Current World Environment

Introduction

The Himalaya mountain region is one of the richest and most unusual ecosystems on Earth.¹Indian Himalayan region covers about an area of 4,19,873 Km.²The unique physiography, climatic conditions, and soil features of the area have resulted in a mixture of habitats and a substantial biological diversity. The Himalayan region affirmsapproximately 8000 plant species (47.06% of the total flowering plants of India) of which 30% are endemics among natives, 10.2% trees, 8.44% wild edibles, and over 15% medicinal. The dependence of human and livestock on this rich plant diversity is long-familiarphysical process since time immemorial.^{2, 3}The Tehri Dam is tallest dam in India. Tehri Dam provides common services such as food mitigation, water supply for agricultural crop cultivation, drinking water, electricity production, employment opportunity, recreational and tourisms facility in surrounding area. The utilization and subsequent changes in hydrological water body has a significantly influencing on river flow and their linked biotic and abiotic organisms. Dams are grant credentials to as having fairly large negative effects on the closely encircling natural ecosystems divesity.⁴In many developing countries tourism was act as revenue generate, employment opportunity to local people, improved living standards and sustainable livihood development with buildup good relationship between people and nature from conservation point of view.^5,6,7The global trade and tourism are key factors concerned with the ecological effects of altering the environment in developing regions.^8,9In the last decades tourisms has rapidly originated worldwide in mountain regions.^10,11The mountain tourisms in new emerging area had negative results on wetlands, protected areas and natural area indicated by previous examines concerned to recreation ecology.^12,13In past 25 years, Nepal has rapidly increased in tourism growth, the positive or negative effect of tourism ontogenesis on forest resource and alpine vegetation plant diversity has been well recorded.¹⁴

Human actions have significant determines on the dispersal of exotic plants.^15,16,17,18In Central Europe, an invasion has been often outcome of interaction between biological and anthropogenic factors.¹⁹Human interruptions enhance alien extend in general.²⁰They are determined that the parameters in a most excellent way to justify the density of alien plants were the human growth index and imports.²¹Some outcomes guided that numbers of individuals per unit area of human population and human action have crucial consequences on the plants invasions.^22,23Biological plant invasion have charming effect on ecologist due to their substantial ecological and economical importance from the conservation threat of plant diversity point of view worldwide.²⁴India is the 7^thlargest country and one of the mega-diversity countries on globe out of 17 most biodiversity-rich countries. With a various types of habitats and different environmental conditions, India is particularly susceptible to attack of invasive species of foreign origin. The sketch of invasive plants in India is now obligating immediate action in practice and also helpful for invasion plant ecology.

The biological invasion involving the entire earth threatens biodiversity, resource availability, ecosystem dynamics, and people health and country economy.²⁵The analyses of the apportioning of invasive alien species and the kinship with existing factors furnish the chances to explore the possible factors that lead to their spatial distribution at a prominent scale.^26,27However, seldom observe the spatial distribution analysis revolve about species with prominent consequence separately from those with miserable effects.^28,29的年代crimpy native diversity privileges to introduce invasion proposed by Elton’s.³⁰Some data-based and model based studies reports support that diversity decreased invisibility.^{31,32,33,34,35}调查在入侵物种的特性d the recipient spatial location is indispensable for recognizing the action of invasion.³⁶因此,数据点不足有关forestinvasivesis a subject of associate as this creats an off-key of complacency. Devoted research antecedence taken to be conceded to buildup detailed database in perspective of forest resources in the state and nation on scientific lines and to updating datum. If so, for this conclusion, periodical assemblage, Identification and collection of such species are needed, thus one can find out and could consider management options to prevent, or at least reduce the damaging effects of biological invasions. And this only can be possible if we have the proper knowledge about their presence in the area, thus need the base line data, and this could gather only through inventory. The objectives of the present study accomplish this research need and provide the basic information for further research in the same field.

Material and Methodology

The present investigation was accomplished in the District Tehri Garhwal of the Garhwal Himalayan region of Uttarakhand which lies at 30⁰55’ to 31⁰18’ N latitude and 78⁰to 79⁰25’ E longitude in Western Himalaya covering 36000 sq. km. The greatest extent of the region is 180 km N to S and 200 km E to W. The region is highly mountainous, ranging in altitude from 300-7000m, therefore by considering the diverse forms of the area the widely renowned TehriDam site was considered as a reference point and further study was carried out at different elevations. Specifically four different sites were marked based on their regional importance showed in Fig.1, i.e. site I (Jardhar VFE), known for its luxuriant forest area, and indigenous agricultural practices, site II (Dikhol VFE), became central hub for all the social activities, followed by site III (Kuttha VFE), this site became central point for the dam site seeing and tourism purposes and site IV (Saundkoti VFE) valuable natural site, as no any human induced pressure is assumed in this site.The concept of village forest exist in the study area, i.e., Tehri, from time immemorial as the forest were aligned to certain villages upto a certain radial distance to meet the bonafied needs and requirements of the village people. The geo-coordinates of each sites has been also recorded by using Global Positioning System (GPS) that are following:

