The conservation of some protected herbaceous plants in a wood park of Nizhni Novgorod metropolis

. The article considers ways to preserve populations of protected plant species on the example of a natural regional wood park "Sludah woods" in Nizhny Novgorod. The population fitness is assessed, including environmental conditions, population density and ontogenetic percentage. The environmental conditions according to the Ellenberg scores are assessed. The conservation and repatriation of the protected species are considered. Recommendations are supposed to use the agrotechnical measures to conserve rare herbaceous species under conditions of urban environment.


Introduction
In present over the world an urgent problem is the preservation and the reasonable use of natural landscapes within the boundaries of a megalopolis, in particular, are wood lands and areas under the status of regional natural landscapes.They are considered as natural elements of the ecological framework of a metropolis and as the cores (specially protected natural areas) or green corridors (gully spurs and river valleys).The use of natural landscapes including shady, low illuminated and highly illuminated landscapes is in the habitual species diversity within the large river valleys to obtain the urban environmental sustainability [1].The natural landscapes provide recreational ecosystem services, thus the importance of rare and endangered herbal species protection and those repatriation in a metropolis [2][3].There are the variety of habitat conditions for the specially protected and rare flora and fauna species.In addition, it is important to determine and select natural suitable environments for the repatriation of endangered species of herbaceous plants [4][5].For this purpose, a preliminary assessment of the environmental conditions of natural habitats to identify the degree of their compliance with the environmental requirements aimed for the conservation of rare plant populations and those for species repatriation [6].
The valley slopes of high indigenous right banks of the Oka and the Volga rivers within the metropolis of Nizhny Novgorod are the most important component of the natural environmental urban framework, which is of fundamental importance for the conservation of biological diversity in an urbanized area.In Nizhny Novgorod, the riverine valley form of landscapes is formed [7].The goal of particular importance is to involve recreational impacts under the conditions of increasing anthropogenic pressure.It is necessary to assess the population fitness concerned to protected plant species to eliminate the environmental and human constraints and to implement effective measures for the conservation and restoration of the species.

Material and methods
The regional protected wood area "Sludah woods" is a preserved section of deciduous wood in the right bank of the Oka River valley covered by trees entirely in the past.The functional role of protected areas is to conserve the species gene pool and biodiversity of herbaceous assemblages in natural riverine catchment landscapes, also used for recreation and in aesthetic importance by residuals.The major protected subjects are the copses of high-age indigenous deciduous woods those are remnants of valley oak tree line and slope meadows derived.The environmental role of this area is evidenced by both the general species richness of the herbaceous vegetation and the list of rare species varied in their taxonomy, body size and environmental requirements.
The slope line is the major environmental corridor used by species to move from the natural habitats to the ecosystems of urban wood-parks and green areas.Simultaneously, the regional landscape wood protected area of "Sludah wood" is in the urban area of the Oka valley that serves as the natural environmental framework core of Nizhni Novgorod metropolis and major conservation habitats of herbaceous species biodiversity.
The spatial heterogenity of multispecies vegetative assemblages is due to the variety of environmental conditions and human impact along the indigenous bank of the Oka Valley, caused by bank patchiness of its shape and sloping.The variation of edaphic conditions is the trophic soil fertility, reduced in the upper part of the slope due to the planar erosion.At the base of the slope there are varieties of alluvial soils with a complete humus horizon and its total amount.The presence of ravines and other erosive landscapes provides an exposure asymmetry of the slopes and local contrasts of illumination, thermal regime and moisture of soils and surface rocks.
The protected area is the northwestern edge of the Volga upland.The uplifting followed by the erosion and denudation forming the relief.The absolute marks of the right bank of the Oka Valley are 160-195 m, average sloping is 15 -17, reaches to 40 degrees in the upper part of the slope.There are two tiers of landslide terraces on the slope cut through by ravines, sometimes branched.The ravine length of the ranges from 150 to 700 m, the width from 50 to 300 m.The mouths of the ravines opened to the riverine shoreline in the past.There are landslides and washouts along the ravine slopes.
The surface rocks are represented by loess-like loams and eluvial-deluvial deposits.The deposit canopys are the Tatar tier of the Permian age represented by the red clay, include pink and light gray marls, bluish-gray siltstones, yellow-white limestones and dolomites.
The soil are gray and light gray deciduous wood soils, light and medium loamy.Where the slope steep, the soils are poorly developed turf formed by the eluvium and deluvium of the bedrock.
The woods on the slopes is represented by derived limestones with a low and moderate values of tree cover.There are conserved areas of old-aged deciduous wood, including those with a predominance of Quercus robur.In order to assess the population fitness of rare protected plant species, determine environmental conditions and the fitness of plant populations.Investigations are conducted mainly in the wood areas of the protected area "Sludah woods".Geobotanical desriptions are on sites of 20x20 m, detailed studies of the age stages of plants, the number of species and other indicators were carried out due to the rarity of protected plants -by a selective method on sites of 1 m2.The following indicators were determined on the test areas: the condition and characteristics of stands, species composition, height and diameter of trees; the condition and characteristics of undergrowth, undergrowth, renewal, herbage; the presence and characteristics of populations of protected plant species [8]

