@article {JRN54189,
	title = {Modifying landscape connectivity by reducing wind driven sediment redistribution, northern Chihuahuan Desert, USA},
	journal = {Aeolian Research},
	volume = {17},
	year = {2015},
	month = {06/2015},
	pages = {129-137},
	chapter = {129},
	abstract = {<p class="rtejustify">Shrub encroachment into perennial grasslands is occurring in many arid parts of the world. As shrubs displace perennial grasslands, bare patches can coalesce creating sediment transport pathways that further enhance sediment fluxes by wind transport. Reducing the connectedness of these pathways could slow or stop grassland loss by limiting sediment redistribution. To test this hypothesis, sediment retention structures, hereafter called {\textquotedblleft}Connectivity Modifiers{\textquotedblright} (Con-Mods), were placed in bare gaps of existing shrublands to block sediment movement by wind transport on two sites: the basin floor and a bajada (i.e. piedmont slope) at the Jornada Basin LTER in southern New Mexico. Wind blown sediment collectors and short-lived radionuclides (<sup>210</sup>Pb<sub>ex</sub>, <sup>137</sup>Cs, and <sup>7</sup>Be) were used to determine if these structures are affecting seasonal aeolian sediment transport within bare gaps. Net sediment flux rates at 10\&nbsp;cm height indicate a loss of 2.5{\textendash}14.2\&nbsp;g\&nbsp;m<sup>-2</sup>\&nbsp;d<sup>-1</sup> for both sites for the monsoon season (Jul{\textendash}Nov), while the basin floor site was the most responsive in reducing sediment transport by collecting 16.5\&nbsp;g\&nbsp;m<sup>-2</sup>\&nbsp;d<sup>-1</sup> over the windy season (Dec{\textendash}May). Con-Mods contained 30{\textendash}50\% higher surface radionuclide activities than the control plots for both transport seasons on the basin floor. However, there was no detectible difference between surface concentrations for the structures and controls seasonally on the bajada site. This study demonstrates that changes in connectivity can influence sediment movement. Altering sediment transport through bare gaps could influence ecosystem state changes in arid systems; thereby increasing the likelihood of recruitment of native plants.</p>
},
	keywords = {aeolian transport, connectivity, desertification, sediment redistribution, short lived radionuclides, shrub encroachment},
	doi = {10.1016/j.aeolia.2015.03.003},
	url = {/files/bibliography/15-011.pdf},
	author = {Rachal, David M. and Gregory S. Okin and Charles E. Alexander and Jeffrey E. Herrick and Debra C. Peters}
}
@article {49901,
	title = {Landform influences on the resistance of grasslands to shrub encroachment, Northern Chihuahuan Desert, USA},
	journal = {Journal of Maps},
	year = {2012},
	month = {11/2012},
	pages = {1-7, iFirst Article},
	abstract = {<p>In arid and semiarid regions, vegetative boundaries are often strikingly similar to landform boundaries. However, it is not well documented whether landforms exert an influence on the resistance of desert grassland to shrub encroachment. Dominant grassland communities have been displaced by woody shrubs over the last 150 years in the Jornada Basin, southern New Mexico. Digital vegetation maps from 1858, 1915{\textendash}1916, 1928{\textendash}1929, 1938, and 1998, in conjunction with a detailed landform map, were analyzed in a Geographical Information System. The generated time series maps and spatial data compiled from these datasets were used to quantify the extent and rate that grasslands were replaced by shrubs on eight contiguous landforms. From this assessment, we generated a resistance index that revealed desert grasslands were least resistant (most susceptible) to shrub expansion on sandy landforms and bajadas and most resistant to shrub invasion on ephemerally flooded playas. This study demonstrates that landforms both provide the broad-scale background for detailed mechanistic studies and affect the sensitivity of grasslands to shrub encroachment.\&nbsp;</p>
},
	keywords = {arid geomorphology, Chihuahuan Desert, desertification, grassland resistance, shrub encroachment},
	doi = {10.1080/17445647.2012.727593},
	url = {/files/bibliography/12-027.pdf},
	author = {Rachal, David M. and Curtis H. Monger and Gregory S. Okin and Debra C. Peters}
}
