The tropical and subtropical forest ecosystems are often referred to have high species diversity that provides a variety of benefits to the local communities which help to endure the maintenance and their livelihood. However, many of these forests are under excessive anthropogenic pressure and necessitate proper management activities to maintain overall biodiversity, productivity, and sustainability. Globally, concerns are raised over the rapid loss of biodiversity in all its forms and at all levels.
Invasive species are considered as the second major threat to the loss of species diversity worldwide (Vitousek
The study of floristic diversity acts as a baseline for the exploration, management, and conservation of the biodiversity of an area and also monitors changes with time (Stork & Samways, 1995). Consequently, the life form spectrum reflects the prevailing ecological conditions (Badshah
The invasive plant species are seen to impact the forest biodiversity by influencing the richness and diversity of native species (Wilcove
Morni Hills constitute the offshoots of the Shiwalik Hills range of the north-western Himalayas and one of the affluent reservoirs of plant diversity in Haryana. In the last few decades, the upsurge of tourism leading to development as well as anthropic disturbances have resulted in the introduction and spread of invasive alien plant species in these forests. Thus, the present study was carried out to understand the biological spectrum, phenology, and the pattern of species diversity of invasive alien plants growing in the forests of Morni Hills, Panchkula. This would be helpful to understand the ecology of these forests more righteously to conserve their integrity which is at risk due to the spread of invasive plant species.
Morni Hills lie in the Panchkula district of Haryana, India (Figure 1) and are a part of the lower Shiwalik range – the outer Himalayas with the highest peak elevation of 1220 m AMSL. They are composed of alluvial detritus obtained from subaerial mountain waste (Wadia, 1961) and harbor the tropical dry deciduous forests. The formation of the Shiwalik Hills occurred by the accretion of molasses depositions in the Himalayan foreland basin and late deformation via tectonic events (Lavé & Avouac, 2000; Kothyari
Vegetation analysis was done by setting 15 plots with five quadrats (10 × 10 m) within each plot selected randomly in each of the 4 altitudinal ranges (Range 1 – 400 to 600 m, Range 2 – 600 to 800 m, Range 3 – 800 to 1000 m and Range 4 – >1000 m AMSL). Thus, a total of 60 plots with 300 quadrats were studied and the vegetational data was collected to analyze the frequency, density, and basal area (Misra, 1968). After that, relative values of the above parameters and the IVI value was calculated following Phillips (1959) and Curtis (1959), respectively. Other than this, diversity indices such as the Shannon-Wiener Diversity Index (Shannon & Wiener, 1963) and Simpson’s Index of dominance (Simpson, 1949) were also calculated for the four altitudinal ranges. During vegetation sampling, thorough observations were made on ecological traits like habit, flowering time, and life forms for all the species as per Raunkiaer (1934).
A total of 31 invasive plant species (1 tree, 4 shrubs, 25 herbs, and 1 climber) belonging to 16 families have been recorded from the present study site (Table 1). The life form pattern distribution showed that 81% of the plant species were herbs, followed by 13% shrubs and 3% of trees and climbers both. As per the longevity of the plants, 64.5% of the plant species were annuals while 35.4% were perennials. Furthermore, the encountered plant species predominantly belonged to American origin; only a few plant species were of African and European origin. The floristic analysis revealed that the dominant life form was therophytes (22) followed by phanerophytes (5), hemicryptophytes (2), chamaephytes (1), and geophytes (1). The species distribution across 16 families was found to be disproportionate as half of the species belong to 5 families, whilst the remaining half were represented by 11 families with single species only (Figure 4). Asteraceae was found to be dominant among the invasive plant species on the present site, followed by Malvaceae, Convolvulaceae, Euphorbiaceae, and others. The study of invasive flora also showed a significant variation in flowering phenology as shown in Table 1. Of the total invasive flora encountered during the study, 8 plant species were found to flower throughout the year while others were blooming at different periods. A hierarchical cluster analysis was also performed on the flowering phenology of the invasive plants and a dendrogram was prepared using R Studio with the package ‘‘Complex Heatmap’’ as shown in Figure 5. During the phytosociological study, it was detected that some plant species were persistent in all the four altitudinal ranges, i.e.,
Summary of invasive alien plant species encountered during the study.
