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
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.
Aktuelle Termine

Fr. 01.07.2022
3. Bayerische Biodiversitätstage in Bayern 2022
Do. 30.06.2022
Plant diversity in a changing world: from individuals to communities
Ökologisch-Botanischer Garten:
Mi. 29.06.2022
Führung | "Klimawandel: Neue Bäume braucht die Stadt"
So. 03.07.2022
Führung | "Mäusedorn und Katzenschwanz: Katzen und Botanik"
Di. 14.06.2022 aktuell
Zwei Nachwuchsgruppen-Leitungsstellen ausgeschrieben
Wetter Versuchsflächen
Luftdruck (356m): 967.7 hPa
Lufttemperatur: 26.9 °C
Niederschlag: 0.0 mm/24h
Sonnenschein: 4 h/d
Wind (Höhe 17m): 5.5 km/h
Wind (Max.): 14.8 km/h
Windrichtung: SO

Globalstrahlung: 648 W/m²
Lufttemperatur: 24.3 °C
Niederschlag: 0.0 mm/24h
Sonnenschein: <1 h/d
Wind (Höhe 32m): 0.0 km/h

Diese Webseite verwendet Cookies. weitere Informationen