Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-08-26 Cooperative journals: 《干旱区研究》
Abstract： As an effective agricultural management method for improving ecological and environmental benefits,the farmland shelterbelt system is crucial in improving soil physical and chemical properties, the ecologicalenvironment, and crop yield. This study clarifies the effects of this system on ecosystem functions and provides aguide for the ecological restoration of fragile ecosystems. In the Hetao Irrigation District, three typical farmlandshelterbelts (four-, five-, and eight-line patterns) were selected to measure soil properties at a 0-100 cm depth andvegetation properties of shelterbelts and farmland at different distances (0.3 H, 0.7 H, 1 H, 2 H, 3 H, and 4 H)from the shelterbelts during the growing seasons from 2019 to 2021. Soil moisture storage (SMS) and soilnutrient storage [soil carbon storage (SCS), soil nitrogen storage (SNS), and soil phosphorus storage (SPS)] weremeasured. The results showed that (1) the soil bulk density and clay content of different shelterbelts differedsignificantly in the horizontal direction, while the soil properties differed significantly in the vertical direction. (2)The shelterbelts had enhanced water retention and nutrient supply functions, and the soil water and nutrientreserves of the four-line pattern were higher than those of the five- and eight-line patterns (SMS = 237.44 mm;SCS = 544.93 g·m− 2; SNS = 953.72 g·m− 2; SPS = 859.04 g·m− 2). (3) The average tree height and DBH of thefour- row shelterbelt were 30.06 m and 0.41 m, respectively. Additionally, the four- row shelterbelt had themaximum crop yield of 15.75 t·hm−2. (4) Redundancy analysis showed that a close relationship existed betweenenvironmental factors and ecosystem functions in the different shelterbelts, soil characteristics were closelyrelated to soil water and nutrient reserves, and vegetation attributes were negatively correlated with SNS andSPS. In conclusion, the four-line pattern demonstrated the strongest capacity for water and nutrient supply. Theresults of this study provide a sufficient theoretical basis for shelterbelt construction and ecological restoration inecologically fragile areas.
Subjects: Geosciences >> Geography submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： This study addresses the insufficient trade-offs between regional vegetation diversity and topographicdifferentiation during restoring vegetation processes in abandoned mines. Based on the basic principles of nearnaturalrestoration, this study examines the primary factors determining a classification of different site types,clarifies the spatial distribution patterns of vegetation and near-natural vegetation configuration modes under varioussite types, and establishes a foundation for near- natural vegetation configuration for ecological restoration inabandoned mine areas. It is crucial to understand the features of the plant communities of various site types forthe selection and allocation of species during the restoration of ecological services in abandoned mines. Herein,we employed field investigation and indoor analysis as our study methodologies, situated within abandonedmines of Inner Mongolia’s Wula Mountains. Using principal component, correlation, and cluster analyses, wechose nine indicators, including topographic features and soil properties (slope, slope position, slope direction,available phosphorus, total phosphorus, available potassium content, soil hardness, soil thickness, and soiltexture), to identify the dominant site types. The variations in plant community traits (e.g., biomass and diversity)among different site types were then compared. Based on correlation analysis and principal component analysis,the results indicated that slope, slope location, and soil hardness were the key characteristics for classifyingdifferent types of sites. The research region was classified into three site type groups and nine site types. Thebiomass, vegetation coverage, Margalef richness index, and Shannon-Wiener diversity index are greater for thegentle-middle slope-medium hard soil site type, slope-middle slope-medium hard soil site type, and lower for thesteep- middle slope- hard soil site type than for other site types. This is because of the variations in moisture,nutritional, and light conditions across the site types owing to topographic influences. In comparison to moderateslopes, steep slopes are more vulnerable to soil erosion caused by gravity and wind, as well as moisture andnutrient loss. Nutrient conditions are better at the downhill than in and on the slope due to the change in slopeposition. Additionally, too soft or too hard soil does not support the plants’development. Consequently, thebiomass and diversity of various site types on abandoned mining sites vary. Therefore, we must consider theeffect of site conditions and create the spatial layout of vegetation according to distinct site types when creatingnear-natural vegetation for mine ecological restoration. We advise the herbaceous mode for poorer habitat types,such as the steep-middle slope-hard soil site type (with a configuration ratio of perennial herb∶annual herb = 4∶1).We recommend the irrigation and grass mode for better-maintained areas. Examples of these site types includegentle-middle slope-medium hard soil (with a configuration ratio of perennial herb∶annual herb∶shrub or semishrub= 5∶4∶1) and slope-middle slope-medium hard soil (with a configuration ratio of perennial herb: annualherb: shrub or semi-shrub = 7∶2∶1).
