Nantes, a city known for its rich history and vibrant culture, is also home to an impressive botanical collection that deserves our attention. Recently, we had the opportunity to analyze a dataset that captures the plant diversity of this beautiful city. From the geographic distribution of species to the richness of botanical families, the results are fascinating and offer a new perspective on urban biodiversity.
Plant collection of the city of Nantes
This inventory of the Nantes plant collection is part of the Nantes Metropole open data system. It was published on December 6, 2019 and is regularly updated to date. The complete dataset provides the family, genus, species, cultivar, location and provenance.
Exploratory Data Analysis (EDA)
Data extraction:
After importing our Python libraries into the Jupyter Notebook: pandas, matplotlib and plotly. We connect to the API of the dataset in CSV format and convert it into a dataframe.
Collection végétale de la Ville de Nantes
By exploring the dataset with Pandas, we obtain 12 columns and 3923 observations.
<class 'pandas.core.frame.DataFrame'>
RangeIndex: 3923 entries, 0 to 3922
Data columns (total 12 columns):
# Column Non-Null Count Dtype
--- ------ -------------- -----
0 Famille 3923 non-null object
1 Genre 3923 non-null object
2 Espèce 3651 non-null object
3 Cultivar 1157 non-null object
4 Origine 1443 non-null object
5 Année de plantation 1596 non-null float64
6 Nom du site 3923 non-null object
7 Localisation 1602 non-null object
8 Photo 1 2321 non-null object
9 Photo 2 1677 non-null object
10 Photo 3 1223 non-null object
11 Géolocalisation 3916 non-null object
dtypes: float64(1), object(11)
memory usage: 367.9+ KBData cleaning
In the data cleaning and preprocessing, we found that only 3 variables have no null or missing data. We have 7 variables that have “high” percentages of missing data, and 2 variables with a low percentage of null data, which makes us reevaluate their use when deciding whether to impute or eliminate them.
We decided to eliminate the 7 columns of variables that had more than 40% of missing data and to eliminate the observations with null data from the column ‘Espèce’ and ‘Géolocalisation’. With these actions the new dataset will have only 5 variables and 3651 observations.
Index: 3651 entries, 2 to 3922
Data columns (total 5 columns):
# Column Non-Null Count Dtype
--- ------ -------------- -----
0 Famille 3651 non-null object
1 Genre 3651 non-null object
2 Espèce 3651 non-null object
3 Nom du site 3651 non-null object
4 Géolocalisation 3645 non-null object
dtypes: object(5)As an extra step, we must separate in 2 new columns the “Latitude” and “Longitude” values that compose the “Géolocalisation”.
Analysis
Plant diversity in Nantes
One of the first questions we asked ourselves was: how many different families, genera and species are there in the collection? In analyzing the data, we discovered that Nantes is home to an astonishing variety of plants, with 161 families, 741 genera and 1913 different species represented in the collection – a biodiversity that speaks to the ecological richness of the city!
Among these species, some are more common than others. The most frequent species include plants that you have probably seen in local parks and gardens, such as camellia japonica and camellia sasanqua. However, we also identified rare species, those that only appear once in the dataset, suggesting the presence of unique plants.
We found that the family with the largest number of genera and species is Asteraceae, and the genus with the most species is Magnolia.
Geographical distribution and biodiversity
Moving on to the geographical aspect, we asked ourselves: how are the different species distributed geographically in Nantes? Using geolocation tools, we mapped the species according to their latitude and longitude. The results showed that the sites with the highest biodiversity are mainly distributed in the larger green areas, such as parks and botanical gardens. For example, the Jardin des Plantes and the Arboretum Cimetière Parc are the first biodiversity hotspots, with a high concentration of species.
In addition, we examined whether there was any correlation between geographic location and species richness. Surprisingly, we observed that areas close to the city center also harbor significant diversity between the Parc de Procé and the Jardin des Plantes, challenging the notion that biodiversity only flourishes in peripheral or rural areas.
After discovering that the Jardin des Plantes has the most species to observe in the city of Nantes, we filtered and counted the frequency of each species to obtain the top 10.
La Folie des Plantes
La Folie des Plantes of Nantes, held the first weekend of every September (September 7-8, 2024 – 37th edition: the Tree in the Spotlight!), is not only a vibrant celebration of botanical diversity, but also a natural extension of the city’s amazing plant heritage, as explored in our recent plant collection analysis. This annual event, which brings together plant lovers, horticultural experts and the curious alike, highlights the ecological richness we have identified in our research. With its focus on rare and collectible plants, and the participation of more than 170 specialized exhibitors, the Folie des Plantes reflects and amplifies the biodiversity found at iconic sites in Nantes, such as the Parc du Grand Blottereau.
Our analysis shows how these areas are home to an impressive variety of botanical species and families, making them true treasures of biodiversity that the Folie des Plantes celebrates and promotes each year. This connection between the event and the plant wealth of Nantes underlines the importance of preserving and enjoying our natural heritage, while giving us the opportunity to discover and acquire unique plants that enrich our gardens and communities.
Invitation to explore further
These findings are only part of what this dataset can reveal about the biodiversity of Nantes. If you are interested in botany, urban ecology, or simply want to learn more about the nature around you, we invite you to explore more of the dataset. In it, you can dive into the details of Nantes’ geographic distribution, species richness, and interesting ecological dynamics.
Don’t miss the opportunity to discover more about the nature of Nantes! Consult the different databases hosted on https://data.nantesmetropole.fr/ an open data portal for your observations and questions. Urban biodiversity is an issue that concerns us all, and together we can learn and do more to protect it.
This blogpost is an open invitation to all nature lovers and curious about science to explore more about the biodiversity of Nantes. We hope you will be inspired to continue discovering the beauty hidden in every green corner of the city!
This academic exercise is part of my continuous learning path in the areas of Data Engineering, Data Science and Remote Sensing with spatial data.🌳
Nantes #Botany #Conservation #DataScience #Environment #UrbanGreenspaces #Biodiversity #PlantScience #EDA
