Ecological characteristics of the basin flora in the Sikhote-Alin Biosphere Reserve and its buffer zone are presented in this paper. The ecological groups, allocated according to plant and water environmental relationships, are presented as 93 species of aquatic flora and also as more numerous representatives of the near-water plant complex for a total of 153 species. Various aspects of the ecological analysis of the reserve basin flora are discussed, and some features of its ecological structure are specified.
Sikhote-Alin Biosphere Reserve ; Basin flora ; Ecological analysis ; Ecological groups
Ecological groups of basin plants are singled out by the degree of their connection with a water environment, which varies greatly depending on the saturation level of the habitats (Lapirov, 2003 ). Research aimed at identifying the degree of relation between plants and their water environment and studying water and near-water life forms is important for understanding the successional processes in plant communities and the factors that determine the nature of water basin overgrowth.
The basin flora of the Sikhote-Alin Biosphere Reserve was studied from 1989 to 2011. This work is based on data collected in the Reserve and its surroundings (Blagodatnoe, Golubichnoe and Yaponskoe freshwater and brackish lagoon lakes; Solontsovye tectonic lakes; sink lakes; streams; oxbow lakes downstream of the Serebryanka, Golubichnaya and Kunaleyka Rivers; estuary parts of rivers; and some intermittent pools). Herbarium collections from the Reserve and the Biology and Soil Institute FEB RAS (VLA, Vladivostok) were also used in analysis of the flora. In addition, the summary data presented from publications on the flora of the Sikhote-Alin Biosphere Reserve (Shemetova, 1975 ; Galanin et al ., 2004 ; Pimenova, 2005 ) were taken into account.
Data characterizing the types of water basins and methodology of field research were previously published (Nesterova, 2001 ; Nesterova, 2003 ; Nesterova, 2005 ). Species are named according to the summaries (Kharkevich & (St. Petersburg), 1985 ; Kozhevnikov & Probatova, 2006 ). Ecological characterization of the flora was carried out in accordance with the classification of water and near-water plants by V.M. Katanskaya (Katanskaya, 1981 ) and V.G. Papchenkova et al. (Papchenkov et al., 2003 ).
The first researchers studying basin plants mostly included true aquatic plants in their reports. In later studies, the plants that develop on the littoral shelf and on the shore in floristic lists of water basins were included. The coastal zone and shallow water a transitional environment for aquatic plants to land and land plants to water (Lapirov, 2003 ). The transition zone creates an original set of species, including land plants (moisture-loving to various extents), coastal-water species, and true aquatic plants.
We define aquatic flora as a phytome of truly aquatic species of plants (hydrophytes), sea-land plants (amphibians), and coastal-water species growing in the study area. Mire plants (helophyte) and plants at the waters edge (hygro-helophytes) are considered to be coastal-water plants.
The flora of the studied water basins, in addition to truly aquatic flora, included coastal plants naturally growing on watered land (Papchenkov et al., 2006 ). Among these plants that occupy the middle and high levels of the coastal flooding zone and uprush zone, we registered hygrophytes, hygro-mesophytes, mesophytes, and some xeromesophytes. Thus, the basin flora of the Sikhote-Alin Biosphere Reserve that includes representatives of aquatic flora (93 species) and a group of coastal plants (153 species), is represented by 246 species from 131 genera and 57 families.
Hydrophytes or true aquatic plants. For a normal (full) life cycle, their vegetative bodies need to be in constant contact with a water medium. This ecological group represented by 38 species in our area includes plants floating on the water surface, as well as fully submerged plants or submerged plants with floating leaves (or without them but with reproductive organs above water): see Table 1 . The greatest diversity of species was registered for hydrophytes in the Golubichnoe and Yaponskoe freshwater lagoon lakes and in the flood plain basins, as well as in the reaches of the Serebryanka, Golubichnaya and other rivers. Hydrophytes prefer reaches and coves that are protected from wave activity and rapid water flows with clean, well-warmed water and sandy or muddy soil; they grow mainly at a depth of 0.5 to 2.5 m. Macrophytes develop in abundance in fading shallow sink lakes and other water bodies located in floodplains (downstream) of the eastern macroslope of the Sikhote-Alin. In contrast, aquatic flora from mountain lakes located in the headwaters of the Solontsoviy stream are quite poor. Coastal-water vascular plants, with common moss cover, are abundant on the banks and in the shallow waters of these water bodies (Nesterova, 2005 ).
