Floral diversity of abandoned mansions and the inuence of soil properties on these unique vegetations.

The ndings of this research will give a better understanding about soil-plant interaction and will reveal a new area in bioscience to develop new technologies regarding in situ plant species conservation.


Introduction
Land is a fundamental element for the survival of human on earth. Construction & agriculture are totally dependent on the availability of suitable land. During the early civilization era, a large amount of land was come under agriculture by deforestation [1][2] . But in the recent past centuries, a retrogressive situation has been observed. Due to the migration of rural people to the urban areas in search of livelihood, many farmlands were abandoned throughout the world, particularly in Europe [3][4][5] . The process is still so pronounced that researches predict, it will be continued for next few decades [6][7][8] . Around 210 million hectare farmland area had been abandoned in Europe, North America and Oceania till 1990, with the most critical condition in Europe where abandoned areas comprised of one-third of the total arable land [9][10] . Land abandonment is one kind of ecological restoration process that transforms cultivated land into wild vegetion 11 .
In recent years, there were few works carried out on abandonend areas in Asia by researchers. Due to low public access, wild ora and fauna get su cient opportunities to ourish in these region .Though these areas are much rich in species diversity as compared to the farm and fellow lands, very few researches have conducted on them to evaluate their oral richness. Moreover, none of the researches have concluded any nding to reveal the exact reasons behind the plant species diversity in these regions.
Passive re-vegetation in permanently abandoned an adorable land (called secondary succession) is characterized by the re-placement species of a variety of habitat species of habitat dispersed species of habitat shapes 12 . Such secondary succession initially starts with annual or biannual plants, is then followed by perennial forbs, grasses and shrubs, and nally under usual Central European conditions ending up in a forest (climax stage). Abandonment of agricultural land is a signi cant change in land use from cultivation to a complex of plant successions. In most of Europe, the vegetation of deserted farmland has evolved into a dense forest or shrub. The expansion of vegetation explains, in part, the perceived decline in water resources, reductions in soil loss, and the progressive improvement of soil characteristics 5 . Determination of species richness of an area is essential to measure its importance in biodiversity conservation 13 . There are a number of diversity indexes exist which are used as bioindicators in studies on both aquatic and terrestrial ecosystems 14 . A comprehensive list of all living organisms of an area along with their present conservation status and future improvement plan is essential to conserve and maintain biodiversity in a wild region. Continuous monitoring on wild ecosystems have a signi cant impact on national biodiversity assessment 15 . Floral diversity of an area plays a vital role on soil microclimate modi cation and nutrient recycling 16 . The interrelationship between soil and plant has been considered as a major mystery of nature and investigated by different researchers [17][18][19][20] .
Biodiversity has developed as a complex concept recently. Plant biodiversity is an obscure understanding that represents heterogeneity and wide variations.Studies of plant variety have shown that secondary succession patterns depend upon the species that are initially present, their persistence or extinction and on the organization of latest species from native or regional species pools 21 . Similar patterns in secondary succession may be expected for soil organizations. However, spatial and temporal scales of spreading and formation take issue between plant and soil organisms similarly as between phyletic cluster of soil organisms. This could end in totally different national diversity patterns for plants and soil organization. A stronger understanding of the mechanism that drive soil diversity patterns will increased our understanding of the relationships between plant diversity and soil.
But it seems to be different for each plant species 22 . The pattern of plant distribution & dynamics of biological resources determine the rational design and choice development of plant succession pathways within an ecosystem 23 . Introducing a new species without maintaining this manner may cause severe anomaly to its natural surroundings 24 . Explanation of vegetion type, composition of species, comment or prediction on the classi cation and pattern of vegetations in a purposeful manner are the basic objectives of phytosociology 25 . It is the study of distribution, composition, classi cation and interrelationship of plant communities 26 . The pattern and classi cation of plant communities within an ecosystem is regarded as phytosociology 25,27 . It is a very useful tool to track changes in vegetion composition and how it alters edaphic components. Succession of plant species & their interactions are affected by several abiotic variables like soil texture, moisture, availability of nutrients, temperture, exposure to light and wind etc. Phytosociological study is regarded as the most advanced and economical method to exploit useful plant species from natural habitats 28 .
Due to the balanced progression of plant succession and soil erosion, a wide range of environments occur in the abandoned regions simultaneously 5,29 . If the environmental factors remain favourable for plant communities, development of forest ecosystem can occur within a short period of time. Land abandonment has several bene ts including i) expansion of vegetion cover that recovers the damaged ecosystem caused by deforestation 30,31 ; ii) higher absorption rate of carbon dioxide (CO 2 ) which is the main culprit for global warming 32 ; iii) increase of vegetion diversity during the secondary succession of plant species [33][34][35][36] ; iv) improvement of water in ltration and interception that reduces the chance of ooding 37,38 ; v) better regulation of water cycle within the area that reduces soil erosion and ensures high quality runoff 5,39 ; vi) promotes higher longevity of adjacent reservoirs as it renders sediment contribution by discontinuing sediment transport network and protecting the soil surface from direct splash 40,41 . As the plant taxonomy and ecology has a prominent importance in different conservation programs, the present research was conducted with the following objectives: (a) analysis of phytosociological attributes of some abandoned mansions' natural vegetations and (b) assessment of the interrelationship between oral diversity and soil physico-chemical properties within the abandoned sites.

