vegetation recovery patterns in early volcanic succession

J. Plant Res. 108 : 241-248, 1995 Journal of Plant Research ~) by The Botanical Society of Japan 1995

Invited Article

Vegetation Recovery Patterns in Early Volcanic Succession

Shiro Tsuyuzaki*

Graduate School of Science and Technology, Niigata University, Niigata, 950-21 Japan

Permanently plots were monitored from 1983 to the present on Mount Usu after the eruptions of 1977-78 which destroyed the pre-eruption vegetation by 1-3 m thick accumulations of ash and pumice in order to clarify the processes and mechanisms of succession. Until now, 163 species were recorded in the summit area. Most of these species were derived from vegetative reproduction throughout the volcanic deposits. Vegeta- tive reproduction plays a major role on increases in cover. Although long-distance seed-dispersal species could immigrate to the crater basin, their cover increase was slow. Seedbank species only established in gullies where the original topsoil was exposed by erosion. Most annuais were supplied by the seedbank in the original topsoil and woody species originated via immigration, suggesting that the source greatly determines the species composition of establishing vegetation. Annual seedlings showed low survival, while overwintering perennial seedlings steadily established. Ground surface movements strongly restricted increases in plant cover and the distance from source vegetation was the principal determinant of plant density. Due to differ- ences in disturbance intensity, successional rates were higher in the stable substrates outside gullies and lower on the exposed original topsoil in some gullies.

Key words : Immigration m Mount Usu m Permanent p lo t - - Seedbank-- Seedling establishment - - Species composition ~ Vegetative reproduction ~ Volcanic succession

Since the first major ecological theory "ecological succession" was proposed (Clements 1916), a large number of studies have been conducted (see, Glenn-Lewin et al. 1992, Miles and Walton 1993). There are some trends in succession (Whittaker 1975, Tilman 1988, Glenn-Lewin eta/ . 1992) : 1) it is a time dependent process with chang- ing vegetation characteristics such as density, cover, and species richness, diversity, and composition, 2) it results from a modification of the stress and disturbance regimes, and 3) i t changes ecosystems which are unstable to

* Recipient of the Botanical Society Award of Young Scien- tists, 1994

stable, concerning cover, biomass, and/or diversity information content.

Plant succession is categorized into primary and secondary succession (Clements 1916, Tsuyuzaki 1993a). Pri- mary succession, which occurs following complete destruction of biosystems where the ground surface is covered by rocks and/or inorganic soil substrates (Vitousek and Walker 1989, del Moral and Bliss 1993), is considerably different from secondary succession which may be initiated by burns or abandoned fields (Walker et al. 1982, McCune 1988, Tsuyuzaki et al. 1994). The most important process of primary succession is the accumula- tion of nutrients including nitrogen in the soil (Whittaker 1975, Tilman 1982). Primary succession was previously considered to be principally initiated by blue-green algae, mosses, lichens, etc., while secondary suceession begins with more or less mature soils containing a sizable bank of seeds and vegetative propagules (Crawley 1986, Fenner 1992). Therefore, primary suceession proceeds very slowly in its early stages, due to a sterile ground surface and the lack of a seedbank and vegetative propagules (Tilman 1982, Miles and Walton 1993). Therefore, to clarify successional trends, we must determine plant origins (Tsuyuzaki 1987).

Sites that support primary succession have been pro- vided following glacial retreat (Bormann and Sidle 1990, Matthews 1992), massive landslides (White 1979, Naka- shizuka et al. 1993), and volcanic eruptions (Matson 1990, Tagawa et al. 1985, Whittaker et al. 1986, del Moral and Bliss 1993, Tsuyuzaki and del Moral 1995). To confirm changes over time in successional seres community structure must be assessed for the long-term using permanent plots, however, these have been rare (Tsuyuzaki 1993). I have annually monitored revegetation on a recently-erupted volcano, Mount Usu, for more than 10 years by measuring vegetation cover and density and also by examining the fates of individual plants belonging to various life form types. The present study was conducted in the crater basin of volcano Usu where many plant species of various life forms were growing. These plants were growing in spite of high seedling mortality induced mainly by ground surface instability.

