Production and rain use efficiency in short‐grass steppe: grazing history, defoliation and water resource

Abstract

Abstract. Grassland in the semiarid shortgrass steppe, subjected to 50 years of heavy, light, and no grazing intensity, was clipped to simulate the natural pattern and intensities of defoliation by cattle or not clipped. A level of water resource treatment was superimposed upon the grazing and clipping treatments. Half of the plots were supplemented with additional water to simulate a wet year and half were not supplemented in a year of average precipitation. All three treatments interactively determined above‐ground production. Water treatment had the largest overall effect on above‐ground production. Current‐year defoliation had no direct significant effect on production, but mediated differences between both longterm grazing and watering treatments. Long‐term ungrazed compared to grazed grassland was capable of responding to high amounts of precipitation, but was also most affected by low amounts of precipitation and, therefore, displayed greater variability in above‐ground production and rain use efficiency. Only in the year of average precipitation, defoliation increased rain use efficiency in long‐term lightly, but not heavily, grazed treatment. This suggests a water conservation mechanism of defoliation that is reduced with heavy grazing.

Defoliation increased above-ground productivity in a semi-arid grassland

“…This particular management style involves logistical obstacles that limit its practical application as a management tool and the appropriateness of high-impact grazing practices in arid grasslands has been contested. Moreover, our results on the influence of defoliation history are consistent with other studies that have shown a decline of compensatory responses after multiple defoliation events (Turner et al 1993, Varnamkhasti et al 1995 suggesting that repeated overgrazing may inhibit plant recovery and community resilience. Nonetheless, the significant increases in productivity in these intensively grazed plots suggest that these grasslands can tolerate some livestock management regimes.…”

Relaciones entre la precipitación, producción de biomasa e índices espectrales de la vegetación: alcances y limitaciones

“…Los cambios en la pendiente b han sido interpretados como producto de la condición del agostadero (Varnamkhasti et al, 1995 (Prince et al, 1998). La condición del agostadero implica el concepto de degradación (perdida de la capacidad productiva) y viceversa, por lo que puede def inirse a través del uso de metodologías de COTECOCA (1967) o relativamente actuales (NRCS, 1997).…”

“…La evidencia experimental consignada por diversos autores (Gómez y Gallopín, 1991;Varnamkhasti et al, 1995;Knapp et al, 2008b;Guevara et al, 2009) plantea que la EUP de los pastizales y matorrales es diferente, por lo que ésta es dependiente del tipo de ecosistema, en una base global y clima similar (la Figura 3 presenta esta situación). Los datos de Knapp et al (2008b) plantean que los pastizales invadidos por matorrales tienen un incremento de alrededor de 400% en la producción, para un mismo régimen de precipitación.…”

Spatio-Temporal Variations of Soil Water Use in the Growing Season in Northeast China Using Modis Data

“…WUE provides the information on the ecological process and hydrological process as well (Kwon et al, 2018;Xue et al, 2015). Another ecosystem water use efficiency, namely, rain use efficiency (RUE), which is defined as the ratio of above net primary production (ANPP) to precipitation, can also help us understand the coupling between the carbon and water cycles (Huang et al, 2016;Varnamkhasti et al, 2010).…”