Urban trees in a culturally evolved Himalayan town - Vegetation and Landscape dynamics
Sheena Narula, Surajit Dutta, Subrat Sharma*
G.B. Pant Institute of Himalayan Environment & Development
Kosi-Katarmal, Almora 263 643
* Author for Correspondence
email – subrats@rediffmail.com
Abstract
This study explores tree diversity and analyzes the effects of urbanization on the landscape
attributes of a mountainous town (Almora) in the Kumaun Himalayan region having a long
history of human settlement. A total of 83 species were recorded in a town of spatial extent of ~
3.5 km2. High tree diversity is attributed to cultural practices and presence of natural taxa. With
an increase in the area of the ward tree cover area was increasing indicating concentration of
human settlements in few wards and sporadic presence all over the landscape, also reflected by
highest number of patches and great variation in size. Among the tree cover classes broadleaf
deciduous class has highest appearance due to dominance of winter deciduous taxa in natural
elements. A strong positive correlation was observed with area of the ward and number of
settlement and tree patches. Over a period of time uneven settlement has caused fragmentation in
the landscape of the town. This can have serious implications on the habitats and niches of
various communities hence affecting the overall biodiversity of the area.
Keywords: Urban landscape, Tree Diversity, Himalayan Town, Fragmentation
1. Introduction
Diverse ecological conditions on the planet those created solely for human-by-human activities
are urban ecosystems, where functional role of the land for economic activities comprise the land
use (Ramachandra et al., 2004), and these ecological systems are very different from non-urban
systems (Collins et al., 2000, Grimm et al., 2000). The ability to quantify and characterize
landscape structure is pre-requisite to the study of landscape function and change (Willeman et
al., 2008) particularly in urban ecosystems, where the presence of tree vegetation or green areas
is controlled by biophysical and ecological drivers (Pickett et al., 2001), however, the landscape
dynamics (patch and heterogeneity) is largely governed by the socio-economic drivers. While
urban vegetation generate a diverse set of ecosystem services of substantial significance for
human well-being (Bolund and Hunhammar 1999), the accelerating rate of urbanization
worldwide is changing landscape and the driving forces may include rapid growth rates of
population (Buyantuyev et al., 2010) and changing patterns of human settlements (Rutherford et
al., 2008). Hence the landscape dynamics are shaped by human activities and referred as a
coupled social–ecological system (Berkes and Folke 1998), where landscape changes are brought
by human influences operating at different spatial and temporal scales. Landscape features
(patch, landcover class, landscape mosaics) can be quantified using metrics or indices (Mc
Garigal and Marks, 2002) of the geographic area mainly larger natural landscapes (Roy and
Tomar, 2000), but also in urban landscape (Ji et al., 2006).
Fragility of Himalayan Mountains is subject to various natural (climatic & seismic) and
anthropogenic forces, however urban forests/vegetation of this mountainous landscape have not
been explored well. Urban forest structure is determined by urban morphology (availability of
space for vegetation), natural factors (amount and type of taxa likely to be found), and human
management system (intra-urban variations in configurations; Sanders, 1984). It is critical to
understand in what ways informally managed green space contribute to biodiversity functions in
urban settings of Himalayan region particularly for developing management policies. For
example, in Australia initially trees were commonly cleared as the urban areas developed in the
natural dominance of trees and forests, however, trees have been formally and informally reestablished in many of the cities for a wide range of reasons (Brack, 2002).