242 S. Tsuyuzaki

Mount Usu

Mount Usu, located on the northernmost Japancse Island, Hokkaido (42~ 140~ is composed of two peaks, O-Usu (727 m) and Ko-Usu (552 m) which are enclosed by a caldera rim and crater basin, with an area of ca. 2 • km. The pre-eruption summit area had been covered mostly with forests of Populus maximowiczfi and Betula platyphylla var. japonica and partly with seeded pasture of Dactylis glomerata, Trifolium repens and T. pratense (Tsuyuzaki 1987). In 1977-78 when I was a high school student, the eruptions completely destroyed the vegetation with thick accumulations of tephra. Soon after the eruptions, the northwest slope of O-Usu and inner wall of the caldera rim were covered by a thick layer of volcanic rocks and the crater basin was ovcrlain by volcanic ash and pumice with some deeply eroded gullies in which the original topsoil was exposed. The inner wall of the caldera rim was inhabited by a community of Petasites japonicus var. giganteus and Polygonum sachalinense, both of which recovered vegetatively soon after the erosion of volcanic deposits, whereas in the crater basin the ash and pumice layer is still thick and revegetation is very slow.

Based on geographical physiognomy, the crater basin was divided into three habitat types. Deep, stable tephra

is the dominant landform outside gullies (i.e., hereafter, T) (Fig. 1). In other locations, erosion was moderated and formed gullies (G) with altered surface conditions but erosion had not reached the original topsoil. Extreme erosion has removed large quantities of ash and pumice, exposing the original surface (E) creating a third type of habitat (Tsuyuzaki 1989a, 1991a). Distance from the caldera rim, which was surrogate for the distance from major plant resources, ranged from 50.0 to 400.0 m (Tsuyuzaki and del Moral 1994). Ground surface movements decreased from -I-41 and --162 cm in 1983 to -I-15 and --2 cm in 1992 in the gullies (positive values mean the accu- mulation of volcanic deposits and negative ones mean the erosion) (Tsuyuzaki 1989a). Ground surface movements were intense in the gullies, but were less than __.10 cm outside the gullies in 1984. On ski slopes in Hokkaido ground surface movements were mostly derived from snow-melt (Tsuyuzaki 1990). Similar processes might occur on Mount Usu (Tsuyuzaki unpublished data).

Organic matter status expressed as loss on ignition ranged from 0.2 to 1.1% in the volcanic deposits and from 2.5 to 13.2% in the original topsoil in 1984 (Tsuyuzaki 1989a), indicating that organic matter content was much greater in E. The loss on ignition of volcanic deposits was less than 5% even in 1994 (Tsuyuzaki unpublished data). These values were only 1/3 of loss on ignition

Species richness and diversity Habitat preference Life form

Contribution and/or Plant origin recovering pace

Medium and high,~-..---

Rich and high

Poor and low ~ "

Plant sourcN~

Immigratior~

G

Microhabitat rills cracks

~-- Slow

~ egetation ~ Rapid and most reproduction ~ contributive

sion) - ~ ( R p )

X Seedbank ,,,,,,,,,,,,4~Rapid but decreased \

Ground surface Original topsoil instability

(=Nutrients)

Fig. 1. Revegetation dynamics in the crater basin of the volcano Usu after 1977-78 eruptions. T : outside gully dominated by thick tephra. E: original-topsoil-exposed gully. G: inside gully without original topsoil. Relationships are connected by solid lines (strong relationships are shown by thick solid lines). Woody species were mostly derived from immigration, and annuals were from the seedbank. Annuals, most of which established in the gullies, and well-rooted perennials, that could reach their roots to the original topsoil even on the thick volcanic deposits, utilized nutrients in the original topsoil. Due principally to ground surface movements, most woody species did not establish inside gullies and annuals disappeared after 1989. Ground surface instability restricted plant growth, while perennials could spread their roots by means of long rhizomes and/or stolonierous shoots in spite of the instability. Therefore, perennial species contributed the most to revegetation. Species diversity is higher in habitats T and E than G, due to seedbank and immigrant species.

