation hybrid) were significantly different from each other. Differing from the previous studies, F₁ hybrids were fertile and coexisting populations of the two species included the F₁ hybrid and the later filial generation hybrid. These results suggest that genetic population dynamics of sympatric populations of the two species would be influenced not only by hybridization but also by ecological and environmental factors. Alternatively, the existence of populations that possessed both the alleles specific to P. pumila pumila and those specific to P. parva may indicate that introgressive hybridization, instead of species displacement, has occurred between the two species under a certain condition.     

Aboveground net production and dry matter allocation ofPinus pumila forests in the Kiso mountain range,central Japan

Aboveground net production rates of the subalpine stone pine (Pinus pumila) forests in central Japan were estimated by the summation method; net production was defined as the sum of annual biomass increment and annual loss due to death. In the two pine stands of different scrub heights, P1 (200 cm) and P2 (140 cm), aboveground biomass reached 177 and 126 ton ha⁻¹, respectively. Leaf biomass was about 14 ton ha⁻¹ in each stand. The estimates of aboveground net production during the 2 year period (1987–1989) averaged 4.1 and 3.7 ton ha⁻¹ y⁻¹ in P1 and P2, respectively, which were at the lowest among the pine forests in the world. Two indices of efficiency of energy fixation, that is, the ratio of net production to the total radiation during a growing season and the ratio of net production to total radiation per unit of leaf weight, were evaluated. Both efficiency indices for the twoP. pumila stands fell in the range obtained for other Japanese evergreen conifer forests. This suggested that the low annual net production of the stone pine stands were mainly due to a limitation in the length of the growing season. The pine forests were also characterized by a small allocation (about 17%) of aboveground net production into biomass increment, in comparison with other evergreen conifer forest types. Annual net carbon gain in theP. pumila forests was suggested to be largely invested in leaf production at the expense of the growth of woody parts.     

Phylogeography of silver‐studded blue,Plebejus subsolanus (Lepidoptera: Lycaenidae), in the central mountainous regions of Japan

The silver‐studded blue, Plebejus subsolanus, is widely distributed in the Russian Altai mountains, northeastern China, the Korean Peninsula, and the Japanese archipelago. In Japan, the species is distributed across wide elevation ranges from the lowlands of Hokkaido to the subalpine zone of Honshu. Current subspecies classification in Japan is as follows: ssp. iburiensis, occurring in lowland grasslands in Hokkaido; ssp. yaginus in lower mountain grasslands in Honshu; and ssp. yarigadakeanus in higher mountain grasslands in Honshu. The habitat of this species has been markedly reduced due to recent habitat destruction and land‐use changes. Here, we undertook phylogeographic analyses of two subspecies, ssp. yaginus and yarigadakeanus in the central mountainous regions of Japan, based on two mitochondrial gene sequences, in order to collect information for establishing effective conservation strategies. From 57 samples from the four mountain ranges, we obtained a haplotype network comprised of 12 haplotypes. Because of the haplotype network topology, the geographic distribution of haplotypes and the correspondence of haplotype divergence to subspecies taxonomy, we provisionally divided the haplotypes into three haplogroups: YR1 and YR2, which comprised ssp. yarigadakeanus, and YG, which comprised ssp. yaginus. Mitochondrial DNA genetic differentiation generally agreed with morphological subspecies classification. The haplotype network suggested that ssp. yarigadakeanus populations had multiple origins, and the subspecies character of “bright blue of the male's wings” was assumed to have evolved independently in each subalpine meadow. We found that P. subsolanus was genetically differentiated depending upon the elevation at each mountain region, suggesting that each haplogroup should be a conservation unit.     

Pine sawfly Gilpinia albiclavata sp. nov. (Hymenoptera: Diprionidae) infesting Pinus pumila in the Japanese Alps

Gilpinia albiclavata Hara, sp. nov. is described from Honshu, Japan. Larvae feed on needles of Pinus pumila (Pinaceae). Since 2001, severe infestations of the sawfly have been often observed in the Japanese Alps. Notes on the immature stages and the life history are presented.     

