Precipitation timing and magnitude differentially affect aboveground annual net primary productivity in three perennial species in a Chihuahuan Desert grassland.

Plant productivity in deserts may be more directly responsive to soil water availability than to precipitation. However, measurement of soil moisture alone may not be enough to elucidate plant responses to precipitation pulses, as edaphic factors may influence productivity when soil moisture is adequate. The first objective of the study was to determine the responses of the aboveground annual net primary productivity (ANPP) of three perennial species (from different functional groups) in a Chihuahuan Desert grassland to variation in natural precipitation (annual and seasonal) and a 25% increase in seasonal precipitation (supplemental watering in summer and winter). Secondly, ANPP responses to other key environmental and soil parameters were explored during dry, average, and wet years over a 5-yr period. ANPP predictors for each species were dynamic. High ANPP in Dasylirion leiophyllum was positively associated with higher soil NH(4)-N and frequent larger precipitation events, while that in Bouteloua curtipendula was positively correlated with frequent small summer precipitation events with short inter-pulse periods and supplemental winter water. Opuntia phaeacantha was responsive to small precipitation events with short inter-pulse periods. Although several studies have shown ANPP increases with increases in precipitation and soil moisture in desert systems, this was not observed here as a universal predictor of ANPP, particularly in dry years.

[1]  J. Zak,et al.  Convergence across biomes to a common rain-use efficiency , 2004, Nature.

[2]  Douglas I. Moore,et al.  Aboveground net primary production dynamics in a northern Chihuahuan Desert ecosystem , 2008, Oecologia.

[3]  J. Cloudsley-Thompson.  Pattern and Process in Desert Ecosystems , 1988 .

[4]  Jan Bogaert,et al.  Multivariate statistics for wildlife and ecology research , 2001 .

[5]  J. K. Koelliker,et al.  Frequency and Extent of Water Limitation to Primary Production in a Mesic Temperate Grassland , 2001, Ecosystems.

[6]  A. Knapp,et al.  Variation among biomes in temporal dynamics of aboveground primary production. , 2001, Science.

[7]  B. Newingham,et al.  Enhanced monsoon precipitation and nitrogen deposition affect leaf traits and photosynthesis differently in spring and summer in the desert shrub Larrea tridentata. , 2006, The New phytologist.

[8]  Colin W. Bell,et al.  Soil Microbial Responses to Temporal Variations of Moisture and Temperature in a Chihuahuan Desert Grassland , 2008, Microbial Ecology.

[9]  W. James Shuttleworth,et al.  Modeling multiyear observations of soil moisture recharge in the semiarid American Southwest , 2000 .

[10]  W. Pockman,et al.  Precipitation pulses and carbon fluxes in semiarid and arid ecosystems , 2004, Oecologia.

[11]  Osvaldo E. Sala,et al.  Thresholds, memory, and seasonality: understanding pulse dynamics in arid/semi-arid ecosystems , 2004, Oecologia.

[12]  William H. Schlesinger,et al.  Desertification alters patterns of aboveground net primary production in Chihuahuan ecosystems , 2002 .

[13]  R. Monson.  The many faces of plant carbon relations: forging an ecophysiological identity in the age of human influence. , 2003, The New phytologist.

[14]  W. Parton,et al.  Primary Production of the Central Grassland Region of the United States , 1988 .

[15]  Osvaldo E. Sala,et al.  CONTROLS OF GRASS AND SHRUB ABOVEGROUND PRODUCTION IN THE PATAGONIAN STEPPE , 2000 .

[16]  A. Novoplansky,et al.  The effect of mean and variance in resource supply on survival of annuals from Mediterranean and desert environments , 2004, Oecologia.

[17]  M. Aide,et al.  GEOCHEMICAL INDICATORS OF EXTERNAL ADDITIONS TO SOILS IN BIG BEND NATIONAL PARK, TEXAS , 2003 .