Vegetation Recovery Patterns in Early Volcanic Succession 243

values from low-productivity abandoned pasture in northern Japan (Tsuyuzaki et al. 1994).

Origin of recovering plants

On the summit areas of Mount Usu, 163 vascular plant taxa were observed during the years of 1983 to 1994 (in detail, see Appendix). Four major plant origins were recognized (Tsuyuzaki 1987): vegetative reproduction, seedbank, immigration and artificial introduction as follows (Fig. 1).

Vegetatively-reproducing species Most perennials originated vegetatively from buried

plants throughout the volcanic landscape, e.g., Angelica ursina, Aralia cordata, Petasites japonicus var. giganteus and Polygonum sachalinense. All the species in this group are perennial herbaceous and woody species.

Clonal expansion effectively succeeds in colonization in highly disturbed sites (Fahrig et al. 1994). On Mount St. Helens, vegetative recovery was conspicuous in areas where volcanic deposits were less than 15 cm deep (Antos and Zobel 1985ab). On Mount Usu, P. sachalinense and P. japonicus var. giganteus often recovered from under- ground organs buried by the volcanic deposits more than 50cm deep (Tsuyuzaki 1989a). Therefore, species characteristics such as life form and root system determine the success rates of vegetative recovery. For example, most needle-leaved species could not repro- duce vegetatively after the eruption of Mount St. Helens, while well-rooted perennial herbs Epilobium angustifolium and Anapharis margaritacea rapidly resprouted vigorously from beneath the tephra (Halpern et al. 1990).

Seedbank species Using a K2CO3 floatation technique which can extract

nearly 100% of the viable seeds from soil samples (Tsu- yuzaki 1993b, 1994a), in 1987 viable seeds of 17 species were extracted from the seedbank of original topsoil buried beneath 65-130 cm of volcanic deposits, indicating that seed viability is at least 10 years (Tsuyuzaki 1989b). The most common seedbank species was Rumex obtusifolius. Seed volume of most species tested was less than 2.0 mm 3 and smaller seeds had a greater rate of survival than larger seeds (Tsuyuzaki 1991b). (The volume was calculated by assuming simple ovoid shapes.) Small seeds survive for longer periods in the soil, and their dormancy is frequently associated with a requirement for light (Cook 1980). However, seed survival rates of a few species including R. obtusifolius in the seedbank of Mount Usu were positively correlated with the thickness of volcanic deposits, suggesting that stable soil tempera- ture with little diurnal fluctuations allowed for long-term survival (Thill et al. 1985, Tsuyuzaki 1991b). In addition, the species composition of the seedbank might be related to the pre-eruption vegetation, although the relation was weak (Tsuyuzaki 1989b). Based on these analyses, I concluded that at least 14 species were derived from the

seedbank (Tsuyuzaki 1994b). While the distribution of seedbank species was

restricted to the deeply eroded gullies of the crater basin where the original topsoil became exposed, these species greatly contributed to increased species richness there (Tsuyuzaki 1989c). The seedbank included both annual and perennial herbaceous species. All the annuals except for Senecio vulgaris were derived from the seedbank, indicating that the seedbank is an important determinant of initial stages of revegetation (Tsuyuzaki 1989c, 1994b). Buried seeds contribute greatly to secondary succession starting with abandoned pastures, post-fire forests, etc. (Archibold 1981, Hill and Stevens 1981). Due to the seedbank containing a large number of the seeds of annuals, secondary succession often starts with the dominance of annual plants (Leck et al. 1989). Revegetation processes on Mount Usu suggest that typi- cal secondary succession could be recognized if seed- rich soil re-appears immediately after the disturbance.

