当前世界环境

Introduction

Planting indigenous tree species and mixing with several other species significantly improve the conservation of biodiversity. Numerous scientific publications are offered the justification for biodiversity conservation (Frankhamet al., 2002; Pregernig, 2006). The number of ecological niches in an ecosystem can be increased by growing a higher number and diversity of tree species. This has been sequentially enhanced the associated species such as understory plants (Kanowaskiet al., 2003) and animals (Wunderle, 1997). Therefore, growing diversity of many tree species on a location not only conserves numerous trees but also other organisms (Markku, 2008).

Oldfieldet al., (1998) reported that ten percent of all trees in the world are threatened with extinction.In situconservation methods are more suitable and successful for conservation of rare, vulnerable, threatened species to reduce extinction. There is a increasingawarenessthat conservation efforts outside the ecosystem (ex situconservation) are essential for species survival (Krameret al.,2011;Oldfield and Newton, 2012; Pritchardet al.,2012).In situconservation methods are not viable for those tree species with a little population size or edging with threat.Ex situconservation method is the only alternative to avoid its immediate extinction (McNamara,2011;Maet al.,2013). Since 1980s, the botanical garden plays a vital role in the field ofex situconservation (Bramwellet al.,1987;Falk,1987;Falk and Holsinger, 1991;Guerrantet al.,2004). Thegardens grown in the urban environment also play vital role in conservation of trees. Trees are our wealth on planet earth. Trees represented in all vascular plants such as tree fern, Gymnosperms include cycads, conifers etc. and Angiosperms include all flowering trees. In a city the streets, parks, playgrounds and backyards of the home are lined with trees that create a peaceful, aesthetically pleasing environment. Being District Science Centre, Tirunelveli, is agovernment and non-profit organization can be effective to excite better involvement by gardens in plant conservation.The objective of this study was to evaluate the diversity of tree species in District Science Centre, Tirunelveli, Tamil Nadu, India. The District Science Centre campus consists of a diversity of plants and the perusal of literature reveals that there is no published record on the flora of this campus which represents an interesting floristic composition.

Study Area

District Science Centre

The District Science Centre (DSC) was opened to the public on 27^thFebruary 1987. It is started with a gallery on "Treasures from Ocean" and a Science Park. It is located near the Collector Office, Kokkirakulam, Tiruneveli Corporation area. It has lot of exhibits, science working models and many displays to gain knowledge. Before long the Center got one of the most well known Centre inNational Council of Science Museums(NCSM) due to the tremendous support from the local community. National Council of Science Museums, Government of India is the controlling authority of the centre. Popularize science and technology among public and to supplement science education in schools and colleges to foster a spirit of scientific enquiry among the students is major objective of the centre. The beautifularchitecturalmain building of the centre locates in the middle of the campus. Many outreach programmes such as rural science camp, workshops, seminars, science quizzes, science fair vacation hobby courses etc., are regularly organized.

Methodology

During the course of present study, regular field trips were carried out to the area in 2019 in different seasons to explore the various tree species. Standard methodology was used to elicit the knowledge of trees. All the relevant information of each tree species was recorded in an index card. The plants specimens collected were processed at the laboratory of Botany, Rani Anna Govt. Arts College for Women, Gandhi Nagar and identified with the help of available literature. The identification of plants was done using The Flora of Tamil Nadu Carnatic by K.M. Mathew (1983 -1988), Flora of Tamil Nadu, India by A.N. Henryet al,(1987),Flowering Plants of Chittoor District, Andhra Pradesh, IndiabyMadhavacheettyet al. (2008),Tropical Garden Plants byBimal Das Chowdhuryet al. (1991)and Flora of Presidency of Madras by Gamble (1915 – 1936). The families and nomenclatures are arranged according to online Tropicos database3.0.2,Missouri Botanical Garden, 2020.