|Group, subgroup of plants||Number of species|
|Absolute||In % from total quantity of flora|
|A. Fully submerged:||12||4.9|
|B. Nearly submerged||17||6.9|
|a) Freely floating, solute||1||0.4|
|b) With floating leaves, rooted||8||3.3|
Submerged hydrophytes are abundant in most deep-water zones of water bodies. The group of fully submerged macrophytes includes: 1) fully submerged rooted plants and 2) fully submerged solute macrophytes. The latter group, which is found in inconsiderable quantities in adjoining floristic areas (represented, for example, by Lemna trisulca L. and Ceratophyllum oryzetorum Kom. in the basin of Lower Amur River ( Kryukova, 2005 )), is not registered in the Reserve. By contrast, the group of submerged rooted plants fully developing underwater is represented by 12 species. For example, the submerged hydrophyte Isoëtes asiatica Makino is found in Golubichnoe and Yaponskoe lagoon lakes. This is a spore plant with a short thickened tuberous sprout and well-developed roots. It grows at a depth of 0.5 to 1.5 m mainly in small groups, sometimes in great abundance, in the form of a continuous carpet. Annual submerged macrophytes, including Caulinia orientalis (Triest et Uotila) Tzvel. and Caulinia tenuissima (A. Br.) Tzvel, grow in freshwater lagoon lakes and some floodplain lakes. These species are rare representatives of the Najadaceae family and are characterized by underwater pollination and seed development with the help of unisexual flowers that are arranged in the axils of leaves on the same plant. The group of nearly submerged hydrophytes with reproductive organs above water is represented by 17 species. The group includes rooted macrophytes that are represented by species of the Potamogetonaceae , Myriophyllum spicatum L., and Hydrilla verticillata (L. fil.) Royle families and solute species floating in the water of genus Utricularia . Communities consisting of floating hydrophytes are located closer to the shore at a depth of 1 to 2.5 (3) m. Among them are rooted hydrophytes with floating leaves, including the Nuphar, Nymphaea, Persicaria amphibia (L.) S. F. Gray species, as well as plants that are free-floating on the surface of the water, such as Lemna minor L.
The hydrophytes group is composed of a total of 9 species of amphibious plants. They can be truly aquatic or land plants (Papchenkov et al ., 2003 ; Shcherbakov, 2006 ). The amphibious group includes Limosella aquatica L., which is found in shallow water and on the wet shores of Lake Blagodatnoe; the species forms cleistogamous flowers and can live a full life cycle in an aquatic medium. Other species include Callitriche palustris L., which exists in three life forms and grows in the shallow water of sink lakes and some lagoon lakes; Elatine spathulata Gorski, which is a completely submerged amphibious plant (amphibiid ) that is found in the shallow waters of Yaponskoe Lake and usually grows at the bottom of water bodies; and Tillaea aquatica L., which is a species representing the amphibious plant group ( Lapirov, 2003 ), registered twice by the Reserve staff on the muddy banks of water bodies: near Golubichnoe and along the Serebryanka River near the Terney settlement. P. amphibia is found in both aquatic and land forms that are quite different. ( Tsvelev, 1989 ) This species is found in aquatic communities of freshwater Yaponskoe Lake, in small groups in shallow brackish Blagodatnoe Lake, and sometimes in other water bodies of the study area, as well as on their shores.
Algae are often a part of higher plant communities. For example, stonewort Nitella sp. is commonly spread in Yaponskoe Lake and some flood basins of the Serebryanka River. Algae Vaucheria sp. ster. occupy a significant space, with an abundance of aquatic weed1–3 , in more deep-water areas of Golubichnoe Lake (closer to the centre of the lake, behind the primary belt of vascular plants). Blue–green algae of the genus Anabaena often grow in masses in this lake because its algal flora is very diverse and abundant compared to other water basins ( Medvedeva, 2006 ). During some periods that are favourable for the growth of these algae, blooming of the water is observed. The water becomes completely opaque and acquires a greenish tint. This phenomenon was observed in Golubichnoe Lake when there was massive growth of Anabaena spiroides Kieb.
