Journal
of Threatened Taxa | www.threatenedtaxa.org | 26 July 2021 | 13(8): 19060–19069
ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.4852.13.8.19060-19069
#4852 | Received 29 January 2019 | Final received 05 July
2021 | Finally accepted 09 July 2021
Species diversity and abundance
patterns of epiphytic orchids in Aralam Wildlife
Sanctuary in Kerala, India
Jis Sebastian 1, Durairaj Kathiresan 2
& Giby Kuriakose
3
1,2 Department of Botany, Saraswathi
Narayanan College, Perungudi, Madurai, Tamil Nadu
625022, India.
3 Department of Botany, Sacred
Heart College, Thevara P.O, Ernakulam, Kerala 682013,
India.
1 alkaeliza@gmail.com, 2 kathiresansnc@gmail.com
(corresponding author), 3 giby.kuriakose@shcollege.ac.in
Editor: Pankaj Kumar, Kadoorie
Farm and Botanic Garden, Tai Po, Hong Kong S.A.R., China. Date
of publication: 26 July 2021 (online & print)
Citation: Sebastian,
J., D. Kathiresan & G. Kuriakose
(2021). Species diversity and abundance patterns of epiphytic
orchids in Aralam Wildlife Sanctuary in Kerala,
India. Journal of
Threatened Taxa 13(8): 19060–19069. https://doi.org/10.11609/jott.4852.13.8.19060-19069
Copyright: © Sebastian et al 2021. Creative
Commons Attribution 4.0 International License.
JoTT allows unrestricted use, reproduction,
and distribution of this article in any medium by providing adequate credit to
the author(s) and the source of publication.
Funding: SERB- DST India (Reg.No.
SR/FT/LS-176/2010) under the
scheme SERB-DST Fast Track
Young Scientist Program and
UGC Minor Research Project (MRP(S)-1130/11-12/KAMY013/UGC-SWRO).
Competing interests: The authors
declare no competing interests.
Author details: Jis Sebastian—Independent
researcher in the Western Ghats. Her interest lies in orchid science and
climate resilient community conservation models. Durairaj Kathiresan—Associate professor at
PG department & Research Centre in Botany, Saraswathi Narayanan College, Perungudi, Madurai. Giby Kuriakose—Assistant professor and
Head of the Department at Department of Botany, Sacred Heart College, Cochin,
Kerala.
Author contributions: JS—data
collection-compilation-analysis and writing of the manuscript; DK—guiding the
data compilation- analysis and writing of the manuscript; GK—conceptualisation of the study, executing the study and
fund management, guiding data collection-compilation-analysis and writing of
the manuscript.
Acknowledgements: This research work was possible
due to the permission granted by the PCCF & CWW, Kerala. We thank the
Department of Science and Technology and UGC Minor Research Project for the
financial support. We acknowledge Saraswathi Narayanan College, Madurai, Tamil
Nadu and Sacred Heart College, Thevara, Cochin,
Kerala for guidance and support. SJ thanks Dr Abin
Varghese, Co-ordinator, Dr R Satheesh Centre for Remote Sensing and GIS, School
of Environmental Sciences, Mahatma Gandhi University, Kottayam; WWF Prince
Bernhard Nature Fund, Switzerland and Idea Wild, USA.
Abstract: Species diversity and abundance
patterns of epiphytic orchids were studied in Aralam
Wildlife Sanctuary, in the Western Ghats of northern Kerala. Habitats sampled
were wet evergreen (EVEG), montane wet evergreen (MEVG), moist deciduous
(MDEC), and semi evergreen (SEVG), on a gradient of altitude from 60 to 1,589
m. Selective tree scanning on linear line transects was deployed (n= 40) across
spatial units. A total of 39 orchid species were recorded. Rarefied species
richness was maximum in the EVEG (20) habitat. Best suited rank abundance
models were analysed for epiphytic orchids in each habitat and checked for
significant differences. Bootstrap and Jackknife-1 estimators and species
accumulation curves suggested higher species richness than observed, therefore
more effort in sampling was needed in order to record all epiphytic orchids of
the area. The difference in species richness between habitat types was not
statistically significant (ANOVA). 38% of recorded epiphytic orchid species
were endemic.
Keywords: Endemic, Orchidaceae,
terrestrials, Western Ghats.
