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Zhang et al. Carbon Footprints 2025, 4, 36 https://dx.doi.org/10.20517/cf.2025.29 Page 3 of 17

species-poor ecosystems, where management focuses on maintaining biodiversity alongside carbon
[18]
storage . In contrast, the Andes, with its complex topography and diverse traditional pastoral systems,
[19]
exhibits highly variable carbon dynamics that depend on specific practices and local climate . QTP,
however, is characterized by its extreme elevation, low temperatures, and relatively short growing season,
which may expose its soil carbon pools to be particularly vulnerable to recent climates and rapid increase in
grazing pressure. The typical alpine grassland soil is a natural carbon sink that can sequester atmospheric
CO and oxidize CH , but the soil has a strong potential to emit GHG if excessively grazed. The key GHG
4
2
emission sources from alpine grassland animal husbandry on the QTP have been widely investigated in
previous studies, i.e., enteric CH emission from ruminant livestock , CH and N O emissions from
[20]
4
4
2
livestock dung and urine patches deposited on pasture [12,21] , and farm manure management and feedlot .
[22]
However, these studies represent only one sector of grazing farm systems, and a few studies have examined
the entire process from a whole farm system modelling approach to examine the entire production process.
Consequently, the net GHG budget associated with animal husbandry in alpine grassland ecosystems is still
poorly understood, and we do not yet know what proportion of these key sources (i.e., enteric fermentation,
manure management, feedlot and the indirect emission from farm input) contribute to the GHG emissions
of the farm system, or by inference, where emission reductions might be most feasible. Based on the theory
of ecology of interference, we propose that there is an optimal stocking rate; that is, during the adaptation
period, GHG emissions increase with stocking rate up to a threshold, after which excessive interference
leads to a decrease in emissions. Therefore, this study based on the pasture GHG cycling process and
grassland energy input and output igure by using life cycle assessment method to adequately assess GHG
emissions[Figure 1]. The specific objectives were to (1) estimate the GHG balance of an entire yak grazing
farm under different grazing intensities in the alpine ecosystems of the QTP in China; (2) determine the
relative contributions of the key sources to the GHG balance of yak grazing farm systems; and (3) determine
optimal GHG mitigation strategies.

METHODS AND MATERIALS
Research areas
The experimental research site is situated at the Azi Research Station in Maqu County, Gansu Province,
China. This research station is located in the eastern part of the QTP at a longitude of 101°53' E and a
latitude of 33°58' N, with an average elevation of 3,700 m. The climate is cold and humid, typical of the
[23]
QTP . The annual average temperature is approximately 1.2 °C, with the lowest monthly average around
-10 °C in December to February and the highest monthly average below 12 °C in June to August each year.
The annual average precipitation is 620 mm, with most falling during the growing season from May to
September. The vegetation is dominated by typical alpine meadow plant species: Carex kansuensis Nelmes
(Cyperaceae); Poa albertii subsp. (Poaceae); Elymus nutans Griseb (Poaceae), and Anemone rivularis Buch
(Ranunculaceae).

To assess the effects of local yak grazing systems on the net GHG balance, we analyzed data from farms
operating under different management practices from 2012 to 2013 [Table 1]. The specific management
treatments investigated were a high stocking rate (HSR), a moderate stocking rate (MSR), a low stocking
rate (LSR), and a fenced enclosure with no grazing. The setting of grazing intensity is based on Yang et al. .
[24]
These selected farming sites have been subject to continuous yak grazing for a considerable period.

Description of yak grazing farm systems climatic data collection and processing
The yak-based agricultural systems of the QTP function as integrated production units where animal
husbandry is intrinsically linked to nutrient cycling. The primary economic yield is yak meat, supplemented