Sites	Latitude (N)	Longitude (E)	Altitude ( m asl )
Site I	30020’ 23”	78020’ 05”	1650 m
Site II	30020’ 21”	78020’ 21”	1570 m
Site III	30023’ 16”	78027’ 23”	1220 m
Site IV	30020’ 26”	78025’ 02”	1630 m

Figure1: Study Sites Click here to View figure

Methodology

A List Of Weed/Exotic/ Invasives Of The Country

Before starting inventory for FIS in the site, secondary data was collected by preparing literature survey, list of weeds/ exotics/ invasives of the country have been prepared as per GIS database www.issg.org/global 2007,³⁷Negi and Hajra 2007,³⁸Reddy 2008,³⁹Biswas and Jain 2003,⁴⁰Sankaran and Sreenivasan 2001,⁴¹Plant Quarantine report and Plant Quarantine list.⁴²The data related to existing invasives of the sites was further gathered by critiquing the literature, research papers, working plan of the District, related flora of the site and explore the review of Biswas Sas 1985 and 1994,^43,44Bhattacharya and Goel 1982,⁴⁵Badoni and Bhatt 1993,⁴⁶Goel and Bhattacharya 1981,⁴⁷and Uniyalet. al.,1995.⁴⁸

Reconnaissance surveys of the areas were carried out for the occurrence ofForest Invasive species.Theavailable populations were studied using the random quadratemethod.⁴⁹The field layout of sample plots was indicated in fig.2 along with various size of quadrate A, B, C for trees, shrubs and herbs field data enumeration. The study was carried out by laying out 50 quadrates (Fig.2) on each site. Thus a total 200 sample plot was laid out in all four sites. The herbarium samplesalong with camera photographs of the various plant species were collected.

Figure 2: Filed Layout of Sample Plot Click here to View figure

The plant species found and recorded in the study sites were identified with the help of the available concerned site specific Floras, Forest flora of the Chakrata, Dehradun and Sahanpur Forest Divisions, Uttar Pradesh by Knajilal, U.P.⁵⁰and Flora of the District Garhwal Northwest Himalaya by Gaur, R.D.⁵¹etc.).Thoroughly identification of the material was done by consulting the material with authentic specimen sheets at, DD Herbarium of FRI, Botanical Survey of India, Northern Circle, Dehradun. Final checklist of the sitewas cross-checked with the list of Invasive Alien Species list of IUCN for the country for the recognition of the site specific Forest Invasive Species, resulting in the form of the FIS checklist.

Result

The plant diversity of Forest Invasive Species of all three life form (tree, shrub and herb) and the potential weed species which could become invasives in the study area is given in Table-I,II,III,IV;Fig. III & IV.

Seventy five (75) Forest Invasive Species (FIS) and forty seven (47) weed species which could become potential invasives were invantorized from the area (Table-III and IV). Among the 75 FIS, 12 species belonging from Asteraceae, 7 species from Poaceae, 7 species of Solanaceae, 5 species of Lamiaceae, followed by four species of each Ranunculaceae and Polygonaceae while the other belongs to Papilionaceae, Cyperacea, Euphorbiaceae and various other angiospermic families were recorded. Habitat analysis of FIS showed that highest percentage of plant diversity was herbs (81.33 %), shrubs (17.33%) and Tree species (1.34%). Whereas, plant diversity among the weed species observed in study sites was maximum belongs to angiospermic family Poaceae.

Data presented in Table I reveals the maximum diversity of invasives was recorded for site I (49 species), followed by site II (45 species), site III (41 species) and least invaded site was IV (27 species).

Table 1: Forest Invasive Species account of the study sites

Category	I (Jardhar)	II (Dikhol)	III (Kuttha)	IV (Saundkoti)
Invasive tree species	1	1	1	0
Invasive shrub species	11	6	6	6
Invasive herb species	37	38	34	21
Invasives total diversity (No. of species)	49.0	45.0	41.0	27.0

Figure 3: FSI Account of the Study Sites Click here to View figure

The maximum number of FIS belongs to family Asteraceae (16%), followed by Poaceae and Solanaceae (9% each), Lamiaceae (7%), Polygonaceae and Ranunculaceae (5%) whereas other angiospermic families constitute between (4 -1%) respective dominance irrespective to other recorded families as given in Table II.