Mire plants (helophytes) are rooted plants with a vegetative body that is located both above and below the water surface. Part of the stem with leaves and flowers is in the air. Plants of this group are represented by 19 species that occupy coastal shallow water primarily at depths of up to 1 (2) m, but can also grow on land in well-saturated soil. Some representatives of this group, e.g., species of the genus Sparganium and Hippuris vulgaris L., are found in aqueous form at great depths in the reaches and channels of the Serebryanka and Golubichnaya Rivers, among others.
Communities containing helophytes are common in the shallow waters of lagoons and sink lakes and other water basins in the floodplains, mainly in the coastal part of the Reserve. These communities are composed of high-grass helophytes, including Phragmites communis Trin., Scirpus species, and Typha ; short-grass species, including Equisetum palustre L., Equisetum fluviatile L., and Scirpus lineolatus Franch. et Savat; among others . In connection with mire plants, we registered submerged hydrophytes, including H. verticillata , Potamogeton perfoliatus L. and Potamogeton maackianus A. Benn., as well as hydrophytes with floating leaves and flowers, such as Nymphaea tetragona Georgi, Nuphar pumila (Timm.) DC. ( Nesterova, 2003 ).
Plants at the waters edge (hygro-helophytes). The term was proposed by V.G. Papchenkov (Papchenkov, 1985 ) for plants that typically inhabit lower levels of coastal flood zones, the contact area of the shore and the waters edge, and coastal shoals with depths of up to 20 (40) cm. Many of them are typical of floating bogs. This group of plants, represented by 36 species, includes Caltha, Sium, Comarum palustre L., Menyanthes trifoliata L., among others. Because of particular conditions at the waters edge, amphibious plants (aphibiids), helophytes and representatives of other ecological groups are found there in addition to hygro-helophytes.
In addition to water and coastal-water species, coastal plants partly growing in the water were attributed to the flora of the basins under study. This category includes species from adjacent areas neighbouring freshwater ecosystems (that often share common long periods of development) that are consistently registered in coastal cenoses of the basins under study. A complex of coastal (semi-aquatic) plants integrates plants of different ecological groups: hygrophytes, hygro-mesophytes, mesophytes and, in some cases, xeromesophytes:
- species of coastal flora that are found on the shores of lagoon lakes, in the estuaries of rivers and in adjacent marine coastline areas, such as Spergularia marina (L.) Griseb., Arctopoa eminens (C. Presl) Probat., Sagina maxima A. Gray, and Salsola komarovii Iljin;
- carried aquatic weeds that frequently inhabit disturbed habitats and a variety of other types of areas and that are frequently found in the shallows, river sands and gravels of different types of water bodies, such as Chenopodium album L. and Cerastoderma glaucum L., Brachyactis ciliata (Ledeb.) Ledeb., Polygonum aviculare L., and Acetosella vulgaris (Koch) Fourr ;
- species of forest ecosystems that are common along the banks of lagoon and mountain lakes that are located in fir-spruce forests, such as Cardamine leucantha (Tausch) Schulz, Chrysosplenium ramosum Maxim., Urtica angustifolia Fisch. ex Hornem., Ulva laetevirens Maxim., etc.
Hygrophytes are plants of damp habitats that grow in waterlogged soils and were defined by A.P. Shennikov (Shennikov, 1950 ) as being associated with “air saturated with water vapour.” Eighty-eight species in total were attributed to the hygrophytes ecological group, including semi-aquatic flora representatives occupying medium levels of the coastal flooded area as well as plants growing on damp and marshy shores surrounding water basins, such as Potentilla egedii Wormsk., Epilobium maximowiczii Hausskn. and E. palustre L., species Lycopus, Scutellaria, Juncus, and Carex . Hygrophytes growing in the area of periodic flooding also have a variety of adaptive features that allow them to adapt to these conditions. For example, Persicaria hydropiper (L.) Spach, Persicaria lapathifolia (L.) SF Gray, and some other species that grow on the waters edge develop an aqueous form with elongated internodes because of the intercalary growth of the internodes of the stem. This phenomenon is specific to certain types of persicaria during temporary flooding ( Probatova, 1965 ), has been registered in the waters of the Lower Amur region (Kryukova, 2005 ), and has been observed in the study of rivers and lakes of the Reserve, more often with considerable fluctuations of the water surface. Usually, mainly herblike species are attributed to water basin flora. However, we often discovered groups containing Salix schwerinii E. Wolf, Salix udensis Trautv. et Mey., Salix myrtilloides L. and other hygrophilic treelike species in the river shallows, gravel and sand spits, and banks of the basins under study. They play an important role in the overgrowth of river spits and sandbanks, and it is justifiable to include these species in basin flora lists ( Papchenkov, 1985 ).