Subjects: Biology >> Botany submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Stand density has an important effect on understory plant community structure and species diversity ofRobinia pseudoacacia plantations. Identifying changes of understory plant community structure and speciesdiversity under different stand densities is helpful for vegetation restoration and improving forest ecologicalfunction in loess regions. Taking a R. pseudoacacia plantation in the Loess area of western Shanxi as the focus ofstudy here, the understory community composition characteristics, growth characteristics, and species diversityassociated with six stand densities (950, 1450, 1950, 2450, 2950 and 3450 trees ·hm- 2) were analyzed throughfield investigation. The following results were obtained: (1) The study identified 77 species of understory plantsin 65 genera in 39 families, including shrubs of 36 species from 29 genera in 16 families, and herbs of 41 speciesfrom 36 genera in 25 families. The number of species in the shrub layer peaked when the stand density was 1950trees·hm-2, and the number of species in the herb layer peaked when the stand density was 2450 trees·hm-2. Theunderstory community of R. pseudoacacia forest mainly consists of Rosaceae, Compositae, Gramineae, andCaprifoliaceae. With increasing stand density, the dominant species transition from heliotropic species andintermediate species to shade species. (2) The height and aboveground biomass of shrubs decreased withincreasing stand density. The aboveground biomass of herb layer had no significant difference among standdensities (P>0.05), and the total coverage of shrub and grass community showed little change. (3) Withincreasing stand density, Margalef richness index and Shannon-Wiener diversity index of the shrub layer firstincreased and then decreased, and peaked when the stand density was 1950 trees · hm- 2, while the Simpsondominance index and Pielou evenness index showed gradually decreasing trends. The Margalef richness indexand Shannon-Wiener diversity index of the herb layer peaked when the stand density was 2450 trees·hm-2, whilethe Simpson dominance index and Pielou evenness index peaked when the stand density was 1950 trees·hm-2. (4)The similarity of species composition of understory communities in R. pseudoacacia forest of different densitieswas above the medium level. When the stand density was 1950-2450 trees ·hm- 2, the understory communityspecies diversity of R. pseudoacacia plantation was optimal, which was conducive to the improvement andsustainable development of its ecological function.
Subjects: Biology >> Botany submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： The purpose of this study was to provide a theoretical basis for the rational selection of different vegetation types for wind and sand control in arid and semiarid areas. Fluent software was used to numerically simulate the flow field around three types of typical strains (altar-shaped, shuttle-shaped, and broom-shaped) of scrub to analyze the influence of different plant forms on wind and sand flow and verify the results using existing wind tunnel tests. Results showed that (1) The flow field around the three types of plants can be divided into five zones, and three eddies exist behind the plants. Due to the intensity of the eddies, during the initial phase of sand accumulation, shuttle- shaped and broom- shaped plants accumulated sand primarily at 6-7 H after the plant, whereas altar-shaped plants accumulated sand at 3 H. (2) Affected by the height layer of the maximum profile area of the plant, the minimum wind speed at 1 H after the three types of plant shrubs appeared at heights of 0.3, 0.4 m, and 0.8 m, and the optimal protection range of height was 0.2- 0.4 m, 0.3- 0.6 m, and 0.8- 1 m, respectively. The aerodynamic roughness of the three plant types decreased gradually, and the roughness of the altar-shaped plants was significantly higher than that of the other two plant types. (3) All three types of strains could effectively reduce wind speed in the range of -2-10 H. The wind protection benefits in the near-surface area after the strains are altar-shaped > shuttle-shaped > broom-shaped the wind protection benefits in the midaltitude area all decrease with increasing plant distance. (4) At T = 10 s, the total duration of sand accumulation around the three plants was 8.5 H, 6 H, and 4.5 H, respectively, and wind erosion existed to different degrees at 5- 5.5 m and 4.5-6 m from the entrance for Haloxylon ammodendron and Calligonum mongolicum, respectively. Compared with other plants, Nitraria tangutorum exerted a better sand-blocking effect. Hence, it is recommended to combine N. tangutorum with H. ammodendron and C. mongolicum in the construction of wind and sand fixation projects, so that the sand- blocking property of N. tangutorum can be effectuated, and the better windblocking effect of H. ammodendron and C. mongolicum can be utilized at medium and high altitudes.
Subjects: Agriculture, Forestry,Livestock & Aquatic Products Science >> Soil Science submitted time 2023-05-30 Cooperative journals: 《干旱区研究》
Abstract： After ecological restoration in Horqin Sandy Land, the soil moisture dynamics of the forest and its response to rainfall affect whether Pinus sylvestris var. mongolica(PSM) can be continuously used for the ecological restoration in the same type of area. To study the characteristics of soil moisture dynamics after vegetation restoration on the southern edge of Horqin Sandy Land, this study used the methods of in situ observation and numerical simulation and corrected the HYDRUS-1D model based on the measured data of soil moisture to explore its relationship with rainfall. We obtained the following results: (1) The regional moisture distribution was changed by the PSM plantation, deep soil recharge at 2.0 m in bare sand accounted for 44.16% of the annual rainfall, whereas deep soil recharge at 2.0 m in PSM land accounted for only 0.7% of the annual rainfall. (2) Soil moisture below a depth of 0.4 m had no response to light rain, but the response depth of soil moisture to moderate rain could reach 1.0 m. The response depth to heavy rain and rainstorm involved the entire observation profile. With increasing soil depth, a decreasing trend was observed in the variation in moisture fluctuation. (3) There was a strong correlation between rainfall and volumetric soil water content at shallow depth, and the cumulative rainfall at weekly and semi- monthly intervals was significantly correlated with the volumetric soil water content of each layer(P<0.05). Rainfall >50 mm can ensure the supply of soil moisture within 2.0 m. (4) The determination coefficient of the model was between 0.61 and 0.85, and the root mean square error ranged from 0.0061 to 0.0096 cm -3·cm -3. The accuracy of the deep layer simulation was higher than that of the shallow layer. These results have important implications for rain- fed vegetation afforestation in the Horqin Sandy Land.
Hits
Hits
Downloads
Comment