Introduction
Epiphytes, a significant group of
slow growing plants (Benzing 1990), are more
associated with tropical rain forests compared to temperate forests (Webb 1959;
Richards et al. 1996). Orchidaceae are dominant among
tropical rainforest epiphytes, possibly due to adaptations to temporary water
stress in different climates and microclimates (Benzing
2004). Orchids make major contributions to the forest communities they inhabit
(Nadkarni 1994) and they are also valued for their horticultural, medicinal,
ethical, and edible prospects.
The Western Ghats is home to 310
orchid species, of which 123 are not found elsewhere (Jalal & Jayanthi
2012), and in Silent Valley National Park 50% of total epiphytes recorded are
orchids (Kumar 1999). The Western Ghats are now inhabited by almost 50 million
people, which has resulted in extensive transformation of landscapes, over
exploitation of natural resources, habitat degradation, habitat loss, and
encroachment. Selective removal of orchids for ornamental and medicinal purposes
without considering their ecological attributes is globally identified as a
threat to orchids (Huang 2011). In order to have a conservation strategy for
specific species or groups in a region, it is important to know their ecology.
However, taxonomic confusion persists in the region over endemic orchid species
and sub species. In a moist lowland forest in the eastern Himalaya, selective
logging was found to affect structural complexity of trees and hence associated
microclimates, gradually threatening pteridophytes, non-orchids, and orchids (Padmawathe et al. 2004). The extensive forests of the
Western Ghats become a challenge for an ecologist when groups such as orchids
with random distribution is in focus. Epiphytes have been associated with trunk size
in tropical evergreen forest in the Western Ghats (Annaselvam
& Parthasarathy 2001). Apart from taxonomic explorations, diversity and
ecology of Dendrobium in Chotanagpur plateau
(Kumar et al. 2011), epiphytic orchid diversity from farmer managed forests in
the Western Ghats (Sinu et al. 2011), habitat studies
of medicinal orchids (Jalal & Rawat 2009), and conservation strategies for
orchids of western Himalaya (Jalal 2012) are the only existing ecological works
on orchids from India.
In order to fill this gap, the
authors have examined ecological aspects of epiphytic orchids in the Western
Ghats of Kerala. This study deals with the epiphytic orchids in Aralam Wildlife Sanctuary (WS) in Kannur district of
northern Kerala. Aralam WS falls in Wayanad Plateau in
the southern Western Ghats. The objectives of this study were to assess
patterns of species diversity, abundance, and endemism among epiphytic orchids
in Aralam WS.
Study
Area
The Aralam
WS is situated between 11.900–11.983 0N 75.783–78.950 0E spanning around
55 km2 (Figure 1). The elevation varies from 60m to ca. 1,589m from
mean sea level with two major peaks, the Katti Betta
(1,145 m) and the Ambalapara (1,589 m). The
temperature varies from 21°C to 40°C in the lower altitudes and 8 °C to 25 °C at
the higher reaches. The south-west and the north-east monsoons together give
annual rainfall between 3,745 mm and 5,052mm. The Sanctuary land slopes from
the east to the west, is drained by the Cheenkannipuzha,
which flows to the west. Aralam WS is known for the
west coast tropical evergreen forest where the unique Dipterocarpus-Mesua-Palaquim
sub-type is seen (Nair 1991). There are about 490 ha of Teak and Eucalyptus
plantations within the forest area (Manju et al. 2009). Apart from this, the
vegetation of the Sanctuary can be classified into low (0–800 m) and medium
(801–1,450 m) elevation types of wet evergreen, semi evergreen, moist
deciduous, and high elevation (>1,450m) montane wet evergreen or hilltop
evergreen forest (Champion & Seth 1968; Ramesh 2001). The floristic
composition of Ambalapara region differs considerably
from shola forests (Menon 1999; KFD 2009; Manju et al. 2009). The
trees of this part are stunted, usually below 20m, belonging to Laurales and Myrtales, with
trunks of heavy loads of epiphytic plants. Therefore, the vegetation from 1,450
to 1,700 m elevation is treated as high elevation/montane wet evergreen forest
(MEVG).
The animal diversity of the
Sanctuary was comparatively well studied (Radhakrishnan 1996; Abraham & Easa 1999; Nair 2001, 2003; Sreekumar & Balakrishnan
2001 etc), but reports on plant diversity are very
few (Menon 1999) and mostly limited to bryophytes and pteridophytes (Manju et
al. 2009; Dantas et al. 2016; Rajesh & Vijisha 2016). So far, 47 orchid species have been reported
from the Sanctuary of which 20 are endemic to India (KFD 2009).