Result
Phytosociological analysis of plant species in abandoned land of krittipasa (study site-1), Duttapara Density and Relative Density : The most densely populated populated species at site-1 (Table 4) were Vernonia cinerea (density of 10.25 and relative density of 9.601) followed by Chromolaena odorata (density of 9.74 and relative density of 9.134), Ardisia solanacea (density of 8 and relative density of 7.495), Mikania micrantha (density of 6.25 and relative density of 5.855), Alocasia acuminata (density of 5.75 and relative density of 5.387), Glycosmis pentaphylla (density of 5.5 and relative density of 5.152). Spathodea campanulata and Ficus benghalensis exhibited least density and relative density (0.25 and 0.234) followed by Alstonia scholaris, Borassus abellifer.
On the other hand at site-2 (Table 5) piper longum was most densely populated species (density of 9 and relative density of 9) followed by Adiantum philippense (density of 8.75 and relative density of 8.57), Mikania micrantha (density of 7 and relative density of 6.86), Achyranthes aspera (density of 6 and relative density of 5.88%) and Phyllanthus niruri (density of 5.5 and relative density of 5.39). Ficus racemosa and Nyctanthes arbor-tristis exhibited least density and relative density (0.25 and 0.24) followed by Carica papaya, Diospyros malabarica, Calamus tenuis and Citrus maxima.
Site-3 (Table 6) represents that most densely populated species were Pteris vittata (density of 2.5 and relative density of 2.04) and Clerodendrum viscosum (density of 2 and relative density of 2 and relative density of 1.64) followed by Solanum indicum (density of 2 and relative density of 1.64), Lepidagathis linearis (density of 1.75 and relative density of 1.43), Synedrella nodi lia ( density of 1.75 and relative density of 1.43) and Urtica nivea (density of 2 and relative density of 1.43). Scoparia dulchis exhibited least density and relative density (0.25 and 0.20) followed by Persicaria lapathifolia, Passi ora foetida, Morinda citrifolia and Solanum torvum.
Abundance: The most abundant species at site-1 (Table 4) was Vernonia cinerea with an abundance of 13.66 followed by Piper longum and Ageratum conyzoides with an abundance of 10 each. On the other hand at site-2 ( Table 5) the most abundant species was piper longum with an abundance of 36 followed by Adiantum philippense (35), Phyllanthus niruri (22) and Phyllanthus reticulatus (21) respectively. At site-3 ( The frequency values refers to the values of Raunkier's formula: A>B>C>D (site -1), A>B>C= D (site-2) and B<C>D>A (Site-3), (Table 10). The present ecological study shows that the given vegetation is heterogenous in nature. Fig. 2 shows that more shrubs (38.93%), climber (16.10%) available at site 1. A lot of herbs (60.5%) were found at site-2 and at site-3 the highest tree percentage (11.38%) in comparison to the other study areas was observed.
Abundance of plant families There were in total 30 families found at the site-1 (Fig. 1a), 31 families were also found at site-2 ( Fig. 1b) and 21 families at the site-3 (Fig. 1c)
Diversity and Dominance of species at site-3 (Fig. 6c, Fig. 4c): A total of 48 plant species with (H= 2.45) diversity value were recorded at site-3. The maximum IVI distribution analysis of the plant species of abandoned land showed that the dominant was Sloanum indicum. The co-dominant species were Albizia richardiana, Microlepia speluncae, Tabernaemontana divaricata, Clerodendrum viscosum and Alstonia scholaris respectively (Table 3).
Species Richness: The species rarefaction curve of the species richness was found to be higher in the quadrat-5 followed by q9, q8 at site-1 (Fig. 5a). However, the trends of species rchness were found to be greater in the quadrat-1 followed by q4, q3 at site-2 ( Fig. 5b)and species richness also found higher at q1 at site-3 (Fig. 5c).

