A study on biodiversity...
This is a study done by a team of students from INDIAN INSTITUTE of TECHNOLOGY, Delhi. The study was aimed at detecting biological diversity on Earth, tracking and predicting changes over time. The study is based on the fact that most of the species require specific temperature range, specific precipitation, specific terrain , specific vegetation etc. to survive properly. Basically, most of the species require specific environment conditions for their survival and if the environment changes, their existence may be threatened . We have used ground based observations and satellite data to carry out this study. This site is to display our study and provide our code and other resources to anyone who wants to study about biodiversity.
Biodiversity is the variety of plant and animal life in the world or in a particular habitat. We can relate it to number of species and population of every species. We are measuring biodiversity using two scales:
Richness
It's simply the number of different species present.
Shannon index
It is defined as: -Σ pi ln(pi ) where pi is ratio of population of ith species to total population.
Example: Coconino National Forest , Arizona (lying in the blue rectangle in Fig. 1) using occurrence data from https://www.gbif.org/ .
Richness : 1166
Shannon index : 4.337133912
We are using a combination of occurrence data from GBIF and satellite data from NEO to predict species in space.
We used ground observation data along with NASA satellite-based remote sensing data of environmental variables, such as temperature, precipitation, and vegetation index to predict habitable places for a particular species around the globe.
Procedure(Explaining using a species of coyote(Canis latrans Say)):
Took occurrence data of the coyote from 2001 to 2020 in USA from https://www.gbif.org/ . (Fig. 3)
For each occurrence, the environmental variable values(temperature, precipitation etc.) were assigned along with latitude and longitude using data from https://datasearch.globe.gov/ and https://neo.sci.gsfc.nasa.gov/view.php?datasetId=TRMM_3B43M . Here, for understanding the model more clearly, statistical analysis of one of the environmental factors (temperature) for that species is shown in detail.
First of all, histogram of temperature is made. So now, we know the fraction of total occurrence of species at any temperature (Fig. 4). Basically, now we have an approximate range of temperature which is suitable for this particular species.
Now using the satellite data of world temperature, the points whose temperature is in the range are marked. These points represent that the probability of finding particular species is relatively much higher than other unmarked points(Fig. 5).
After doing the same for all environmental variables, we take the intersection of marked points from all the maps(Fig. 6). (Here as an example, I have shown intersection of three factors viz. temperature, aerosol optical thickness and vegetation index).
Thus points marked on the new map created, represent the most probable habitable places for the coyote.
We can always take more and more environmental variables and optimize the model to get better prediction.
We used ground occurrence data and previous 70 years temperature data of a particular place (CHARLESTON INTL. AIRPORT, SC US) and predicted if there are considerable chances of finding any particular species (Canis latrans Say) at that location in future.
Procedure(Explaining, using previous 70 years data of CHARLESTON INTL. AIRPORT, SC US and occurrence data for a particular species of coyote(Canis latrans Say) and temperature data from https://datasearch.globe.gov/) Here, for understanding the model more clearly, statistical analysis of one of the environmental factors (temperature) of that location is shown in detail :
Yearly average temperature from 1950-2020 of a particular location (CHARLESTON INTL. AIRPORT, SC US) is taken from https://www.noaa.gov/ .
Now using previous years temperature data for Charleston Airport, we have done the curve fitting and predicted, what will be the temperature in future(Fig. 7).
Now we have average temperature of Charleston Airport in 2080, and we can compare it with the temperature range.
The temperature range suitable for particular species (coyote) is calculated in the above model(Fig. 4).
In our case, temperature range for the coyote is 5.78-22.36 degree Celsius. So there are very low chances that the coyote would be found at Charleston Airport in year 2080 since the predicted temperature of the airport in 2080 is 23.9 degree Celsius.
So, as explained, we can easily extend this model to many environmental variables as well as to different locations and see if the predicted values of each environmental variable lies within the required range.
We have described space prediction and time prediction. Now using these two, we can predict biodiversity for any place for any upcoming year.
Example predicting biodiversity for Coconino National Forest , Arizona for year 2080:
So we can use this model to predict biodiversity of any region and any future time, if we have enough data. We can always optimize every step to get better and better prediction.
This is the link to public GitHub Repository, containing all the code and other resources. Anyone who wants to study biodiversity can use them.
Link to our presentation : https://docs.google.com/presentation/d/1CLKUGhR-Iw0V54seG-Wc6qLkALDwfd8R1F89e0JInXk/edit?usp=sharing