Results
The ravine bottom and areas of the slopes base are wetland, and the lower are partly swampy, that contribute to the growth of some species of hygrophyte orchids (Dactylorhiza baltica, Epipactis palustris whereas limestone outcrops and the springs to provide the massive growth of the reviving moonstone (Lunaria rediviva).
Moderate recreational pressure promotes the repatriation of ruderal and meadow plant species, those enrich floral species diversity.The upper part of the slope along asphalt paths and landslide terraces are mostly impacted that provide the species mixing from adjacent wood and meadow assemblage, the ecotone pattern is revealed on the borderline.
Most of the protected plant species (67%) are occasional, either a few individuals and the only site marked or more than one, or few individuals in a small area (Table 1).Orchis militaris L.
-R1 U Symbols: + -a species in the list of the federal Red Book; O (occasional) -the only occurrence or the only habitat; U (uncommon) -small in number; C (common) -common; V -vulnerable declining species; R1 -poorly abundant species is usually sparse; H -species key habitats are conserved in the regional Red Book due to special protection.
The assessment of the population fitness to consider the anthropogenic effects is important for the conservation of rare plant species in the protected area "Sludah woods" and in the adjacent area.Density assessment and ontogenetic stages have been considered for protected orchid species.An assessment of the population density of the protected orchid species showed a significant difference in this characteristic for different species (Table 2).
Since both orchid species: Cypripedium calceolus and Epipactis helleborine (L.) Crantz are not currently found in the protected area "Sludah woods", we provide data in the protected area "Raspberry wood" which is a similar wood area on the indigenous right bank of the river Okah within the metropolis of Nizhny Novgorod.The maximum average density is marked in the population of Epipactis palustris (Table 3a).In populations of Orchis militaris, the average density of individuals and shoots are the lowest, it is characterized by sporadic occurrence with a small number of generative plants (Table 3, Figure 1c).
The low density of protected orchid species may indicate depressed conditions; density dynamics indicates a decrease in the number of the populations is informative.
An assessment of the stages of development in populations showed that the majority of orchid species in the protected area "Sludah woods" are characterized by the predominance of generative flowering or vegetative plants (40-60%) (Figure 1).The adult plants predominance that live at this stage 3-5 times longer than the other stages is normal for the orchid family.However, an absence or a sharp decrease in the proportion of juvenile and immature stages in some orchid populations indicates the activation of vegetative and inefficiency in seed reproduction.Further development of this trend may reduce in the number of populations up to species extinction.
The population of Epipactis palustris is dominated by plants of the virginal and immature stages (30% and 21%, respectively) and the slight plants of the juvenile stage (4%) (Figure 1a).
In the population of Dactylorhiza baltica the generative plants predominate (49%), virginal individuals are slightly less generative (35%), the proportion of juvenile and immature plants is less (16%) (Figure 1b).
Generative plants predominate in the Orchis militaris populations of (80%); virginal individuals are found to have no individuals of juvenile and immature stages (Figure 1c).
The degradation of the populations of the Orchis militaris and the Dactylorhiza baltica is associated with natural successional processes -the capture of meadow edges by woody species.In this case, it is possible to transplant species into right conditions, care for wood species plantations, thinning of trees and shrub.It is necessary to continue monitoring the condition of the populations of protected orchid species.
Anthropogenic impacts mainly negative affect the protected species.A current importance in the deterioration of the populations is an enhance in the recreational pressure concerned with an increase in the attendance of the protected area.It provides the trampling of the grass cover, compaction of soils and the extirpating of protected plant species.One of the measures to reduce the anthropogenic impact is to limit the attendance of protected habitats of species protected by fencing, planning the paths and trails of recreants.Moderate meadow mowing in the protected area can contribute to the conservation and spread of a number of meadow orchid species that cannot compete with other species.The destruction of habitats of protected plant species is found, for example, as a result of construction in one of the ravines in the protected area "Sludah woods", which reduced number of habitats of Lunaria rediviva.There are some habitats of protected species, may be negatively affected by a change in the hydrological regime: waterlogging and an increase in the groundwater level for Cypripedium calceolus or, conversely, artificial soil drainage for hydrophytes: Lunaria rediviva, Dactylorhiza baltica, Epipactis palustris).
The habitats are deciduous woodlands and dry meadows in the indigenous right-bank slope of the Oka River, including landslide terraces.Wood areas of Quercus robur and Tilia cordata dominants with a predominance grass of Aegopodium podagraria are considered, with Acer platanoides, Fraxinus excelsior, Ulmus laevis dominate patchily.The tree cover is 70-80%.
The predominant species of trees and grass in the geobotanical sites are presented in the Table 3.
The indication of abiotic conditions is carried out by Ellenberg scale for the covering of grass species (Table 4).
The light of sites is assessed by 4 scores and varied from 3 to 5 scores (species range from 5% shading to moreover 10% the daylight) (Table 4).The soil moisture level of biotopes averaged 6 points and varied from 5 to 6 points (medium humid -humid habitats).