Ecological characterization
Soil properties: Within the three study sites, sandy loam and sandy clay loam type soils were prominent.
Usually these soil types have high fertility and provide suitable environment for different insects and micro-organisms. Fig. 7 shows that in these three study areas, reddish brown coloured soil was predominant followed by blackish brown and light brown soils. In some reddish brown soil samples, small granules of concrete were found which limited the establishment of higher plants as evidenced by the absence of plant roots. Soils from lower areas were blackish, heavy and clayey.
Soil Colour: Fig. 7 shows that in these three study areas, reddish brown coloured soil was predominant followed by blackish brown and light brown soils. In some reddish brown soil samples, small granules of concrete were found which limited the establishment of higher plants as evidenced by the absence of plant roots. Soils from lower areas were blackish, heavy and clayey. Nitrogen : It was observed that percentage of total nitrogen of the soil samples were 0.015 to 0.699% within average value 0.15% (at site-1), 0.100 to 0.600% wihin average value 0.42% (site-2) and 0.100 to 0.600% within average value 0.23 % (site-3), (Table 9).
Phophorus: The highest concentration (84.7µ g/g soil) of phophorus was observed at quadrat no.08 at site-1 within average value of 27.9 g/g ( Table 7). The lowest concentration (2.5 µg/g) of phophorus also observed at quadrat no.05 at site-2 ( Heirarchical cluster of the species based on the dominance of the species In order to determine the dominance of the tree species, produced the hieriachial cluster.Figure shows that rcorded species in abandoned land of three different site. Clerodendrum viscosum are most dominant species which are the member of rst cluster and rest of the species (Alocasia acuminata, Chromolaena odorata, Ardisia solanacea and Vernonia cinerea) were co-dominating species at site-1.The rest of species form 2nd, 3rd, 4th, 5th cluster (Fig. 8a).
At site-2, Figure shows that recorded species produced species hierarchial cluster. Mikania micrantha and Cassia stula are most dominant species which are the member of rst cluster and rest of species form 2nd, 3rd, 4th and 5th cluster (Fig. 8b). On the other hand, at site-3 Solanum indicum and Clerodendrum viscosum are most dominant within member of rst cluster (Fig. 8c). Microlepia speluncae, Albizia richardiana and Tabernae-montana divaricata form the second dominant cluster of species in the study site-3. All these species are of natural origin. This signi es the importance of the abandoned land for native tree diversity conservation.
Relationship between vegetation spatial distribution and environmental factor RDA was used to analyze the relationship between the soil factors and abandoned land vegetation distribution in Barishal. Biplot score of the plant species derived from RDA analysis where soil properties were used as environmental variable shown in Fig. 9a, 9b, 9c respectively.
Relationship between vegetation and soil factors at site-1.
RDA analysis showed that soil moisture, electric conductivity, potassium, organic matter, nitrogen, phosphorus and pH were signi cantly correlated with species data at site-1 (Fig. 9a). Ardidisia solanacea, Alocasia acuminata showed signi cant correlation with soil potassium. The distribution of Laportea interrupta, Ageratum conyzoides, Centella asiatica, Adiantum Philippense was mainly affected by soil pH and electric conductivity. The distribution of Mikania micrantha, Ipomoea hederifolia was mainly affected by soil moisture. Pteris vittata, Phyllanthus reticulatus, Xanthosoma violaceum and Calophyllum inophyllum showed signi cant correlation with soil organic matter, phosphorus and Nitrogen.
Relationship between vegetation and soil factors at site-2.
Relationship between vegetation and soil factors at site-3.
The distribution of Clerodendrum viscosum, Dioscorea alata, Urtica nivea and Microlepia speluncae was mainly affected by soil organic matter. Synedrella nodifolia, Desmodium gangeticum and Piper longum showed signi cant correlation with soil electric conductivity. The distribution of Rungia pectinata was mainly affected by soil pH (Fig. 9c).

