Progressive Change BACIPS: Estimating the Effects of Environmental Impacts over Time

Post provided by Lauric Thiault

BACIPS (Before-After Control-Impact Paired Series) is probably the best-known and most powerful approach to detect and quantify human interventions on ecosystems. In BACIPS designs, Impact and Control sites are sampled simultaneously (or nearly so) multiple times Before and After an intervention. For each sampling survey conducted Before or After, the difference in the sampled response variable (e.g. density) is calculated. Before and After differences are then compared to provide a measure of the effect of the intervention, assuming that the magnitude of the induced change is constant through time. However, many interventions may not cause immediate, constant changes to a system.

We developed a new statistical approach – called Progressive-Change BACIPS (Before-After Control-Impact Paired-Series) – that extends and generalises the scope of BACIPS analyses to time-dependent effects. After quantifying the statistical power and accuracy of the method with simulated data sets, we used marine and terrestrial case studies to illustrate and validate their approach. We found that the Progressive-Change BACIPS works pretty well to estimate the effects of environmental impacts and the time-scales over which they operate.

The following images show the diversity of contexts in which this approach can be undertaken.

To find out more about Progressive Change BACIPS, read our Methods in Ecology and Evolution article ‘Progressive-Change BACIPS: a flexible approach for environmental impact assessment’.

A Homage to EC Pielou: One of the 20th Century’s Most Accomplished Scientists

Post provided by Daniel Simberloff, Nathan Sanders and Pedro Peres-Neto

Evelyn Chrystalla ‘E.C.’ Pielou. © Sharon Niscak

Evelyn Chrystalla ‘E.C.’ Pielou. © Sharon Niscak

Evelyn Chrystalla ‘E.C.’ Pielou (February 20, 1924 – July 16, 2016) – a towering figure in ecology – was a key pioneer in the incorporation of statistical rigor into biogeography and ecology. She devised many important statistical hypotheses tests for spatial arrangements and patterns ranging in scale from individual plants in a field through to elevational zonation of vegetation to ranges of groups of species distributed over regional through to continental-scale ranges. Her research has provided the impetus for biogeographical analyses for generations.

She published ten books, including several long after her formal retirement in 1988. Her book Biogeography (1979) is a masterpiece. It covers historical biogeography (including inferences from cladograms, which were just beginning to be a hot topic at that time) and ecological biogeography with keen insight and treats topics like long-distance dispersal (that had largely been the subject of just-so stories) with her characteristic statistical rigor. Her books on mathematical ecology have a strong emphasis on models of spatial pattern and ways to estimate biodiversity, and her methods – including the famous Pielou‘s evenness index – are still widely used. Continue reading

Issue 7.12

Issue 7.12 is now online!

The final 2016 issue of Methods is now online!

This month’s issue contains four Applications articles and two Open Access articles, all of which are freely available.

– iNEXT: The R package iNEXT (iNterpolation/EXTrapolation) provides simple functions to compute and plot the seamless rarefaction and extrapolation sampling curves for the three most widely used members of the Hill number family (species richness, Shannon diversity and Simpson diversity).

– camtrapR: A new toolbox for flexible and efficient management of data generated in camera trap-based wildlife studies. The package implements a complete workflow for processing camera trapping data.

– rotl: An R package to search and download data from the Open Tree of Life directly in R. It uses common data structures allowing researchers to take advantage of the rich set of tools and methods that are available in R to manipulate, analyse and visualize phylogenies.

– Fluctuating-temperature chamber: A design for economical, programmable fluctuating-temperature chambers based on a relatively small commercially manufactured constant temperature chamber modified with a customized, user-friendly microcontroller.

Continue reading

Issue 7.8

Issue 7.8 is now online!

The August issue of Methods is now online!

This month’s issue contains two Applications articles and two Open Access articles, all of which are freely available.

Plant-O-Matic: A free iOS application that combines the species distribution models with the location services built into a mobile device to provide users with a list of all plant species expected to occur in the 100 × 100 km geographic grid cell corresponding to the user’s location.

RClone: An R package built upon genclone software which includes functions to handle clonal data sets, allowing:

  • Checking for data set reliability to discriminate multilocus genotypes (MLGs)
  • Ascertainment of MLG and semi-automatic determination of clonal lineages (MLL)
  • Genotypic richness and evenness indices calculation based on MLGs or MLLs
  • Describing several spatial components of clonality

Continue reading

Issue 6.9

Issue 6.9 is now online!

The September issue of Methods is now online!

This month’s issue contains one Applications article and two Open Access articles, all of which are freely available.

POPART: An integrated software package that provides a comprehensive implementation of haplotype network methods, phylogeographic visualisation tools and standard statistical tests, together with publication-ready figure production. The package also provides a platform for the implementation and distribution of new network-based methods.

Michalis Vardakis et al. provide this month’s first Open Access article. In ‘Discrete choice modelling of natal dispersal: ‘Choosing’ where to breed from a finite set of available areas‘ the authors show how the dispersal discrete choice model can be used for analysing natal dispersal data in patchy environments given that the natal and the breeding area of the disperser are observed. This model can be used for any species or system that uses some form of discrete breeding location or a certain degree of discretization can be applied.

Our September issue also features articles on Animal Movement, Population Dynamics, Statistical Ecology, Biodiversity, Conservation Biology and much more. Continue reading