Tree species classification using very high reslolution satellite imagery for Da'an Park

 

There are more than 60,000 tree species Worldwide, and they could be grouped into two primary categories: Deciduous tree and Coniferous trees.

Deciduous tree are also called hardwoods, these tree types typically shed their leaves in autumn. Deciduous trees have different-shaped leaves, depending on tree species; for example, star, heart and oval shapes It refers to the trees that shed leaves seasonally, and most of the broadleaf trees are deciduous. It has a high rate of photosynthesis because of the shape and the arrangement of the leaf patterns. Shedding leaves prepare them for winter and have good water preservation. Since there is seasonal shedding, these trees are affected by winter weather conditions.

Most of Coniferous trees are evergreens, which means you'll have greenery year-round on these tree types. Coniferous trees have leaves that are needle-shaped.

In Da'an Park, there are about 14 typical trees species, which mainly belong to the Decidous group, including: Alstonia scholaris, Bischofia javanica, Ficus elastica, Ficus microcarpa, Bambusa vulgaris, Tabebuia aurea, Liquidambar formosana, Pistacia chinensis, Pterocarpus indicus, Cinnamomum camphora, Morus australis. Conifer species include Araucaria heterophylla and Roystonea regia (Palm), the rest are grasses.

In this study, we classified the flora in Da'an Park into 7 main categories, including 4 types of Deciduous group: Tree type 1, tree type 2, tree type 3, and tree type 4. Besides, There are also classes Palm, Conifers, and Grass (Table 1)

Table 1. Tree species classification in Da'an Park

 

Google Earth images - very high-resolution satellite images are used for classification. It was derived on 23th, March, 2018 with 3 visible bands: Red, Green, and Blue (Figure 1)

Figure 1. Google earth image of Da'an Park

A total of 316 photos of trees in Daan Park were taken for training and validating of the classification model using Decision Tree algorithm (Figure 2). The results of the classification model give an accuracy of up to 89.98%

Figure 2. General workflow of tree classification

The results of tree species classification in Da'an Park showed that Deciduous trees occupy most of the park's area, of which type 2 trees occupy the most, up to more than 11 hectares, followed by type 1, type 3, and type 4. Conifers occupy only a small area, only about 0.2 ha. Meanwhile, the area for grass and flowers occupies an area of up to 7.2ha.

Figure 3. The final tree classification of Da'an Park

Tree species sampling in Da'an Forest Park

 

Daan Forest Park - a green lung of Taipei - is a public park near the centre of Taipei city, Taiwan. The park occupies twenty-six hectares, and is used by residents of Taipei as a green activity space and for various outdoor activities.

The purpose of the tree sampling field trip in Da'an Park was to classify tree species using Satellite images. Samples used for training, testing, and validating from supervisor classification model by artificial intelligence algorithm.

How can we differentiate between types of trees? There are few key things to look at in order to tell trees apart. Some of these are dependent on the season. For example, we can rely on differences in leaves, flowers, fruit, or cones.

In this field trip, the characteristics of each species was identified from ‘‘tree’’ pictures taken with a RICOH WG-4 GPS Camera and total 316 points with corresponding Geotagged photos were used as dataset for training and validation the results.

The points of tree sampling

Below are some pictures of trees in the Da'an Park

Alstonia scholaris (deciduous tree)

Bischofia javanica (Deciduous Trees)

Ficus elastica (Deciduous Trees)

Ficus microcarpa (Deciduous Trees)

Bambusa vulgaris (Deciduous Trees)

Tabebuia aurea (Deciduous Trees)

Liquidambar formosana (Deciduous Trees)

Pistacia chinensis (Deciduous Trees)

Pterocarpus indicus (Deciduous Trees)

Cinnamomum camphora (Deciduous Trees)

Morus australis (Deciduous Trees)

Araucaria heterophylla (Coniferous Trees)

Roystonea regia (Palm)

Flowers and Bushes

Grass

Water

For more pictures, please see here 

https://www.flickr.com/photos/192234925@N04/51662295372/in/album-72157720172003100/

Publication list

1. Liou, Y.-A.*, Nguyen, K.-A, Ho, L.-T., 2021. Altering urban greenspace patterns and heat stress risk in Hanoi city during Master Plan 2030 implementation. Land Use Policy 105 (2021) 105405. https://doi.org/10.1016/j.landusepol.2021.105405. (SSCI, IF = 5.398, RF = 28/123, Environment Studies)

2. Nguyen, K.A., Liou, Y.-A.*, T.-H. Vo, D.C. Dao, H.S. Nguyen, 2021: Evaluation of urban greenspace vulnerability to typhoon in Taiwan. Urban Forestry & Urban Greening, Volume 63, August 2021, 127191, https://doi.org/10.1016/j.ufug.2021.127191. (SCI, IF=4.537; RF = 3/68, Forestry)