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Meet The Trees of Bengaluru: BBMP Tree Census Data Analysis

January 22, 2025

Bengaluru loves its trees! India hasn’t had its human population census in 14 years now, but here’s our city, doing a tree census. The priorities are clear. I was born and (mostly) live here, and needless to say, these trees are a huge part of my life. Obviously, I wanted to get my hands on this data and see what it says.

A Bangalore Mirror article from November 2024 says that the census data for about 3 lakh trees is accessible at a certain Tree Census Dashboard at the URL https://kgis.ksrsac.in/test/. As expected, the URL presented me with a login gate, and I could not access the data. However, the data was accessible on the OpenCity Urban Data Portal. I downloaded this dataset and ran some exploratory data analyses on it. The data consists of 2,86,780 trees with the species name, zone name, ward number, and geographical coordinates of each tree. As per the news article above, this data is only partial, and more than 15 lakh trees are yet to be counted.

I’m presenting my findings below.

Index

  1. City-Wide Tree Density
  2. Zone-Wise Tree Distribution
  3. Tree Species Distribution
  4. Popular Trees By Zone
  5. Unidentified Trees
  6. Conclusion

City-Wide Tree Density

I divided the city map into small hexagonal bins using Uber’s H3 grid system. Using the geographical coordinates of each tree, I counted how many trees fell into each bin. The result is a heatmap of surveyed tree coverage in the city:

BBMP Tree Census Density Map

Trees in the data are not evenly distributed across the city. They rather appear in small clusters, suggesting that the survey may be ongoing area-wise. This map does not seem to represent the green cover distribution in Bengaluru yet.

Zone-Wise Tree Distribution

The next thing I explored was how the surveyed trees were spread out across the zones. BBMP has 8 zones, namely East, West, South, Rajarajeshwari Nagar, Mahadevapura, Bommanahalli, Yelahanka, and Dasarahalli.

NOTE: There were no data points from Dasarahalli in this dataset.

By counting the number of trees in each zone and dividing it by the sq. km. area of that zone, I was able to compute the tree density for the zones. This is shown below, as a map and in a table.

BBMP Tree Census Zone-Wise Density Map

Zone Total Surveyed Trees Trees Per Sq. km
South 58652 961
Rajarajeshwari Nagar 90205 779
Bommanahalli 50096 513
East 29803 325
West 13581 272
Mahadevapura 33936 198
Yelahanka 10507 106
Dasarahalli 0 0

As of now, South and Rajarajeshwari Nagar zones are leading the tree density table, while Yelahanka has the least number of trees per sq. km.

Tree Species Distribution

The data also had a ‘TreeName’ column with the scientific name of each tree. This led me to analyze the diversity of tree species.

The data had mentions of 233 different species of trees, excluding the trees labeled as ‘Others’, which I refer to as ‘unidentified trees’ and discuss in a later section. Unidenfitied trees accounted for 14% of the total. The full list of trees is available here. The most common trees (greater than 1% of total) are shown in the table below:

Tree Name Common Name Count Percentage
Pongamia Pinnata (L.) Pierre Honge 68982 24%
Others - 39565 14%
Swietenia Mahagoni (L.) Jacq. American Mahogany 16313 6%
Tabebuia Rosea (Bertol) Dc. Rosy Trumpet 9690 3%
Saraca Asoca (Roxb.) De Wilde Ashoka Tree 8523 3%
Cocos Nucifera L. Coconut Tree 6597 2%
Peltophorum Pterocarpum (Dc.) Back. Ex K. Heyne Yellow Flame Tree 6232 2%
Markhamia Lutea (Benth.) K.Schum Nile Trumpet 6099 2%
Terminalia Catappa L Indian Almond 6052 2%
Wrightia Tinctoria (Roxb.) R. Br Pala Indigo 5967 2%
Samanea Saman (Jacq.) Merr. Rain Tree 5828 2%
Acacia Auriculiformis Cunn. Ex Benth Earleaf Acacia 4865 2%
Roystonea Regia (H.B.K) O. F. Cook Royal Palm 4013 1%
Mangifera Indica L. Mango Tree 3972 1%
Ficus Benghalensis L. Banyan Tree 3907 1%
Azadirachta Indica A. Juss. Neem / Margosa 3896 1%
Ptychosperma Macarthuri Nichols Macarthur Palm 3865 1%
Delonix Regia (Bojer Ex Hook.) Raf. Flame Tree 3718 1%
Eucalyptus Tereticornis Sm. Nilgiri Tree 3582 1%
Hydristele Wendlandiana (C. Moore & F. Muell.) H. Wendl. & Drude Wendland’s Palm 3579 1%
Spathodea Campanulata P. Beauv African Tulip Tree 3354 1%
Syzygium Cumini (L.) Skeels Jamun Tree 3322 1%
Grevillea Robusta Cunn. Ex R. Br. Silver Oak 3303 1%
Thespesia Populnea Indian Tulip 2963 1%
Millingtonia Hortensis L.F Indian Cork Tree 2887 1%