Methods
Field sampling
Field sampling was done from
September to November in 2015. Selective tree scanning (to ensure
representation of vertical distribution and diversity of orchids) on linear
line transects (to enable spatial scaling of orchids in heterogeneous habitats)
was developed (Sebastian et al. 2017) through trial and error integrating
sampling of vascular epiphyte richness and abundance (SVERA, Wolf et al. 2009)
and line transects (Jacquemin et al. 2007). Transects
were laid 100 m from each other in linear direction in different habitat types
based on the presence of epiphytic orchids (see Table 1). A line transect was
laid after finding a host tree with at least three individuals of orchids on
it. Then, the next neighbouring tree was selected at the 10th meter
point from the first individual and this was repeated until data collected from
a total of 10 individual trees from each line transect. Data on three levels of
sampling were taken from each transect. Data on characteristics of habitat,
host tree, and the substrate (immediate surrounding) of orchids were recorded.
Due to limitations in canopy access, orchid species were identified with a pair
of binoculars (VORTEX 8X42) from ground, using the field key (Pradhan 1976,
1979; Abraham & Vatsala 1981; Joseph 1982; Kumar &
Manilal 1994, 2004).
Statistical analysis
Statistical analysis of data from
40 transects was performed using statistical software R (version 3.5.0) and
PAST 3.19. Orchids were ranked based on their abundance to check on singletons
and doubletons. Due to the difference in the number of transects in different
spatial units, rarefied diversity indices were estimated. Different habitats
were compared using graphical representation of diversity indices and dominance
indices in point plots to focus on difference with the help of error bars from
bootstrap sampling. Rank abundance model (rad) for habitats was prepared using
the best suited model (with lowest Akaike Information Criteria, AIC) to
visualise the site diversity/dominance. In order to understand total species
richness of epiphytic orchids in Aralam, total
species was estimated based on incidence-based estimators. Species accumulation
curve was prepared for species across transects in habitats using random
accumulator function based on individual accumulation model. The rarefied
species richness was compared across habitats. The significance of difference
was tested using ANOVA and Welch T-test. The proportion of endemic species
richness and abundance in the sample was plotted as a bar diagram and has been
compared with a previous research paper.
Results
and Discussion
Patterns in species diversity and
abundance
In total, we found 2,831
individuals belonging to 39 species of epiphytic orchids (a complete species
list is given in Table 2) from 400 individual trees (of >10cm GBH) spread
across 40 transects. Also, 29 terrestrial orchids (of which, nine were
unconfirmed species but morphologically distinct) were recorded from the study
area. Bulbophyllum fischeri
and B. fuscopurpureum were found growing both
as epiphyte and terrestrial forms. The host trees sampled were grouped into 96
species and 15 unidentified species that were morphologically distinct. Among
orchids, Gastrochilus acaulis
was present in all habitats followed by Cleisostoma
tenuifolium, Cottonia peduncularis, and Liparis
viridiflora in three habitats each. The common
species with the highest abundance was Cleisostoma
tenuifolium. Two species were recorded with
single individuals (singletons) and another six species were represented by two
individuals (doubleton) each.
Species Abundance Distribution
(SAD) model, based on rank abundance of species for each habitat (Figure 2),
explained the diversity of respective habitats with the help of basic models
Null, Pre-emption, and Lognormal. Rank abundance models with least AIC values
suggested an abundance model for each vegetation (habitat) type (Table 3). The
relative abundance of species against their rank in EVEG habitat, best
explained by the Null model, indicates that individuals are randomly
distributed among observed species. Whereas, the Log normal model explained
ranking based on relative abundance in MDEC and SEVG habitats as the abundance
of species are in normal distribution with high evenness among species.
Pre-emption model fitted to MEVG habitat describes least evenness among species
with respect to the distribution of individuals. Interestingly, MEVG habitat
had four dominant species: Bulbophyllum fischeri, Sirhookera lanceolata, Coelogyne nervosa,
and Conchidium microchilos,
while other species were barely represented.
EVEG habitat recorded 20 species
with just 579 individuals, whereas SEVG habitat recorded 12 species with the
highest abundance of 1,253 (Table 4). Biodiversity indices such as
Shannon-Weiner index, Margalef & Fisher alpha
showed variations with high diversity in EVEG, and the lowest was in SEVG
habitat (Figure 3). Meanwhile, in a comparison of Simpson 1-D values (Figure
4), a dominance index that accounts for diversity and evenness between
habitats, only EVEG and MEVG were significantly different from each other (Mann-Whitney
pairwise test, df= 3, at p= 0.05). MVEG
habitat had only one species in common with other habitats. Six species were
found shared between MEVG and EVEG habitat with more or less equal individuals.