Kumaun Himalayan region has a long history of human settlements and convergence of villages
in towns/urban centers. Landscape changes are usually governed by socio-economic causes, such
as expanding and changing patterns of human settlements and accelerating urbanization. The
existence and quantum of urban taxa is influenced by the prevailing cultural practices and
environmental setting of the towns. This paper explores tree species diversity (as species
richness) in an urban landscape of Almora town, having a historical account, and analyzes
landscape pattern of occurrence of tree vegetation in the cultural landscape, i.e., fragmentation in
urban greens,
2. History of settlements and cultural evolution of town
Historically, Almora is located in the part of the Central Himalaya which falls in the ManasaKhanda section of the Skanda Purana; traditionally described as the land of lords and demons, is
also known as cultural heart of Kumaun region (Atkinson 1882). This region has a unique
topology and settlement history. Almora town has a history of cultural development as old as
capital city during Chand Dynasty of the Kumaun region. It has been known to be inhabited
during the pre-historic times by different rulers from Katyuris to Chands, Gorkhas and finally the
British. The landscape has undergone tremendous change since then. The town is surrounded by
different villages and hence has a typical rural-urban gradient.
The area covered by Almora town lies between 29 37 3 and longitude 79 40 20. The civil
and military stations (now cantonment area) were built on a bare saddle-shaped ridge running
from north-west to south-east with an average elevation ca. 1600m amsl (Atkinson 1882).
Almora has temperate climate with average rainfall of 1152 mm and has maximum & minimum
temperature of 30°C & 12°C in summer which ranges from 10°C & - 2°C during winter months
(VPKAS). In winters snow falls occasionally, but rarely lies beyond a few hours on the ground.
October and November are beautiful clear cold months and most of the fruit trees then loose their
leaves. March and April are generally marked by thunder-storms, but in all the summer months,
till the regular monsoon rain falls and a thick haze obscures all the view.
3. Methodology
3.1. Tree Species Richness: A detailed inventory of trees in each premise (individual house,
hotels, colonies, offices, schools, etc.) and areas (open, along the road, park, etc) of the Almora
Municipal town was done by the extensive field work following census method and locations
were geocoded through GPS. Ward boundary map of Almora town (obtained from Municipal
office) was used for segregation between areas and samples. Detailed analysis was carried out to
describe the floral composition of trees (family, genus, and species) considering one premise as
one sample and aggregation at ward level. The trees were also categorized according to
occurrence and uses (e.g., natural, fodder, ornamental, fruit and other species).
3.2. Land use/Land cover Mapping (LULC): High resolution (spatial resolution of 5m) satellite
image of LISS 4 (dated 28th October 2009) was obtained, and geometrically corrected (orthorectification with lambert conformal conic projection). On-screen visual interpretation was done
with the help of interpretation key (Table 1) and knowledge from field surveys. Ground truthing
was done for refining and verification and after detailed survey attributes were given to each
interpreted class for LULC map of Almora Municipal area. Unfortunately avenue
plantations/trees along the road do not provide much opportunity to map the road at this pixel
level due to overlap of canopy cover. Even at further higher resolution difficulty was faced in
certain segments of the road in the municipal area. Tree species were also categorized on the
basis of use and natural occurrence (natural, ornamental, fodder, fruits and others). Tree cover
was further classified either into exclusive dominance of species (pine, cedar or deodar) or mixed
species those can be discriminated by other attributes (evergreen/deciduous; mixed
Coniferous/broadleaf). In this area deciduous and evergreen elements dominate at different
places due to preferences/naturalness of a species (e.g., Toona ciliata, Aesculus indica, Juglans
regia, Celtis austrelis) hence separability between classes is higher which gives synoptic view of
distribution of tree elements. A single class as “Mixed” will suppress this information. To realize
the natural tree vegetation, the area forests adjacent to the town were also explored and
inventoried using phyto-sociological methods (Saxena and Singh 1982).
3.3. Landscape Analysis: The LULC map prepared for the town was analyzed for various
landscape attributes using FRAGSTATS (Garigal et al., 2002) and indices expressing the
attributes of composition and configuration of the landscape were used. This includes Class Area
(CA), Percentage of Landscape occupied (PLAND), Number of Patches (NP), Largest Patch
Index (LPI), Landscape Shape Index (LSI), Patch density (PD), Mean patch area, Range in patch
area (Max - Min) and Diversity indices were used following Garigal et al., 2002.