Table 2: Dominating FIS families of the study area

Family	No of species	Dominance of family (%)	Family	No of species	Dominance of family (%)
Asteraceae	12	16.00	Brassicaceae	1	1.33
Solanaceae	7	9.33	Cannabinaceae	1	1.33
Poaceae	7	9.33	Caryophyllaceae	1	1.33
Lamiaceae	5	6.67	Chenopodiaceae	1	1.33
Polygonaceae	4	5.33	Cleomaceae	1	1.33
Ranunculaceae	4	5.33	Commelinaceae	1	1.33
莎草科	3	4.00	Crassulaceae	1	1.33
Euphorbiaceae	3	4.00	Cuscutaceae	1	1.33
Fabaceae	3	4.00	Fumariaceae	1	1.33
Rosaceae	3	4.00	Nyctaginaceae	1	1.33
Amaranthaceae	2	2.67	Tiliaceae	1	1.33
Apiaceae	2	2.67	Linaceae	1	1.33
Malvaceae	2	2.67	Papavaraceae	1	1.33
Oxalidaceae	2	2.67	Verbenaceae	1	1.33
Rubiaceae	2	2.67

Table 3: FIS diversity of the study area, Site 1 –Jardhar(I), Site 2 –Dikhol(II), Site 3 –Kuttha(III), Site 4-Saundkoti(IV)

