The state of biodiversity in the world is critical where natural grassland is one of the habitat types showing the strongest deteriorating trend of biodiversity loss. At European Union level, 75 % of all grassland habitats have poor or bad status, with cessation of farming and subsequent overgrowth posing the greatest threat. To achieve favorable conservation status of natural grasslands, the area given over to grazing livestock or hay mowing needs to increase in many regions. The aim of this study was to calculate the number of cattle required to manage various types of unfertilized grazing land, and associated enteric methane emissions from these cattle, using Sweden as the study area. Four different scenarios with various categories of grazing cattle were evaluated: beef suckler cows and their offspring or dairy and beef cows in the current ratio and their offspring, combined with all male calves being raised as grazing steers or with males being raised as grazing steers in the current ratio and other males being raised as indoor bulls. Potential important factors that could reduce the number of additional cattle required were considered. The scenario requiring the smallest number of animals, beef cows and their grazing offspring, gave the lowest methane emissions, 16 kg/ha/year for low-yielding grazing land, such as wooded pasture, and 117 kg/ha/year for high-yielding grazing land, such as wet meadows. Taking all cattle reducing factors into account (mowing parts of the area, lower predicted stocking rate, use of all existing male cattle) significantly reduced the required cattle stock to one-third, corresponding to methane emissions of 5 and 34 kg/ha/year for low and high-yielding grazing land, respectively. In Sweden, 2.2 million ha of grazing land need to be restored to favorable conservation status, which would require 150 000–510 000 new beef cows and their grazing offspring would be needed, producing 33 000 to 109 000 tonnes of methane, compared to the 105 000 tonnes emitted by the present cattle stock (around 300 000 dairy cows and 210 000 beef cows).

中文翻译：

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依赖管理的半天然草原和森林的良好保护状态所需的牛群数量以及相关的肠道甲烷排放量增加

世界生物多样性状况至关重要，天然草地是生物多样性丧失恶化趋势最严重的栖息地类型之一。在欧盟层面，75%的草原栖息地状况较差，其中农业停止和随后的过度生长构成了最大的威胁。为了实现天然草原的良好保护状态，许多地区需要增加放牧牲畜或割草的面积。本研究的目的是以瑞典为研究区域，计算管理各种类型未施肥牧场所需的牛数量，以及这些牛的相关肠道甲烷排放量。评估了不同类别放牧牛的四种不同情景：肉乳牛及其后代或当前比例的奶牛和肉牛及其后代，结合所有雄性小牛作为放牧公牛饲养或雄性作为放牧公牛饲养目前的比例和其他作为室内公牛饲养的雄性。考虑了可能减少所需额外牛数量的潜在重要因素。在需要最少数量的动物、肉牛及其放牧后代的情景中，甲烷排放量最低，低产牧场（如树木繁茂的牧场）的甲烷排放量为 16 公斤/公顷/年，高产牧场的甲烷排放量为 117 公斤/公顷/年。肥沃的牧场，例如潮湿的草地。考虑到所有牛减少因素（割草部分区域、较低的预测存栏率、使用所有现有公牛），所需的牛存栏量显着减少到三分之一，相当于甲烷排放量为 5 公斤/公顷/年和 34 公斤/公顷/年分别为低产和高产牧场。在瑞典，220万公顷牧场需要恢复到有利的保护状态，这将需要15万至51万头新肉牛及其放牧后代，与之前相比，将产生3.3万至10.9万吨甲烷。现有牛群（约 30 万头奶牛和 21 万头肉牛）排放 105 000 吨。