不同形成时间高原鼢鼠鼠丘土壤养分分配规律

高原鼢鼠(Myospalax baileyi)作为青藏高原唯一营地下生活的鼠类,其造丘活动不仅能影响草地群落演替的方向和进程,而且对鼠丘土壤养分含量和分配造成空间异质性。关于不同形成时期的高原鼢鼠鼠丘养分含量及在垂直高度的分配规律研究报道尚少。基于此本研究以不同形成时期的鼢鼠鼠丘为研究对象,对鼠丘土壤养分含量及空间分配规律进行探讨。结果表明:随着鼠丘形成时间的推移,土壤养分总体表现为:1年鼠丘多年鼠丘对照区;与非鼠丘区相比,随着土壤土层增加,土壤养分未呈现规律性的变化。其中,土壤全氮和速效氮含量表现为1年鼠丘3年鼠丘5年鼠丘对照区;0—10cm土壤全磷和速效磷含量变化总体表现为多年鼠丘1年鼠丘对照区,10—30cm土层1年鼠丘土壤中全磷和速效磷含量最高。土壤速效钾和有机质含量随着鼠丘形成时间推移总体表现为:1年鼠丘5年鼠丘3年鼠丘;其中在10—30cm土层,1年鼠丘速效钾和有机质含量显著高于多年鼠丘和对照区。由此可见,高原鼢鼠造丘活动能显著改变土壤养分分配格局,短期内形成养分富集的肥力岛,为鼠丘土壤种子库中种子的萌发和植被生长提供必需的养分保证。

The allocation pattern of soil nutrients in plateau zokor mounds of different ages

Alpine grassland is an important andcharacteristic ecosystem of the Qinghai-Tibet Plateau, but about 30% has been severely degraded by the combined effects of climate change, human activity, overgrazing, and rodent damage.Plateau zokor (Myospalax baileyi) are endemic subterranean herbivores on the Qinghai-Tibet plateau and they exhibit several ecological characteristics that not only influence the succession of plant communities, but also cause soil moisture, organic carbon, and soil nutrient heterogeneity. However, few studies have investigated vertical soil nutrient allocation in plateau zokor mounds, something that this study addresses by investigating zokor mounds with different formation times. Total nitrogen, available nitrogen, total phosphorus, available phosphorus, available potassium, and the organic contents of different soil samples from a number ofzokor mounds, and a control sample where plateau zokor did not inhabit in this region, were measured. Our results showed that soil nutrients were highest in the one-year old mound and lowest in the control sample, and that the nutrient content found in the mounds did not change with soil depth. These results contrasted with those from the control sample, which recorded decreasing soil nutrients with increasing soil depth. The results for total nitrogen and available nitrogen showed that the one-year-old mound > three-year-old mound > five-year-old mound > control. Total nitrogen content was found to increase with soil depth in the one-year old mound, whereas total nitrogen levels decreased in the three- and five-year-old mounds. Available nitrogen content decreased in the 0-10cm and 10-20cm layers in the one-year-old mound, five-year-old mound and in the control. However, available nitrogen content rose as the profile depth increased. In the 0-10cm layer, the total phosphorus content increased as the mounds got older, i.e.five-year-old mound > three-year-old mound > one-year-old mound > control.The total phosphorus content in the five-year-old mound was significantly higher than the control (P < 0.05), and the total phosphorus content of this mound considerably decreased with increasing depth.Available phosphorus content in the 0-10cm layer of the mounds decreased as the age of the mound increased.The available potassium contents inthe five-year old mound and control were higher than the three-year old mound in the 0-10cm layer. In the 10-20 cm layer, the available potassium content was significantly higher than in the other layers of the mounds. The one-year old mound also contained more available potassium than the other mounds or the control. Our study has indicated that the burrowing activity of plateau zokor can change the physical and chemical properties of the soil, and that the zokor mounds can form a "fertile island" in a relatively short period. These mounds provide a suitable environment for seed germination and survival, and they are important as a soil seed bank. Therefore, plateau zokor play an important role as "ecosystem engineers"in the Tibetan plateau ecosystem.