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Dehing Patkai! Amazon of the East

An analysis of Dehing Patkai Wildlife Sanctuary on Google Earth Engine

Dehing Patkai popularly referred to as “The Amazon of East” located in the Upper Assam, India stretches for over roughly 600 square kilometers and comprises three large blocks of forests (Jeypore, Upper Dehing West Block, and Upper Dehing East Block) and several forest fragments. The forest is classified as a lowland Tropical Wet Evergreen Forest (Dipterocarpus-Mesua). Due to its biodiversity and significance for elephant habitat, parts of the landscape are recognized as Dehing Patkai Elephant Reserve and 111.19(sq.) km is protected as the Dehing Patkai Wildlife Sanctuary since June 13, 2004. There is a second largest tributary of the river Brahmaputra that flows through it named "Dihing", and "Patkai" is the hill on the foot of which the river flows so that's what the name Dehing Patkai resembles. It is the largest surviving perennial rainforest in entire East India.

Fauna

Source: Dehing Patkai Elephant Reserve

Due to the towering Hollong and Mekai trees, that provide a habitat to countless species. This makes spotting a lot of animals quite difficult, but it isn't impossible. The sanctuary’s most ubiquitous inhabitant is the Asian elephant. The mega-herbivore can be seen in herds as well as alone, and is considered a sight to behold, but also one to be wary of, especially for travelers on foot. Dehing Patkai sanctuary is relatively small, but it is home to a number of mammals, including rarities like the Malayan sun bear, binturong, crab-eating mongoose, marbled cat, golden cat, fishing cat, and clouded leopard. the forests have one of the largest assembles of wild cats. Some of the more commonly seen mammals such as the barking deer, Assamese macaque, capped langur, tree shrew, and the famed hoolock gibbons. As many as 47 species of mammals, 50 species of snakes, 13 species of lizards, a few rare and threatened turtle species, more than 350 species of butterflies. Also, Dehing Patkai was the first place in the world to have the presence of seven different species of wild cats in the world -tiger, leopard, clouded leopard, leopard cat, golden cat, jungle cat, and marbled cat.


Flora

Dehing Patkai has hundreds of plant species which range from the Dipterocarpus retusus, occupying the top canopy of the forest at heights of 50 m, to Mesua ferrea and Vatica lanceaefolia, which dominate the middle canopy, and a number of woody shrubs such as Saprosma ternatum, Livistonia jenkinsiana, and Calamus Erectus, which constitute the undergrowth.

Source: By Debuapriyo(wikipedia)

Dipterocarpus retusus or Hollong, the state tree of Assam dominates the forest while the forest floor is home to charismatic ground orchids. Some of the important tree species found in the forest area are - Hollong, Mekai (Shorea assamica), Dhuna, Nahar, Gurjan (Dipterocarpus tubinatus), Samkothal, Outenga (elephant apple) different species of Ficus, etc. It is also an important biodiversity spot for its range of orchid species. There are around 107 species of orchids in this region. Some of the orchids found in this region are Bulbophylum ebulbum, Chrysoglossum erraticum, Chrysoglossum robinsonii, Eria connate, E. pudica, Zeuxine clandestine, Hetaeria affinis, Thelasis pygmaea, Taeniophyllum crepidiforme, etc.

The tree "Hollong" can reach a height of 150 feet and is one of the tallest trees in Assam and Arunachal Pradesh.


Analyzing the Dehing Patkai region on Google Earth Engine

Lets us have a look at the forest cover change in the region of Dehing Patkai from the past many years. With the help of Google Earth Engine, we can easily have a look at any region of interest and gain an insight into the changes taking place to be its forest cover, Surface Temperature, Climate, Weather, etc. with help of a presently available large number of datasets containing several bands, and with a quite good resolution.


Forest Cover Change(Deforestation)

Proceeding with the initial step i.e., importing the respective dataset and then selecting the required bands. Also, from beforehand the shapefiles of the region of interest(ROI) should be imported or the ROI has to be selected with the area and imported in the code editor.

Dataset: Here, we have used the `Hansen Global Forest Change v1.7 (2000-2019)` which is a result of time-series analysis of Landsat images in characterizing global forest extent and change. It contains several bands out of which we are only going to use the `treecover`, `loss`, and `gain` band.

Step1: Creating the ROI polygons, which will be by default imported in the present code editor.

Step2: Writing the scripts.

var gfc2019 = ee.Image("UMD/hansen/global_forest_change_2019_v1_7").clip(roi_Dehing_Patkai);

// Selecting the interested bands from the available bands
var treeCover = gfc2019.select(['treecover2000']);
var lossImage = gfc2019.select(['loss']);
var gainImage = gfc2019.select(['gain']);

// Add the tree cover layer in green.
Map.addLayer(treeCover.updateMask(treeCover),
    {palette: ['000000', '00FF00'], max: 100}, 'Forest Cover');

// Add the loss layer in red.
Map.addLayer(lossImage.updateMask(lossImage),
            {palette: ['FF0000']}, 'Loss');

// Add the gain layer in blue.
Map.addLayer(gainImage.updateMask(gainImage),
            {palette: ['0000FF']}, 'Gain');

In the above script, we have defined the color of the `treecover` as "00FF00" which is green. The loss in the vegetation or forest cover will be represented as "FF0000" i.e., red and lastly, the gain in the vegetation will be represented with blue color.

