Abstract
The xerophytic desert shrub Haloxylon ammodendron (C. A. Mey.) Bunge. is distributed naturally in Asian and African deserts, and is widely used for vegetation restoration in the desert regions of Northern China. However, there are limited long-term chrono-sequence studies on the impact of changed soil properties and vegetation dynamics following establishment of this shrub on mobile sand dunes. In Minqin County, Gansu Province, we investigated soil properties and herbaceous vegetation development of 10, 20, 30, 40, 50-year-old H. ammodendron plantations on mobile sand dunes. Soil sampling at two depths (0–5 and 5–20 cm) under the shrubs determined SOC, nutrition and soil physical characteristics. The results showed that: establishment of H. ammodendron had improved soil physio-chemical properties, increased thickness of soil crusts and coverage of biological soil crusts (BSCs), and promoted development of topsoil over an extended period of 5 decades. Soil texture and soil nutrition improved along the chrono-sequence according to three distinct phases: i) an initial fast development from 0 to 10 years, ii) a stabilizing phase from 10 to 30 years followed by iii) a relatively marked restoration development in 40 and 50-year-old plantations. Meanwhile, herbaceous community coverage also markedly increased in 30-year-old plantations. However, both soil and vegetation restoration were very slow due to low annual precipitation in Minqin county compared to other Northern China sand afforestation sites. Canonical Correspondence Analysis results demonstrated that herbaceous plant development was closely associated with changes in soil texture (increased clay and silt percentage) and availability of soil nutrients. Thus our results indicated that selection of the long-lived shrub H. ammodendron is an essential and effective tool in arid desert re-vegetation.
Highlights
Desertification is considered one of the most critical ecological and environmental issues worldwide and has gained increasing attention [1] especially in China
The cover reduction in our study was much less than other shrubs planted in the Shapotou region for example, where after 50 years cover was reduced from 33% to 9% and which was associated with a development of micro-biotic crusts (BSCs) and reduced soil water contents at depths [18]
Our results correspond with these previous studies in Inner Mongolia, we found significant responses in particle size distribution (PSD) and soil nutrients with increasing soil depth during this restoration process in 40 and 50-year-old plantations, as shown in the canonical coordinate analysis
Summary
Desertification is considered one of the most critical ecological and environmental issues worldwide and has gained increasing attention [1] especially in China. Short-term afforestation may show initial success in revegetation processes in arid regions, but its impact on biodiversity and its ability to achieve full ecological restoration will depend on the type of reforestation carried out and its suitability to the local environment [5,6,7]. In parts of the MuUs Desert of Inner Mongolia Autonomous Region, a number of researchers reported successful afforestation in short-term studies, tree mortality reached 70% after 20 years, with renewed desertification, it erased the earlier reported gains. The lack of long-term field research largely limits our understanding of ecological restoration effects across varied ecological regions. This affirms the necessity to conduct long-term field investigations on ecological restoration of desert steppe ecosystems
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