Pongamia pinnata (Honge) single-handedly accounts for about a quarter of the data. No other tree species is above 6% of the total. Opencity has a similar analysis, and they say this is a pretty diverse distribution.

Popluar Trees By Zone

Combining the above two analyses, I looked at which are the most popular trees in each zone. The top 3 trees in each zone are shown below:

Zone TreeName Common Name Count
Bommanahalli Pongamia Pinnata (L.) Pierre Honge 16877
  Tabebuia Rosea (Bertol) Dc. Rosy Trumpet 2588
  Swietenia Mahagoni (L.) Jacq. American Mahogany 2375
       
East Pongamia Pinnata (L.) Pierre Honge 3884
  Markhamia Lutea (Benth.) K.Schum Nile Trumpet 3639
  Swietenia Mahagoni (L.) Jacq. American Mahogany 2444
       
Mahadevapura Pongamia Pinnata (L.) Pierre Honge 4501
  Tabebuia Rosea (Bertol) Dc. Rosy Trumpet 1706
  Markhamia Lutea (Benth.) K.Schum Nile Trumpet 1412
       
Rajarajeshwari Nagar Pongamia Pinnata (L.) Pierre Honge 33877
  Wrightia Tinctoria (Roxb.) R. Br Pala Indigo 5471
  Acacia Auriculiformis Cunn. Ex Benth Earleaf Acacia 4446
       
South Pongamia Pinnata (L.) Pierre Honge 7182
  Swietenia Mahagoni (L.) Jacq. American Mahogany 4662
  Ptychosperma Macarthuri Nichols Macarthur Palm 3302
       
West Pongamia Pinnata (L.) Pierre Honge 2114
  Swietenia Mahagoni (L.) Jacq. American Mahogany 1614
  Saraca Asoca (Roxb.) De Wilde Ashoka Tree 1142
       
Yelahanka Acacia Nilotica (L.) Del. Subsp. Indica (Benth.) Brenan Babul / Gum Arabic Tree 1060
  Pongamia Pinnata (L.) Pierre Honge 547
  Roystonea Regia (H.B.K) O. F. Cook Royal Palm 299

Pongamia pinnata tops in each zone, except Yelahanka, where it is Acacia nilotica (Babul/Gum Arabic Tree). It is well adapted to dry weather, and this could be a possible explanation of its popularity in Yelahanka.

Unidentified Trees

Around 14% of the trees in the dataset were labeled as ‘Others’ and it is not yet known whether the species names for these trees will be made available. To dig deeper, I determined the zone-wise distribution of unidentified trees, shown below:

Zone Unidentified Trees % Unidentified
Yelahanka 7545 72%
Mahadevapura 10380 31%
Bommanahalli 9820 20%
Rajarajeshwari Nagar 6701 7%
South 3716 6%
West 517 4%
East 886 3%

While Mahadevapura has the highest number of unidentified trees, Yelahanka tops the list when we see it percentage-wise. Yelahanka has only ~10,000 of the around 3 lakh trees surveyed, and only ~3,000 of these have been identified. This could either suggest that most trees here are wild and diverse or that there may be operational or skill bottlenecks leading to trees not being identified. Or it could be that the identification is being done by a common off-field team, and they haven’t gotten around to the Yelahanka data yet. This should hopefully be clear when the final data is published.

Conclusion

A tree census by BBMP in Bengaluru is a first-of-its-kind activity, and this is my analysis of the data I could procure. My motivation to do this is my love for the city and its trees (maybe a bit of my love for number crunching too). Special thanks to OpenCity for hosting the data I used in the analysis: the tree census dataset and the BBMP zone boundaries map.

As mentioned earlier, the census is far from complete, and this analysis only gives us preliminary insights. BBMP has not either completed the census or published the full dataset. Whenever the full data is publicly available, I hope to update this analysis.

I used Python for the analysis, and the code is on my GitHub. I’m also exploring building software tools/apps for GIS data analysis. If you have any suggestions or requirements, please email me.