After clicking on the Run this is what the generated output will look like.
Various Ranges and Reserves of the Dehing Patkai region

In the above analysis, we can see that in the east of the reserves there have been some portion in red which is resembling forest loss and the deforestation taking place in it. Also, some portion of the west, near the Jeypore area, is depicting the massive loss of vegetation. There is also growth or increase in some portion of the forest, which has been depicted in blue color.


Forest Canopy Height analysis in NE-Region/Dehing Patkai

Source: wisegeek.com/what-is-the-forest-canopy

The forest canopy is the uppermost layer of a forest, characterized by the crowns of the trees and a handful of emergent specimens with heights that shoot above the canopy. The canopy is critical to a forest's well-being, and it provides habitat to a wide range of plants and animals. In fact, the canopy is so unique that some organisms spend their entire lives there, never venturing down to the ground. The Dehing Patkai sanctuary is blessed with exotic species of canopy trees. The orchids and bromeliads are spread all over the rainforest. Some important species of trees here are hollang, mekai, dhuna, nahar, bheer, nahor, and au – tenga (elephant apple).

 

Now, to proceed with the analysis as usual first of all we will need to import the dataset, so we are going to use the `Global Forest Canopy Height, 2019` dataset. This time we have built an external GEE application to perform the analysis, for analyzing the different regions of Assam along with the Dehing Patkai region.

For real-time Analysis visit: App Link

Experiment with different tools of the App

Here we have used different pallet colors to differentiate the canopies' heights. As well as different labels, widgets, and tools are added for more user interactivity. On visiting the app this the analysis which we get to see.

Forest Canopy Height Analysis

In the above depiction, a whiter area or lacks of shades of green areas represents the less or no canopies trees present in that area. But, the darker shades of greener areas represent that there is more number of taller trees. Also with this analysis, we can say that Assam and all the NE-Region of India are richer in Vegetation and Forest Areas as compared to other parts of the country. If we have a look at the heights of the canopies height in different regions of Assam.

A `legend` Panel is also been added for reference. Which depicts that some of the major portions of the upper Assam area are full of vegetation with trees exceeding the height of 30m or above. And most of the areas near the river bank are more bounded to whiter or lighter color which depicts that most of the population of Assam is habitat close to the river.



If we zoom in on the Dehing Patai Wildlife Sanctuary region.

Different Regions of Dehing Patkai

We can see very dark green shades which resemble very dense vegetation in that area. Also, a river flows through the sanctuary, known as the `Dihing` river. which helps in satisfying the quest of wild elephants and other animals. Also due to its dense forest which is why it is counted in one of India’s most important rainforests.

 

Why in News?

Source: https://thenewsmill.com/

Dehing Patkai landscape has been a site for legal and illegal coal mining for many years. Recently in April 2020, a coal mining project was approved by the National Board for Wildlife of India which allowed the use of 98.59 hectares of land of the Sanctuary for coal mining by Coal India Limited. This decision was challenged by environmental groups from Assam and other parts of the country, which highlighted the rich biodiversity harbored in the Dehing Patkai landscape. It is feared that drilling, blasting, extraction, transportation and crashing operations, noise pollution, etc. may damage the environment and ecology to an unacceptable extent. It may destroy the flora of Dehing-Patkai; and loss of animal habitat leading to man-animal conflicts vis a vis man-elephant conflict. As a result of these awareness campaigns and protests, the North Eastern Coalfields (NEC), temporarily halted all of its operations in the region from June 3, 2020. Also, the Assam government has decided to upgrade Dehing Patkai Wildlife Sanctuary into a National Park, after which it will be the sixth national park in Assam, the other five being Kaziranga, Nameri, Manas, Dibru-Saikhowa, and Rajiv Gandhi Orang National Park. After being converted to a National Park (i) the area will be exclusively designated by the government for the conservation of wildlife and biodiversity due to its natural, cultural, and historical significance. (ii) Human activities are strictly prohibited in the National Parks and many more protections and restrictions will be incorporated.

 

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Conclusion:

Link to the scripts and datasets used in this analysis:

  1. Forest Cover Change(Deforestation) Analysis:

  2. Forest Canopy Height Analysis:

Since day by day, we are losing many trees and somehow resulting in the destruction of mother nature and creating a disturbance and chaos to the wildlife. Regions like Dehing Patkai should be protected at any cost. Though after so much care and protection the Dihing Patkai Reserve Forests, especially Saleki has been widely threatened by an elaborate chain of coal mafias, timber thieves, poachers, and illegal foreign settlers which altogether deprive the forest of its richness and greatly impacts the ecosystem. We can hope that after the govt. converts the Wildlife sanctuary into a National Park the forest will be protected and Illegal & Legal coal mining takes a halt. Also, In our analysis, we have noticed an interesting fact that though there has been deforestation in some portions, there is also an increase in the vegetation in different sections of the forest.


If you have enjoyed reading this article or gained some insights from it please go through this article Link as well, where different analysis is performed on Google Earth Engine.

I frequently publish article/blog in domains like Data Science/ML/DL, connect with me on GitHub & LinkedIn.

References:

[1] https://en.wikipedia.org/wiki/Dehing_Patkai_Wildlife_Sanctuary

[2] https://blog.codepth.com/coal-mining-in-the-dihing-patkai-a-quest-to-save-the-last-surviving-amazon-of-the-east/

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