Robert McGrath's Blog (EUA)

Distribution of Butterflies of the Amazon

Publicado em 07 maio 2021

The forests of Brazil are some of the most diverse ecosystems on Earth, and also some of the most disturbed by human activity.  But it isn’t easy to monitor what is happening in such a complex system, with zillions of plants and animals, and a patchwork of habitats.

This spring researchers in Brazil report a broad study of the distribution of butterflies in the Brazilian Atlantic Forest region [1].  The study combined observational data of fruit eating butterflies with information about climate and landscape.  The idea is to map these species across the area, to estimate “species richness”.  These estimates are combined with fine grained information about the landscape and climate conditions to yield an indication of the amount of undisturbed forest extant, i.e., the amount of human disturbance.

This work involved estimating the population of species in specific areas based not only on the counts but on predictions from the local conditions.  The observed counts represent samples from the actual population, and the model is used to estimate what the population is.

The models are fairly fine grained, with data for 1 km2 areas.  At this granularity, many microclimates are represented, capturing the patchiness of the region.

The observational data was processed to represent “presence/absence” for each species for each bin.  This information for more than 200 species is combined in what I learned is called a “stacked species distribution model” (SSDM).  I.e., for each bin, there is a record of all the species present there.  This is a measure of “richness”.

Including the butterfly “richness” data adds a dimension to the interpretation of landscape and climate data.  The presence of a rich collection of species indicates an area that still has enough natural forest to be important for conservation.  Conversely, areas under climate and landscape degradation that also have relatively few butterflies is probably not a good candidate for conservation, but probably needs restoration.

The researchers use the combined model to identify areas under the greatest stress from human disturbance, and relatively undisturbed areas that are high priorities for conservation.  These insights can guide conservation and restoration efforts.

  1. Jessie P. Santos, Thadeu Sobral-Souza, Keith S. Brown Jr, Maurício Humberto Vancine, Milton C. Ribeiro, and André V. L. Freitas, Effects of landscape modification on species richness patterns of fruit-feeding butterflies in Brazilian Atlantic Forest. Diversity and Distributions, 26 (2):196-208, 2020/02/01 2020.
  2. Janaína Simões, Mapping of butterfly species distribution in Atlantic Rainforest areas identifies conservation priorities, in Agência FAPESP – News, April 28, 2021.