Immigration Most immigrating species produce long-distance wind-

dispersed seeds. Most. woody species such as Salix hultenii var. angustifolium, Populus maximowiczii, Betula plaryphylla var. japonica, and Larix kaempferi were immi- grants into the crater basin. Herbaceous species, e.g., Senecio vulgaris, Anaphalis margaritacea var. angus- tifolior, Aster ageratoides var. ovatus, and Epilobium montanum also recovered via immigrant seeds (Tsuyuzaki 1987). Animal-dispersed species such as Prunus sargentii and Fragaria vesca were infrequently observed and they did not persist in the crater basin.

Floristic sources surrounding the crater basin strongly determined the rate of vegetation recovery (Tsuyuzaki 1991a, 1994b). For example, due to the paucity of annuals in the intact vegetation, annuals were rare in the crater basin. Similar trends were also observed after the eruption of Mount St. Helens (del Moral 1988). Vegetation recovery was faster in areas where plant sources were closely available (Wood and del Moral 1987, del Moral and Wood 1988). Therefore, wind-dispersal is often the most important determinant of vegetation recovery (Dale 1985, Nakashizuka et al. 1993). On newly-emerged islands such as Anak Krakatau in Indonesia and Surtsey in Iceland, all seeds must immigrate from outside of the island. In these cases, water-dispersal as well as wind -dispersal contribute to make up the new species composition (Fridriksson 1992).

Artificially-introduced species A few grass and legumes were introduced for artificial

erosion control. The major species were Festuca rubra and F. elatior (Tsuyuzaki 1987). These species were aerial sprayed shortly after the eruptions, and to a much lesser extent invaded from outside of the caldera rim. However, their total cover was very small, i.e., less than 3% even in 1989 (Tsuyuzaki 1989a), indicating that the effects of artificial introduction to prevent ground surface

244 S. Tsuyuzaki

movements are minimal.

Determinants of vegetation dynamics

Based on eight environmental factors, loss on ignition of volcanic deposits collected from the ground surface, tephra deposition and erosion, distance from the caldera rim, relative elevation difference, and three nominal habitat variables (T, G and E), canonical correspondence analysis (CCA) was conducted (Tsuyuzaki and del Moral 1994). This analysis evaluates the influence of environmental variables on vegetation development patterns (ter Braak 1986, Palmer 1993). Plant density and plant cover were analyzed separately because these two parameters fluctuated somewhat differently over time. As expected, the CCA suggested that the environmental factors which influence plant density and cover differ. Distance from the source of colonizing species source, i.e., from the caldera rim, primarily affected plant density, while erosion strongly affected cover. Therefore, plant growth which is represented by fluctuation in cover seems to be principally limited by ground surface stability. In addition, the pre- eruption surface played a special role in vegetation development because the original topsoil supplied both nutrients and seedbank species. In an Alaskan floodplain, many woody species could establish even in the early stages of primary succession, due to the species composition of the surrounding vegetation (Walker et al. 1986). Therefore, species composition in the early stages of succession seems to be somewhat determined by that of the source vegetation (Tsuyuzaki 1989a, 1993a).

Diverse microhabitat characteristics, e.g., large parti- cles on the ground surface, microtopography such as rill development, and dead lupine patches, promote seedling establishment (del Moral and Bliss 1993). Since seeds are often entrapped by cracks and rills, seedlings frequently emerged in such sites even under low nutrient conditions (Smathers and Muller-Dombois 1974, Cham- bers 1991). On Mount Usu, many seedlings emerged in areas where the large volcanic deposits were accumulat- ed and inside rills (Tsuyuzaki unpublished data). There- fore, the availability of safe sites for germination and establishment may limit the rate of primary succession (Wood and Morris 1990).