MEVG significantly differed from EVEG with the presence of five unique species,
and of which species, Bulbophyllum fischeri was well represented in number of individuals.
Furthermore, higher abundance of species, Dendrobium nutans
in MEVG from that of EVEG habitat could have also contributed to it.
EVEG habitat with Simpson 1-D value 0.92 indicated highest diversity amongst
and SEVG habitat the lowest with 0.74. SEVG habitat showed maximum abundance
per species and the abundance distribution across species was found to be in
normal distribution with high evenness.
The transects were standardised
and rarefied species richness was estimated for minimum and maximum abundances.
Total species richness was estimated for Aralam WS
based on this rarefied data. One species per transect was added on average in
accumulation of species for total species richness. The species observed, Sobs,
was close to the bootstrap estimator which predicted a total of 46 species
whereas, Chao estimator provided the highest predicted richness, 74 for the WS.
This indicates the need of more transects to get a better picture about the
distribution pattern of species and abundance of epiphytic orchids of Aralam WS. The relationship between species and individuals
in each habitat was plotted (Figure 5). The number of species initially increased
in a strong and steady manner along with the addition of individuals in
habitats such as EVEG and MDEC. This clearly indicated the spacing of species
in these habitats were not too far from each other. At the same time, the pattern of species accumulation
was very gradual in MEVG and SEVG habitats in the beginning as a result of
larger spacing between species in a wider area when compared to shorter spacing
in EVEG and MDEC. Then the addition of individuals to species in SEVG reached
an asymptote indicating that epiphyte assemblage in SEVG is not as diverse as
other habitats but represented by high abundance. A comparison between rarefied
species richness for minimum and maximum abundances in habitat types was tested
(Figure 6). However, they were not statistically significantly different from
each other (ANOVA at p =0.05, df= 3). MEVG
shared only one common species between SEVG and MDEC. However, MDEC and SEVG
had nine common species. Lastly, EVEG shared six species with MDEC; seven
species with MEVG; seven species with SEVG. Four habitats shared only one
species in common.
The total extent of the study
area is just 55 km2 and it contains at least four major habitat
types, other than plantations and riparian forests. The distribution of
different habitats within the study area is highly contiguous and not
continuous that creates several ecotones at places. Although the present study
covered maximum area in each habitat the present results clearly shows the
diversity in microhabitats and microclimates within each habitat type as the
estimated species richness (74 species) differed greatly to that of observed
species richness (39 species). Therefore, an approach involving identification
of different microhabitat and microclimate zones should be deployed to maximise
the likelihood of recording maximum species in the study area. Further, species
abundance pattern (Figure 2) across different habitats varies greatly and
different habitats fit in with different SAD models with different patterns of
distribution of species.
Endemism
Endemism among epiphytic orchids
of Aralam WS deserves further attention, as 29% of
total orchids (N= 62) and 38% of epiphytic orchids (N= 39) from the area were
endemic to the Western Ghats (Figure 7). Abundance of endemic orchids alone
made up 28% of total abundance. However, the difference in endemic species
richness and abundance between habitats was not significant (Kruskal Wallis
test, p= 0.8). Interestingly, of
these endemic orchids, eight species were seen only in one habitat and five
species in two habitats each. However, associations amongst species with
respect to habitat could not be identified with sample size as low as 40
transects. Furthermore, three terrestrial endemics were also recorded. These
terrestrial endemics such as Eria albiflora, Brachycorythis iantha and Habenaria
perrotettiana belonged to MEVG habitat but data
was not sufficient to check if relationships existed with the habitat. Chao and
ACE estimators suggested all endemic epiphytes of Aralam
had been obtained through sampling from 40 transects. Species estimation for
endemic epiphytes in Aralam WS was compared with that
of entire southern western Ghats in Kerala (Figure 8). Species accumulation
curve was almost stabilized at 181th transect for data on endemic
epiphytic orchids from entire southern Western Ghats in Kerala (Refer Sebastian
et al. 2017). Further, high endemic epiphytic species diversity and abundance
was observed in EVEG habitat followed by MEVG in Aralam
WS.
