石羊河下游不同类型荒漠草地黑果枸杞群落结构特征及土壤特性研究

通过对石羊河下游4种不同类型荒漠草地黑果枸杞群落物种组成及土壤特性的研究,结果表明:1)所调查群落中共有植物31种,分属9科27属,其中灌木植物12种,多年生草本8种,一年生草本11种; 单科单属种较多,占到了总科数的50%;且黑果枸杞在不同群落中优势地位明显,对群落的结构、生态系统功能及稳定性具有重要作用。2)相同土层不同类型荒漠草地,0~10 cm、10~20 cm、20~40 cm及40~60 cm下盐碱地有机碳含量最高,其值分别为1.08%、0.98%、0.89%、0.972%。与沙地相比,土壤有机碳(盐碱地)差异显著(P<0.05),土壤速效钾盐碱地(除20~40 cm外)和土壤全磷含量(盐碱地0~10 cm)差异显著(P<0.05),土壤全氮、碱解氮、有效磷、全钾含量没有显著性差异(P>0.05)。同一类型荒漠草地不同土层,土壤有机碳、土壤有效磷(盐碱地)、土壤全钾(沙丘)、土壤全磷(盐碱地和砾石)具有明显的表聚效应。3)不同类型荒漠草地土壤微生物量总体表现为盐碱地>沙地>固定半固定沙地>砾石,不同类型荒漠草地土壤微生物量差异不同,盐碱地中4种酶活性均为最高,同一类型荒漠草地不同土层,随着土层的加深,土壤微生物量和蔗糖酶逐渐减少。4)土壤有机质与微生物生物量碳、微生物生物量氮和磷酸酶、蔗糖酶呈极显著正相关(P<0.01),与脲酶和过氧化氢酶呈显著正相关(P<0.05);土壤全磷含量与脲酶、磷酸酶、蔗糖酶呈极显著正相关(P<0.01),与微生物量氮呈显著正相关(P<0.05)。土壤速效钾含量与微生物量碳和磷酸酶呈极显著正相关(P<0.01)。

Structural features of Lycium ruthenicum communities and associated soil characteristics on different types of desert rangeland in the lower reaches of the Shiyang River

The species composition and soil characteristics of black wolfberry communities in four different types of desert rangeland (loose sand dunes, salt flats, gravels, vegetated or semi-vegetated dunes) in the lower reaches of the Shiyang river were studied. Key content of this paper includes: 1) Among the plant communities investigated, there were 31 species (12 shrub plants, 8 perennial herbs and 11 annual herbs) belonging to 9 families and 28 genera. Hence the community structure at each studied site typically comprised a few families represented by a single taxon from one or more genera. Lycium ruthenicum had a dominance role in each of the 4 communities with ‘importance values’ of 58.9%, 17.6%, 18.2% and 38.1%, respectively, for the above 4 site categories. Only at the gravel flats site was another species more important (Setaria viridis, 28.9%). 2) A range of soil chemical properties are tabulated for 0-10 cm, 10-20 cm, 20-40 cm, and 40-60 cm soil depths. Soil organic C for the 0-10 cm soil depth was 0.30%, 1.08%, 0.29%, and 0.37% (mean s.e.±0.05%), respectively, for loose dune, salt flat, gravel and vegetated dune sites. The measured soil properties generally did not vary significantly with soil depth, but along with SOC, soil total P and available K were markedly higher in saline flats than at the other site categories. 3) Site rankings for soil microbial biomass were saline soil (-300 mg·kg^-1)>loose sand>vegetated dunes>gravel (-125 mg·kg^-1). Soil enzyme activities are reported for the 4 soil depths for catalase, sucrose, urease, phosphatase and invertase, and were highest in the saline soil in each case. 4) There was a significant positive correlation between soil organic matter and microbial biomass carbon, microbial biomass nitrogen, phosphatase and sucrase (P<0.01), and a significant positive correlation with urease and catalase (P<0.05). Phosphorus content was significantly positively correlated with urease, phosphatase and invertase (P<0.01), and positively correlated with microbial biomass carbon (P<0.05). Soil available potassium content was significantly positively correlated with microbial biomass nitrogen and phosphatase (P<0.01).