3.1 Vegetation Cover
The figures given below depict the declining vegetation cover (green color) and increasing non-vegetation cover (yellow color) in the East-Khasi hill district of Meghalaya in every five year since 1993. Figure 7 and table 4 showing the depicts 85.58% of area of the East Khasi hill dominated by vegetation cover. In the course of the five year in 1998, the vegetation cover of East Khasi hills district decreased from 235177 hectares in 1993 to 226916 hectares in 1998. In 1998, 82.58 % area is covered by vegetation. Further, in five years, in 2004 the vegetation declined to 225118 hectares. In terms of percentage, the total area covered by vegetation reached to 81.92%. In 2008, the vegetation cover decreased to 222229 hectares in absolute terms and 80.87 in percentage terms.A major decline in the vegetation cover can be noticed in 2013, 2018 and 2022. From 2008 to 2013, the vegetation cover declined from 80.87 in 2008 to 77.47 in 2013, to 70.94 % in 2018 and to 67.75 % in 2023. Even the Graph shows that the significant declines in vegetation cover from 2013 to 2022 (figure 8).
Table 4 Temporal vegetation cover scenario of East Khasi Hills district
Year
|
Area (hec)
|
Area (%)
|
1993
|
235177
|
85.58
|
1998
|
226916
|
82.58
|
2004
|
225118
|
81.92
|
2008
|
222229
|
80.87
|
2013
|
212894
|
77.47
|
2018
|
194929
|
70.94
|
2022
|
186188
|
67.75
|
3.1.1. Vegetation Cover Change
The below table shows the percentage of vegetation cover and the decrease in vegetation cover area percentage wise of East Khasi Hills of Meghalaya in every five years. As per table 5 the highest decline in vegetation cover is noticed between 2013-2018 is 6.54 %, followed by 2018-2022 is 3.18%. The lowest decline is experienced in the period between 1998 to 2004 is 0.65%. The bar graph plots the percentage decline in area of vegetation cover over five years’ time periods from 1993-2022 (figure 9).
Table 5 vegetation cover change analysis of the five years interval
Year
|
1993
|
1998
|
2004
|
2008
|
2013
|
2018
|
2022
|
Area (%)
|
85.58
|
82.58
|
81.92
|
80.87
|
77.47
|
70.94
|
67.75
|
3.1.2. Elevation wise Vegetation Cover Change
The vegetation cover change analysis of the five years interval and Table 6 shows the elevation wise vegetation cover change in East Khasi hills of Meghalaya. Elevation less than 200 m the percentage of vegetation cover declined from 8.46 % in 1993 to 7.54 % in 2022. For 200-400 m elevation the major decline in vegetation cover noticed between 2013-2018, from 6.02% to 5.69%.
Table 6 Elevation wise vegetation cover change
Year
Elevation (m)
|
1993
|
1998
|
2004
|
2008
|
2013
|
2018
|
2022
|
<200
|
8.46
|
8.30
|
8.20
|
8.25
|
8.05
|
7.84
|
7.54
|
200-400
|
6.04
|
5.99
|
6.12
|
6.05
|
6.02
|
5.69
|
5.75
|
400-600
|
6.66
|
6.64
|
6.78
|
6.69
|
6.69
|
6.55
|
6.50
|
600-800
|
6.94
|
6.94
|
7.10
|
6.99
|
6.99
|
6.88
|
6.70
|
800-1000
|
7.97
|
7.84
|
7.76
|
7.71
|
7.60
|
7.38
|
7.31
|
1000-1200
|
9.99
|
9.38
|
9.47
|
9.37
|
9.24
|
8.53
|
8.72
|
1200-1400
|
10.20
|
9.33
|
9.35
|
10.04
|
9.49
|
7.83
|
7.81
|
1400-1600
|
10.48
|
9.59
|
9.74
|
9.77
|
9.19
|
7.41
|
7.51
|
1600-1800
|
15.08
|
14.81
|
13.61
|
12.85
|
11.24
|
10.17
|
8.11
|
>1800
|
3.76
|
3.75
|
3.80
|
3.16
|
2.98
|
2.66
|
1.81
|
In figure 10 shows the drastic decrease of vegetation cover above 1400m elevation and below 1400m have been shows the minimum decreasing trend over EKH district of Meghalaya. Analyzing overall changes in vegetation cover during the period 1993 to 2022. The maximum area decreasing in above 1000m elevation 14.28% and below the 1000m elevation shows the change of 2.5%. This change represents the high human influence in this elevation and maximum geographical area covered (62.54%) by 1000m above elevation.