Conclusion
The total number of epiphytic
orchid species recorded in this study was 62, higher than noted previously by
KFD (2009). Species accumulation curves suggest that there are species that are
yet to be sampled from Aralam WS (Figure 5). It is
also possible that the exempted Teak plantations in the WS could have added a
few more species into the list.
It is remarkable that all four
habitat types possessed distinct epiphytic orchid diversity, and that sharing
occurred mostly along transition zones. Based on different diversity indices
explored, EVEG was the most diverse habitat for epiphytic orchids. Next, MDEC,
MEVG, and SEVG habitats shared a more or less equal number of species. As Annaselvam & Parthasarathy (2001) discussed, sometimes
epiphytic orchids that preferred deciduous trees in low wet evergreen forests
contributed largely to abundance. As per the rate of species accumulation in
response to individuals, EVEG habitat clearly varied from other habitats as was
also indicated by the dominance index. Nonetheless, with few more transects all
habitats could have added new species. In MEVG habitat the best explained rad
model pre-emption was rather steep compared to suggested models for other
habitats. This indicated less species evenness in MEVG habitat. Generally,
log-normal models indicate habitats that are at equilibrium or perturbation is
maintained, here for SEVG and MDEC. Whereas undisturbed forest such as EVEG and
MEVG, however, may not necessarily be at equilibrium and do not fit log normal,
a model for undisturbed habitat. A hierarchy based on dominance was evident in
MEVG with less species evenness and therefore best explained by dominance
pre-emption model. Null model for EVEG indicated a more neutral community with
no species interactions among them and species equivalence or in other words more
random. This might be because of the random distant presence of species or
individuals in EVEG when compared with MDEC, where the species distribution was
rather closer. Because of the absence of distinct patterns in composition from
sampled data there was no significant difference between species richness
across habitats. The trend of results suggested a possible preference of
epiphytic orchids towards evergreen habitats. The two habitats of evergreen
nature gathered 27 epiphytic orchid species of a total 39 species.
Wet evergreen and montane wet
evergreen habitats from low to high elevations also supported both epiphytic
and terrestrial endemic orchids in Aralam WS. It is
suggested that long term research in these habitats could throw light on new
perspectives on distribution of Endemic orchids. This area is located in Nilgiris-Silent valley-Wayanad-Kodagu region, a centre of
endemism in the Western Ghats. This probably contributed to the high rate of
endemism. Of 62 orchid species, 18 represented endemic orchids of the Western
Ghats. Endemic orchids obtained from Aralam WS
exhibited similar distribution patterns in as other studies (Sebastian et al.
2017).
The results obtained shows that
all studied habitat types contribute to epiphytic orchid diversity and
abundance in Aralam WS. An integrated approach to
address both epiphytic and terrestrial orchids might pave the way to
understanding the pattern of endemism among orchids. The location, size and
diversity of the Aralam WS provides an opportunity
for scientists to do a full-fledged experimental study on the mechanisms behind
its floral and faunal diversity.
Table 1. Habitat types used for
the study.
|
Habitat types (following Ramesh
2001) |
|
|
EVEG MDEC SEVG MEVG |
Wet evergreen (low-mid
elevation) Moist deciduous Semi evergreen Montane wet evergreen (high
elevation) |
Table 2. The list of identified
epiphytic and terrestrial orchids from Aralam
Wildlife Sanctuary, Kannur.
