Vegetation dynamics in response to human and climatic factors in the Tanzanian Coast
Herrieth MACHIWA1,2, Bo TIAN1, Dhritiraj SENGUPTA1, Qian CHEN1, Michael MEADOWS3,4,5, Yunxuan ZHOU1()
1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China 2. University of Dar es Salaam, College of Information and Communication Technologies, Department of Computer Science and Engineering, Dar es Salaam 33335, Tanzania 3. Key Laboratory of Geographic Information Science (Ministry of Education), School of Geographical Sciences, East China Normal University, Shanghai 200241, China 4. Department of Environmental & Geographical Sciences, University of Cape Town, Rondebosch 7701, South Africa 5. College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, China
This study of vegetation dynamics in the coastal region of Tanzania provides a fundamental basis to better understand the nature of the factors that underlie observed changes. The Tanzanian coast, rich in biodiversity, is economically and environmentally important although the understanding of the nature and causes of vegetation change is very limited. This paper presents an investigation of the relationship between vegetation dynamics in response to climate variations and human activities using Moderate Resolution Imaging Spectroradiometer (MODIS), Normalized Difference Vegetation Index (NDVI), meteorological, and Globeland30 Landsat data sets. Spatio-temporal trends and the relationship of NDVI to selected meteorological variables were statistically analyzed for the period 2000–2018 using the Mann-Kendall test and Pearson correlation respectively. The results reveal a significant positive trend in temperature (β>0, Z = 2.87) and a non-significant trend in precipitation (|Z|<1.96). A positive relationship between NDVI and precipitation is observed. Coastal Tanzania has therefore experienced increased temperatures and variable moisture conditions which threaten natural vegetation and ecosystems at large. Classified land cover maps obtained from GlobeLand30 were analyzed to identify the nature and scale of human impact on the land. The analysis of land use and land cover in the region reveals an increase in cultivated land, shrubland, grassland, built-up land and bare land, while forests, wetland and water all decreased between 2000 and 2020. The decrease in forest vegetation is attributable to the fact that most livelihoods in the region are dependent on agriculture and harvesting of forest products (firewood, timber, charcoal). The findings of this study highlight the need for appropriate land-use planning and sustainable utilization of forest resources.
. [J]. Frontiers of Earth Science, 2021, 15(3): 595-605.
Herrieth MACHIWA, Bo TIAN, Dhritiraj SENGUPTA, Qian CHEN, Michael MEADOWS, Yunxuan ZHOU. Vegetation dynamics in response to human and climatic factors in the Tanzanian Coast. Front. Earth Sci., 2021, 15(3): 595-605.
Land use for agriculture including paddy fields, irrigated and dry farmland, vegetation and fruit gardens, etc.
Grassland
Land covered by grasses mainly used for grazing
Forest
Natural and secondary forest covered with trees, including woodlands, dense and open forests
Shrubland
Land that is dominated by shrubs and bushes
Wetland
Land consisting of standing water bodies and wetland plants such as mangroves and salt marshes
Water
Land covered by water bodies such as rivers, lakes and ponds
Built-up land
Land that is modified by human activities including residential, industrial, transportation and other infrastructures
Bare land
Land which is typically not covered by any vegetation, i.e., bare soil, sandy beaches
Tab.1
Fig.2
Fig.3
Fig.4
Land Use
Year 2000
Year 2010
Year 2020
Change 2000–2010
Change 2010–2020
Land/ha
Percent/%
Land/ha
Percent/%
Land/ha
Percent/%
Land/ha
Percent/%
Land/ha
Percent/%
Cultivated land
923375.88
6.35
1356133.50
9.32
1744766.19
12.06
432757.62
2.98
388632.69
2.74
Forest
9063002.97
62.29
7917180.39
54.42
7596891.27
52.53
−1145822.58
−7.87
−320289.12
−1.89
Shrubland
50422.41
0.35
125711.10
0.86
121369.95
0.84
75288.69
0.52
−4341.15
−0.02
Grassland
4240074.78
29.14
4870028.79
33.48
4698764.10
32.49
629954.01
4.33
−171264.69
−0.99
Built-up land
89119.35
0.61
92005.20
0.63
121395.69
0.84
2885.85
0.02
29390.49
0.21
Wetland
126976.86
0.87
124706.70
0.86
127366.56
0.88
−2270.16
−0.02
−252073.26
0.02
Water
54883.17
0.38
52965.09
0.36
40192.20
0.28
−1918.08
−0.01
−12772.89
−0.09
Bareland
1399.59
0.01
8951.22
0.06
11739.15
0.08
7551.63
0.05
2787.93
0.02
Total
14549255.01
100
14547681.99
100
14462485.11
100
–
–
–
–
Tab.2
Land Use/cover
Year 2010
Bareland/ha
Built-up/ha
Cultivated/ha
Forest/ha
Grassland/ha
Shrubland/ha
Water/ha
Wetland/ha
Year 2000
Bareland
517.79
0.06
2.69
7.86
131.46
25.31
302.17
3.87
Built-up
24407.70
4504.51
1043.26
580.03
1.91
0.27
91.27
Cultivated
1.28
1021.13
162886.29
56354.72
35782.97
501.43
59.66
107.61
Forest
28.55
789.60
259756.60
638772.65
144135.89
5382.81
187.72
313.64
Grassland
196.13
565.35
104977.66
74894.20
188192.49
18088.20
2512.36
1567.12
Shrubland
35.83
0.10
22.11
548.75
787.76
70.44
0.28
Water
157.65
1.81
200.33
175.74
4628.46
66.06
6909.19
254.62
Wetland
20.66
0.65
70.09
741.43
527.28
30.72
622.84
10393.70
Total
957.89
26786.31
532398.26
772011.97
374527.34
24884.20
10664.645
12732.10
Tab.3
Land Use/cover
Year 2010
Bareland/ha
Built-up/ha
Cultivated/ha
Forest/ha
Grassland/ha
Shrubland/ha
Water/ha
Wetland/ha
Year 2010
Bareland
780.89
4.08
2.36
5.95
140.11
34.47
1.77
24.58
Built-up
3.45
28809.37
5001.11
37.45
56.79
7.37
0.88
2.04
Cultivated
5.00
1080.70
384978.71
60201.11
36100.10
700.66
37.02
336.83
Forest
40.74
905.00
207259.33
574708.65
3576.06
6007.34
133.54
70.25
Grassland
207.00
801.00
105012.11
85056.21
201011.40
422.37
73.52
1625.70
Shrubland
47.00
120.63
206.30
927.10
418.62
30803.71
34.35
23.82
Water
168.00
5.15
176.77
96.00
59.83
40.03
5700.78
42.65
Wetland
32.00
89.06
64.00
658.92
38.62
14.22
55.69
9716.61
Total
1284.08
31814.98
702700.69
721691.39
241401.52
38030.17
6037.55
11842.49
Tab.4
Administrative region
Rural/urban coastal regions population/%
1988
2002
2012
Tanga
82.4/17.6
81.6/18.4
78.4/21.6
Pwani
85.2/14.8
78.9/21.1
67.2/32.8
Dares Salaam
10.4/89.6
6.1/93.9
0/100
Lindi
85.0/15.0
84.0/16.0
81.3/18.7
Mtwara
85.6/14.4
79.7/20.3
77.1/22.9
Tab.5
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