RevegetaUon dynamics

Total cover increased annually in the crater basin, however, the rates of increase differed among the three habitats, T, G and E (Tsuyuzaki 1991a) (Fig. l). The species with the greatest cover were perennials, due to the rapid expansion of long rhizomes and/or stoloniferous shoots. In habitat G their cover increased dramatically probably because the layer of volcanic deposits was thinner than at T and the intensity of ground surface movements was more moderate than at E. Most annual species disappeared after 1989 due perhaps to low fruiting success and/or fragile root systems, whereas perennial

species derived from the seedbank yearly increased in cover (Tsuyuzaki 1994b). Of these, nitrogen-fixing stoloniferous perennials, Trifolium repens and Lotus cor- niculatus var. japonica, both of which were derived from the seedbank only, gradually increased in cover (Tsuyuza- ki 1994b). Nitrogen-fixing species such as legumes and alders are often dominant in the early stages of primary succession (Vitousek et al. 1987, Walker 1993). Woody plants such as willows, birches and alders also immigrat- ed from the external environment, but they grew slower than the perennial herbs. In contrast to gradual increase in cover, the large fluctuations in density suggests that mortality is high in young seedlings but relatively low once plants establish (Tsuyuzaki 1989a). The survival rates of annual seedlings were 20-40% in a permanent plot outside the gully from 1983 to 1987, while seedlings once they overwintered persisted there. There were no clear differ- ences in survival rates between herbaceous and woody plants.

Although rate of vegetation change is one of the important characteristics of both primary and secondary succession, analyses of successional rates are rare. This may be because of difficulties in generalizing changes to different vegetation properties (Bornkamm 1981, Prach 1993). Evaluations of stability, diversity and evenness have been applied to various communities (e.g., Peet 1974, McCune 1988, del Moral and Wood 1988). Fluctua- tions in these properties are considered to express trends in successional state over time. Percentage similarity PS) and community cocfficient (CC) were originally used to express inter-community heterogeneity (Dahl and Hadac 1941, Sorensen 1948), and can be used to express rates of vegetation change during succession (Bornkamm 1981). If a chronofunction v=f(t) is used for the descrip- tion of vegetation, a stable situation at the end of a succession is indicated by dv/dt=O. It was proposed that the terminal stage of suceession is reached when dv/ dt is less than 5% (Tagawa 1964, Bornkamm 1981). Although species diversity often increases with time in the early stages of succession (Drury and Nisbet 1973, del Moral and Bliss 1993), species diversity remained low and did not change over time on Mount Usu due principally to low species richness and evenness (Tsuyuzaki 1991a). Therefore, species richness, diversity and evenness do not yet show a clear trend. Instead of using those diversity indicators, successional changes, expressed as PS and CC, showed the fastest change in habitat T and the slowest in habitat G (Tsuyuzaki 1991a). Furthermore, the year-to-year changes were more than 20% in all of the habitats, suggesting that the vegetation status was still unstable in spite of showing stable, low diversities (Tsuyuzaki 1991a).

Future scopes

A volcano is a unique site for monitoring plant succession because there are wide ranges in stresses and disturbances (Tsuyuzaki 1991a, del Moral and Bliss 1993).


Secondary succession on ski slopes shows similar trends to volcanic succession ; viz. large ground surface movements occur on the slope, bare ground remains unvegetat- ed for a long time, and distance from plant sources is related to revegetation patterns (Tsuyuzaki 1990, 1993c, 1994c, 1995). Therefore, trends in the early stages of primary and secondary succession might be similar under certain conditions such as steep slopes.

Thus far, there has been little information on a flora prior to the eruption on any volcano, even at Mount St. Helens where numerous plant ecologists surveyed. The per- iodicity of eruption on Mount Usu ranges from 30 to 40 years, inferring that the next eruption will occur in a few decades. The flora list is necessary to estimate the effects of eruptive disturbances on post-eruption vegetation. I list here the taxa observed in the crater basin, inner-wall of the caldera rim and northwest face of O-Usu (Appendix).

I wish to express sincere thanks to S. Yoshida, K. Ito, M. Kurogi, S. Higashi, M. Haruki, T. Sato, M. Maeshima, and S. Hino for their useful advice, and all staff members of Usu Volcano Observatory and many colleagues for their field assistance. Cordial thanks are also due to J.H. Titus for his critical readings of the manuscript. This work is partly supported by Grants from the Ministry of Education, Science and Culture of Japan.