3.1.3. Slope wise Vegetation Cover Change
Table 7 presents a time-series analysis of the vegetation cover percentage across different slope categories (measured in degrees) in East Khasi Hills for the year’s temporal years.The vegetation cover percentage in Very Gentle (0-5) category has decreased over the years, from 9.06% in 1993 to 5.81% in 2022. This suggests a notable decline in vegetation on very gentle slopes.A decreasing trend is observed in Gentle (5-10) category as well, with vegetation cover declining from 15.95% in 1993 to 10.89% in 2022. This indicates a reduction in vegetation on slopes with a moderate incline.The vegetation cover percentage on Moderate (10-15) slopes has decreased from 21.82% in 1993 to 17.95% in 2022. This indicates a reduction in vegetation on slopes with a relatively steeper incline.The vegetation cover on Steep (25-35) slopes has experienced a decline from 15.60% in 1993 to 14.21% in 2022.
Table: 7 Slope wise vegetation cover change
|
1993
|
1998
|
2004
|
2008
|
2013
|
2018
|
2022
|
Very Gentle (0-5)
|
9.06
|
8.40
|
7.84
|
7.80
|
7.49
|
7.42
|
5.81
|
Gentle (5-10)
|
15.95
|
15.03
|
14.99
|
14.32
|
13.72
|
11.43
|
10.89
|
Moderate (10-15)
|
14.63
|
14.00
|
13.98
|
13.68
|
12.91
|
11.23
|
10.80
|
Moderately Steep (15-25)
|
21.82
|
21.28
|
21.23
|
21.20
|
19.86
|
18.38
|
17.95
|
Steep (25-35)
|
15.60
|
15.42
|
15.45
|
15.45
|
15.00
|
14.36
|
14.21
|
Excessively Steep (>35)
|
8.52
|
8.44
|
8.43
|
8.42
|
8.46
|
8.11
|
8.09
|
This suggests a modest reduction in vegetation on steeper terrain. The Excessively Steep (>35)slopes exhibit a varying trend, with a slight increase in vegetation cover from 8.52% in 1993 to 8.09% in 2022 after experiencing a decline in the intervening years (figure 11).The declining trends in most slope categories suggest potential environmental changes or human impacts affecting vegetation distribution on different terrains in the region. Understanding these variations is crucial for informed land management and conservation strategies.
3.2. Land Surface Temperature
3.2.1. Winter Season
Table 8 provides a comparative analysis of Ambient Temperature (AT) and Land Surface Temperatures (LST) for the winter season. Additionally, it calculates the difference between AT and LST, indicating the variation between these two parameters.The minimum AT temperature ranges from 6.9°C in 2018 to 9.25°C in 2008. The maximum AT temperature varies from 8.45°C in 1993 to 9.25°C in 2008.The LST exhibits a minimum value of 16.65°C in 2004 and a maximum of 19.7°C in 2018. The temperature differences between AT and LST are calculated for each year. The minimum difference occurs in 2018 with 9.95°C, while the maximum difference is observed in 2013 with 15.3°C.The fluctuation in temperature differences over the years suggests dynamic interactions between atmospheric and land surface temperatures, potentially influenced by climatic variations or local environmental changes.
