PARENT SESSION
Poster Session 9: Arid Lands and Deserts
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Seasonal above-ground net primary production in black grama and blue grama grasslands, and creosotebush shrubland on the Sevilleta LTER, New Mexico: 1999-2004.
Muldavin, Esteban*,1, Moore, Douglas1, Wetherill, Karen1, Lightfoot, David1, Collins, Scott1, 1 University of New Mexico, Albuquerque, NM, USA
ABSTRACT- In 1999, the Sevilleta LTER installed a set of above-ground net primary production (ANPP) measurement stations in semiarid grasslands and shrublands. To support cross-site analysis, sampling procedures followed those established at the Jornada LTER, i.e., double sampling whereby plant volumes were non-destructively measured on permanent one-meter quadrats and related by regression to biomass samples of similar volumes collected adjacent to the sampling grids. After six years of seasonal (winter, spring, and fall) data collection, sufficient annual regressions between biomass and volume were developed for most species. For the dominants such as black grama (Bouteloua eriopoda), blue grama (B. gracilis) and creosotebush (Larrea tridentata), seasonal regressions were necessary, and may be needed on a yearly basis in the near future to increase precision and accuracy across a range of seasonal precipitation amounts. Regardless, there were clear trends in production that were related to seasonal precipitation patterns. The C4 black grama closely tracked precipitation through the year with growth peaks typically corresponding to wet summer monsoon seasons. In contrast, and the C3 creosotebush responded primarily to winter moisture with production highest in the spring. Yet, there was some indication that creosotebush production can be significant in the fall if temperatures are cooler than normal and there is adequate moisture. Overall, average annual above-ground NPP was highest in the black grama-dominated site, followed by blue grama, and then creosotebush.
Key words: anpp, Bouteloua eriopoda, B. gracilis, Larrea tridentata