4. Results and Discussion
4.1. Tree diversity and LULC:
A great tree diversity (as richness) exists in the Almora town as apparent from 83 tree species
from 57 Genera of 35 Families (Table 2). Among the various families Rosaceae, Rutaceae, and
Moraceae were the dominant (having 11, 10 and 6 species each, respectively). Cultural practices
are predominant factor for holding such large tree diversity in the town area as evident by the
facts that (i) among the 57 genus recorded from the town, species richness was found maximum
in a fruit species i.e., Citrus (8 species) followed by fodder species (Pyrus 6 and Ficus 5 species),
(ii) maximum tree species are grown for fruit purpose (28 in number), and (iii) high number of
ornamental trees (11 species). Presence of natural vegetation in the area dominates in the
landscape as apparent by the total number of species (part of natural forests of the region, 13
species; Figure 1). A large number of species were grouped together in the category of ‘others’
with minor uses or no direct use (27 species). Comparing with three natural forests (Cantonment
forest, Forest near Hotel management Institute and Dollidana forest) adjacent to the town
illustrates that only 16 species (19% of the total reported species) occur in these forests. Thus the
urban landscape of the Almora town conserves more tree diversity than the surrounding areas
due to cultural practices. Among the different wards tree species richness was maximum (72) in
Laxmeshwar ward while was minimum in Muralimanohar and Sailakhola wards (34 in each
ward). These two wards have higher proposition of builtup area but are in smaller size than the
other wards of the town, however Laxmeshwar ward was one of the biggest ward of the town.
LULC map of the Almora town is given in Figure 2. Tree cover of the town includes either
exclusive dominance of species such as pine (7.1% of the total area) and cedar (3.4%), or mixed
species e.g., coniferous (pine, cedar, and cypress) (1.9%), broad leaf evergreen (0.5%), broad
leaf deciduous (15.1%), mixed broad leaf (11.6%) and mixed broad leaf-coniferous trees(13.6%,
Table 2). Pine is the dominant species of the Almora town covering an area 25.2 ha, while the
broadleaf deciduous species covers maximum area 53.82 ha (15.1%; Table 3).
LULC analysis illustrates that total tree cover (190.26 ha) with in the municipal limits was
53.8% of the total urban area, however non-tree areas (built-up, open area, play ground, shrubs,
and agricultural land) has a spatial extent of 166.39 hectares (~47 % of the total landscape, Table
3). However, various tree patches together occupy more than half of the landscape, human
activities (urbanization) dominate over naturalness. It is apparent from the fact that as an
individual land use built-up occupies maximum area in the town covering 28.9% of the entire
urbanized landscape. Spread of urbanization is well distributed over the landscape through
numerous uneven patches. Traditional traits of the development of the town are evident by the
presence of agriculture (1.0%) and occurrence of fodder species in different premises of town
(influence of village practices-maintaining livestock and crop cultivation). Distribution of open
areas without trees is also widespread in the landscape (13.29%) and comprise of barren /grassy
hill slopes.
4.2. Landscape Analysis:
Various landscape attributes of Almora town are given in the Table 4. Despite of having tree cover
in more than half of the town area, Almora urban area is highly heterogeneous as evident by (i)
total number of patches in an area of 3.5 km2 (i.e., 2516 of all the LULC), (ii) patch density (7.5
patches per km2), (iii) small size of the patch (mean patch area 0.141 ha), and (iv) a high Shannon
Wiener Index (2.02). Number of patches between different LULC varies from 15 (agriculture) and
675 (built up area). Patch density (per km2) in the Almora town varies from 4 (agriculture) to 189
(built up; Table 4). Human settlements are sporadically present all over the urban landscape as
reflected by highest number of patches and great variation in size among the patches of this class
(difference of 13.7 ha between minimum and maximum patch sizes). An interesting feature was
observed for patches of built up area and broadleaf deciduous trees. However, both the classes
have nearly same patch numbers (181 & 189, respectively), total area under former class is half of
the later (53.8 ha & 103 ha, respectively). This indicates a higher fragmentation of broadleaf
deciduous trees in small size patches but mostly of similar size (variation of 1.07 ha among the
smallest and largest patch) while this variation was much greater in case of settlements (~13 ha)
indicating greater concentration in some areas but present all over the landscape.
