关键词: 植被类型, 防风效能, 固沙效率, 坝上地区

Abstract:

Objective: This study quantitatively evaluated the differences in windbreak efficiency and sand-fixation efficiency of typical sand-fixing tree species (Populus simonii, Pinus sylvestris var. mongolica, and Caragana korshinskii) within the shelterbelt systems of the Bashang region during winter and spring. It further investigated the response relationships and driving mechanisms linking these differences to key near-surface attributes, including vegetation morphology, surface cover, and soil properties. This study aims to provide a scientific basis for optimizing the local vegetation-based protection system and enhancing its year-round windbreak and sand-fixation performance. Method: Field observations were conducted in Kangbao County, Hebei Province, in November 2024, March and April 2025. The shelterbelts of three dominant tree species (P. simonii, P. sylvestris var. mongolica, and C. korshinskii) were selected as experimental objects, with the adjacent bare land as control plots. For each vegetation type, three observation points were set up along the prevailing wind direction at the windward side, within, and leeward side of the shelterbelt, and wind speed and sand transport flux were measured synchronously using cup anemometers and omnidirectional rotating sand collectors to calculate windbreak efficiency and sand-fixation efficiency. The tree height, crown width, coverage, litter thickness and density (undecomposed and semi-decomposed layers), understory vegetation height and coverage were investigated, and the surface soil (0–10 cm) properties: particle size distribution (sand, silt, clay), soil density, and moisture content were analyzed. One-way ANOVA was used to compare differences, Pearson correlation was used to examine associations, and redundancy analysis combined with multiple regression was used to quantify key drivers and their contributions. Result: There were significant differences in windbreak effectiveness and sand-fixation efficiency among vegetation types during winter and spring: the windbreak effectiveness was shown as the order of P. sylvestris var. mongolica (81.16%) > P. simonii (63.94%) > C. korshinskii (47.96%), while sand-fixation efficiency was ranked as P. simonii (97.78%) > P. sylvestris var. mongolica (96.23%) > C. korshinskii (89.39%). Compared to bare land, vegetation restoration significantly modified near-surface characteristics, reducing surface soil clay content by 1.80%–2.62%, increasing silt content by 10.88%–11.84%, and decreasing soil density by 11.52%–20.00%. The litter characteristics and understory vegetation height of the P. simonii plots were significantly better than those of the other species plots. Redundancy analysis indicated that near-surface characteristics collectively explained 89.2% of the variation in protective functions, with crown width identified as the dominant driver (60.3%), followed by soil moisture content (9.4%), clay content (6.0%), and density of the undecomposed litter layer (4.5%). The multiple regression model quantitatively characterized the contribution of key factors. Conclusion: During the wind-prone winter and spring seasons in arid regions, there are significant differences in windbreak and sand-fixation efficiency among different sand-fixing vegetation types. The evergreen arbor maintains the highest windbreak efficiency owing to their persistent canopy, while deciduous trees exhibit optimal sand-fixation performance due to substantial litter accumulation. Crown width is the most critical factor regulating protective efficiency, yet its direct management remains constrained. Enhancing ground coverage, particularly through high-litter accumulation, proves to be an effective approach for strengthening wind erosion control in winter and spring. The findings suggest that vegetation restoration practices should account for seasonal protection needs: in areas with severe wind erosion, P. sylvestris var. mongolica should be prioritized to reduce wind speed, whereas in areas with vulnerable surface soil, greater emphasis should be placed on P. simonii to suppress particle transport. This tailored approach can enable effective year-round control of regional soil wind erosion and support sustainable ecosystem management.

Key words: vegetation type, windbreak efficiency, sand-fixing efficiency, Bashang region