Lecture 6 Flashcards
Why is choosing the correct spatial and temporal scales important in ecological modelling?
It ensures accurate representation of ecosystem processes and prevents over-simplification or loss of important dynamics.
What is a 0D (zero-dimensional) model?
A model that represents the system as a single point with uniform conditions (e.g., lake-wide average).
What is a 1D (one-dimensional) model?
A model that captures gradients in one direction, such as vertical profiles in lakes or longitudinal changes in rivers.
What is a 2D (two-dimensional) model?
A model that includes horizontal gradients, useful for estuaries or coastal ecosystems.
What is a 3D (three-dimensional) model?
A model that represents full spatial variability, incorporating vertical and horizontal changes.
What are Continuous Stirred Tank Reactor (CSTR) models?
Models that assume complete mixing and uniform conditions.
What are Plug Flow Reactor (PFR) models?
Models that assume no mixing in the flow direction, typically representing processes in rivers or pipes.
What is Ecospace?
A spatial extension of Ecopath and Ecosim, running multiple 0D models across a spatial grid to capture local dynamics and spatial interactions
What temporal scales are commonly used in ecological models?
Short-term (e.g., daily cycles) and long-term (e.g., decadal trends).
What are cascading models?
Models that link processes across scales to account for feedback mechanisms and interactions.
What is model validation, and why is it important?
Model validation tests the calibrated model against an independent dataset to assess its generalizability. A valid model performs well on new data, indicating robust parameters.
What is cross-validation?
Cross-validation divides the dataset into k parts and validates the model on one part while calibrating on the rest. The process repeats for all parts, and the average RMSE indicates model performance.
What are potential issues with k-fold validation?
Challenges include the choice of k, increased computation time, and potential dependence between validation sets.
What are constraints in ecological models?
Constraints limit model parameters to ensure realistic outcomes. For example, mass balance ensures that accumulation equals input minus output plus reactions.
How is spatial dimensionality used in ecological models?
0D (e.g., lakes) assumes uniformity, 1D represents gradients (e.g., depth in rivers), 2D models capture horizontal variability (e.g., lagoons), and 3D (e.g., Ecospace) represents full spatial complexity.
