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Degree-days Estimator to Predict Phenological Stages (DJPheno)

The logo of the Degree-Days Estimator to Predict Phenological Stages (DJPheno) software.

DJPheno software is used to determine the required parameters of a bioclimatic model based on the degree-days approach. These parameters are the base temperature of a living organism (plant or insect), and the number of degree-days required to reach clearly defined stages of development of this organism. The base temperature is the minimum temperature at which the organism can develop. The number of required degree-days predicts biological events in the life of this organism.

Firstly, DJPheno computes the average of degree-days required to reach given thresholds for all data sets, and that constitutes the model. Then, a comparison is done between field observations and model predictions. Comparative statistics are displayed and it is then possible to check the quality of model predictions.

To use DJPheno, it is necessary to have scouting data (insects) or phenology observations (plant) that will be matched with daily weather data for each site and each year of observed data. The software estimates the base temperature of the organism according to one of six methods loaded in the software for calculating degree-days and a statistical criterion selected. If the base temperature was measured experimentally, it is possible to use that data item rather than the one mathematically determined by the software.

Screenshots from the DJPheno software

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The biological data processing module

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The biological data processing module of the Degree-Days Estimator to Predict Phenological Stages (DJPheno) software. In the upper left corner, one can choose the group of observations to work with. The different data sets observed are listed to the right. Below these, the data is displayed. A drop-down menu permits the selection of data pertaining to a specific variety. Underneath the data, the type of prediction (cumulative percentage, cumulative value, observed value) can be selected. The start date and the prediction can also be specified. The button “Create data file for processing” can be selected once all the information is entered.

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Results from best base temperatures for a given organism

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An example of the window displaying the results of the best base temperatures for a given organism in the Degree-Days Estimator to Predict Phenological Stages (DJPheno) software. The period, the number of data sets observed and the method for calculating degree-days are listed in the top left corner of the window. Under these notes is the list of the 15 best base temperatures of the organism based on the selected statistical criterion. To the right of the list are the statistical results for all the base temperatures between 0 and 15 C. The data can be saved by selecting the “Save…” button located under that list. The “Graph” button to the right will display the graph at the bottom of the window. The data can be viewed in the graph based on the statistical criterion selected from the beginning (here, the Root Mean Square Error (RMSE)), the frequency of the minimum temperature or the frequency of the maximum temperature. The horizontal axis of the RMSE graph represents the base temperature in degrees Celsius. The vertical axis indicates the RMSE. A blue line on the graph illustrates the data.

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Results from comparisons between observations and model predictions

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An example of the window from the Degree-Days Estimator to Predict Phenological Stages (DJPheno) software displaying the results from the comparisons between observations and model predictions. The period, the number of data sets observed and the number of predictions are listed at the top of the window. The comparisons are listed below these notes. Different data on the magnitude of difference, the direction of difference, the quality of match and the probability of significant difference are indicated underneath the comparisons. The “Save…” button allows saving of the data while the “Graph” button further right allows viewing the frequency of differences or the linear regression in the form of a graph. The horizontal axis of the bar graph depicting the frequency of differences indicates the difference (observation minus prediction). The vertical axis indicates the frequency. The exact number of frequency for each difference is specified above the red bars of the graph.

Get a copy of DJPheno

To get a copy of the DJPheno software, please contact Bioclimatology and Modelling.

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