S.N. | Name | Family | Habit | Nativity | Longevity | Flowering |
---|---|---|---|---|---|---|
1 | Herb | Tropical America | Annual | Dec-May | ||
2 | Tropical America | Annual | May-Nov | |||
3 | Amaranthaceae | Herb | Tropical America | Perennial | Mar-Oct | |
4 | Papaveraceae | Herb | Tropical south |
Annual | Jan-Dec | |
5 | Herb | Tropical America | Annual | Jan-Dec | ||
6 | Herb | Tropical America | Annual | Mar-Sept | ||
7 | Shrub | Tropical south |
Annual | Jan-Dec | ||
8 | Asclepiadaceae | Shrub | Tropical Africa | Perennial | Jan-Dec | |
9 | Amaranthaceae | Herb | Tropical Africa | Annual | Sept-Jan | |
10 | Herb | Tropical America | Perennial | Dec-Mar | ||
11 | Herb | Europe | Annual | Mar-Aug | ||
12 | Euphorbiaceae | Herb | Temperate south America | Annual | Jan-Dec | |
13 | Herb | Tropical south |
Annual | Jun-Sept | ||
14 | Herb | Tropical America | Annual | Jul-Oct | ||
15 | Euphorbiaceae | Herb | Tropical America | Annual | Sept-Mar | |
16 | Paplionaceae | Herb | Tropical Africa | Perennial | May-Oct | |
17 | Shrub | Tropical America | Perennial | Jan-Dec | ||
18 | Climber | Tropical America | Annual | Jun-Oct | ||
19 | Verbenaceae | Herb | Tropical America | Perennial | Jan-Dec | |
20 | Lamiaceae | Herb | Tropical America | Annual | Sept-Nov | |
21 | Tree | Tropical America | Perennial | Apr-Jul | ||
22 | Malvaceae | Herb | Tropical America | Annual | Oct-Apr | |
23 | Pedaliaceae | Herb | Tropical America | Annual | Jul-Oct | |
24 | Oxalidaceae | Herb | Europe | Perennial | Feb-Oct | |
25 | Asteraceae | Herb | Tropical north |
Annual | Oct-Mar | |
26 | Acanthaceae | Herb | Tropical Africa | Perennial | Sept-Jan | |
27 | Malvaceae | Herb | Tropical America | Perennial | Sept-May | |
28 | Asteraceae | Herb | Mediterranean | Annual | Mar-Nov | |
29 | Asteraceae | Herb | Tropical central |
Annual | Jan-Dec | |
30 | Malvaceae | Shrub | Tropical America | Perennial | Feb-Oct | |
31 | Asteraceae | Herb | Tropical America | Annual | Aug-Sept |
Apart from this, the floristic composition of the invasive plant species was seen to be changing along with the altitude (Table 2–5). As the altitude increases in the four ranges, the diversity of the invasive plant species varied. The value of the Shannon-Wiener Diversity Index increased first from Range 1 to Range 2 and then it further decreased in the subsequent ranges i.e., Range 3 and Range 4 (H’ – 3.5331<3.6605>3.1186>2.9162). Other than this, species dominance calculated by Simpson’s Index first decreased from Range 1 to Range 2 and then increased for the upper altitudinal ranges i.e., Range 3 and Range 4 (Cd – 0.26108>0.2483<0.3275<0.4019).
Phytosociology of invasive plant species encountered from 400–600m AMSL (Range 1).
