Patch-scale connectivity: Where and why does it matter?

TitlePatch-scale connectivity: Where and why does it matter?
Publication TypeConference Paper
Year of Publication2009
AuthorsHerrick JE, Peters DC, Okin GS, Anderson JP
Conference NameLTER All Scientists Meeting
Date Published09/11/2009
Conference LocationEstes Park, Colorado
ARIS Log Number243382
Keywordsconnectivity, degradation, Patch-scale
AbstractPatch-scale connectivity is frequently cited as a significant factor controlling redistribution of water, organic matter and nutrients in many arid and semi-arid ecosystems. The ‘leakiness’ of these systems has been cited as an indicator of degradation. Methods to limit or modify soil loss and redistribution are included in many restoration strategies. There are surprisingly few data, however, about the extent to which reducing connectivity at the patch to plot level results in increased resource retention or plant establishment, or how these effects might vary across the landscape. Our objectives were to (1) determine the extent to which reducing connectivity in plant interspaces can increase resource retention and plant establishment at plant and patch scales in three contrasting sites and (2) identify potential mechanisms and key landscape attributes that may explain among site differences. Two of the sites are on gravelly soils dominated by alluvial processes. One of these is on a geomorphically stable and the other on a geomorphically unstable surface. The third site is located on a sandy soil and is believed to be dominated by aeolian processes. Four paired treatment and control plots were established in late spring – early summer 2008 and evaluated in fall 2008 with digital photographs. The results showed significant reductions in bare ground at all three sites that were associated with increases in litter cover. The reductions were much greater at the aeolian site (26%) and the alluvial site on an geomorphically unstable surface (22%) than on at the geomorphically stable, lower productivity site (3%). Unique soil and geomorphic attributes at each of the sites are associated with mechanisms that may explain measured and observed differences. These preliminary results illustrate the importance of testing hypotheses about the importance of connectivity across a broad variety of plant communities and geomorphic surfaces.