S.No	Species	Family	I	II	III	IV	Habit
1	Achyranthes asperaL.	Amaranthaceae	+	+	+	+	H
2	Anaphalis busuaBuch.Ham ex D.Don DC	Asteraceae	+	_	+	_	H
3	Apludamutica, L.	Poaceae	+	+	+	-	H
4	Argemone mexicanaL.	Papavaraceae	+	+	+	+	H
5	Arundinella nepalensisTrinius	Poaceae	+	_	_	_	H
6	Ageratum conyzoidesL.	Asteraceae	_	+	+	+	H
7	Amaranthus spinosusL	Amaranthaceae	_	_	+	_	H
8	Blainvilleaa cmella(l)Philipson	Asteraceae	+	_	_	_	H
9	Bupleurum hamiltoniiBalakrishnan	Apiaceae	+	_	_	_	H
10	Biden spilosaL.	Asteraceae	-	+	+	+	H
11	Bistorta amplexicaulis(D.Don) Greene	Polygonaceae	_	+	_	_	H
12	Boerhavia diffusaL.	Nyctaginaceae	_	+	+	+	H
13	Clematis gourianaRoxb. ex DC.	Ranunculaceae	+	+	+	+	S
14	Clematis montanaBuch.-Ham. ex DC	Ranunculaceae	+	_	_	+	S
15	Cleome viscosaL.	Cleomaceae	+	_	_	+	H
16	Cuscuta reflexaRoxb	Cuscutaceae	+	_	_	_	H
17	Cymbopogon martinii(Roxb) W.Watson	Poaceae	+	_	_	_	H
18	Cynodon dactylonL. Persoon	Poaceae	+	+	+	+	H
19	Cyperus niveusRetz.	莎草科	+	_	_	_	H
20	Cannabis sativaL.	Cannabinaceae	_	+	_	_	H
21	Chenopodium albumL.	Chenopodiaceae	_	+	_	_	H
22	Commelina benghalensisL.	Commelinaceae	_	+	+	+	H
23	Datura metelL	Solanaceae	_	+	+	_	H
24	Delphinium denudatumWallich ex Hook.f. & Thomson	Ranunculaceae	+	_	_	_	H
25	Desmodium triflorum(l)DC	Fabaceae	_	_	+	_	H
26	Eupatorium glandulosumH.B.K.	Asteraceae	+	+	+	+	H
27	Euphorbia hirtaL.	Euphorbiaceae	+	+	+	+	H
28	Euphorbia royleanaBoissier.	Euphorbiaceae	+	+	+	_	T
29	Echinochloa colona(l)链接	Poaceae	+	+	_	_	H
30	Fimbristylis falcata(Vahl) Kunth	莎草科	+	_	_	_	H
31	Fumaria indica(Haussknecht) Pugsley	Fumariaceae	+	_	_	_	H
32	Gerbera gossypina(Royle)G. Beauv.	Asteraceae	+	_	_	+	H
33	Heteropogon contortusL. Beauv. ex Roemer & Schultes	Poaceae	+	+	_	_	H
34	Indigofera heteranthaWallich ex Brandis, SynI. gerardiana(Wallich ex Baker) Ali	Fabaceae	+	_	_	_	S
35	Koenigiadelicatula(Meisn.) Hara SynPolygonumdelicatulumMeisn	Polygonaceae	+	_	_	_	H
36	KyllingabrevifoliaRottboell	莎草科	_	_	+	_	H
37	Lantana camaraL.	Verbenaceae	+	+	+	+	S
38	Leucas lanataBenth	Lamiaceae	+	_	_	+	H
39	Micromeria biflora(Buch.-Ham.exD.Don) Benth	Lamiaceae	+	+	_	_	H
40	Nepeta gracilifloraBenth	Lamiaceae	+	_	_	_	H
41	Nicotiana plumbaginifoliaViviani	Solanaceae	_	_	+	_	H
42	OcimumbasilicumL.	Lamiaceae	+	+	_	_	H
43	Oxalis corniculataL.	Oxalidaceae	_	+	+	+	H
44	Oxalis dehradunensisRaizada	Oxalidaceae	_	+	+	+	H
45	Origanum vulgareL.	Lamiaceae	_	_	+	_	H
46	Parthenium hysterophorusL.	Asteraceae	+	+	+	+	H
47	Pavetta indica L.	Rubiaceae	+	+	_	_	S
48	Physalis peruvianaL.	Solanaceae	+	+	_	_	H
49	Polygonum plebeiumR.Br.	Polygonaceae	_	+	+	_	H
50	Reinwardtia indicaDumortier	Linaceae	+	+	+	+	H
51	Rosa brunoniiLindley	Rosaceae	+	+	+	+	S
52	Rubia cordifoliaL.	Rubiaceae	+	+	+	+	H
53	Rubus ellipticusSmith.	Rosaceae	+	+	+	+	S
54	Rubus niveusThunb.	Rosaceae	+	_	_	_	S
55	Rumex hastatusD.Don	Polygonaceae	+	+	+	+	H
56	Ranunculus sceleratusL.	Ranunculaceae	_	+	_	_	H
57	Ricinus communisL	Euphorbiaceae	_	+	+	_	S
58	Rorippa indica(l)Hiern	Brassicaceae	_	+	+	_	H
59	Saccharum spontaneumL.	Poaceae	+	+	+	_	H
60	Sedum multicauleWallich ex Lindley	Crassulaceae	+	_	+	_	H
61	Senecio nudicaulisBuch.-Ham.exD.Don	Asteraceae	+	_	+	+	H
62	Solanum anguiviLam	Solanaceae	+	_	_	_	S
63	Solanum nigrumL.	Solanaceae	+	+	+	+	H
64	Solanum verbascifoliumauct.pl.	Solanaceae	+	_	_	_	S
65	SonchusolearecusL	Asteraceae	+	+	+	+	H
66	SelinumcandolliiDC	Apiaceae	_	+	_	_	H
67	Sida rhombifoliaL.	Malvaceae	_	+	+	_	H
68	Solanum surattenseBurm.f. SynS.xanthocarpum,Schrader &Wendland	Solanaceae	_	+	_	_	H
69	Stellaria media(l)Villars	Caryophyllaceae	_	+	+	_	H
70	Syndrellaspp.		_	+	+	_	H
71	Tridax procumbensL.	Asteraceae	+	+	+	_	H
72	Triumfettar homboideaJacquin	Tiliaceae	+	_	_	_	H
73	Trifolium repensL.	Fabaceae	_	+	_	_	H
74	Urenal obataL.	Malvaceae	+	_	_	_	S
75	Xanthium strumariumL	Asteraceae	_	+	+	+	S