Results and Discussion

在实地调查的基础上进行的rict Science Centre campus area, 80 tree species were collected and identified. They belong to 68 genera and 29 families. Out of the identified tree species 75 are dicot and belong to 63 genera and 27 families; 5 tree species are monocot and belongs to 5 genera and 2 families (Table 1). Among the dicots, 53 species are Polypetalae and family Fabaceae is the most dominant with 16 genera and 20 species. In Gamopetalae 15 genera covering 15 species are recorded and Bignoniaceae is the most dominant family.In Monochlamydeae 7 species covering 4 genera are recorded and Euphorbiaceae is the most dominant family.In the present study 15 families reported with only one species, 9 families represented by more than 2 species. Present study recorded 12 fruit yielding trees, 9 medicinal trees, 26 ornamental trees, 29 timber value trees and 1 fibre yielding tree. The total number of trees observed during the period of study was 338.

Table 1: List of trees available in the campus

S.No	Name of Species	Family	Economical importance	Reference	Voucher number
	Lannea coromandelica (Houtt.) Mann.	Anacardiaceae	Timber	Flo. Pts. Chittoor District A P. 76, 2008.	RAC 367, RAC 401
	Mangifera indicaL.	Anacardiaceae	Fruit, Timber	Fl. Pres. Madras 1:259. 1918.	RAC 371
	Polyalthia longifolia(Sonner.) Thw.	Annonaceae	Ornamental	Flo. Pts. Chittoor District A P. 17, 2008.	RAC 302
	Polyalthia longifoliaHook. &Thoms. var.pendula	Annonaceae	Ornamental	Flo. Pts. Chittoor District A P. 17, 2008.	RAC 248
	Alstonia scholaris(L.) R. Br.	Apocynaceae	Medicinal	Flo. Pts. Chittoor District A P. 196, 2008.	RAC 360
	Holarrhena pubescens(Buch.-Ham.) Wall. ex G. Don	Apocynaceae	Medicinal	Flo. Pts. Chittoor District A P. 198, 2008.	RAC 263
	Borassus flabelliferL.	Arecaceae	Timber	Fl. Tamil Nadu Carnatic 3:1670. 1983	RAC 379
	Caryota urensL.	Arecaceae	Ornamental	Flo. Pts. Chittoor District A P. 366. 2008.	RAC 346
	Cocos nuciferaL.	Arecaceae	Fruit	Flo. Pts. Chittoor District A P. 367, 2008.	RAC 402
	Millingtonia hortensisL.f.	Bignoniaceae	Ornamental	Flo. Pts. Chittoor District A P. 245, 2008.	RAC 288
	Spathodea campanulataP. Beauv.	Bignoniaceae	Ornamental	Flo. Pts. Chittoor District A P. 246, 2008.	RAC 300
	Tabebuia rosea(Bertol.) DC.	Bignoniaceae	Ornamental	Flo. Pts. Chittoor District A P. 247, 2008.	RAC 293
	Tecoma stans(L.) Kunth.	Bignoniaceae	Ornamental	Flo. Pts. Chittoor District A P. 248, 2008.	RAC 323, RAC 254
	Ceiba pentandra(L.) Gaerten	Bombacaceae	Fibre	Fl. Tamil Nadu Carnatic 3: 1983	RAC 354
	Cordia dichotomaForst. F	Boraginaceae	Timber	Flo. Pts. Chittoor District A P. 216, 2008.	RAC 388
	Carica papayaL.	Caricaceae	Fruit	Flo. Pts. Chittoor District A P. 136, 2008.	RAC 306
	Casuarina littoreaL.	Casuarinaceae	Ornamental, Timber	Flo. Pts. Chittoor District A P. 335, 2008.	RAC 340
	Cassine glauca Kuntze	Celastraceae	Timber	Fl. of Tamil Nadu. 1: 1983	RAC 279
	Terminalia arjuna(Roxb. ex DC.) Wt. &Arn.	Combretaceae	Medicinal	Flo. Pts. Chittoor District A P. 125, 2008.	RAC 261
