Daizy R. Batish. Department of Botany Panjab University Chandigarh, India

Transcription

1 Daizy R. Batish Department of Botany Panjab University Chandigarh, India

2 Biological invasion has globalized world biota resulting in biotic homogenization Not restricted to plants only also includes mammals, insects and microbes Invasive alien species (IAS) cause greatest threats to biodiversity loss, and are most significant drivers of environmental degradation and change worldwide Threaten the ecosystem integrity 2

3 o About 18% of Indian flora is adventive aliens of which 55% are American, 30% Asian and 15% European and Central Asian o Many of the Introduced plants that include agricultural crops and trees are useful! o As per another report, there are a total of 173 invasive alien species which belong to 117 Genera under 44 families o Tropical America (74%) & Tropical Africa (11%) contribute maximum o However some of the purposeful introductions later became invasive and weedy while others invaded accidentally!

4 Some introduced plants assumed the proportion of serious invaders Examples: Lantana camara, Prosopis juliflora, Eichhornia cassipes, Mikania micarantha Some have invaded accidentally Parthenium hysterophorus, Ageratum conyzoides, Eupatorium odoratum 4

5 In northern parts of India several woody and nonwoody invasive plants have created havoc with the native flora Prominent invasive plant species are Parthenium hysterophorus, Lantana camara, Ageratum conyzoides, Leucaena leucocephala, Prosopis juliflora etc. Of late Broussonetia papyrifera a tree belonging to family Moraceae is spreading fast in the Northern region of India

6

7 Native to eastern Asia, especially Japan and Taiwan Introduced intentionally for economic and aesthetic purposes Fast growing, dioecious and deciduous tree High reproductive potential (Both vegetative as well as sexual)

8 SITES DBH HEIGHT (m) NO. of TREES AMOUNT of LITTER (g) SITE 1 SITE 2 SITE ± ± ± ± ± ± ± ± ±

9 Broussonetia papyrifera - Reproduction Female Flower and Fruits Male Flowers in Catkins

10 Vegetative Reproduction Adventitious roots of B. papyrifcera New plant growing from old root

11

12

13 The tree forms its own monocultures and supports very poor understorey vegetation as indicated above There is no quantitative data to support Also, the reason for poor understorey remains unknown 6/6/2012 A study was, therefore, planned to investigate the understorey vegetation and to investigate the possible role of some chemical interference

14 Vegetation analysis was done by quadrat method Quadrats were laid randomly under Broussonetia invaded (BI) and uninvaded (BC) dry deciduous forest selected on the outskirts of Chandigarh (India) The study was conducted in two seasons i.e. before and after monsoon

15 Number of plants were counted in each quadrat and their abundance and IVI were calculated (Ambasht, 1990) Various ecological indices were calculated as per Ludwig and Reynolds (1988)

16 Indices of Species Diversity Species richness R = S-1 / Log N (Margalef, 1958) where S = number of species N = number of individuals, etc.

17 Index of Dominance (λ) λ= Σ (ni /N) 2 n i = importance value for each species (number of individual, biomass, production and so forth) N = total of importance values (Simpson, 1949)

18 Shannon index of general diversity(h ) H = Σ (ni/n) log (ni/n) or ΣP i log P i where ni = N = importance value for each species H total of importance values P i = importance probability for each species = ni/n as per Shannon-Weaver (1963) Most commonly used index of diversity in ecological studies Values range from 0 to 5, usually ranging from Calculated

19 Hill s Diversity Number N1 = e H (Hill, 1973) Hill s Diversity Number N2 = 1/ λ (Hill, 1973) N2 1 Evenness Index E = (Hill, 1973) N1 1

20 Role of chemical interference: Batish et al. (2009) Collection of Material: Plant litter Since forest floor invaded by Broussonetia harbored large amount of leaf litter Growth Studies: Pot conditions Bioassay plants: Bidens pilosa: commonly found understorey weed Extraction of plant phenolics: Swain and Hillis (1959)

