In the Chihuahuan Desert of Mexico and New Mexico, shrub invasion is a common problem, and once-abundant grassland ecosystems are being replaced by shrub-dominated habitat. The spatial arrangement of grasses and shrubs in these arid grasslands can provide better insight into community dynamics and can provide information on grass shrub interactions. To better understand the dynamics of the Chihuahuan Desert ecosystem and to provide information regarding the interactions between grasses and shrubs, we examined the spatial patterns of grasses and shrubs in remaining grass-dominated areas, interspersed with some shrubs. We developed 18, 10 3 20 m vegetation distribution plots by mapping the location of all grasses and shrubs on each and repeating the measurements three years later. Spatial patterns were then assessed for each plot using a second-order spatial statistic, Ripley's K-function, as well as any observed changes in the spatial patterns over a three-year period. We observed clumped grass distributions, indicating a lack of competition among grasses; random shrub distributions; and even grass distribution with respect to shrub locations, indicating competition between grasses and shrubs. We also observed a tendency for grass distributions to become more even over time, and grasses to become less even with respect to shrub locations over time. These changes occurred during a period of greater than average rainfall, indicating that greater water availability may lead to increased competition among grasses and decreased competition between grasses and shrubs.

Abstract-A new addressing and routing design called the LessIs-More Architecture (LIMA) is proposed as an inter-domain solution for a future Internet. Unlike recently proposed identifierlocator split solutions, LIMA uses just (topological) locationindependent names and location-dependent addresses. The feasibility of using a policy combination of restricting stubs to provider-aggregatable addressing only, and disallowing stub-level reachability from being propagated into the global routing tables, is studied. This policy combination results in significantly smaller global routing tables but creates four challenges of address renumbering (when stubs change providers), multihoming, mobility, and traffic engineering. Solutions to these challenges include the use of multiaddressing, name based sockets, a LIMA concept of address dismemberment, transport protocols such as SCTP that are capable of dynamic address reconfiguration, and new management-plane and control-plane procedures. Preliminary RIB data analysis quantify the benefit of LIMA in global routing table size reduction (to 6815 entries from today's 335K entries), and a cost of LIMA in terms of number of provider changes made by stubs in the last six months (about 2450 provider changes per month across 33K stubs).