The soil acidity level of biotopes averaged 7 points and slightly varied from 6,8 to 7,3 points (slightly acidic -slightly alkaline soils).
The soil fertility level of biotopes in terms of nitrogen content averaged 7,5 points and ranged from 7 to 8 points (nitrogen-normally-enriched to nitrogen-highly enriched soils).
The assessed environmental factors are favorable for the most protected plant species requirements, including orchids.Optimal environmental conditions of four protected orchid species and Lunaria rediviva are shown in the Table 5.The scores indicate that protected species are divided into two groups by light: from shade-tolerant to shade-loving plants (Cypripedium calceolus, Lunaria rediviva), for those the optimal lighting is 4-5 scores and light-loving (Dactylorhiza baltica, Epipactis palustris, Orchis militaris) those prefer 7-8 scores (30-40% of the daylight).According to soil moisture, the species are also divided into two groups: the first includes Cypripedium calceolus and Orchis militaris with optimal moisture of 3-4 points (from dry to mediummoist habitats), in the second -Dactylorhiza baltica, Epipactis palustris and Lunaria rediviva -6-9 (wet to moist conditions).In relation to soil acidity, the optimum of protected species ranges from neutral and slightly acidic (score 7) to slightly alkaline (8-9 scores) in carbonate soils.In relation to soil fertility, Orchidaceae do not impose high requirements on nitrogen content (scores 2-4, from poor to moderately nitrogen-rich), Lunaria rediviva prefers to grow in rich and very rich soils (8).
The study of natural regimes is important from the point of view of assessing biotopes for the repatriation of rare plant species or the expansion of their range in the area under consideration.Of the surveyed sites No. 5-7, 9-15 are the most suitable for repatriation of Cypripedium calceolus, the most important characteristics of lighting and moisture for the species (Tables 4 and 5).For Dactylorhiza baltica and Epipactis palustris, open habitats with high soil moisture are the most favorable, among which there is only one site -17, where these species grow.Orchis militaris prefers daylighting habitats with moderate and high soil moisture, these conditions correspond to site 16, which is the habitat for this species.Lunaria rediviva in moist soils in conditions of strong shading, sites No. 2-4, 8, 18 are correspondent to conditions required (Tables 4 and 5).
Cypripedium calceolus grows in the slopes of ravines and steep river banks with limestone outcrops.Prefers places with moderate illumination, neutral and slightly alkaline and moist drained soils with a high humus content.The species has the ability to go into a dormant state for several years, while leading an underground living at the expense of symbiotic fungi.It disappears as a result of recreational stress (trampling, grass fires, collecting flowering plants in bouquets), changes in the natural conditions, shading from growing shrubs and trees).The self-regeneration of populations is hampered by the biological characteristics of the species: the complexity of seed reproduction, the development stage and a mycotrophic lifestyle.It is recommended to preserve habitats, regulate recreational load, lighten the tree canopy, mass cultivation and reproduction in specialized nurseries with further repatriation [9][10].
Dactylorhiza baltica is in a small area, in one of the areas of grassland near springs [11].The species is a group of hygrophytes to mesophytes in high-humid and waterlogged habitats: through damp and swampy meadows, in floodplains of small rivers, along overgrown ditches, along roadsides, at springs of carbonate groundwater.It disappears when overgrown with trees and shrubs, tall grasses and semi-shrubs, as well as from changes in hydrological conditions.Every found D baltica population is characterized by a small number of plants, and their dependence on springs, occur in lighted or shadowed landscapes (wood edges), within landslide terraces.It is necessary to monitor the plant populations and effort to protect.It is recommended to preserve, fence habitats, recreative constrains, lighting the tree canopy and shrub, weed large grasses and other agrotechnical measures, preserve the hydrological conditions [9][10][11].
Epipactis palustris occurs in a lighted grass area near springs.It likes lighted habitats, excessive wet and insufficient aeration of the soil.It disappears when hydrological conditions change, as a result of shading and recreational use of the area, intensive haymaking [10].It is recommended to fence the habitats recognized, mitigate recreation pressure, lighten the tree canopy, and keep hydrological conditions.
Orchis militaris likes meadow slopes.The species require soil fertility, drainage and calcification.It occur in damp meadows and wood edges, in the ravine slopes, sometimes under the canopy of sparse deciduous woods, likes calcareous, enriched, well-drained soils, grows in small groups.The species suffers from changes in hydrological conditions and lighting, damaged to the recreation [9][10].The preservation of populations is hindered by the seed reproduction and the long ontogenetic development.It is recommended to preserve recognized habitats, move recreative zones away, thin out the shrub and keep hydrological conditions.
Lunaria rediviva is a thermophilic tertiary relic, does not tolerate late spring frosts and cold snowless winter.The species is located on the border of its range.Mesophyte can occur with severe non-stagnant moisture in the places of springs.It likes woods, usually the slopes of ravines in river banks, but can grow in clearings and edges.It requires rich, aerated light soils with a neutral or slightly acidic reaction.The orchid disappeares because of recreational pressure and habitat disturbance, changes in hydrological conditions, logging, and collecting plants for bouquets.In order to protect the species, it is recommended to preserve the natural conditions, including landslide-prone areas.[10].
Some agrotechnical efforts are important for the conservation of rare plant species, as well as monitoring of their populations (Table 6).

