摘要
种子库是潜在的植物群落并在一定程度上预示着群落的演替方向。草原牧区自退牧还草政策实施以来，草原利用方式由自由放牧为主逐步转向以围封割草为主。为研究割草和放牧对土壤种子库密度、植物功能群和种类组成的影响及其与地上植被的相似性关系，在内蒙古克氏针茅（Stipa krylovii）典型草原区设置3个不同强度的刈割处理，即无刈割对照（CK）和分别留茬15 cm（M15）、5 cm（M5）的处理，以及一个自由放牧处理（GR），土壤种子库采用环刀法多点取样结合四唑染色法测定种子活力，计数所有被检测有生命力的种子，并计算土壤种子库与地上植被在物种组成方面的相似性。结果表明：不同处理的土壤种子库密度范围为6245.0±1351.9～8155.9±909.1粒·m-2，无刈割对照的土壤种子库密度显著高于M15；从种子库的功能群组成来看，多年生杂类草种子密度最大，占种子库总量的55%～60%，1年生杂类草占36%～43%，GR与M15有显著差异；从物种组成来看，只有克氏针茅、砂韭的种子数量在刈割和放牧处理下显著低于对照。采用Sorensen指数计算土壤种子库与地上植被的物种相似性，CK、GR、M5、M15相似系数分别为0.55、0.58、0.48和0.60；研究预示，内蒙古典型草原土壤种子库对割草和自由放牧有很强的敏感性，刈割和自由放牧均降低土壤种子库密度，将降低退化克氏针茅草原的自然恢复能力。
The seed bank is a potential plant community and indicates orientation of plant community succession. Since the grazing ban policy was implemented, grassland utilization has been shifted from free grazing to hay-making. In this study, we assessed the impacts of clipping and grazing on soil seed bank composition （density, functional and species composition） and its similarity with aboveground vegetation. We established four different clipping treatments： no clipping control （CK）, clipping at 15 cm high （M15）, at 5 cm high （M5） and free grazing （GR） in a typical Stipa kryloviidominated steppe in Inner Mongolia. The seed bank was sampled with cutting ring and TTC method was used for testing seed viability. Viable seeds were counted and the Sorensen’s similarity between the species composition of soil seed bank and above ground vegetation was calculated. The results showed that soil seed bank density ranged from 6245.0±1351.9 to 8155.9±909.1 seeds per square meter across all treatments. The CK had a higher soil seed bank density than M15. Of all the functional groups, perennial forbs had the highest soil seed bank density and accounted for around 55%-60% of the total seed bank density. Annual forbs accounted for 36%-43% of the soil seed bank density and showed significantly a higher seed density at GR than at M15. From the individual species level, the seed density of Stipa krylovii and Allium bidentatum was significantly affected by clipping and grazing. Sorensen’s similarity index for CK, GR, M5 and M15 was 0.55, 0.58, 0.48 and 0.60, respectively. Our experiments indicated that seed bank in the Inner Mongolia typical steppe was highly sensitive to free grazing and clipping. Both clipping and grazing reduced the soil seed bank density, and thus were predicted to retard the restoration of the degraded Stipa krylovii natural steppe.
出处
《生态学杂志》
CAS
CSCD
北大核心
2014年第1期1-9,共9页
Chinese Journal of Ecology
基金
国家自然科学基金面上项目(30370268和30870422)资助
关键词
土壤种子库
放牧
刈割
植物功能群
soil seed bank, grazing, clipping, plant functional group.