	Terminalia catappaL.	Combretaceae	Timber	Flo. Pts. Chittoor District A P. 126, 2008.	RAC 233
	Dillenia indicaL.	Deliniaceae	Ornamental	Flo. Pts. Chittoor District A P. 14, 2008.	RAC 223
	Phyllanthus acidus(L.) Skeels.	Euphorbiaceae	Fruit	Flo. Pts. Chittoor District A P. 321, 2008.	RAC 342
	Phyllanthus emblicaL.	Euphorbiaceae	Fruit	Flo. Pts. Chittoor District A P. 322, 2008.	RAC 364
	Acacia auriculiformisA.Cunn. ex Benth.	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 114. 2008.	RAC 203
	Adenanthera pavoninaL.	Fabaceae	Timber	Flo. Pts. Chittoor District A P. 116, 2008.	RAC 243, RAC 399
	Albizia lebbeck(L.) Benth.	Fabaceae	Timber	Fl. Pres. Madras 1:432. 1919	RAC 332
	Bauhinia purpureaL.	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 106, 2008.	RAC 283
	Bauhinia variegataL	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 107, 2008.	RAC 315
	Cassia fistulaL.	Fabaceae	Ornamental	Fl. Tamil Nadu Carnatic 3:499	RAC 289
	Cassia javanicaL.	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 109, 2008.	RAC 231
	Cassia siameaLam.	Fabaceae	Ornamental	Fl. Pres. Madras 1:285, 1957	RAC 215, RAC 377
	Dalbergia sissooRoxb.	Fabaceae	Timber	Fl. Pres. Madras 383, 1918	RAC 259
	Delonix regia(Boj. ex Hook.) Rafin	Fabaceae	Ornamental	Fl. Pres. Madras 1:280, 1957	RAC 295
	Erythrina variegataL.	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 90, 2008.	RAC 358
	Hardwickia binataRoxb.	Fabaceae	Timber	Fl. Pres. Madras 1:412, 1919.	RAC 286
	Leucaena leucocephala(Lam.) de Wit	Fabaceae	Timber	Flo. Pts. Chittoor District A P. 118, 2008.	RAC 374
	Parkia biglandulosaWt. &Arn.	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 119, 2008.	RAC 256
	Peltophorum pterocarpum(DC.) Baker ex Heyne	Fabaceae	Ornamental	Flo. Pts. Chittoor District A P. 112, 2008.	RAC 313, RAC 362, RAC 200
	Pithecellobium dulce(Roxb. )Benth	Fabaceae	Fruit	Flo. Pts. Chittoor District A P. 119, 2008.	RAC 383
	Pongamia pinnata(L.) Pier.	Fabaceae	Timber, Medicinal	Flo. Pts. Chittoor District A P. 97, 2008.	RAC 212, RAC 333
	Pterocarpus santalinusL.f.	Fabaceae	Timber	Flo. Pts. Chittoor District A P. 98, 2008.	RAC 319
	Saraca asoca(Roxb.) Wilde	Fabaceae	Medicinal	Flo. Pts. Chittoor District A P. 113, 2008.	RAC 271
	Tamarindus indicaL.	Fabaceae	Fruit	Flo. Pts. Chittoor District A P. 113, 2008.	RAC 272
	Tectona grandisL. f.	Lamiaceae	Timber	Flo. Pts. Chittoor District A P. 270, 2008.	RAC 355
	Vitex altissimaL.f.	Lamiaceae	Medicinal	Flo. Pts. Chittoor District A P. 271, 2008.	RAC 226
	Couroupita guianensisAubl.	Lecythidaceae	Medicinal	Flo. Pts. Chittoor District A P. 129, 2008.	RAC 350
	Lagerstroemia indicaL.	Lythraceae	Ornamental	Flo. Pts. Chittoor District A P. 132, 2008.	RAC 210, RAC 359
	Lagerstroemia parvifloraRoxb.	Lythraceae	Ornamental	Flo. Pts. Chittoor District A P. 132, 2008.	RAC 301
	Lagerstroemia reginaeRoxb.	Lythraceae	Ornamental	Flo. Pts. Chittoor District A P. 132, 2008.	RAC 328