|
|
Species |
Epiphytic |
Terrestrial |
Endemic** |
|
1 |
Aerides crispa |
+ |
- |
- |
|
2 |
Aerides ringens |
+ |
- |
- |
|
3 |
Bulbophyllum fischeri |
+ |
+ |
- |
|
4 |
Bulbophyllum fuscopurpureum |
+ |
+ |
+ |
|
5 |
Bulbophyllum neilgherrense |
+ |
- |
- |
|
6 |
Bulbophyllum tremulum |
+ |
- |
- |
|
7 |
Chiloschista pusilla |
+ |
- |
- |
|
8 |
Cleisostoma tenuifolium |
+ |
- |
- |
|
9 |
Coelogyne mossiae |
+ |
- |
+ |
|
10 |
Coelogyne nervosa |
+ |
+ |
+ |
|
11 |
Conchidium exile |
+ |
+ |
+ |
|
12 |
Conchidium microchilos |
+ |
+ |
+ |
|
13 |
Cottonia peduncularis |
+ |
- |
- |
|
14 |
Cymbidium aloifolium |
+ |
- |
- |
|
15 |
Dendrobium aquem |
+ |
- |
+ |
|
16 |
Dendrobium macrostachyum |
+ |
- |
- |
|
17 |
Dendrobium microbulbon |
+ |
- |
+ |
|
18 |
Dendrobium jerdonianum |
+ |
- |
- |
|
19 |
Dendrobium ovatum |
+ |
- |
+ |
|
20 |
Dendrobium panduratum
|
+ |
- |
- |
|
21 |
Eria reticosa |
+ |
+ |
- |
|
22 |
Gastrochilus acaulis |
+ |
- |
- |
|
23 |
Gastrochilus flabelliformis |
+ |
- |
+ |
|
24 |
Phalaenopsis deliciosa |
+ |
- |
- |
|
25 |
Liparis elliptica |
+ |
- |
- |
|
26 |
Liparis viridiflora |
+ |
- |
- |
|
27 |
Oberonia brunoniana |
+ |
- |
+ |
|
28 |
Oberonia santapaui |
+ |
- |
+ |
|
29 |
Oberonia tenuis |
+ |
- |
- |
|
30 |
Papilionanthe subulata |
+ |
- |
- |
|
31 |
Pholidota imbricata |
+ |
- |
- |
|
32 |
Pomatocalpa spicata |
+ |
- |
- |
|
33 |
Porpax jerdoniana |
+ |
- |
+ |
|
34 |
Porpax reticulata |
+ |
- |
- |
|
35 |
Rhyncostylis retusa |
+ |
- |
- |
|
36 |
Seidenfadeniella rosea |
+ |
- |
+ |
|
37 |
Sirhookera lanceolata |
+ |
+ |
- |
|
38 |
Smithsonia straminea |
+ |
- |
+ |
|
39 |
Bulbophyllum stocksii |
+ |
- |
+ |
|
40 |
Calanthe sylvatica |
- |
+ |
- |
|
41 |
Cheirostylis flabellata |
- |
+ |
- |
|
42 |
Disperis neilgherrensis |
- |
+ |
- |
|
43 |
Eria albiflora |
- |
+ |
+ |
|
44 |
Habenaria gibsonii var. gibsonii |
- |
+ |
- |
|
45 |
Habenaria longicorniculata |
- |
+ |
- |
|
46 |
Habenaria perrotettiana |
- |
+ |
+ |
|
47 |
Malleola gracilis |
- |
+ |
- |
|
48 |
Pecteilis gigantea |
- |
+ |
- |
|
49 |
Satyrium nepalense |
- |
+ |
- |
|
50 |
Sirhookera latifolia |
- |
+ |
- |
|
51 |
Tainia bicornis |
- |
+ |
- |
|
52 |
Tropidia angulosa |
- |
+ |
- |
|
53 |
Brachycorythis iantha |
- |
+ |
+ |
|
54 |
Liparis sp.* |
- |
+ |
- |
|
55 |
Liparis sp.2* |
- |
+ |
- |
|
56 |
Bulbophyllum sp.* |
- |
+ |
- |
|
57 |
Bulbophyllum sp. 2* |
- |
+ |
- |
|
58 |
Cheirostylis sp.* |
- |
+ |
- |
|
59 |
Oberonia sp.* |
- |
+ |
- |
|
60 |
Spiranthes sp.* |
- |
+ |
- |
|
61 |
Zeuxine sp.* |
- |
+ |
- |
*genus with unconfirmed species.
** Endemics (Jalal 2012; Kumar et al. 2000; Jayalakshmi 2016).
Table 3. RAD models for habitats
with the least AIC value marked in red.
|
|
EVEG |
MDEC |
MEVG |
SEVG |
|
Null |
117.9956 |
168.7757 |
128.51493 |
491.0734 |
|
Pre-emption |
125.6122 |
197.9680 |
77.26034 |
125.5718 |
|
Lognormal |
129.4657 |
151.8832 |
99.69576 |
102.5774 |
Table 4. Orchid diversity across habitat types.
|
Orchid Diversity |
Habitat |
|||
|
EVEG (N= 12) |
MDEC (N= 6) |
MEVG (N= 9) |
SEVG (N= 13) |
|
|
Rarefied species richness* |
20 |
13 |
12 |
12 |
|
Individuals |
579 |
679 |
317 |
1253 |
*rarefied at
301 individuals
For
figures & image - - click here
References
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