S.N. | NAME | F | D | BA | IVI | H’ | Cd |
---|---|---|---|---|---|---|---|
1 | 33.3 | 32.32 | 0.00394 | 10.1166 | 0.15448 | 0.00115 | |
2 | 8.3 | 4 | 0.00046 | 2.07456 | 0.04168 | 0.00004 | |
3 | 16.6 | 12.32 | 0.04708 | 5.81129 | 0.10980 | 0.00045 | |
4 | 8.3 | 2.64 | 0.00022 | 1.92299 | 0.03721 | 0.00004 | |
5 | 16.6 | 68.32 | 0.00355 | 10.6636 | 0.20085 | 0.00127 | |
6 | 25 | 12.32 | 0.00019 | 6.24665 | 0.09767 | 0.00043 | |
7 | 16.6 | 8.32 | 0.00113 | 4.18879 | 0.07271 | 0.00019 | |
8 | 16.6 | 39.32 | 0.00053 | 7.48600 | 0.14396 | 0.00062 | |
9 | 16.6 | 13 | 0.01592 | 5.07357 | 0.09351 | 0.00031 | |
10 | 83.3 | 102.64 | 2.51676 | 92.8332 | 0.66177 | 0.16358 | |
11 | 33.3 | 3.32 | 0.53093 | 20.7231 | 0.31077 | 0.00796 | |
12 | 16.6 | 23.64 | 0.00513 | 5.92999 | 0.11234 | 0.00040 | |
13 | 25 | 51.32 | 0.00046 | 10.4214 | 0.17827 | 0.00121 | |
14 | 91.6 | 366.32 | 0.69915 | 75.3754 | 0.61101 | 0.07856 | |
15 | 25 | 34 | 0.00392 | 8.66049 | 0.14647 | 0.00084 | |
16 | 25 | 9 | 0.00415 | 5.99485 | 0.09214 | 0.00040 | |
17 | 16.6 | 105 | 0.00162 | 14.5332 | 0.26031 | 0.00236 | |
18 | 8.3 | 2.32 | 0.00044 | 1.89451 | 0.03636 | 0.00004 | |
19 | 25 | 45.64 | 0.0095 | 10.0495 | 0.17178 | 0.00115 | |
Total | 507.6 | 935.76 | 3.84508 | 300 | 3.53318 | 0.26108 |
Abbreviations: F = Frequency (%); D = Density (individuals/hectare); BA = Basal Area (m2/hectare); IVI = Important value index; H’ = Shannon-Wiener Index; Cd = Simpson’s Index.
Phytosociology of invasive plant species encountered from 600–800m AMSL (Range 2).
S.N. | NAME | F | D | BA | IVI | H’ | Cd |
---|---|---|---|---|---|---|---|
1 | 66.6 | 84.32 | 0.0103 | 17.4961 | 0.24433 | 0.00344 | |
2 | 58.3 | 76.32 | 0.00691 | 15.5278 | 0.22705 | 0.00270 | |
3 | 16.6 | 5.32 | 0.00006 | 2.80783 | 0.05174 | 0.00008 | |
4 | 41.6 | 49 | 0.00533 | 10.5581 | 0.17147 | 0.00125 | |
5 | 8.3 | 5.32 | 0.00028 | 1.66458 | 0.03779 | 0.00003 | |
6 | 16.6 | 10.64 | 0.00029 | 3.32528 | 0.06539 | 0.00012 | |
7 | 16.6 | 12 | 0.00099 | 3.46679 | 0.06900 | 0.00013 | |
8 | 16.6 | 9.32 | 0.01143 | 3.35802 | 0.06623 | 0.00013 | |
9 | 16.6 | 1.32 | 0.00008 | 2.42154 | 0.04096 | 0.00006 | |
10 | 25 | 5.64 | 0.00006 | 3.99897 | 0.06541 | 0.00017 | |
11 | 25 | 3.32 | 1.6503 | 27.5216 | 0.41079 | 0.01570 | |
12 | 100 | 189.64 | 4.8336 | 101.695 | 0.68362 | 0.19388 | |
13 | 50 | 23 | 0.3643 | 14.3711 | 0.22116 | 0.00314 | |
14 | 41.6 | 60 | 0.00261 | 11.5820 | 0.18894 | 0.0015 | |
15 | 41.6 | 112.64 | 0.00084 | 16.6439 | 0.26548 | 0.00309 | |
16 | 91.6 | 312 | 0.05954 | 43.6618 | 0.47971 | 0.02166 | |
17 | 16.6 | 6.64 | 0.00011 | 2.93612 | 0.05520 | 0.00009 | |
18 | 25 | 53 | 0.00075 | 8.58599 | 0.16250 | 0.00082 | |
19 | 16.6 | 5.32 | 0.00076 | 2.81790 | 0.05201 | 0.00008 | |
20 | 16.6 | 7.64 | 0.00038 | 3.03665 | 0.05788 | 0.00010 | |
21 | 16.6 | 2.32 | 0.00036 | 2.52221 | 0.04383 | 0.00007 | |
Total | 724 | 1034.72 | 6.94928 | 300 | 3.66058 | 0.24832 |
Abbreviations: F = Frequency (%); D = Density (individuals/hectare); BA = Basal Area (m2/hectare); IVI = Important value index; H’ = Shannon-Wiener Index; Cd = Simpson’s Index.