	MalpighiaemarginataDC.	Malphigiaceae	Ornamental	Tro. Gar. Plts. 1991	RAC 394
	Grewia tiliifoliaVahl.	Malvaceae	Timber	Flo. Pts. Chittoor District A P. 50, 2008.	RAC 321
	Guazuma ulmifoliaLam	Malvaceae	Timber	Flo. Pts. Chittoor District A P. 45, 2008.	RAC 356
	Pterospermum acerifolium(L.)Willd.	Malvaceae	Timber	Flo. Pts. Chittoor District A P. 321, 2008.	RAC 347
	Sterculia foetidaL.	Malvaceae	Ornamental	Flo. Pts. Chittoor District A P. 47, 2008.	RAC 318
	Thespesia populnea(L.) Soland. ex Correa.	Malvaceae	Timber	Flo. Pts. Chittoor District A P. 43, 2008.	RAC 208
	Azadirachta indicaA.Juss	Meliaceae	Timber, Medicinal	Fl. Pres. Madras 1:177. 1915	RAC 268
	Swietenia mahagonia(L.) Jacq.	Meliaceae	Timber	Flo. Pts. Chittoor District A P. 64, 2008.	RAC 335
	Ficus religiosaL.	Moraceae	Timber	Fl. Pres. Madras 3:1368; 1919.	RAC 284
	Ficus benghalensisL.	Moraceae	Timber	Fl. Pres. Madras 1361,1928	RAC 273, RAC 398
	Ficus racemosaL.	Moraceae	Timber	Flo. Pts. Chittoor District A P. 333, 2008.	RAC 246
	Morus albaL.	Moraceae	Timber	Flo. Pts. Chittoor District A P. 334, 2008.	RAC 311
	Moringa pterygospermaGaertn	Moringaceae	Vegetable	Flo. Pts. Chittoor District A P. 77, 2008.	RAC 207
	Ensetesuperbum(Roxb.) Cheesman	Musaceae	Ornamental	Flo. Pts. Chittoor District A P. 345, 2008.	RAC 344
	Ravenala madagascarensisSonner.	Musaceae	Ornamental	Flo. Pts. Chittoor District A P. 346, 2008.	RAC 220
	Callistemon citrinus(Curtis) Skeels	Myrtaceae	Ornamental	Flo. Pts. Chittoor District A P. 127, 2008.	RAC 251
	Eucalyptus globulesLabill.	Myrtaceae	Medicinal	Flo. Pts. Chittoor District A P. 128, 2008.	RAC 317
	Psidium guajavaL.	Myrtaceae	Fruit	Flo. Pts. Chittoor District A P. 321, 2008.	RAC 276
	Syzygium cumini(L.) Skeels	Myrtaceae	Fruit	Flo. Pts. Chittoor District A P. 47, 2008.	RAC 361, RAC 280
	Averrhoa carambolaL.	Oxalidaceae	Fruit	Flo. Pts. Chittoor District A P. 55, 2008.	RAC 378
	Ziziphus mauritianaLam.	Rhamnaceae	Fruit	Fl. Tamil Nadu Carnatic 3:271. 1983.	RAC 308
	Morinda pubescensJ.E. Smith	Rubiaceae	Timber, Medicinal	Fl. Pres. Madras 651, 1921;	RAC 236, RAC 330
	Neolamarckia cadamba(Roxb.) Boss.	Rubiaceae	Timber	Flo. Pts. Chittoor District A P. 160, 2008.	RAC 303
	Aegle marmelos(L.) Correa.	Rutaceae	Medicinal	Fl. Tamil Nadu Carnatic 101,1982	RAC 309
	Murraya koenigii(L.) Spreng.	Rutaceae	Food preparation	Flo. Pts. Chittoor District A P. 58, 2008.	RAC 352
	Murraya paniculata(L.) Jack.	Rutaceae	Timber	Flo. Pts. Chittoor District A P. 58, 2008.	RAC 298
	Santalum albumL.	Santalaceae	Timber, Medicinal	Flo. Pts. Chittoor District A P. 306, 2008.	RAC 253
	Madhuca longifolia(Koen.) Macbr.	Sapotaceae	Timber, Medicinal	Fl. Pres. Madras 2 : 536. 1957.	RAC 385
	Manilkara zapota(L.) P. Royen	Sapotaceae	Fruit	Flo. Pts. Chittoor District A P. 187, 2008.	RAC 337
	Mimusops elengiL.	Sapotaceae	Medicinal	Flo. Pts. Chittoor District A P. 187, 2008.	RAC 265
	Ailanthus excelsusRoxb.	Simaroubaceae	Timber	Flo. Pts. Chittoor District A P. 60, 2008.	RAC 325, RAC 381

