Sun, Y; Schleuss, P-M; Pausch, J; Xu, X; Kuzyakov, Y: Nitrogen pools and cycles in Tibetan Kobresia pastures depending on grazing, Biology and Fertility of Soils, 54, 569-581 (2018), doi:10.1007/s00374-018-1280-y
Abstract:
Kobresia grasslands on the Tibetan Plateau comprise the world’s largest pastoral alpine ecosystem. Overgrazing-driven degradation strongly proceeded on this vulnerable grassland, but the mechanisms behind are still unclear. Plants must balance the costs of releasing C to soil against the benefits of accelerated microbial nutrient mineralization, which increases their availability for root uptake. To achieve the effect of grazing on this C-N exchange mechanism, a 15NH4+ field labeling experiment was implemented at grazed and ungrazed sites, with additional treatments of clipping and shading to reduce belowground C input by manipulating photosynthesis. Grazing reduced gross N mineralization rates by 18.7%, similar to shading and clipping. This indicates that shoot removal by grazing decreased belowground C input, thereby suppressing microbial N mining and overall soil N availability. Nevertheless, NH4+ uptake rate by plants at the grazed site was 1.4 times higher than at the ungrazed site, because plants increased N acquisition to meet the high N demands of shoot regrowth (compensatory growth: grazed > ungrazed). To enable efficient N uptake and regrowth, Kobresia plants have developed specific traits (i.e., efficient above-belowground interactions). These traits reflect important mechanisms of resilience and ecosystem stability under long-term moderate grazing in an N-limited environment. However, excessive (over)grazing might imbalance such C-N exchange and amplify plant N limitation, hampering productivity and pasture recovery over the long term. In this context, a reduction in grazing pressure provides a sustainable way to maintain soil fertility, C sequestration, efficient nutrient recycling, and overall ecosystem stability.
Upcoming ...


BayCEER Colloquium:
Th. 2024-04-18
The Canvas of Change: Creative Marketing for Behaviour Change, Sustainability and Social Good
Th. 2024-04-18
Survival, 'dormancy', and resuscitation of microorganisms in water-limited environments: insights from coastal salt flats and desert soil crusts
BayCEER Short Courses:
Tu. 2024-04-16
Geographical information system and R environment for conservation biology
Ecological-Botanical Garden:
Su. 2024-04-07
Führung | Talking Tree: Was Bäume über´s Klima erzählen
Fr. 2024-04-19
Führung | Gesteine im Ökologisch-Botanischen Garten
Weather research site
Luftdruck (356m): 956.3 hPa
Lufttemperatur: 12.5 °C
Niederschlag: 1.3 mm/24h
Sonnenschein: 1 h/d

...more
Globalstrahlung: 441 W/m²
Lufttemperatur: 11.9 °C
Niederschlag: 1.3 mm/24h
Wind (Höhe 32m): 8.2 km/h

...more
This site makes use of cookies More information