Zhou Xuanbo, Wang Xiaoli, Ma Yushou, Wang Yanlong, Ma Yuan, Xie Lele
Academy of Animal Husbandry and Veterinary Sciences, Key Laboratory of Alpine Grassland Ecosystem in the Three-River-Source (Qinghai University), Ministry of Education, Qinghai Provincial Key Laboratory of Adaptive Management on Alpine Grassland Qinghai University Xining Qinghai China.
Ecol Evol. 2023 Nov 27;13(11):e10734. doi: 10.1002/ece3.10734. eCollection 2023 Nov.
Overgrazing leads to grassland degradation and productivity decline. Rest-grazing during the regreen-up period can quickly restore grassland and fertilization is a common restoration strategy. However, the effects of rest-grazing time and fertilization on soil microorganisms are unclear in the alpine grasslands. Therefore, the experiment of rest-grazing time and fertilization was carried out to explore the response of soil microorganisms to rest-grazing time and fertilization measures. A field control experiment with rest-grazing time and fertilization as factors have been conducted from the time when grass returned to green till the livestock moved to the summer pasture in Dawu Town of Maqin County of China. The primary treatment we established was the five rest-grazing time, including rest-grazing time of 20 days, 30 days, 40 days, 50 days, and traditional grazing was used as a check group. At the same time, the secondary treatment was nitrogen addition of 300 kg·hm in each primary treatment. The results showed that the total phospholipid fatty acid (total PLFA), actinomyces (Act), and arbuscular mycorrhizal fungi (AMF) showed an ever-increasing biomass with the increase of rest-grazing time and the highest was at 50 days of rest-grazing, and they were all significantly higher than CK. In addition, soil microbial biomass carbon-nitrogen ratio (MBC/MBN) had great influence on the change of microbial community. Applying nitrogen fertilizer can increase the maximum value of biomass of all PLFA groups and the biomass of all PLFA groups changed in an "inverted V" shape with the increase of rest-grazing time. Besides, instead of MBC/MBN, NO -N was positively correlated with the biomass of all PLFA groups, which actively regulated the trend of microbial functions. The longer rest-grazing time is more conducive to the biomass of all PLFA groups. However, applying nitrogen fertilizer could break this pattern, namely, the 30 days rest-grazing would be beneficial to the biomass of all PLFA groups. These findings provide key information that rest-grazing during the regreen-up period is benefiscial to the all PLFA groups and fertilization could change the response of microorganisms to rest-grazing, which provide reference measures for the restoration of degraded alpine meadows.
过度放牧导致草地退化和生产力下降。在返青期进行休牧能够快速恢复草地，施肥是一种常见的恢复策略。然而，在高寒草地中，休牧时间和施肥对土壤微生物的影响尚不清楚。因此，开展了休牧时间和施肥试验，以探究土壤微生物对休牧时间和施肥措施的响应。在中国青海省玛沁县大武镇，从草地返青到牲畜转场至夏季牧场期间，进行了一项以休牧时间和施肥为因素的田间对照试验。我们设置的主要处理为五个休牧时间，包括20天、30天、40天、50天的休牧时间，以及以传统放牧作为对照组。同时，在每个主要处理中进行二次处理，即施氮量为300 kg·hm 。结果表明，总磷脂脂肪酸（total PLFA）、放线菌（Act）和丛枝菌根真菌（AMF）的生物量随着休牧时间的增加而不断增加，在休牧50天时达到最高，且均显著高于对照。此外，土壤微生物生物量碳氮比（MBC/MBN）对微生物群落变化有很大影响。施用氮肥可增加所有PLFA组生物量的最大值，且所有PLFA组生物量随休牧时间增加呈“倒V”形变化。此外，与MBC/MBN不同，NO -N与所有PLFA组生物量呈正相关，积极调控微生物功能趋势。休牧时间越长越有利于所有PLFA组生物量增加。然而，施用氮肥会打破这种模式，即休牧30天对所有PLFA组生物量有益。这些研究结果提供了关键信息，即返青期休牧有利于所有PLFA组，施肥会改变微生物对休牧的响应，为退化高寒草甸的恢复提供了参考措施。