Abundance patterns of soil micro-arthropods at aPinus pumila scrub in an alpine range of central Japan

Seasonal changes in abundances of major soil micro-arthropods were assessed at aPinus pumila scrub in an alpine range of central Japan during a period with no snow coverage. The total abundance showed a peak in late August, reaching no less than 140 000 m⁻², which was comparable to that in an evergreen coniferous plantation in the cool-temperate zone. Collembola was the most dominant group of soil micro-arthropods, comprising about 50% of the total, followed by oribatid mites (Acari [O]) occupying 20%. Annual mean air temperature was no more than 2.1 °C and the daily fluctuation in temperature was less in soil layers. The thickness of the A₀ layer reached 9–10 cm and soil organic matter accumulation was estimated to be 45–58 ton dry weight ha⁻¹. The large amount of litterfall and organic matter accumulation in the soil, comparable to those of sub-alpine evergreen coniferous forests, and a lower decomposition rate due to severe environmental conditions, suggest the relative importance of litter processing by soil micro-arthropods such as Collembola and Acari, especially in alpine regions.     

Impact of Asymmetrical Hybridization Followed By Sterile F1 Hybrids on Species Replacement in Pseudorasbora

Pseudorasbora pumila, one of the endangered freshwater minnows in eastern Japan, has been largely replaced by the accidentally introduced species, P. parva, which originated from western Japan. In the contact zone, P. pumila and P. parva have hybridized intensively, producing sterile F₁ hybrids. The present study determined the maternal parent of F₁ hybrids using mtDNA haplotypes to investigate the mating system between P. parva and P. pumila in the hybrid zone. We also pursued the successive changes in the genetic structures of hybridizing populations over a 5-year period using allozymes. A total of 100 natural F₁ hybrids collected from six different populations had P. pumila mtDNA without exception, suggesting that sterile F₁ hybrids resulted from mating only between P. pumila females and P. parva males. Such asymmetrical hybridization implies that P. pumila females waste considerably greater reproductive efforts compared with P. parva males. The data suggest that the rapid replacement of P. pumila by P. parva has been promoted by asymmetrical hybridization, resulting in sterile F₁ hybrids.     

845. KINUGASA JAPONICA

Kinugasa is a monotypic genus of the family Melanthiaceae, consisting only of K. japonica, endemic to Japan. It grows in subalpine forests, often along the valleys where snow covers in winter, and is conspicuous by its large white or yellowish white petaloid outer tepals.     

Stand dynamics of Pinus flexilis-dominated subalpine forests in the Colorado Front Range

Population age structure and succession were investigated in subalpine forests in the Colorado Front Range dominated by Pinus flexilis (limber pine). Age, size, and spatial data were collected from three recent burns (<100 yr old), six ca. 240 year-old post-fire stands, and two old-growth stands (individuals > 400 yr old). The sequence of colonization of now extant trees on these post-fire sites appeared to be consistent: first Pinus flexilis, then Picea engelmannii (Engelmann spruce), and later Abies lasiocarpa (subalpine fir) with a delay between the first Pinus flexilis and Abies of as long as 140 yr. The advantage of Pinus flexilis on post-burn sites can be attributed to avian seed dispersal and the exceptional drought tolerance of its seedlings. The three recent burns were not extensive, and the delay in establishment of Picea and Abies appeared to be limited by harsh site conditions rather than lack of seed dispersal. Spatial analysis indicated a consistent, although sometimes weak, attraction between Pinus flexilis and Picea and Pinus flexilis and Abies at a scale of 1–4 m, suggesting that Pinus flexilis may facilitate establishment of Picea and Abies seedlings by providing shade or protection from wind. On xeric to slightly xeric sites, Pinus flexilis appeared to form broadly even-aged, non-regenerating populations that were gradually being replaced by Picea and Abies. Replacement is proceeding at a faster rate on the least xeric sites (north aspects, valley bottoms) compared to the most xeric sites (south aspects). On the most extreme sites, Pinus flexilis formed all-aged, self-maintaining populations with no evidence of replacement by Picea and Abies. In these old-growth forests with occasional trees aged at > 1300 yr, recruitment is continuous or episodic.     

Ecological geography of the range of theAbies mariesii forest in northeast Honshu,Japan, with special reference to the physiographic conditions

In the subalpine areas of the snowy regions of Japan (the Japan Sea side), there are some mountains with no or very small stands ofAbies mariesii, although this species dominates the subalpine coniferous forests of the region. In order to discuss the cause and process of this phenomenon, present horizontal and vertical ranges, as well as physiographic conditions, of theA. mariesii forest were examined in detail on the mountains in the Tohoku District. Sites in the subalpine zone were classified into two types: ‘azonal sites’ which should be excluded from the habitat ofA. mariesii because of their edaphic or small-scale climatic properties, and ‘zonal sites’. Mountains with vast less-inclined zonal sites generally had well developed stands ofA. mariesii forest. On the mountains with only small, solitary stands ofA. mariesii, the distribution was limited to flats or slightly inclined slopes at relatively low altitudes. These less-inclined zonal sites were regarded as an important habitat for theA. mariesii forest in the Hypsithermal period and the extent of these sites controls the extent of the stands in that period and the success of the subsequent range expansion of the forest.     