Table 8 Temporal Land Surface Temperature (LST) map of East Khasi Hills
|
Minimum
|
Maximum
|
Deference of AT and LST.
|
Year
|
AT
|
LST
|
AT
|
LST
|
Minimum
|
Maximum
|
1993
|
8.45
|
10.60
|
17.70
|
33.00
|
2.15
|
15.3
|
1998
|
9.25
|
13.20
|
18.75
|
29.80
|
3.95
|
11.05
|
2004
|
8.50
|
16.65
|
17.30
|
31.73
|
8.15
|
14.43
|
2008
|
8.75
|
18.00
|
17.40
|
31.00
|
9.25
|
13.6
|
2013
|
7.30
|
17.65
|
17.30
|
30.45
|
10.35
|
13.15
|
2018
|
6.90
|
18.17
|
19.70
|
29.65
|
11.27
|
9.95
|
2022
|
8.60
|
19.00
|
19.42
|
31.43
|
10.4
|
12.01
|
Figure12 and 13 present a comprehensive view of AT and LST over several years, highlighting the variations and temperature differences between these two parameters. Understanding these differences is crucial for interpreting local climate dynamics and their potential implications for the environment (figure 14).
3.2.2. Summer Season
The lowest AT temperature is recorded in 2022, measuring 16.80°C and the highest AT temperature is observed in 2013, reaching 18.05°C.The lowest LST occurs in 2018, registering 20°C and highest noted in 2022, reaching 35.4°C (table 9).The calculated differences between AT and LST provide insights into the thermal contrast between the atmospheric boundary and land surface (table 8). The minimum difference is 2.4°C in 2018, while the maximum difference is 13.24°C in 2022 (figure 15 and figure 16).
Table 9 Temporal Land Surface Temperature (LST) map of East Khasi Hills
|
Minimum
|
Maximum
|
Deference of AB and LS Temp.
|
Year
|
AB Temp.
|
LS Temp.
|
AB Temp.
|
LS Temp.
|
Minimum
|
Maximum
|
2004
|
17.55
|
23.55
|
23.30
|
31.63
|
6
|
8.33
|
2008
|
17.75
|
23
|
23.15
|
32
|
5.25
|
8.85
|
2013
|
18.05
|
24.39
|
24.85
|
33.77
|
6.34
|
8.92
|
2018
|
17.60
|
20
|
23.90
|
32.21
|
2.4
|
8.31
|
2022
|
16.80
|
22.49
|
22.16
|
35.4
|
5.69
|
13.24
|
The fluctuation in temperature differences over the years indicates dynamic interactions between the atmospheric boundary and land surface temperatures, potentially influenced by changes in environmental factors.Monitoring AT and LST and their differences is essential for understanding the complex dynamics of the Earth's surface-atmosphere interactions.Variationsin these temperatures can have implications for local climate, ecology, and human activities, making this data valuable for scientific research and environmental monitoring.These variations are crucial for understanding the local climate dynamics and their potential impacts on the environment (figure 17).
3.3. Comparative analysis of vegetation cover change and Climate Factor
The provided data presents a comparative analysis of Average Temperature (AT), Average Land Surface Temperature (LST), and Vegetation Cover Percentage over the years 1993, 1998, 2004, 2008, 2013, 2018, and 2022. The Average Temperature fluctuates over the years, ranging from 12.3°C in 2013 to 14.0°C in 1998 and 2022.The variation in Average Temperature suggests temporal changes in the region's climate, potentially influenced by atmospheric conditions, geographical factors, or climate cycles. The Average LST exhibits variability, with a noticeable increase from 21.8°C in 1993 to 25.2°C in 2022 (table 10). Rising LST values may indicate changes in land surface conditions, urbanization, or altered thermal characteristics, emphasizing the need for further investigation into local environmental factors.Vegetation Cover shows a declining trend from 85.6% in 1993 to 67.8% in 2022 (figure 18). As LST increases, vegetation cover tends to decrease. This pattern suggests a potential correlation between land surface temperature and vegetation dynamics.The interplay between Average Temperature, Average LST, and Vegetation Cover Percentage reveals potential environmental changes that warrant further investigation for sustainable land management and conservation efforts.
Table 10 Comparative analysis of the VC and climate
|
1993
|
1998
|
2004
|
2008
|
2013
|
2018
|
2022
|
Average Temp (˚C)
|
13.1
|
14.0
|
12.9
|
13.1
|
12.3
|
13.3
|
14.0
|
Average LST (˚C)
|
21.8
|
21.5
|
24.2
|
24.5
|
24.1
|
23.9
|
25.2
|
Vegetation Cover (%)
|
85.6
|
82.6
|
81.9
|
80.9
|
77.5
|
70.9
|
67.8
|