21 Bioassay plant

22 Results

23 PLANT SPECIES Abundance IVI Abutilon indicum BC BI BC BI Achyranthes aspera Ageratum conyzoides Albizia lebbeck Boerhavia diffusa Broussonetia papyrifera Cannabis sativa Cassia occidentalis Cocculus hirsutus Commelina Cynodon dactylon Desmodium gangeticum Ipomoea

24 PLANT SPECIES ABUNDANCE IVI Lophochloa phleoides Malvastrum coromandelianum BC BI BC BI Murraya koenigii Oxalis corniculata Panicum repens Parthenium hysterophorus Peristrophe sp Portulaca Ricinus communis Sida acuta Urena lobata Vernonia cinerea Species Species

25 Nearly 60 to 80% loss of species was encountered in forest invaded by Broussonetia (BI) BI forest was dominated by few opportunistic species like Broussonetia itself It contributed maximum IVI in the invaded forest. Consequently the floor was occupied by lot of litter compared to uninvaded area

26 No. of type of species (N o ) Richness Index (R) Index of Dominance (λ) Index of Diversity (H ) Parameter BC BP Hill s Diversity Number (N 1 ) Hill s Diversity Number (N 2 ) Evenness index (E) (-40.7) (-15.6) (6.67) (-17.9) (-35.0) (-19.3) (2.5)

27 Parameter No. of type of species (N o ) Richness Index (R) Index of Dominance (λ) Index of Diversity (H ) Hill s Diversity Number (N 1 ) Hill s Diversity Number (N 2 ) Evenness index (E) BP BP (-62.2) (-62.1) (41.7) (-49.4) (-58.9) (-57.2) (-20.0)

28 Shannon s diversity index, richness index and evenness index were measured to be lesser in the BI forest area On the other hand index of dominance was measured to be more in the inved area compared to control area showing homogenization of species Hills diversity numbers reflecting most abundant species were also reduced in the invaded area Effect was more in the post-monsoon compared to pre-monsoon

29 Chemical interference or Allelopathy Most plausible answer! Reason: Accumulation of leaf litter on the forest floor that might contribute inhibitory substances playing havoc with the understorey plants In order to check this dried and powdered litter was amended in the pots and its effect was studied on the germination and growth of Bidens pilosa one of the common understorey tree. 6/6/

30 onc. (%) Root length (cm) Shoot length (cm) Control a ± a ± b ± b ± c ± c ± d ± d ± 0.15 control 0.5 % 1 % 2 % 4 % e ± d ± 0.31

31 Growth of test plant significantly retarded Both root and shoot growth was retarded but root growth was more affected than shoot A concentration dependent effect was evident Possibly there are some inhibitory chemicals such as Phenolics Amount of phenolics was therefore checked in the medium 6/6/

32 Amount of litter (%) Amount of Phenolics mg GAE /g Significant amount of Phenolics were found in the amended soils Amount increased with increasing amount of litter in soil

33 Broussonetia papyrifera is a fast emerging invasive tree in Northern parts of India It forms its own monocultures thus affecting local biodiversity It reduces understorey begetation as revealed by the values of IVI and diversity indices The study also revealed some type of chemical interference that might be responsible for this possibly through the release of phenolics in soil

34 Ambasht, R.S A Text book of Plant Ecology. Students Friends and Company, Varanasi, India. Hill, M.O Diversity and its evenness, a unifying notation and its consequences. Ecology 54: Ludwig, J.A. and J.F. Reynolds Statistical Ecology, A Primer on Methods and computing. John Wiley and Sons, New York, 337 p. Margalef, R Temporal succession and spatial heterogeneity in phytoplankton. In: A.A. Buzzati-Traverso (ed.), Perspective in Marine Biology. University of California Press, Berkeley, pp , Misra, B Ecology Work Book. Oxford and IBH Company, New Delhi, 244p. Shannon, C.E. and W. Weaver The Mathematical theory of Communication. University of Illinois Press, Urbana, Illinois, 117 p. Simpson, E.H Measurement of diversity. Nature 163:688

35 Thanks for your attention