Stand structure and dynamics of wave-typeAbies sachalinensis coastal forest

Stand structure and regeneration pattern were examined inAbies sachalinensis coastal forest in northern Hokkaido. In the forest a similar phenomenon to the wave regeneration in subalpine forests has been found. Wave regeneration has been reported for montaneAbies forests in central Japan and North America. Differences and similarities between wave-type stands in this coastal forest and wave-regenerated montane forests were clarified. The shift of dead tree zone, stand structure and regeneration pattern in wave-type stands are the same as in subalpine wave-regenerated forests. High density of individuals is considered to be an internal factor which causes stand-level dieback and also enables the stands to persist in the severe environment in both forests. A difference between wave-regenerated forests andA. sachalinensis wave-type stands is the number of dead tree zones, which is only one in wave-type stands. Changes of regeneration patterns ofAbies sachalinensis with environmental gradient from seaward to inland were related to this difference.     

Fagus silvatica L. und das aceri-fagetum an der alpinen Waldgrenze in Mitteleuropäischen gebirgen

Summary In the Central Europaean mountain ranges, the alpine timberline is usually formed by Picea abies or by other conifers (Larix decidua, Pinus mugo, Pinus cembra). Unlike in the East Europaean mountains, the Balkan Peninsula, the Europaean Mediterranean and Les Vosges, Fagus silvatica occurs sporadically on the alpine timberline in this area where it forms very specific woods.This type of the alpine timberline is bound to the association Aceri-Fagetum (Bartsch 1940, Moor 1952). This association is found on the highest sites of the Fagion alliance in the subalpine vegetation zone. Within this zone, the association is bound to localities with heavy snowfall and a submaritime climat. It occupies larger areas in the Swiss Jura and in Les Vosges. In other Central Europaean mountains (the Alps, Schwarzwald, Krkonoe etc.) it occus in isolated areas only.Many trunk deformations and bush forms are found with Fagus on a large scale in the snow impacted localities (steep slopes, periphery of corries, avalanche slopes etc.). Crawling and sliding snow causes these growth deformations in the Fagus seedlings since their first year.The general increase of the vegetative propagation is a remarkable and exceptional response of Fagus in adapting to these extreme growth conditions. Under alpine timberline conditions, the generative propagation is very limited.The vegetative shoots with adventitious root systems are formed mainly from branches layering in the humus. The typical monocormonal tree-form of Fagus from lower altitudes turns in this way into a polycormon. From an evolutionary point of view, it is a suitable substitution; but from the ecological viewpoint, however, it is a sturdy growth form. In its typical form, the polycormon is formed by a number of vegetative shoots, which may be deformed but are very elastic and resistent. The number of shoots in a polycormon varies from 3–5 below, and up to 40–50 at and above the timberline. They are formed by shoots of a number of filial successions. The decay of a polycormon results from decreasing vitality of single shoots or, very often, it is caused by the impact of snow and ice. Considering, however, the fact that single shoots have a sufficient adventitious root system and are thus physiologically independent, the dying of the other shoots does not mean a danger for the existence of the remaining part of the polycormon. The age of a polycormon as a whole is difficult to determine. Fagus polycormons can be considered as a typical growthform of the highest sites of the association Aceri-Fagetum. No other tree species is able to form close stands under these conditions. This phenomenon is of primary importance for the existence of this plant community.The unusual character of the structure and dynamics of the highest Aceri-Fagetum stands gives rise to a special type of the alpine timberline which should be understood not as a line but as a transitional zone between the closed stands and the hon-wooded plant communities of the subalpine vegetation zone. The dynamic succession of the Fagus polycormons guarantees the stability of the Fagus stands forming the alpine timberline.