Phytosociology of invasive plant species encountered from 800–1000m AMSL (Range 3).
S.N. | NAME | F | D | BA | IVI | H’ | Cd |
---|---|---|---|---|---|---|---|
1 | 16 | 13 | 0.00078 | 6.09844 | 0.10686 | 0.00041 | |
2 | 16 | 51.64 | 0.00145 | 12.3487 | 0.22044 | 0.00171 | |
3 | 16 | 10.64 | 0.00072 | 5.71551 | 0.09853 | 0.00036 | |
4 | 16 | 2.32 | 0.21657 | 15.2191 | 0.26305 | 0.00442 | |
5 | 16 | 89.32 | 0.00678 | 18.6790 | 0.30901 | 0.00396 | |
6 | 25 | 15 | 0.00093 | 8.65901 | 0.13139 | 0.00084 | |
7 | 16 | 16 | 0.04195 | 8.64880 | 0.15758 | 0.00103 | |
8 | 83 | 73.64 | 1.70715 | 118.181 | 0.67004 | 0.26830 | |
9 | 33 | 20.32 | 0.00103 | 11.5036 | 0.16115 | 0.00148 | |
10 | 75 | 240.32 | 0.00528 | 57.5282 | 0.53101 | 0.03706 | |
11 | 83 | 82.32 | 0.00806 | 34.2300 | 0.34643 | 0.01321 | |
12 | 8.3 | 7 | 0.00008 | 3.18831 | 0.06541 | 0.00011 | |
13 | 16 | 4.54 | 0.0006 | 4.57218 | 0.07431 | 0.00023 | |
Total | 419.3 | 626.06 | 1.9914 | 300 | 3.11860 | 0.32753 |
Abbreviations: F = Frequency (%); D = Density (individuals/hectare); BA = Basal Area (m2/hectare);
IVI = Important value index; H’ = Shannon-Wiener Index; Cd = Simpson’s Index.
Phytosociology of invasive plant species encountered at >1000m AMSL (Range 4).