Discussion
Phytosociology is the branch of science which deals with plant communities, their composition and development, and therefore the relations between species. The structure of a community is set chie y by the dominant plant species and not by different characteristics 25 . All of these species don't seem to be equally necessary however there are solely a couple of overtopping species that by their bulk and growth modify the home ground and management the expansion of different species of the community as these species are known as dominants 42 . The current analysis is an attempt to assess composition, structure and diversity of plant species in abandoned land. The research analysis of information revealed that most herb species were recorded from the study sites. There were in total thirty families found at the site-1 (Fig. 1a), family of Moraceae possessed the highest number of species followed by Asteraceae and Araceae.There are also thirty families were also found at site-2 (Fig. 1b) and family of Verbanaceae possessed highest number of species followed by Moraceae, Euphorbiaceae and 21 families at the site 3 (Fig. 1c). Family Verbenaceae, Acanthaceae, Apocynaceae, Mimosaceae and Rutaceae possessed highest number of species. Analysis of IVI provides data concerning the status of a species and may be recognized as patterns of association of dominant species during a community 43 . Throughout the present study it had been found that each one of the 3 sites were dominated by Clerodendrum viscosum, Mikania micrantha, Solanum indicum with the utmost IVI value. It's dominance at the particular sites was preably on account of awareness of optimum conditions for its growth.Higher IVI of a species confers dominance over a vegetation by that species and plants having low IVI are entangled by the dominating ones. However, every species in a plant community has a speci c role and there is always a qualitative interrelationship present between the rare and abundant species 44  Family of family Verbenaceae emerged as dominant species at site-3. This may be as a results of (Verbenaceae) includes the following ingredients: (1) spreading of seeds for long distances by several native and introduced birds; (2) toxicity of its fruit for several mammals, that limits damage by herbivore; (3) its ability to sprout smartly following harm (e.g., by trampling); (4) its ability to invade a wide range of habitats; (5) production of allopathic substances, that improves its competitive ability; and (6) its ability to ower copiously for long periods, therefore attracting pollinators and making certain copious seed set. Species richness generally will increase throughout secondary succession once environmental and edaphic conditions area unit favorable with low uctuations 63 .
The quantitative relationship between abundance and frequency (A/F) indicated the contiguous distribution of plant species rather than regular distribution. Perhaps, contiguous distribution pattern is a notable characteristic of natural ecosystems 25 shown to improve soil nutrient status and thus develop grass-growing conditions 68,69 .
Diversity indexes provide valuable information regarding the composition and quality of vegetation in a study area and thus ultimately helps us to understand the community structure of a natural ecosystem. The values of Shannon-Wieners diversity index of the three sites were 3.47, 3.20 and 2.45 respectively which indicates that these are relatively diversity rich area as the values laid between 1.5 to 3.5 range 53 .
The values of Simpson's diversity index were also found extremely high as 0.99, 0.99 and 0.96 respectively (Fig. 3) which means if we take two plant samples randomly from two different quadrats, there are at least 96% chance that the samples we choose are two different species 54 . The Margalef's Richness Index (7.43, 7.82, 5.62) and Menhinick's Richness Index (2.23, 2.38, 2.53) of the three study sites (Fig. 3) re ect their high species richness. The Pielou's Evenness Index values were 0.26, 0.83 and 0.88 respectively for the study sites (Fig. 3) which indicate that the continuity of vegetation varies signi cantly from one place to another. However, all these values were considerably higher than that obtained from different studies on the natural forests of Bangladesh [70][71][72][73][74][75][76] . One of the probable reasons behind this phenomenon is that, natural forests are well-stablished ecosystem sustaining over a long time while vegetations of abandoned mansions are comparatively recent establishments via secondary succession of plant species. Thus, there are a large number of competitor species gather to run a struggle for existence and ensure survival of the ttest on that territory. There is a part of society which gives positive response to conserve abandoned lands, which assists these locations to achieve aesthetic look [77][78][79] .
Natural forest conservation requires authentic and consistent information on species composition and diversity pattern. Multivariate statistical methods including clustering of species are well developed in vegetation ecology [80][81][82] . Hierarchial cluster of the species based on dominance of the species shown Solanum indicum, Tabernaemontana divaricata, Albizia richardiana, Mikania micrantha, Cassia stula, Clerodendrum viscosum were most dominant. All these species are of natural origin. Plant species found in this study are of natural origin, which indicates the importance of indigenous plant species conservation in abandoned land ecosystem. Abandoned land increase in natural vegetation provides aesthetic values 77-79. The pH of all soil samples was found to be ranged in between 7.4 to 8.1 (for site -1), 7.1 to 7.7 (site-2), 7.2 to 7.6 (site-3) within average value 7.8, 7.43, 7.44 respectively which indicates slightly alkaline soil. In most cases, pH range of 6.0-7.5 is optimum for the adequate availability of nutrients in the soil 83  Spatial distribution and aggregation of plant communities were affected by their dynamic state and spatial heterogeneity to a great extent during this process 100,101 . We mainly focused on the interaction between the distribution pattern of plant communities and the physico-chemical properties of soil with some relatively remarkable effects of this interaction on population dynamics.