[18]  Esteban Muldavin,et al.  Spatial heterogeneity in Chihuahuan Desert vegetation: implications for sampling methods in semi-arid ecosystems , 2001 .

[19]  John F. B. Mitchell,et al.  The second Hadley Centre coupled ocean-atmosphere GCM: model description, spinup and validation , 1997 .

[20]  Pattern and process in desert ecosystems , 1986 .

[21]  James F. Reynolds,et al.  Modifying the ‘pulse–reserve’ paradigm for deserts of North America: precipitation pulses, soil water, and plant responses , 2004, Oecologia.

[22]  A. Powell.  Trees and shrubs of the Trans-Pecos and adjacent areas , 1998 .

[23]  J. Weedin,et al.  Cacti of the Trans-Pecos and Adjacent Areas , 2004 .

[24]  Plant-soil Interactions in Deserts , 1998 .

[25]  A. Porporato,et al.  Water pulses and biogeochemical cycles in arid and semiarid ecosystems , 2004, Oecologia.

[26]  A. Field.  Discovering statistics using SPSS for Windows. , 2000 .

[27]  I. Noy-Meir,et al.  Desert Ecosystems: Environment and Producers , 1973 .

[28]  Osvaldo E. Sala,et al.  Inter-annual variation in primary production of a semi-arid grassland related to previous-year production , 2001 .

[29]  John F. B. Mitchell,et al.  The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments , 2000 .

[30]  A. Knapp,et al.  Physiological and Morphological Traits of Exotic, Invasive Exotic, and Native Plant Species in Tallgrass Prairie , 2001, International Journal of Plant Sciences.

[31]  W. Lauenroth,et al.  Response of a Grassland Cactus to Frequency and Size of Rainfall Events in a North American Shortgrass Steppe , 1996 .

[32]  W. Schlesinger,et al.  Nutrient losses in runoff from grasslandand shrubland habitats in southern New Mexico: II. Field plots , 2000 .

[33]  J. Reynolds,et al.  Impact of drought on desert shrubs : Effects of seasonality and degree of resource island development , 1999 .

[34]  Colin W. Bell,et al.  Physiological responses of two contrasting desert plant species to precipitation variability are differentially regulated by soil moisture and nitrogen dynamics , 2009 .

[35]  E. Skidmore,et al.  Leaf and stem area relationships to masses and their height distributions in native grasses. , 2000 .

[36]  Tony J. Svejcar,et al.  The effects of precipitation timing on sagebrush steppe vegetation , 2006 .

[37]  A. Weaver,et al.  The Canadian Centre for Climate Modelling and Analysis global coupled model and its climate , 2000 .

[38]  James F. Reynolds,et al.  Plant responses to precipitation in desert ecosystems: integrating functional types, pulses, thresholds, and delays , 2004, Oecologia.

[39]  James H. Brown,et al.  Interactions between winter and summer annuals in the Chihuahuan Desert , 1997, Oecologia.

[40]  W. K. Lauenroth,et al.  Small rainfall events: An ecological role in semiarid regions , 1982, Oecologia.

[41]  J. Blair,et al.  Rainfall Variability, Carbon Cycling, and Plant Species Diversity in a Mesic Grassland , 2002, Science.

[42]  G. Robertson,et al.  Standard soil methods for long-term ecological research , 1999 .

[43]  O. Sala,et al.  Vegetation structure constrains primary production response to water availability in the Patagonian steppe. , 2006, Ecology.

[44]  J. Weltzin,et al.  Resource pulses in arid environments - patterns of rain, patterns of life. , 2003, The New phytologist.

[45]  Keirith A. Snyder,et al.  Multi-scale temporal variation in water availability: Implications for vegetation dynamics in arid and semi-arid ecosystems , 2006 .

[46]  R. Gibbens,et al.  Root systems of some Chihuahuan Desert plants , 2001 .

[47]  David G. Williams,et al.  Precipitation pulse use by an invasive woody legume: the role of soil texture and pulse size , 2005, Oecologia.