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(Received January 9, 1995 : Accepted April 11, 1995)

Appendix

Vascular plants collected in the volcano Usu during the years of 1983 and 1994. O, B, and C indicate the location of north-west slope of O-Usu, crater basin, and inner-wall of caldera rim, respectively. Nomenclature follows Ohwi (1975).

Division Pteridophyta Family Equisetaceae

Equisetum arvense i-0, B, C] Family Aspidiaceae

Dryopteris austriaca E O, C ] Dryopteris crassirhizoma E 0, B] Matteuccia struthiopteris [0, B ]

Division Spermatophyta


Subdivision Gymnospermae Family Pinaceae

Larix kaempferi EO, B] Subdivision Angiospermae Class Monocotyledoneae Family Gramineae

Agrostis alba EO, B] Agrostis scabra I-O] Alopecurus aequalis var. amurensis i-B] Calamagrestis epigeios I-O, C] Calamagrostis pseudo-phragmites FO] Dactylis glomerata i-O] Dig#aria adscendens I-B, C] Festuca elatior I-O, B, C] Festuca ovina I-O, B, C] Festuca rubra vat. rubra EO, B, C] Lolium perenne I-B, C] Miscanthus sinensis I-O, B, C] Phleum pratense [O] Poa annua i-B]

Family Cyperaceae Carex leucochlora EO, B, C] Carex flavocuspis [O] Carex lanceolata [O] Carex Iongerostrata i-O] Carex ryngbyei [0] Carex oxyandra I-O, B, C]

Family Juncaceae Juncus effusus var. decipiens I-B] Juncus fauriensis EB] Luzula capitata EO, B]

Family Liliaceae Polygonatum odoratum var. pluriflorum I-C] Trillium tschonoskii EC-I

Family Orchidaceae Spiranthes sinensis I-B] Gymnadenia camtschatica EB, C]

Class Dicotyledoneae Subelass Choripetalae Family Salicaceae

Populus davidiana I-BI Populus maximowiczii iO, B, C] Salix hultenfi var. angustifolia [0, B, C~ Salix integra Thunb. I-O, B, C] Salix miyabeana EB] Salix reinii [O] Salix sachalinensis I-O, B, C]

Family Betulaceae Alnus hirsuta I-O, B, C] Alnus maximowiczfi i-O, B, C] Betula ermanii [0, B] Betula maximowicziana EO, B] Betula platyphylla var. japonica I-B]

Family Ulmaceae Ulmus davidiana var. japonica I-C] Ulmus davidiana var. japonica f. suberosa I-C] Ulmus laciniata I-C]

Family Moraceae

Morus bombycis E C ] Family Urticaceae

Boehmeria spicata EO, C] Family Polygonaceae

Polygonum aviculare EB] Polyognum cuspidatum EO, B] Polygonum Iongisetum EO, B] Polygonum sachalinense iO, B, C] Polygonum thunbergfi ro] Rumex acetosella [B] Rumex obtusifolius IB-I

Family Chenopodiaceae Chenopodium centrorubrum [B]

Family Caryophyllaceae Cerastium holosteoides var. angustifolium rB] Moehringia lateriflora ro, B] Stellaria fenzlii i-B]

Family Ranunculaceae Ranunculus repens [B] Ranunculus quelpaertensis var. glaber [B]

Family Magnoliaceae Magnolia obovata [C-I

Family Cruciferae Arabis lyrata var. kamtschatica I-O, B] Arabis pendula FB] Arabis serrata vat. glauca EB, C] Cardamine flexuosa EO, B, C-J Cardamine flexuosa var. fallax I-B, C] Rorippa islandica [B] Turritis glabra I-C]

Family Saxifiagaceae Astilbe thunbergii var. congesta I-O, B] Hydrangea paniculata i-O, B, C] Hydrangea petiolaris I-O, C] Schizophragma hydrangeoides •C]