(+)Present; (-) Absent


Table 4: Check list of weedy species of the study area

S.No.	Species	Family	Habit
1	Agave wightii,Drummond&Prain	Agavaceae	S
2	Ajuga bracteosa,Wallich ex Benth	Lamiaceae	H
3	Alloteropsis cimcina(l)Stapf	Poaceae	H
4	Amaranthusspp.	Amaranthaceae	H
5	Anagallis arvensis, L.	Primulaceae	H
6	Androsace lanuginose, Wall	Primulaceae	H
7	Androsace umbellate(Lour.) Merrill	Primulaceae	H
8	Apluda mutica, L.	Poaceae	H
9	Avena sativaL.	Poaceae	H
10	Barleria cristataL.	Acanthaceae	H
11	Chenopodium album,L.	Chenopodiaceae	H
12	Chenopodium ambrosiodes,L.	Chenopodiaceae	H
13	Cichorium intybus, L.	Asteraceae	H
14	Commelina benghalensis,L.	Commelinaceae	H
15	Crotalaria prostrate, Rottler ex Willd	Papilionaceae	H
16	Cynoglossum zeylanicum(VahlexnbHornem) Thunb.ex Lehmann	Boraginaceae	H
17	Cyperus rotundus	Poaceae	H
18	Desmodium triflorum(l)DC	Papilionaceae	H
19	Diclipteraspp.	Acanthaceae	H
20	Digitaria sanguinalis(l)Scop	Poaceae	H
21	Drymaria cordata(l)Willd	Caryophyllaceeae	H
22	Eragrostisspp.	Poaceae	H
23	Euphorbia hypericifolia, L	Euphorbiaceae	H
24	Fimbristylis falcate(Vahl) Kunth	莎草科	H
25	Fumariaindica,(Haussknecht) Pugsley	Fumariaceae	H
26	Galinsoga ciliate(Raf.Schm.)Blake	Asteraceae	H
27	Geranium nepalense, Sweet	Geraniaceae	H
28	Hedyotis corymbosa(l.) Lam	Rubiaceae	H
29	Kyllingaspp.	莎草科	H
30	Lathyrus sativus,L.	Papilionaceae	CS
31	Leucas lanata,Benth	Lamiaceae	H
32	Micromeria bifloraBuch.-Ham.ex D Don. Benth	Lamiaceae	H
33	Nepeta graciliflora, Benth	Lamiaceae	H
34	Oplismenus compositus(l)P.Beauv	Poaceae	H
35	Peristrophe speciosa(Roxb) Nees	Acanthaceae	S
36	Pogonantherumspp.	Poaceae	H
37	Polygala chinensis, L.	Polygonaceae	H
38	Rumex hastatus,D.Don	Polygonaceae	H
39	Rungia parviflora, Nees	Acanthaceae	H
40	Setaria gluca(l)P.Beauv	Poaceae
41	Sileneconoidea,L.	Caryophyllaceae	H
42	Sporobolus diander(Retz) P. Beauv	Poaceae	H
43	Stellaria media(l)Villars	Caryophyllaceeae	H
44	Torenia cordifolia, Roxb.	Scrophulariaceae	H
45	Triumfetta annua, L.	Tiliaceae	H
46	Trium fettapilosa,Roth	Tiliaceae	S
47	Vernonia cinerea(l)Lessing	Asteraceae	H
	*H-Herb, S-Shrub

Figure 4: Dominant Weedy Species faimly of the Study Area Click here to View figure

Discussion

目前研究背景下坝址是缺点idered as a reference point, and this have been widely observed that disturbed habitats are more prone to invasion. The present study observed that the cumulative effects of dam construction activities resulted in greater amount of invasion in nearby areas, whether it is forest, agriculture, wasteland, and village common land etc.Similar study was carried out in Arizona, Colorado and eastern Oregon arid area, the permanent water availability has promote the growth invasion of exotic species such as Tamarix that flourish in such considerations.^52,53,54The inventorization carried out for the area, resulted that the forest ecosystem of four villages have similar native species in floristic composition except for dominant species while a single invasive,Euphorbia royleanais reported from the tree layer of the ecosystem. Site IV (Saundkoti village forest ecosystem) is free from this invasive because less anthropogenic disturbance in site like very few people in village carried out agriculture practices and an area is rich in native species diversity.

Level of invasion varies in all the sites, maximum invasion proportion in tree layer is reported in site II (Dikhol VFE) followed by site III (Kuttha VFE), and then site I (Jardhar VFE) (table I). In site I (Jardhar VFE), the less invasion may be due to higher diversity of native species,invasives though present but could not get accommodated or spread their area of occupancy, thus proportion of invasion is least among all three invaded sites II (Dikhol), III (Kutta), I (Jardhar) (Fig I). Our finding agree with the protocol designed to distinguish between species that induce higher, medium, lower, or undistinguished negative affect to indigenous biodiversity within the region, state or nation of interest.⁵⁵

While disturbance in site II attributed for developing empty niche which in turn promoted invasion in the area. Similar problem is also attributed in site III, where habitat disturbance is very high due to the close vicinity of Tehri Hydroelectric dam. Another important reason of invasion is the association ofPinus roxburghiiin all the affected sites, as it is associated with the acidity in soil, where invasives likeEuphorbia royleanacan flourish⁵⁶and the present study reveals that site III (Kuttha) is Pinus dominated might be create a favorable condition to growth of invasive species and hence, proportion of invasion this site is maximum in comparison to the other study sites.