Among the tree cover classes broadleaf deciduous class has highest appearance (647 patches) due
to dominance of winter deciduous taxa in natural elements (Aesculus indica, Toona ciliata,
Populus ciliata) as well as cultivated diversity - fruit species (Juglans regia, Pyrus malus, P.
persica, P. pyrifolia), and fodder species (Grewia optiva, Celtis australis). Among the patches of
mixed trees, mixed coniferous and broadleaf has most common appearance on the landscape (230
patches) followed by mixed broadleaf (151 patches).
8
The elevation range of Almora town falls in the upper limits of habitat zone of Pinus roxburghii in
this region, hence pine occupies maximum area under a species exclusive dominance (25.2 ha) and
mixed in other tree cover classes. Another coniferous species (Cedrus deodara) is confined to
higher elevations of the town or in isolated areas within the settlements (conserved due to religious
significance or aesthetic purpose) as reflected by exclusive presence in high number of patches
(139) with average patch size of about 0.08 ha, hence occupying only ~12 ha area in the town.
Changes in the land cover and land use due to anthropogenic activities such as urbanization affect
the habitats and niches of different communities. Besides the human habitation, the town also
houses a great wealth of biodiversity (in this case trees) through cultural practices (cultivated) and
conservation of natural vegetation (elements of natural vegetation of the area) which creates and
provide habitats for various organisms, as apparent from very high tree diversity (83 species in an
area of 3.5 km2), however emergence and expansion of urban areas are often seen as a threat to the
biodiversity. With an increase in the area of the ward tree cover area was increasing (r2 = 0.97)
indicating dominance of trees in the open areas and concentration of human settlements in few
wards of the town. This is also apparent from weak relationship between built up area and area of
the ward (r2 = 0.7, Fig. 3A) which indicates uneven distribution of built up area in different ward.
But strong positive correlation (Fig. 3B) between the number of settlement (patches of built up)
and total area of the ward (r2 = 0.9) and between tree patches and area of the ward (r2 = 0.84)
indicates that sporadic settlement form of urbanization over a period of time has resulted in
fragmentation and segmentation of the overall landscape of the town into numerous small islands
of settlements and tree patches. This can have implications on the habitat and niches of different
communities and hence may affect the biodiversity of other life forms. Small patches will hold
9
fewer species as compared to an area of similar size in continuous habitat or larger patches those
will tend to hold more species as apparent from tree species richness in different sized wards.
Urbanized landscapes can be perceived as local environments for human well being, biodiversity
conservation and also as centers facilitating in-situ germplasm conservation, provided they are
planned and designed in such a way that they meet the needs of ever-expanding human population.
Sustainability of urban forests/vegetation depends on several factors including optimal canopy
cover for the town, uneven age distribution of tree population on the landscape, diversity in species
to sustain against various threats of monoculture, and presence of native/natural elements in the
landscape.
Acknowledgements
Authors are thankful to Ms Sheetal Chauhan & Ms Monika Rawat for detailed field work, and
Director of the institute for providing necessary facilities. Ministry of Environment & Forests,
Government of India is great fully acknowledgement for financial assistance.
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12
Tables
1. Interpretation key
2. Floristic details of trees found in Almora town.
3. LULC statistics of Almora town.
4. Landscape attributes of Almora town.
13
Table 1: Interpretation key
S.No.