Polyalthiais the dominant species followed byLagerstomiaspecies.Many introduced tree species likeLagerstomia flos-reginae, L. reiginae, Parkia bigalandulosa,Sterculia foetidaalso recorded in the study area. The timber yielding trees likeDalbergia sisso, Acacia auriculiformis, Tectona grandis, Neolamarckia cadamba, Casuarina littoreaalso recorded. The two scared treesAegle marmelos, Couroupita guianensiswas observed. The fruit yielding tree likeSyzigium cumini, Mangifera indica, Carica papayaetc. are also observed.Neolamarckia cadamba, Madhuca longifolia, Alstonia scholaris, Ficus religiosa, F. racemosa, Millingtonia hortensis, Erythrina variegataare huge trees in the campus. Some tall trees likeCassine paniculataare now in the shrub state.

Two endanger treeSaraca asokaalso grown in the study area.This small tree has become threatened in some parts of its range mainly through the loss of its habitat and overexploitation for medicinal use.Considering the conservation need of this species, it has been listed under the threat category of ‘Vulnerable’ byInternational Union for Conservation of Nature (IUCN, 2013) and ‘Endangered’ byConservation Assessment and Management Prioritisation (CAMP, 2001).Santalum albumis another IUCN listed vulnerable species (The IUCN Red List of Threatened Species2019).Pterocarpus santalinus(Red sanders) is listed as an endangered plant species on the IUCN red data list as a result of the exploitation of its wood and essential oil.Holarrhena pubescensandCouroupita guianensisareclassified as 'Least Concern'inthe IUCN Red List of Threatened Species2013.

The number of viable tree saplings grown under the shade of the tree is a crucial aspect within the study of biodiversity. They might determine the regeneration of new plants in the study area. Additionally, it plays a crucial role in carbon trapping and sequestration. The previous reports suggested that the dense young tree saplings trap more carbon from the atmosphere than the mature trees. Thus the germination of seeds and associated survival of the saplings is a positive indicator of the healthy ecosystem.Moreover, it also provides information about the ability of plant species to adapt, compete and grow in several climates.The campus was recorded many tree saplings ofCassia fistulaandMillingtonia hortensis. Less number of tree saplings was recorded forHolarrhene pubescens. The most remarkable tree species in this area of study includesDelinia indica, Saraca asoca,Holarrhene pubescensandSterculia foetida.

Flowering Phenology

Summer flowering species such asAzadirachta indica,Lannea coromandelica¸Erythrina variegata,Cassia fistula,Moringa pterygospermaandDelonix regiaare initiate flower budson foliated shoots during the hot-dry period (March–June). For these species probable flowering cue increasing day length/temperature. South west monsoon rainy flowering species such asSyzygium cumini, Eucalyptus globules,Peltophorum pterocarpum,Mangifera indica, Averrhoa carambolaare initiate flower budson foliated shoots during the warm-wet period (June–August). The first significant rains after the summer may act as flowering cue for these species. Autumn flowering species such asMalpighiaemarginata,Bauhinia purpurea,Bauhinia variegatainitiate flower budson shoots with mature leaves (September–December) during the period of decreasing day length. In such species, the frequent rain and less photoperiod may signal the flowering. Dry-season flowering species such asTerminalia catappa, Dalbergias sissoo,Hardwickia binata,Leucaena leucocephala,Parkia biglandulosa,Lagersroemia indica,initiation of floweringoccur on twigs during cool dry season (December–March), soon after sporadic winter rains.

