Landscapes

Authored by Javan Bauder

What could bring together people with interests diverse as black bear movements in an urban environment, detailed mapping of Longleaf Pine habitat, connecting protected lands for wildlife connectivity, simulating prairie chicken populations or mapping important ecological communities? The 2016 annual meeting of the United States Regional Association of the International Association for Landscape Ecology (US-IALE)!

This past April, I had the opportunity to attend the 2016 US-IALE meeting in beautiful downtown Asheville, North Carolina. Landscape ecology is a relatively recent scientific field that did not fully emerge in North America until the 1980s. What is landscape ecology? As its name suggests, most landscape ecologists study ecological patterns and processes over very large spatial areas, watersheds or ecoregions, for example. But the central focus of landscape ecology is on something called spatial heterogeneity. What is that? Spatial heterogeneity is simply variation in some feature across space. That feature could be forest cover, elevation, vegetation communities, urban development or species abundance. But the key is that landscape ecologists study how this variation across space influences ecological patterns and processes. The absolute scale of the “landscape” can vary depending on the questions being asked or the species being studied. For example, a study of the effects of habitat fragmentation on small mammal communities may occur over a few hundred acres, but a study on the effects of fire on vegetation communities may cover thousands of square miles. This flexibility of focus makes landscape ecology a very exciting and diverse field.

This diversity was reflected in the variety of presentations delivered at the meeting. There were presentations about maintaining wildlife connectivity among protected lands, landscape planning, invasive species, ecosystem responses to climate change, habitat mapping, phenology (the study of seasonal plant cycles), urban development, wildland fire, ecosystem services, habitat mapping and even sustainable wood-based bioenergy! One theme running throughout the meeting was connectivity and corridors. Connectivity is widely discussed in conservation biology and refers to connecting habitat patches or protected lands so that plants and animals can move between them. Many conservation biologists advocated connecting such patches using corridors, yet whether corridors actually work is debated.

Landscapes

The first morning of the meeting featured a dual-speaker plenary session by two leading authorities on wildlife corridors where each speaker’s presentation focused on the pros and cons of corridors. It seems that corridors do work in some systems, but managers should not automatically assume that providing corridors will maintain connectivity. Another fascinating presentation was given by a researcher studying black bears within the city limits of Asheville. Turns out bears spend quite a bit of time within the city of Asheville, yet human-bear conflicts are uncommon. One of their bears actually hibernated under the porch of a house while the owners were away for the winter! This bear study has proved to be a phenomenal opportunity for public outreach educating people about bears and their roles in the ecosystem.

In addition to hearing about such fascinating research, I was particularly excited to attend this year’s IALE meeting because I would finally be presenting some of the results of my PhD dissertation research on Eastern Indigo Snakes in Central Florida. This project began back in 2010 while I was on staff with The Orianne Society. We began radio-tracking Indigo Snakes in Highlands County, FL to collect data to build a population viability model for Indigo Snakes in central Florida. To develop this model, The Orianne Society generously supported my long-time goal of returning to school for a PhD. Since 2012, I have been working with Dr. Kevin McGarigal at the University of Massachusetts to analyze our radio telemetry data to obtain the right information needed to build our model.

To build this model we need to know how Indigo Snakes select different habitats. That is, which habitats do snakes actually prefer or avoid versus which do they use just because the habitats are there? We also need to understand the scale at which Indigo Snakes select habitats. Scale is a very important concept in landscape ecology, so let me explain using the analogy of buying a house. When you buy a house, you first consider factors within several or many miles of the house, such as neighborhood quality, proximity to work, city versus suburb, number of nearby parks, etc. But then once you’ve selected a good location, you focus your search within that location based on characteristics of individual lots and houses: does this house have a big yard, is there a space for a garden, how many rooms are there, does it have hardwood floors or carpet? So you select your house based on both “broad-scale” and “fine-scale” features. Well, most animals appear to select their habitats using the same process.

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Our research indicates that Indigo Snakes in Central Florida prefer to place their home ranges within large tracks of natural upland habitats (like scrub and flatwoods) that have a diverse mosaic of both wetland and upland habitats. This makes sense given their large home ranges (up to several hundred acres). A diversity of habitats also allows Indigo Snakes easy access to foraging in both upland and wetland habitats. When we looked at how Indigo Snakes select habitats within their home ranges, the story become more complex. It appears that males and females respond differently to certain habitat features. We think these differences reflect differences in how far they move and the size of their home ranges.

For example, males move much more extensively than females and have larger home ranges, especially during the breeding season. During these extensive movements males tend to avoid developed habitats like urban, citrus and improved pasture. Females, on the other hand, tend to have small home ranges, which they have already selected within relatively suitable habitat. As a result they have less exposure to developed habitats and show weaker avoidance for those habitats. Both males and females still select well-vegetated, upland habitats within their home ranges. Our results suggest that conserving large tracts of undeveloped land containing a diversity of habitat types is important for maintaining suitable habitat for Indigo Snakes in Central Florida.

True to expectations, the 2016 US-IALE was an exciting and inspiring time. It is always refreshing to learn about new and exciting research and to hear new concepts or methods that can be applied to your research.

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