Workflows developed to process pollen data to estimate components of ecosystem change

Alistair Seddon

Ondřej Mottl

PAGES Planetary Boundaries WG

  • Holocene variability is a key component of planetary boundaries concept
  • Focus on temporal dynamics / safe operating spaces

Steffen et al. 2009


“To meet the challenge of maintaining the Holocene state, we propose a framework based on ‘planetary boundaries’. These boundaries define the safe operating space for humanity with respect to the Earth system and are associated with the planet’s biophysical subsystems or processes.”

Introduction

  • How can we use palaeoecological (and related fields) data to address the planetary boundaries concept?

Example from pollen data

  • Focus on temporal dynamics
  • We need:
  1. a metric (or series of metrics) that can reflect something related to the planetary boundary
  2. a method for describing the variability (e.g. a generalised additive model)
  3. to look at multiple records (if we are talking global planetary boundaries), so need a reproducible method for data synthesis and analyses.

1. Metric

Ecosystem diversity metrics

  • Richness, evenness etc., can be estimated using Hill Numbers
  • One component of ‘Ecosystem Condition’ (see, e.g. Dearing et al. 2014)
  • Other metrics are available!

2. method for describing the variability

GAMs: a generalised additive models

  • Statistical model - non-linear trends through time
  • Gavin Simpson - transition of GAMs to palaeoecological data (Simpson 2018, Presentation on Wednesday, 11-11.15)
  • Models a trend (e.g. diversity against time) using a series of basis functions

GAMs

GAMs

  • ‘Generalised’ framework - highly flexible, used on multiple data types
  • it doesn’t tell us where the boundary is, but statistically robust description of the variability (we can make informed decisions)

3. reproducible workflows

  • If integrating across multiple sites, then it is important to have standardized data that are comparable
  • In pollen this means- same depositional environment, same age-depth models, same levels of taxonomic harmonisation, (same/ similar temporal resolution), comparable temporal ranges etc.
  • We have been developing reproducible workflows for pollen data in the HOPE project, we will show an example of this today (see Ondrej’s poster)

FOSSILPOL

Aims of this practical exercise

  1. Give an example data preparation and analysis of one metric (related to the Biodiversity Planetary Boundary).
  2. Give hands-on practice of applying the code to other examples.
  3. Stimulate some discussion points related to the types of metrics / standardization procedures that are relevant for your data and for the Planetary Boundaries’ concepts

Practical exercise

Go to bit.ly/INQUA2023-PBW

Example: Global changes in rates of vegetation change

Example: Global changes in rates of vegetation change


Wrap up

  • Used this example of how to process the pollen data in standardized methodology
  • See the whole workflow which enables you to do this on Neotoma and other datasets (FOSSILPOL).
  • Interpretation of results in relation to the Planetary Boundaries would be open ended, and is the focus of the group and for discussion here.

Discussion points

  • Here we focused on temporal dynamics, but how can we get from response to control variables?
  • What other metrics/ ecosystem components could be used on pollen data? What about other proxy types
  • What would be the challenges of doing large syntheses in the context of the planetary boundaries for your data types?

Discussion points

How can paleoecological-data be used to help define safe operating spaces?