Discussion
The light is the resource for most species (excepting Lunaria rediviva) extinguished due to the tree-shrub canopy and high grasses shading.The most of the orchid species are depressed, up to extinction from their habitats, Thus, it is important to thin out the treeshrub canopy and weed the herbage from competitive species.Since dry periods are observed in the summer in the temperate continental climate in the Nizhny Novgorod region, protected species, especially in the case of their repatriation, need watering.To restore populations of rare species, they should be returned into habitats to meet their environmental requirements by means of sowing seeds (Lunaria rediviva) or planting the young orchids.For the reproduction of orchid species, asymmetric methods (in vitro) are used in the laboratory, this process takes several years, young individuals are planted in the natural environment.There are examples of successful repatriation of wood plants into natural conditions, including orchid species [4,6,12].Thus, in order to preserve protected plant species in a metropolis, monitoring of their condition is necessary, as well as the implementation of a number of agrotechnical efforts that are important for the conservation of rare and vulnerable species to anthropogenic pressure: limiting the flow of vacationers to their habitats, species repatriation, weeding from competitive plants, increasing lighting by thinning trees and shrubs, watering plants in the dry period.

Conclusion
 Recreational pressure negative affects the fitness of protected species populations of herbaceous plants.An important role in the deterioration of the rare species populations is an increase in the attendance of the protected area "Sludah woods", which leads to trampling of the grass cover, compaction of soils and the disappearance of protected plant species.One of the measures to reduce the impact of this anthropogenic pressure may be to limit the attendance of habitats with protected plant species by recreants. The indication of environmental conditions in the natural habitats is important to assess the state of populations of protected species and choose some habitats for the repatriation of rare plant species or the expansion of their range in the protected area.Of particular importance for most species (except Lunaria rediviva) is the lighting.Environmental conditions of importance are soil fertility and acidity; the most significant is moisture. Some agrotechnical measures are of great importance to conserve the protected rare herbaceous species, including species repatriation, weeding from competitive plants, thinning trees and shrubs to increase lighting, watering juvenile plants in summer.It is also recommended to implement regular monitoring surveys to assess population dynamics of protected plant species.

Table 1 .
The list of rare species of herbaceous plants registered in the natural wood area "Sludah wood" and in the adjacent area.

Table 2 .
Population density of orchid species in both protected area: "Sludah woods" and "Raspberry wood".

Table 3 .
Dominant species of trees and grass in the geobotanical sites.

Table 4 .
Indicative scores in the considered sites by Ellenberg scale of grass species.factors Examined by the particles.

Table 5 .
Optimal environmental conditions by Ellenberg scale some protected grass species.

Table 6 .
Recommendations for the conservation of rare herbaceous species.