ThoughPinus roxburghiiis also reported in site IV (Saundkoti), but as per field observations this place is situated at higher elevation and far from the reference point as a disturbing factor, dominated byQuercus leucotrichophora, Rhododendron arboreum,andCedrus deodara,which likely to be assumed for prohibition of the growth ofEuphorbia royleanain the forest.

The invaded environment was providing desirable condition to invasion of species from outset, that likewise, the invasive species has the potentiality of obtruding upon that environment without any intrinsic ecological or evolutionary changes being necessitated.Therefore, wherever space is found to be free from the natives,invasives encroached those as revealed from the study and also supported by the Empty niche hypothesis proposed by Elton.⁵⁷

Site II and III are equally affected by invasion of shrubaceous flora indicating a high disturbances level and invasion proportion. Both the phenomena are related to each other thus supporting the theory that more disturbances will promote more invasions. Invasion by herbaceous invasive species was almost equal in all the sites as the herbs establish easily irrespective of shrub or tree species and their seedlings. And this is also proven by the inventory that maximum numbers of invasive are from herbs.

In a number of cases, intense biotic interference (as in Dikhol, Saundkoti and Kuttha forest) does not permit the native scrub vegetation to progress any further whereas invasive herbs and few of shrubs by virtue of their specific traits gradually make thickets in these threatened areas.Another result of the biotic interference is the occurrences of blank covers over large areas, which eventually become the home of invasive shrubs, annual and perennial herbs.

Studies reveal that Asteraceae was the higher number (12) of species than other families thus it is most dominant family in study area. It is due to the fact that the members of the family are best equipped to the study area, possess best traits among all. The family is followed by invasives belonging to Poaceae and Solanaceae. The representative of the families are of herbaceous life form having short life cycle, few are perennials, thus possessing better opportunities for their survival and better growth and thus encroach the area without any natural hindrance.⁵⁸Kumariet alalso carried out study on a preliminary survey of invasive alien angiosperms of Rohilkhand region (U.P), India, revealed that maximum species (21) was from the family Asteraceae, Amaranthaceous (7), Euphorbiaceae (5), Papilionaceae (4) and Caesalpiniaceae (4) respectively.⁵⁶This conclude that the heightening a number of invasive alien species increased with disturbance and may affect the native diversity threat. This study will help in carrying out further research work on it; and also helpful support to ecologist, agriculturist, forest and concerned stack holder to understand the pattern of distribution of plant in area. Assist as conservation of natural resources against step-down of quality and quantity of resources.

Acknowledgements

The authors are grateful to Forest Research Institute authorities for providing necessary facilities. The First author (Arti Khanduri) thankful to all the Tehri Village people and her classmates for support during field study.