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Fagus silvatica L. und das aceri-fagetum an der alpinen Waldgrenze in Mitteleuropäischen gebirgen

     

Damage of alpine vegetation by the 2009 fire on Mt. Shirouma, central Japan: comparison between herbaceous vegetation and Pinus pumila scrub

A fire occurred (0.59 ha) in an alpine fellfield (2600 m a.s.l.) on Mount Shirouma, central Japan, on 9 May 2009 before the start of the growing season. Herbaceous plants and dwarf pine Pinus pumila dominated the site. Plots were established in burned and unburned herb vegetation and P. pumila scrub just after the fire to monitor vegetation recovery. This study reports the short-term monitoring results 3 months after the fire. Burned herb vegetation mostly recovered by late August 2009. However, burned P. pumila did not recover, and other alpine plants were scarce in burned P. pumila scrub. The observed number of species in herb vegetation was 15–20 m⁻² whereas it was only 1–6 m⁻² in P. pumila scrub. The total cover of plants was 111–129% for burned herb vegetation but was only 8–31% for burned P. pumila scrub. Although the species composition in P. pumila scrub distinctly differed between burned and unburned plots, in herb vegetation it was similar between them. Therefore, P. pumila scrub was greatly damaged by the fire, whereas herb vegetation was not damaged. Rapid recovery of herbaceous plants was because winter buds in the soil were not damaged by the fire, but winter buds on shoots of P. pumila were burned. Therefore, the difference in winter bud location (above or belowground) may have resulted in the difference in damage between herbaceous plants and P. pumila.     

Extensive Mitochondrial Introgression from Pinus pumila to P. parviflora var. pentaphylla (Pinaceae)

Pinus species exhibit a paternal chloroplast inheritance and a maternal mitochondrial inheritance. The levels and patterns of cpDNA and mtDNA introgression between the two pine species, P. pumila and P. parviflora var. pentaphylla, were examined at three mountain sites in Japan. The pine species were examined by using PCR-based diagnostic genetic markers of cpDNA and mtDNA. The survey which was carried out in multiple hybrid zones demonstrated a generality in the uni-directional pattern of cytoplasmic gene flow between the two pine species, i.e. paternal cpDNA flowed from P. parviflora var. pentaphylla to P. pumila, and in contrast, maternal mtDNA flowed from P. pumila to P. parviflora var. pentaphylla. Whenever plants which had a non-native combination of cpDNA and mtDNA were observed, they always had the cpDNA haplotype of P. parviflora var. pentaphylla and the mtDNA haplotype of P. pumila. The existence of only this type of cytoplasmic chimera may suggest that F₁ hybrids are successfully produced only in the crossing of P. pumila as the maternal parent and P. parviflora var. pentaphylla as the paternal parent. The present study also detected extensive mtDNA capture in populations of P. parviflora var. pentaphylla located in the southern and middle parts of the Ohu Mountains, Tohoku, Japan. In that area, nearly all of the plants examined had the mtDNA haplotype of P. pumila. The extensive mtDNA introgression suggests that seed flow could be an effective medium for interspecific gene exchange. Received 17 August 1998/ Accepted in revised form 7 January 1999     

Alpine and subalpine snow patch vegetation on the Bogong High Plains,SE Australia

Abstract. Snow patch vegetation in Australia is rare, being restricted to the relatively small area of alpine and subalpine country in the highlands of southeastern Australia. Snow patch vegetation occurs on steeper, sheltered southeastern slopes, where snow persists until well into the growing season (December/January). We surveyed the vegetation of 33 snow patch sites in the alpine and subalpine tracts of the Bogong High Plains, within the Alpine National Park, in Victoria. The vegetation was dominated by herbs and graminoids, with few shrubs and mosses. Major structural assemblages identified included closed herb‐fields dominated by Celmisia spp, and grasslands dominated by Poa fawcettiae or Poa costiniana. These assemblages occurred on mineral soils. Open herb‐fields dominated by Caltha introloba and several sedge species occurred on rocky and stony substrata. Vegetation‐environment relationships were explored by ordination and vector fitting. There was significant variation in the floristic composition of snow patch vegetation as a function of duration of snow cover, altitude, slope and site rockiness. Alpine sites were floristically distinct from subalpine sites, with a greater cover of Celmisia spp. and a lesser cover of low shrubs in the former. There was floristic variation within some snow patches as a function of slope position (upper, middle or lower slope) but this was not consistent across sites. The current condition of snow patch vegetation on the Bogong High Plains is degraded, with bare ground exceeding 20% cover at most sites. Snow patch vegetation is utilized preferentially by domestic cattle, which graze parts of the Bogong High Plains in summer. Such grazing is a potential threat to this rare vegetation type.