Landscape Mosaics

The Landscape Feature Summaries discuss conservation actions, research and monitoring needed to address threats to individual landscape features within specific regions. However, conserving any one landscape feature alone is not going to lead to the conservation of many species. Landscape features are components of the various landscapes that occur throughout Michigan; that is, landscape features occur intermixed on the landscape, creating a pattern or 'mosaic' of different features used by wildlife in daily, annual, or life cycles. These mosaics result from a multitude of variables, including differences in soils, topography, microclimate and disturbance regimes (e.g., Great Lakes fluctuations, seasonal flooding, beaver activities, fire, windthrow).

This dynamic mosaic influences associated plant and animal communities (Bormann and Likens 1979, Albert 1995). Adding to this complexity in terrestrial systems are the various vegetative communities associated with many landscape features and the continuum of successional stages that may be expressed, depending primarily on how recently and how extensively any disturbance events have occurred. Conserving all aspects of this mixture is important to conserving the full complex of native wildlife species (Haufler 1990). Additionally, understanding the role of landscape mosaics in wildlife distribution, abundance, movements and threats is vital, because without this knowledge, conservation actions cannot be properly defined.

The 'dry hardwood forest' landscape feature may include areas with very different dominant vegetation and, therefore, different wildlife compositions. Areas of more recent disturbance, dominated by cherry, trembling aspen and large-tooth aspen, are preferred by Prairie Warbler, Ruffed Grouse, snowshoe hare and woodland vole. In areas with less recent disturbance events, cherry and aspen may be replaced by white, red or black oak. Areas that remain undisturbed for long periods of time may eventually be dominated by shade-tolerant species such maple. These more mature dry hardwood forests are more likely to harbor species such as Red-headed Woodpecker, Yellow-billed Cuckoo, eastern box turtle, woodland jumping mouse and hoary bat (Kurta 1995, Hunter et al. 2001).

The combination of landscape features that define particular aquatic systems influences the species that will be present. A headwater stream will have a different and more diverse fish assemblage if it flows into a large river, than if it flowed into another small stream (Osborne and Wiley 1992). Stream proximity to a lake or beaver pond will also result in a different fish assemblage (Schlosser 1995a, Schlosser 1995b, Snodgrass and Meffe 1998, Fausch et al. 2002). Similarly, lakes with higher connectivity to other waterbodies will be more diverse than isolated lakes (Tonn and Magnuson 1982, Radomski and Goeman 1995, Olden et al. 2001).

The juxtaposition of landscape features within a mosaic influences which species use a particular area. Bats use forested features during daylight hours for roosting, but also require grassland, wetland, or other semi-open features for foraging. Use of open features appears to be determined by nocturnal insect abundance. Massasauga rattlesnakes usually use wetland areas for winter hibernacula, but spend more time in adjacent upland areas during summer (Reinert and Kodrich 1982, Seigel 1986). Fish, both migratory and non-migratory, also tend to require different features for various parts of their annual cycles (e.g., reproduction, over-wintering, nursery). Distance and barriers between required landscape features will influence presence and abundance of wildlife in a mosaic.

Within wildlife species, animals of different genders and ages may be associated with different landscape features. Indiana bat maternal colonies have been located only in dead flooded timber; surveys have not detected similar site-use by males. Male Indiana bats have been identified using caves and upland forests (Kurta et al. 1993, Kurta 2004). Male American Woodcock generally select openings in shrubby sites as singing grounds (Gutzwiller and Wakeley 1980), but only shrub density and proximity to an edge appear to have any relation to nest site selection (Coon et al. 1980). As broods get older, males tend to select more mature, open stands (Dwyer et al. 1980). Also, location of sites with good soils and abundant earthworm populations may influence woodcock distribution, because earthworms are their primary food source (USGS 2005b). This multiplicity of feature use, both between and within species, requires maintenance of all landscape feature types.

The flow of organisms, material and other influences between landscape features can affect the characteristics of a feature itself (Meffe and Carroll 1994), not just the wildlife that occurs within it. For example, a bog in southern Michigan has different characteristics than those of bogs in the eastern Upper Peninsula due to differences in latitude, soil composition and chemistry, and differences in vegetative composition and structure of the surrounding area that influence the ongoing ecological processes. These various juxtapositions and interactions add to the overall biological diversity in Michigan, and should be considered during planning and implementation of conservation activities.

Conservation Needs to Address Landscape Mosaic Issues:

Land, Water & Species Management

• Develop management plans and actions that consider maintenance and restoration of multiple successional stages of landscape features
  
  
• Develop management plans and actions to maintain the necessary juxtaposition of landscape features for specific wildlife species

Education & Awareness

• Educate private landowners on how their property fits into the functioning of the larger landscape

Research, Surveys & Monitoring

• Continue to develop and improve habitat models to predict changes over time and responses to potential threats, and to identify appropriate metrics/indicators for monitoring
  
  
• Conduct research to identify relationships between specific landscape features
  
  
• Conduct research and develop models to identify the influence of feature juxtaposition on wildlife distributions and abundance
  
  
• Conduct research to examine how seasonal diversity in agricultural landscape features affect their use by wildlife
  
  
• Conduct research to determine whether agricultural landscape features act as buffers between natural and urban/suburban landscape features
  
  
• Conduct research to determine the relative value of temporal feature diversity to spatial feature diversity