Effects of climate variables on ecosystem carbon exchange and
soil respiration
As expected, we found that NEE, ER and GEP were all influenced by
precipitation which was highest in July and August (Fig. S1, Fig. S2b).
This is likely primarily a result of the influence of aboveground
biomass and its influence on productivity and ecosystem carbon exchange,
which is strongly influenced by variation in rainfall (Jobbagy et
al. 2002). We also showed that
soil moisture was positively correlated with ER and SR (Fig. S2d), which
likely promoted the growth of plant roots to enhance microbial activity
and promote organic matter decomposition, leading to an increase soil
respiration (Helfter et al. 2015; Peng et al. 2015). This
is consistent with previous studies in desert steppe (Jin et al.2023; Wang et al. 2023).
Likewise, variation in temperature influences ecosystem carbon exchange
mainly by affecting GEP and ER (Luo et al. 2001; Ganjurjavet al. 2018; Li et al. 2019). However, consistent with our
results showing a minimal influence of temperature on ecosystem carbon
exchange in a desert steppe (Fig. S2a), WU et al. (2021) found similar
results in a 12-year study. We did, however, find that variation in soil
temperature contributed to ER (Fig. S2c), which was consistent with
results from a previous analysis.