Does ecosystem sensitivity to precipitation at the site-level conform to regional-scale predictions?

Abstract

Abstract. Central to understanding global C cycle dynamics is the functional relationship between precipitation and net primary production (NPP). At large spatial (regional) scales, the responsiveness of aboveground NPP (ANPP) to interannual variation in annual precipitation (AP; ANPP sens ) is inversely related to site-level ANPP, coinciding with turnover of plant communities along precipitation gradients. Within ecosystems experiencing chronic alterations in water availability, plant community change will also occur with unknown consequences for ANPP sens . To examine the role plant community shifts may play in determining alterations in site-level ANPP sens , we experimentally increased precipitation by ~35% for two decades in a native Central U.S. grassland. Consistent with regional models, ANPP sens decreased initially as water availability and ANPP increased. However, ANPP sens shifted back to ambient levels when mesic species increased in abundance in the plant community. Similarly, in grassland sites with distinct mesic and xeric plant communities and corresponding 50% differences in ANPP, ANPP sens did not differ over almost three decades. We conclude that responses in ANPP sens to chronic alterations in water availability within an ecosystem may not conform to regional AP-ANPP patterns, despite expected changes in ANPP and plant communities. The result is unanticipated functional resistance to climate change at the site scale.

Assessing precipitation, evapotranspiration, andNDVIas controls of U.S. Great Plains plant production

“…The Konza Prairie (KNZ) is a Long‐Term Ecological Research site located in the Flint Hills of northeastern Kansas (Wilcox et al. ). KNZ is a native tallgrass prairie.…”

“…The details of the KNZ ANPP data are described in Wilcox et al. , . The data from the KNZ site came from the upland site representing typical ANPP observed at the KNZ site located on more shallow, rocky soils (Knapp et al.…”

Nitrogen deposition magnifies the sensitivity of desert steppe plant communities to large changes in precipitation

“…Precipitation is a predominant climatic factor that controls plant growth and distribution across most of the globe, particularly in arid and semi‐arid grasslands (Knapp, Ciais, & Smith, ; Yang, Fang, Ma, & Wang, ). In the past few decades, numerous studies documenting above‐ground net primary production (ANPP) in response to precipitation changes have developed two distinct models: temporal models—ANPP increases linearly with increasing annual precipitation amount at one site, and spatial models—ANPP increases nonlinearly to saturation across arid to extremely humid sites (Huxman et al, ; Ponce‐Campos et al, ; Wilcox, Blair, Smith, & Knapp, ; Yahdjian & Sala, ). However, some studies have shown inconsistent results.…”

Climate warming reduces the temporal stability of plant community biomass production

“…Climate warming has been demonstrated to influence community structure242526 and species interactions272829 that could potentially translate into changes in community biomass stability303132. Likewise, changes in precipitation could alter community biomass production33, species diversity34 and species relative abundance patterns35 that may also have consequences for biomass stability1617. Notably, the effects of climate warming and altered precipitation on community properties, including stability, may not be independent of each other, given that warming is expected to impose its strongest effect under drought conditions333637.…”