Mesophytes are plants in sufficiently saturated habitats and represented in the area under study by P. aviculare , Fallopia convolvulus (L.) A. Löve, C. album , C. glaucum, Myosotis caespitosa KF Schultz and a number of other species. Hygro-mesophytes and mesophytes are common along the banks of water bodies; often species of these ecological groups grow on periodically dried shallows. Occasionally these groups include xeromesophytes, which prefer a sandy, pebble-growing medium in the highest areas of the coastline, in the splash zone near the forest border, such as Atriplex patens (Litv.) Iljin, Atriplex patula L., and A. vulgaris .
The banks and shallows of lagoon lakes feature a unique diversity of species, for example, Blagodatnoe Lake, which periodically interlocks with the sea. During the time period when the channel appears, the decline of the water level exposes mudflats that extend for tens of metres to the centre of the lake. The development of a particular complex of plants represented by species from different ecological groups may be observed here. In areas adjacent to the water and in saturated soil among puddles, live shoots of Potamogeton pectinatus L., Potamogeton octandrus Poir., M. spicatum , and some other species are found.
Plants from the ecological groups of species growing on shoals dominate in exposed areas. N.S. Probatova and A.P. Sokolovskaya (Probatova & Sokolovskaya, 1981 ) classify flora of “low islands and coasts of silt and sand subject to periodic flooding” to this group. For example, species with a short vegetation period (ephemera and ephemeroids) are often found in shallows and dried areas of lagoons, sink lakes and other water bodies. These species are Alopecurus aequalis Sobol., Juncus bufonius L., L. aquatica , Rorippa palustris (L.) Bess., B. ciliata , Ranunculus sarmentosus Adams, Gnaphalium uliginosum L., Bidens tripartita L., and Montia fontana L. in association with perennial species, such as Eleocharis, Scirpus, and Cicuta . Specimens growing on shallows, as a rule, are smaller in size (oppressed), but many of them blossom. The projective cover in these areas sometimes reaches 80–90%. Plants on shoals are characterized by a small size, short life cycle, economical use of macronutrients ( Nechaev and Nechaev, 1973 ; Probatova and Sokolovskaya, 1981 ) and number of other features that allow plants to adapt to periodic flooding.
A particular complex of seashore-growing halophilous species is observed in water bodies located directly on the marine coast in lakes and estuaries of rivers that periodically become brackish. Potamogeton pectinatus and Potamogeton pusillus L., as well as eurybiont M. spicatum , grow directly in brackish water. The most halophilic species of the Zannichelliaceae family; Zannichellia pedunculata Reichenb is found in one of the tributaries of the Golubichnaya River that becomes brackish during storms, as well as on the shallows of Blagodatnoe Lake (near the channel). Zostera japonica Aschers. et Graebn. grows in brackish lagoons near the mouth of the Golubichnaya River and near Blagodatnoe Lake. Zostera marina L. and Zostera asiatica Miki develop in coves and bays of the Sea of Japan. Halophyte Ruppia maritima L. has been registered in the macrophyte growth of Blagodatnoe Lake. The following species are common on the borders of water bodies, in damp areas and on marine coastal hills: R. sarmentosus, S. maxima, S. marina, S. komarovii, Rumex maritimus, Mertensia maritima (L.) SF Gray, Chorisis repens (L.) DC., Carex macrocephala, Eleocharis parvula (Roem. et Schult.) Bluff, A. eminens, Leymus mollis, among others.