Conclusion And Recommendation
This study gives us insight into the oral richness hidden inside the abandoned mansions that have never been explored before. If these vegetation's are kept outside from human exploitation for a longer time, their soil will get more chances to be forti ed with organic matter and will ourish with more plant species over time. By implementing the knowledge of soil-plant interaction discovered in the present study, in-situ conservation can be improvised to save a large amount of germplasm within a limited area.
Moreover, these sites can be studied as a model ecosystem because of secondary succession of plant species in human intervened regions. Data obtained from this survey can also be utilized e ciently to develop new technologies regarding ex-situ conservation of plant species in botanical gardens to cope up with other modern conservation strategies.

Materials And Methods
Selection of the study sites The study was planned to be meted out within the following areas of Bangladesh in Barisal division-

Data analysis
Following eld data collection, the information was processed and compiled using Microsoft Excel and SPSS. Soil properties were used as an environmental variable for vegetation structure analyses. Of the two main ordination techniques of Redundancy Discriminant Analysis (RDA) and Canonical Correspondence Analysis (CCA)), RDA explained more interspeci c variation in soil properties data than the CCA in the present study. Therefore, RDA was used for ordination analysis using log-transformed abundance data each species. The analyzed were performed using the R-Studio software. Species richness rarefaction curve, dominance (D) curve and diversity pro le and hierarchical cluster (Dendogram) analysis were conducted using Paleontological Statistics (PAST) software package version 2.17 113 . Phytosociological analysis were conducted following the formulas [114][115][116] .

Analysis of vegetation
After eld data were collected, data on quantitative characteristics were compiled and processed for the diversity index. The basal area of the tree species has been calculated using the following equation 117 .
Basal area = πD 2 /4; where, D = Diameter at breast height, π = 3.1416 For each species, relative density, relative frequency, relative abundance and signi cance index (IIV) were calculated. Identi ed plants have been arranged taxonomically and classi ed according to their usual form.

Functional Diversity
Functional diversity is de ned as the variety of interactions within ecological process and can be quanti ed by determining the nature and extent to which functional groups are represented in an ecological system 118 . Functional diversity, evenness and richness were measured using different methods.
Generally, species diversity is determined not only by the number of species within a biological community, such as; species richness, but also by the relative abundance of individuals in that community. Species abundance is the number of individuals per species, and relative abundance refers to the uniform distribution of individuals across species within a community. Two communities may be equally rich in species but differ in relative abundance 119 .

Soil sampling and analysis
Soil samples were collected at 0-15 cm depth from center of every quadrat. Collected soil samples were unbroken in plastic baggage, right away when assortment, soil samples were brought at the Soil Research Development Institute (SRDI) in Barishal division. The collected soil samples was sieved through a 2mm-mesh screen to get rid of plant roots, rocks etc. when sieving, soil samples were analyzed for physico-chemical properties. Soil pH, conductivity, moisture, total nitrogen, potassium phosphorus and organic matter were determined.
The soil PH was determined using digital pH meter. Electrical conductivity was determined by EC meter.
Soil moisture content was determined using 10 g fresh soil at 80℃. Total percentage of nitrogen, organic carbon, available phosphorus and potassium were determined by standard protocols [125][126][127][128] . Competing interests: The authors declare no competing interests.