1
2
3
4
5
6
7
8
9
10
11
12
Class name
Built-up area
Open area without trees
Playground
Pine
Deodar
Mixed Coniferous
Broadleaf evergreen
Broadleaf deciduous
Mixed broadleaf
Mixed broadleaf and coniferous
Shrub
Agricultural land
Tone/ colour
Light blue
Greenish blue
Grayish white
Blackish red
Deep blackish red
Reddish brown
Light red
Bluish red
Light blue
Red mix bluish
Light grey with red tinge
Pinkish red
14
Texture
Coarse & Mottle
Medium to smooth
Smooth
Soft but Coarse
Hard & Coarse
Coarse
Smooth to medium
Smooth to medium
Mottle
Soft but coarse
Coarse
Smooth
Table 2.Floristic details of trees found in Almora town.
S. No.
1.
2.
3.
Category
Angiosperms
Gymnosperms
Total Species
Families
33
3
36
Genus
53
4
57
Species
76
7
83
Table 3.LULC statistics of Almora town.
Classes
Tree cover
Pine
Deodar
Mixed Coniferous
Mixed Broad leaf
Broad leaf evergreen
Broad leaf deciduous
Mixed broad leaf and Conifer
Non-tree Areas
Built-up area
Open area without trees
Playground
Scrub
Agriculture
Area (ha)
190.24
25.20
11.99
6.63
41.57
1.87
53.82
49.16
166.38
103.03
47.43
6.54
5.92
3.46
15
% of Total Area
53.3
7.0
3.4
1.8
11.6
0.5
15.0
13.8
46.7
28.9
13.3
1.8
1.6
1.0
Table 4. Landscape attributes of Almora town.
Area
Pine
25.02
Patch
Density Mean
% of
Number
(Per
Area
Total
2
km )
(ha)
7.06
190
53.26
0.13
Deodar
11.99
3.36
139
38.97
0.08
1.78
0.50
15.94
Mixed Conifers
Broad leaf
evergreen
Broad leaf
deciduous
Mixed broad leaf
Mixed broad leaf
and conifers
Scrub
6.63
1.86
70
19.62
0.09
1.57
0.44
13.53
1.87
0.52
63
17.66
0.02
0.13
0.03
9.75
53.82
15.09
647
181.39
0.08
1.07
0.30
35.84
41.57
11.65
151
42.33
0.27
12.27
3.44
32.56
49.16
13.78
230
64.48
0.21
4.30
1.20
35.48
5.92
1.66
60
16.82
0.09
0.47
0.13
12.62
3.46
0.97
15
4.20
0.23
0.79
0.23
9.17
103.03 28.88
675
189.24
0.15
13.72
3.85
37.71
47.43
13.29
249
69.80
0.19
2.65
0.74
33.57
6.54
1.83
27
7.56
0.24
1.60
0.45
6.92
Class
Agriculture
Built-up area
Open area without
trees
Playground
ha
16
Range
(maxmin)
4.72
Largest
Patch
Index
Landscape
Shape
Index
1.32
18.60
Figures
1. Distribution of tree species based on ecological/commercial importance in the study
area.
2. Satellite based LULC map of Almora town.
3. Relationship between area of the wards and (A) area of Built-up and Tree cover, and
(B) Total Patch, and patches of Built-up and Tree Cover.
17
Natural
elements
17%
Other species
31%
Ornamental
species
12%
Fodder species
7%
Fruit speices
33%
Figure 1: Distribution of tree species based on ecological/commercial importance in the study
area.
18
Figure 2: Satellite based LULC map of Almora town.
19
40
35
Built-up Area
30
Area under Tree Cover
Area (ha)
2
R = 0.9749
25
20
2
R = 0.7021
15
10
5
0
0
10
20
30
40
50
60
70
Ward Area (ha)
A
600
R2 = 0.9585
Total Patch
500
Built-up Area Patch
Tree Patch
Number
400
R2 = 0.8473
300
200
2
R = 0.9077
100
0
0
10
20
30
40
50
60
70
Ward Area (ha)
B
Figure 3. Relationship between area of the wards and (A) area of Built-up and Tree cover, (B)
Total Patch, and patches of Built-up and Tree Cover.
20