Storage of C, N, and P affected by afforestation with Salix cupularis in an alpine semiarid desert ecosystem

Abstract

Few systemic assessments have evaluated the success of these afforestation programs in alpine semiarid desert ecosystems in the Qinghai-Tibet Plateau. In this study, we investigated the influences of three Salix cupularis plantation age classes (6, 18, and 34 years) on the carbon (C), nitrogen (N), and phosphorus (P) storages and stoichiometry of the soil-plant ecosystem. The consequences of S. cupularis plantation induced soil spatial heterogeneity. The soil-plant ecosystem C storage increased after the plantation. The N storage showed an increasing trend from 6 to 18 years and then slightly decreased. The P storage presented a continuously declining trend. The result indicated that the imbalance in soil N, P, C occurred with plantation age because of the imbalance of their inputs. The N and P uptakes from subsoil and redistribution to topsoil by S. cupularis may contribute to meet N and P demands for the understory plants. Leaf N:P ratios varied from 8.3 to 17.5. These results imply that N and P status are the main factors limiting plant growth in the alpine-cold desert ecosystem. Thus, we recommend adding N and P fertilizers during plant growth. KEYWORDSafforestation, alpine semiarid desert, soil-plant system, stoichiometry, C,N and P storage, salix plantations 1 | INTRODUCTION Arid and semiarid regions are widely distributed in China, accounting for more than 16% of the land area (Wang, Zhang, Hasi, & Dong, 2010). For a long time, these regions have been managed using traditional agricultural and pastoral practices (Liu, Wu, Ding, Tian, & Shi, 2017;Wiesmeier et al., 2016). The land desertification in this region has primarily resulted from an imbalance of between human activities and global climate changes (Wang, Xue, Zhou, & Guo, 2015). Afforestation is an effective method of restoring desert lands, and it has a potentially useful impact on soil quality, vegetation structure, soil nutrient storages, and stoichiometry Therefore, the impact of changes in these nutritive element cycles on soil-plant ecosystems has received widespread attention.Salix cupularis is a shrub that belongs to the Salicaceae family, and it can grow in extremely harsh alpine semiarid environments. In addition, this shrub plays an important role in resisting wind erosion, fixing sand, preserving water, and increasing plant diversity. Since the 1980s, the Qinghai-Tibet Plateau, China, has become one of the key , bulk density (BD), sand content 95.83%, silt 2.04%, and clay 2.13%. | Experimental design and samplingSoil and plant sample collection was conducted in August 2016.Several typical areas along the eastern Qinghai-Tibet Plateau with negligible human disturbance were selected as sample collection sites.Each age class was represented by three plantation ages (6, 18, and 34 yr-old), and each plantation was repeated three times. Three clusters of S. cupularis were randomly selected for each plantation age, and basic information on the S. cupularis samples of each age is shown in Table S1. First, to test the understory plants, ...

Afforestation and agroforestry enhance soil nutrient status and carbon sequestration capacity in eastern China

“…Nutrient stoichiometry plays an essential role in our understanding of nutrient status and deepens our understanding of nutrient cycling in ecosystems. In this study, the soil C:N, C:P, and N:P ratios ranged from 2.9 to 20.8, from 3.7 to 43.0, and from 0.9 to 2.7, respectively, which was similar to the results of Hu et al (). The C:N ratio (ranging from 2.9 to 20.8) exactly indicated the increase in soil microbial biomass, the release of soil mineralized N, and the decay of organic matter in all sampled depths and systems (Han et al, ).…”

Changes in soil phosphorus and its influencing factors following afforestation in Northern China

“…However, the enhanced primary vegetation productivity also increased the exogenous inputs (litter and rhizodeposition), and ultimately causing an increase in the source of soil P . To date, afforestation have been reported to either increase (Chen, He, et al, 2016;Zhang et al, 2019), decrease (Hu et al, 2018;Li et al, 2017), or have no effect (Shi et al, 2016;Wei et al, 2009) on total and available P.…”

“…However, the enhanced primary vegetation productivity also increased the exogenous inputs (litter and rhizodeposition), and ultimately causing an increase in the source of soil P (Cao & Chen, ). To date, afforestation have been reported to either increase (Chen, He, et al, ; Zhang et al, ), decrease (Hu et al, ; Li et al, ), or have no effect (Shi et al, ; Wei et al, ) on total and available P. The current studies on changes in soil TP (available phosphorus [AP]) stocks following afforestation are mostly focusing on the plot scale, which fail to involve more affecting factors and extrapolate to a more convincing conclusion. For example, studies on P dynamics following grassland (GL) afforestation focused on the effect of the tree species, and the studied plantation ages were not dynamic (Chen, Condron, Davis, & Sherlock, ; Chirino‐Valle, Davis, & Condron, ).…”

Variation in physicochemical and biochemical soil properties among different plant species treatments early in the restoration of a desertified alpine meadow

“…Although S . cupularis (Salicaceae) lacks local economic value (Zhao, Wu, Fang, & Yang, ), this perennial shrub grows quickly and has favourable wind‐proofing effects (Hu, Shu, et al, ). K .…”

“…kirilowii (Crassulaceae) is a perennial forb that is valued for its enlarged fleshy rhizomes and is a popular source for traditional Tibetan medicine (Zuo, Li, Chen, & Xu, 2007). Although S. cupularis (Salicaceae) lacks local economic value (Zhao, Wu, Fang, & Yang, 2017), this perennial shrub grows quickly and has favourable windproofing effects (Hu, Shu, et al, 2017). K. rigidula cv.…”