S.N. | NAME | F | D | BA | IVI | H’ | Cd |
---|---|---|---|---|---|---|---|
1 | 41 | 11.64 | 0.00107 | 10.33411 | 0.15129 | 0.001193 | |
2 | 50 | 22.32 | 0.00066 | 14.76674 | 0.20840 | 0.002433 | |
3 | 50 | 34 | 0.00335 | 17.95162 | 0.25468 | 0.003606 | |
4 | 16 | 7.64 | 0.00018 | 4.858068 | 0.09495 | 0.000263 | |
5 | 50 | 84.32 | 0.01354 | 31.64427 | 0.40873 | 0.01126 | |
6 | 25 | 5.32 | 0.00081 | 5.828146 | 0.09551 | 0.00038 | |
7 | 91 | 86.64 | 4.87483 | 138.601 | 0.67241 | 0.367264 | |
8 | 58 | 23 | 0.00079 | 16.35513 | 0.21853 | 0.002985 | |
9 | 66 | 22 | 0.00262 | 17.52797 | 0.22224 | 0.003435 | |
10 | 66 | 49.64 | 0.00409 | 24.96496 | 0.31784 | 0.00697 | |
11 | 41 | 23.32 | 0.00062 | 13.45496 | 0.20403 | 0.00202 | |
12 | 16 | 3.32 | 0.0008 | 3.713032 | 0.06762 | 0.000154 | |
Total | 570 | 373.16 | 4.90336 | 300 | 2.91626 | 0.401966 |
Abbreviations: F = Frequency (%); D = Density (individuals/hectare); BA = Basal Area (m2/hectare);
IVI = Important value index; H’ = Shannon-Wiener Index; Cd = Simpson’s Index.
The value of IVI was found to be maximum for
The world’s flora and fauna are getting homogenized due to the global extent and rapid spread of invasive species (Mooney & Hobbs, 2000). Species invasion or bio-invasion is also regarded as a form of biological pollution and has a conspicuous role in global change; and is also thought to be one of the serious causes of species extinction (Mooney & Drake, 1986; Drake
The present study site was found to be inhabited by a total of 31 invasive alien plant species. The therophytes were found to be the dominant life form followed by others. It indicates the presence of anthropic disturbances as this life form is seen to be accompanied by dry and unfavorable environmental conditions and is a type of strategy adopted for survival (Manhas
A considerable variation was seen in the pattern of flowering phenology of invasive flora under study. They were found to bloom in different seasons. This can be attributed to variation in temperature with changing seasons. With the high peaks during hierarchical clustering, the maximum number of species were seen to be flowering during September and October followed by June and July. Minimum flowering was observed during December and January. This can be compared with the results of Malik & Malik (2014) who reported two spells of flowering during their study in the forests of Bagh district. The plants with similar flowering periods are in proximity and are clustered in one limb (Figure 5).
Moreover, the phytosociological analysis revealed that the floristic composition and diversity of invasive plant species changes along with the change in altitude on the present study site. It was found to be increasing from Range 1 to Range 2 and then it further decreased in the subsequent ranges i.e., Range 3 and Range 4 with the increase in altitude. There are two different types of patterns that are commonly observed for species diversity along with the increase in altitude. These are a monotonically decreasing curve along with an increase in altitude and a hump-shaped curve showing maximum diversity at intermediate altitudes (Rahbek, 1995; Rahbek, 2005). The present study does not show the general trend of linear decrease in diversity along with an increase in altitude, such as reported by Kosaka
The invasive plants like
From the Pearson Correlation of the studied parameters (Figure 6) it can be depicted that frequency and density positively correlated with each other as well as with the basal area and Shannon-Wiener Index while negatively correlated with Simpson’s Index. Other than this, the Shannon-Wiener Index was positively correlated with frequency, density, and basal area but negatively correlated with Simpson’s Index. Whilst Simpson’s Index was seen to be positively correlated with frequency, density, and basal area but correlated negatively with the Shannon-Wiener Index.
Invasive species affect human wellbeing directly as well as indirectly by threatening biodiversity and ecosystem processes. Subsequently, they suppress native biodiversity, alter wildlife habitats, and can also cause local extinctions. Thus, we need a single policy framework to inventory and document invasive species, and not just list them, but understand their ecology and economic impacts.
The present study reveals that invasive plants have influenced the floristic composition of Range 2 followed by Range 1 in the forests of Morni Hills due to their high diversity in comparison to upper altitudinal ranges (Range 3 and 4). Also, the assessment of flowering phenology will help comprehend the effects of climate change on the flowering of species in the outer Himalayas. The study also suggests the presence of acute anthropogenic pressure on the present study site due to therophytes being the dominant life form. Thus, it can help policymakers in ecosystem management by providing insights into the diversity and ecological characteristics of the invasive alien plant species.