References

1. Salick, J., Zhendong, F. and Byg, A. Eastern Himalayan alpine plant ecology, Tibetan ethnobotany, and climate change,Global Environmental Change,19(2): 147–155 (2009)
   CrossRef
2. Dhar, U., Rawal, R. S. and Samant, S. S. Structural diversity and representativeness of forest vegetation in a protected area of Kumaun Himalaya, India: implications for conservation,Biodiversity & Conservation,6(8): 1045–1062 (1997)
   CrossRef
3. Rawat V.S. and Chandra, J. Vegetational Diversity Analysis across Different Habitats in Garhwal Himalaya,JournalofBotany, Vol.2014(Article ID 538242): 5 (2014)
4. New, T and Xie, Z. Impacts of large dams on riparian vegetation: applying global experience to the case of China’s Three Gorges Dam,BiodiversConserv,17:3149–3163 (2008)
   CrossRef
5. WTO (World Tourism Organization). Tourism's potential as a sustainable development Madrid: World Tourism Organization (2005)
6. Gurung, C.P, DeCoursey, M.A., Too much too fast: lessons from Nepal's Lost Kingdom of Mustang. In: Godde PM, Price MF, Zimmermann FM, editors. Tourism and development in mountain regions. Wallingford: CABI Publishing, p. 239–54 (2000)
7. ^aBrohman,旅游的新方向for third world development. Ann Tour Res,23: 48–70 (1996)
   CrossRef
8. ^bBrohman,旅游的新方向for third world development. Ann Tour Res,23: 48–70 (1996)
   CrossRef
9. Hulme, P.E. Trade, transport and travel: managing invasive species pathways in an era of globalization. J.Appl.Ecol.46:10-18 (2009)
   CrossRef
10. 苔藓,L,女神,点战略为未来的山tourism. In: Godde PM, Price MF, Zimmermann FM, editors. Tourism and development in mountain regions. Wallingford: CABI Publishing, p. 323–38 (2000)
11. Price, M.F. Patterns of the development of tourism in mountain environments.Geo Journal,27:87–96 (1992)
    CrossRef
12. Stevens, S. Tourism and deforestation in the Mt Everest region of Nepal. Geogr J,169: 255–7 (2003)
    CrossRef
13. Buntaine, M.T., Mullen, R.B., and Lassoie, J.P. Human use and conservation planning in Alpine areas of Northwestern Yunnan, China. Environ Dev Sustain,9:305–24 (2006)
    CrossRef
14. Stevens,. S. Tourism and Deforestation in the Mt. Everest Region ofNepal.TheGeographicalJournal,169(3): 255-277 (2003)
15. Elton, C.S .The Ecology of Invasions by Animals and Plants. Methuen, London (1958)
    CrossRef
16. Burke, M.J.W. and Grime, P. An experimental study of plant community invasibility. Ecology,77: 776–790 (1996)
    CrossRef
17. Mack, M.C. &D’Antonio, C.M.. Impacts of biological invasions on disturbance regimes.Trends in Ecology and Evolution,13: 195–198 (1998)
    CrossRef
18. Sax, D. F., Gaines, S. D., and Brown, J. H. Species invasions exceed extinctions on islands worldwide: a comparative study of plants and birds.AmericanNaturalist160: 766–783 (2002)
19. Kowarik, I. Human agency in biological invasions: secondary releases foster naturalization and population expansion of alien plant species.BiologicalInvasions,5: 293–312 (2003)
    CrossRef
20. Rodgers, J.C. & Parker, K.C. Distribution of alien plant species in relation to human disturbance on the Georgia Sea Islands.DiversityandDistributions,9: 385–398 (2003)
    CrossRef
21. Vila, M. & Pujadas, J. Land use and socio economic correlates of plant invasions in European and North African countries.BiologicalConservation,100: 397–401 (2001)
    CrossRef
22. Pyiek, P., Kopecky, M., Jaroiik, V. &Kotkova, P. The role of human density and climate in the spread of Heracleummantegazzianum in the Central European landscape. Diversity and Distributions,4: 9–16 (1998)
23. Myers, J. and Bazely, D. Ecology and control of introduced plants. Cambridge University Press, Cambridge (2003)
    CrossRef
24. Reichard, S.H., and White, .P. Invasion biology: an emerging field of study.Ann Mo Bot Gard,90:64–66 (2003)
    CrossRef
25. Ricciardi, A., Steiner, WWM., Mack, R.N. and Simerloff, .D. Towards a global information system for invasive species.Bioscience50(3): 239–244 (2000)
26. Whittaker, R.H. Species diversity in land communities.EvolutionaryBiology,10: 1–67 (1977)
27. ^aDark, S.J. The biogeography of invasive alien plants in California: an application of GIS and spatial regression analysis.DiversityandDistributions,10:1–9 (2004)
    CrossRef
28. Levine, J. &D’Antonio, C.M. Elton revisited: a review of evidence linking diversity and invasibility. Oikos,87:15–26 (1999)
    CrossRef
29. ^bDark, S.J. The biogeography of invasive alien plants in California: an application of GIS and spatial regression analysis.DiversityandDistributions,10:1–9 (2004)
    CrossRef
30. Elton, C.S. The ecology of invasions by animals and plants, 2nd edn.Methuen, London (1958)
    CrossRef
31. Levine, J.M. Species diversity and biological invasions: relating local process to community pattern.Science,288: 852–854 (2000)
