In contrast, actual stocking rate increased from \(1.1\times 10^{8}\) SSU in 2005 to \(1.4\times 10^{8}\) SSU in 2009, resulting in an increase in overgrazing rate from 23% to 112% during the same period [4]. Conversely, continued grassland degradation is expected to harm economic development as well as cause ecosystem instability at the regional to national scales [21]. By the end of the 20 th century, 90% of the grassland condition of Inner Mongolia had been degraded to various extents [22], compared to an average of 22% at the national level [7]. This sharp contrast has stimulated growing attention to the protection and restoration of grasslands in recent decades. Many scientists have engaged in combating grassland degradation. Progress has been made in many areas including rational grazing [7; 23; 24], enclosure [11; 25; 26], moving [12; 27; 28], rapid planting [7; 29; 30], etc. Among others, fence enclosure is regarded as a simple yet effective measure [26; 31] to increase vegetation coverage [30; 32], improve species richness [33; 34], raise productivity [35; 36], and conserve soil water and nutrients [32; 37]. Technically, the duration of the enclosure engagement is an important factor affecting the structure and diversity of plant species in grassland communities [30], especially in the moderately degraded pasture or heavily degraded grassland. An earlier study [38], conducted in a Hulunbuir desertified grassland, showed that longer enclosure duration tended to increase plant diversity and stability. However, some other studies suggested contrary effects of enclosure duration on plant community. For instance, [PERSON] et al. [39] found that longer duration of enclosure reduced plant diversity in the neighboring Horqin desertified grassland. Although the effects of enclosure duration are being disputed, not only based on results from different types of grasslands, but also based on results from the same type of grassland [28], the enclosure itself has been recognized as an economical and effective measure to achieve self-healing and to rebuild ecosystem balance in degraded grasslands [8; 26]. On the one hand, beneficial effects can usually be expected from an enclosure treatment. The enclosure creates a physical protection to the grassland from external disturbances, allowing the plants enough time to reproduce, which in turn results in an increased species diversity [40] and a higher chance to restore the plant communities [41]. On the other hand, the enclosure treatment may also give rise to adverse effects. As a matter of fact, enclosure is a human disturbance which eliminates grazing and trampling by large herbivores and blocks the exchange of energy and substances between the enclosed grassland and the external ecosystem [42]. Therefore, finding a balance between beneficial and adverse effects of an enclosure on the community structure and species diversity of grassland ecosystems has become a hotspot of debate. From a practical perspective, finding such a balance also has great significance for the sustainable use of grasslands. Therefore, we aim to quantitatively determine the optimal duration of the enclosure engagement for the restoration of a typical heavily degraded temperate meadow steppe of the region using field experiments in this research. More specifically, the objectives of this paper are: (1) to determine the effects of a fence enclosure on grassland productivity; (2) to evaluate plant community's responses to the enclosure treatment; (3) to determine the optimal duration of the enclosure treatment; and (4) to formulate technical options and policy recommendations for the restoration and sustainable use of the regional grassland resources. We fulfil these objectives by measuring how long it takes the degraded meadow steppe under the enclosure treatment to reach maximum biomass harvest on a yearly basis, and by analyzing the compositional changes in plant species of the meadow steppe vegetation in relation to the enclosure duration.