Family Rosaceae Aruncus dioicus vat. tenuifolius I-O, C] Geum aleppicum I-B, C] Geum japonicum I-BI Geum macrophyllum var. sachalinense I-O, B] Fragaria iinumae i-O, C~] Fragaria vesca I-B] Potentilla freyniana rB] Prunus sargentii I-B, C] Rosa multiflora I-C] Rubus phoenicolasius I-C] Sorbus alnifolia rc] Sorbus commixta I-C]

Family Leguminosae Desmodium oxyphyllum i-C] Lespedeza bicolor [ C ] Lotus comiculatus vat. japonicus iB] Medicago lupulina EB] Robinia pseudo-acacia I-B, C] Trifolium hybridum I-B, C] Trifolium pratense IB] Trifolium repens I-O, B]

Family Rutaceae

248 S. Tsuyuzaki

Phellodendron amurense var. sachalinense i-C] Family Anacardiaceae

Rhus ambigua I-O, C] Rhus trichocarpa i-C]

Family Celastraceae Celastrus orbiculatus E O, c ] Euonymus sieboldianus I-B, C]

Family Aceraceae Acer japonicum FB, C] Acer mono I-B, C] Acer mono var. mayrii I-C]

Family Vitaceae Vitis coignetiae i-C]

Family Tiliaceae Tilia japonica I-C]

Family Actinidiaceae Actinidia arguta I-C]

Family Guttiferae Hypericum erectum I-B]

Family Violaceae Viola grypoceras I-O, B] Viola phalacrocarpa FB] Viola rossii l-B]

Family Elaeagnaceae Elaeagnus umbellata FB, CI

Family Onagraceae Epilobium angustifolium I-B, C] Epilobium cephalostigma EBI Epilobium dielsfi FB] Epilobium montanum ro, B, C] Epilobium palustre var. lavandulaefolium FB, C] Oenothera biennis [O, B, C-I

Family Araliaceae Aralia cordata I-O, B, C] Aralia elata I-C] Kalopanax pictus [ C ]

Family Umbelliferae Angelica ursina FC] Angelica edulis ro, c ] Pleurospermum camtschaticum [C] Torilis japonica F C ]

Subclass Gamopetalae Family Oleaceae

Fraxinus lanuginosa EC-I Family Boraginaceae

Myosotis palustris FB] Myosotis svlvatica EBI

Family Labiatae Stachys japonica var. intermedia I-O~

Family Scrophulariaceae Veronica arvensis i-B] Veronica schmidtiana [0, B]

Family Plantaginaceae Plantago asiatica iB, C] Plantago camtschatica I-O]

Family Caprifoliaceae Lonicera morrowii EO, B, C] Sambucus sieboldiana var. miquelii l-O] Viburnum dilatatum FC] Viburnum sargentii EC]

Family Valerianaceae Patrinia villosa FCI

Family Compositae Adenocaulon himalacium i-B-I Ambrosia artemisiaefolia var. elatior I-B] Anaphalis margaritacea var. angustior EO, B, C] Artemisia japonica I-C] Artemisa montana FO, B, C] Aster ageratoides var. ovatus f. yezoensis I-B, CI Aster glehnfi I-B, C] Aster scaber l-B, Cl Cacalia hastata var. orientalis I-B, C] Erigeron annuus FB, CI Erigeron canadensis I-B] Eupatorium chinense vat. sachafinense EO, B, C] Eupatorium chinense var. simplicifolium ro, c] Hieracium umbellatum l-B] Hypochaeris radicata I-B3 Ixeris dentata l-B ~ Leibnitzia anandria I-B] Petasites japonicus var. giganteus EO, B, C] Picris japonica E O, B, C ] Senecio cannabifolius I-B, C] Senecio vulgaris I-B] Solidago virgaurea var. leiocarpa i-C] Sonchus asper l-B] Taraxacum hondoense I-C] Taraxacum officinale I-B, C] Youngia denticulata i-B] Youngia japonica FB]

vegetation recovery patterns in early volcanic succession

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