Characteristic tree species with large branches are nurtured and given preferences by the management to create picnic/play spaces for tourist. Routine weeding of the gardens ensured only desired trees are allowed to thrive while naturally regenerated seedlings are removed for easy human movement and excellent scenic view. This is in line with the report of Agarwalaet al.(2016) who asserted that tree species populations and regeneration is impacted by purpose and level of human use in India.

The present study recorded many man-made activities that are not favourable to conserve the available vegetation in the campus. Cutting of branches of trees, plastic bags and plastic bottle thrown around the vegetated area of the campus are supported the unpleasant anthropogenic activities. The following measures should be taken in the campus to maintain and enrich the biodiversity.

1. The pruning or cutting of branches should be avoided during the summer season. This promotes bird populations and insect diversity in the campus.
2. A green house should be constructed to maintain the tree saplings.
3. A separate model star garden is an immediate need of the hour.
4. Planting endemic and endangered trees should be given more importance.

Role of Gardens in Conservation

The present study reveals the District Science Centre is one of the most suitable areas to conserve important tree species. Presently the garden in DSC critically contributes to conservation of biodiversity.Tree conservation should include in all aspects of garden operations and activities.花园可以通过建立更多的协同工作ing or joining a hub of conservation action. The participation of non-traditional gardens in tree conservation and provides an exponential increase in the number of threatened trees protected. These gardens can collaborate with leading gardens by volunteering to grow threatened tree species. Empowering smaller gardens it is particularly important for the global garden community to build capacity for tree conservation in biodiversity (Nicoleet al., 2015).

Suggestions

The Distract Science Centre, Tirunelveli is known for its Science related programmes and training camps. The entire campus is planted with a variety of trees. It is a valuable asset. It provides space forpeople to engage in recreational activities. People from the local area regularly visit this centre, thus provides space to interact with each other and meet new people. It will be more informative, if more interpretation panels are setup at many locations给动植物的整个数据campus. This will able to produce awareness among the visitors towards the conservation of flora and fauna. In near future the entire campus to be converts into an ecological laboratory.

1. Still Campus area is not fully used for the garden making, so the entire campus should be utilized for the garden development.
2. Government should appoint gardener and a Botanist for maintenance of the garden.
3. Growing Gymnospermous trees give more attraction
4. Naming of trees give more exposure on medicinal plants to the students and visitors.

At present, diversity and number of plants in an ecosystem is degraded at an exponential rate. This reduction in the diversity of flora is directly associated decrease in ecosystem services (Gao Chen and Weibang, 2018). Recently, the increasing agricultural and forestry practices cause over-harvesting and over-exploitation of vegetation, rapid increasing urbanization, various serious environmental pollution, change in land use pattern, invasion of alien species, and world climate change due to the numerous anthropogenic activities, encompass tremendous pressure on vascular plants. This resulted in a third of the world's 300,000 - 450,000 vascular plant species face extinction (Pitman and Jørgensen, 2002; Ren and Duan, 2017).Hence, there is a greater need to widen integrative conservation approaches to conserve the rare and vulnerable plant species in the natural habitats (Li and Pritchard, 2009) and therefore our approaches on the plant conservation should be an integrative. Gardens in the scientific institutions offer their resources to the study and conservation of plants, as well as making the world's plant species diversity known to the public.

Acknowledgement

We thank everyone in the District Science Centre, Tirunelveli, who participated in the insightful discussions.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Conflict of Interest

The authors do not have any conflict of interest.

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