2Restoration of alpine sand dunes has been increasingly attracting the attention of ecologists due to their 3 difficulty and importance among the mountain-river-forest-farmland-lake-grass system (referred as 4 meta-ecosystem) restoration. Alpine sand dunes are suffered from unstable soil and lack of plants.
5Efficient restoration measures are vital to guide the sand dune restoration. Whether the engineering 6 materials co-applied with seeding could achieve considerable restoration in such areas? Here, sandbag 7 and wicker as environmental friendly materials combined with Elymus nutans seeding were 8 implemented on the Zoige Plateau sand dune, comparing with the 'control' treatment that only seeding.
9We assessed the topsoil conditions by sampled the surface soil and measured the water capacity and 10 nutrients. We also utilized interspecific relationship and population niche to analyse the plant 11 community structure variances among different restoration measures. Results showed that the soil 12 conditions got clearly improved in sandbag area than that in wicker area when compared with that in 13 control area. The community in control area was the least structured, while the species showed the 14 closest related in sandbag area. In addition, average population niche overlap showed a control (0.26) 15 ﹤wicker (0.32)﹤sandbag (0.39) ranking. Thus, we suggested that sandbag or wicker co-applied with 16 indigenous grass seeding is a practical and quick restoration approach in alpine sand dunes, and the 17 sandbag may surpasses the wicker. Moreover, soil amending measures including nutrient improvement,
18and microbial fertilizer addition may further accelerate sand dune restoration. 19 Keywords: interspecific relationship; niche; Elymus nutans; sand barrier; restoration 3 20
Introduction
21The terrestrial ecosystem has experienced increasingly severe land degradation and desertification
22[1]. Desertification threatens the ecological safety and its restoration is one of the vital elements in the 23 mountain-river-forest-farmland-lake-grass system (referred as meta-ecosystem) restoration [2, 3]. The 24 long-termed complex causes (e.g., overgrazing, climate change) accelerate desertification process and 25 the sand dunes are expanding continuously on the Zoige Plateau [4-6]. Sand dunes are generally 26 covered by nutrient devoid sandy soil that lacks favourable properties for plant growth and is prone to 27 wind erosion [7]. The expanded sand dunes destroy fertile land and welfare of local populations. For 28 example, they threaten livestock productivity, society development, ecological civilization, household 29 income or human beings health [8-10]. Hence, sand dunes restoration is crucial in ensuring the 30 conservation and sustainable development of the Zoige Plateau and meeting aspiration for better living 31 standards in local people.
32Decades worth of works have been conducted on sand dunes restoration [11, 12]. Mechanical sand 33 barriers as the classical and simplest measure have been shown to contribute to re...