    CrossRef
32. Naeem, S., Knops, J.M.H., Tilman, D., Howe, K.M., Kennedy, T. & Gale, S. Plant diversity increases resistance to invasion in the absence of covarying extrinsic factors. Oikos,91: 97 - 108 (2000)
    CrossRef
33. Hector, A., Dobson, K., Minns, A., Bazeley-White, E. and Lawton, J.H. Community diversity and invasion resistance: an experimental test in a grassland ecosystem and a review of comparable studies. Ecological Research,16: 819–831 (2001)
    CrossRef
34. Kennedy, T.A., Naeem, S., Howe, K.M., Knops, J.M.H., Tilman, D. and Reich, P. Biodiversity as a barrier to ecological invasion.Nature, 417: 636–638 (2002)
    CrossRef
35. Van Ruijven, J., de Deyn, G.B. &Berendse, F. Diversity reduces invasibility in experimental plant communities: the role of plant species.EcologyLetters,6: 910–918 (2003)
    CrossRef
36. Vermeij, G. An agenda for invasion biology.BiologicalConservation,78: 3–9 (1996)
    CrossRef
37. GIS database (2007) .The Invasive Species Specialist Group (ISSG) .Online searchable database www.issg.org/global 2007.
38. Negi, P.S. and Hajra, P.K. Alien flora of Doon Valley, North-west Himalaya.Current Science,92(7): 968-978 (2007)
39. Reddy, S. Catalogue of invasive alien flora of India.Life science Journal,5(2):84-89 (2008)
40. Biswas Sas。耆那教徒,党卫军侵入性外来species of India and biodiversity conservation: In:National workshop on Invasive Alien Speciesorganized by Banaras Hindu University, 18-20 August 2004 (2004)
41. Sankaran, K.V. and Sreenivasan., M.A. Status of Mikania infestation in the Western Ghats. In: Proceedings of Workshop on Alien weeds in moist tropical zones: Banes and Benefits. KFRI, India,CABIBiosciene, U.K., pp. 67-76 (2001)
42. Ministry of Agriculture, The Gazette of India, Extraordinary Part-ii-Section 3-Sub-Section (ii) New Delhi 2003. Retrieve from: http://dbtbiosafety.nic.in/act/Plant% 20 Quarantine % 20_order_ 2003.pdf
43. Biswas, Sas. Studies on the forest flora of TehriGarhwal, U.P. Introduction, plant exploration andIndian J. Forestry,8(3):199-204 (1985)
44. Biswas, Sas. Potential economic forest produces of TehriGarhwal Himalaya (U.P) with reference to the systematic studies.Higher Plants of Indian Subcontinent.3: 281-287, (1994)
45. Bhattacharya, U.C. and Goel, A.K. Studies on the Vegetation of Tehri Dam and Some Rare Plants in Garhwal Himalayas.Botanical Survey of India. Howrah. pp.1-38 (1982)
46. Badoni, A.K. and Bhatt, B.P. Addition to the Pteridophytic flora of Tehri District in GarhwalHimalya.Higher Plants of Indian Subcontinent,4: 235-242 (1993)
47. Goel, A.K. and Bhattacharya, U.C. Contribution to the Pteridophytic Flora of Tehri District (Garhwal)Indian J. For.,4:30-37 (1981)
48. Uniyal, B.P., Singh, S. and Singh, D.K.Plant Diversity in the Tehri Dam Submersible Area.BotanicalSurveyofIndia, Govt. India (1995)
49. Mishra, R. Ecology Work Book. Oxford and IBS Publishing Company, Calcutta (1968)
50. Kanjilal, .U.N. Forest Flora of the Chakrata, Dehradun and Saharnpur forest divisions, Uttar Pradesh. 3rd ed. Delhi: Manager of publications, Government of India Press (1928)
51. Gaur, R.D. Flora of the District Garhwal North West Himalaya, Transmedia: Srinagar Garhwal, India (1999)
52. Friedman, J.M, Osterkamp, W.R, Scott, M.L, Auble, G.T. Downstream eVects of dams on channel geomorphology and bottomland vegetation: regional patterns in the Great Plains. Wetlands 18:619–633 (1998)
    CrossRef
53. Stromberg, J.C., Beauchamp, V.D., Dixon, M.D., Lite, S.J., and Paradzick, C. Importance of low-Xow and high- Xow characteristics to restoration of riparian vegetation along rivers in arid south-western United States. Freshw Biol,52:651–679(2007) doi:10.1111/j.1365-2427.2006.01713.x
    CrossRef
54. Nagler, P.L, Glenn, E.P, Hinojosa-Huerta, O., Zamora, F., Howard, K., Riparian vegetation dynamics and evapotranspiration in the riparian corridor in the delta of the Colorado River, Mexico.J Environ Manage, 41(3):322–335 (2008)
    CrossRef
55. Randall, J.M., Morse, L.E., Benton, N., Hiebert, R., Lu, S. and Killeffer, T. The Invasive Species Assessment Protocol: A Tool for Creating Regional and National Lists of Invasive Nonnative Plants that Negatively Impact Biodiversity,Invasive Plant Science and Management, 1:36–49 (2008)
    CrossRef
56. 在热带森林ecosyste Banerjee, a . k .灌木m example from India. In:World Bank Technical Paper Number 103.The World Bank, Washington, DC, U.S.A (1989)
57. Elton, C.S. The ecology of invasions by animals and plants, 2nd edn.Methuen, London (1958)
    CrossRef
58. Kumari, B., Singh, S.P., Singh, A.P., Kumar, R. and Verma, S. A preliminary survey of invasive alien angiosperms of Rohilkhand region (U.P.), India.Plant Archive, 16 (1): 45-50 (2016)