【作者】 殷晓洁；

【导师】 李玉灵；

【作者基本信息】 河北农业大学 ， 生态学， 2009， 硕士

【摘要】 南山嘴沙荒地位于河北省北部的围场县,地处北方干旱半干旱区。长期以来,由于人类不合理的生产活动、干旱多风的气候条件以及该地脆弱的生态系统,引起了严重的土地荒漠化。因此,南山嘴沙荒地成为研究土地荒漠化的典型区域。本文选取了南山嘴沙荒地的封育区、未封育区及处于当地植被演替顶级阶段的南沙坨子油松林对照区三种立地类型,调查了土壤理化特性及植被特征,分析了短期封育在土壤及植被恢复过程中的作用;同时,进行了土壤种子库控水试验,对沙荒地植被的自然恢复潜力和水分制约特点进行了研究,得出以下主要结论:(1)封育5年后,南山嘴沙荒地封育区0～10cm土层土壤的入渗系数较未封育区显著降低,且10～20cm土层有机质含量显著提高,但是封育区0～40cm土层的土壤孔隙度、土壤容重、水分指标、速效磷、速效钾含量较未封育区均无显著提高。且各指标值表明,沙荒地封育区和未封育区土壤仍处于紧实的中、粗沙土水平,保水保肥能力差,营养供应水平极低,较处于该地植被演替顶级阶段的对照区仍存在较大差异。(2)短期封育下,豆科植物增多而菊科植物减少,多花胡枝子(Lespedeza floribunda)代替猪毛蒿(Artemisia scoparia)、野麻(Boehmeria gracilis)、金毛狗尾草(Setaria viridis)等成为了群落优势种。(3)短期封育使植被状况明显改善,封育区植被盖度有42%以上的明显提高,草本层生物量、枯落物干重均有60%的增加,草本层物种丰富度指数、Shannon-Wiener指数和Simpson指数也均有提高。(4)短期封育减少了降水对沙荒地植物群落的生态位分布及优势种比例的影响,增加了群落稳定性;同时,使优势种的生态位重叠现象明显增加,加剧了优势种间的竞争和共存,促进了资源的充分利用。(5)各水分处理下,沙荒地的种子库发生密度及物种多样性均远低于对照区。且沙荒地和对照区种子库均在良好水分处理下出现最大发生密度,其中,沙荒地的为2608粒/m2,表明其具备一定的恢复潜力。(6)干旱处理下,C4植物在种数和密度上均占有优势,使其更为适应干旱多风的沙荒地环境。而C3植物受水分限制明显,尤其表现在表土层以下的种子库中。(7)沙荒地及对照区的种子库与地上植被相似性均低,不足0.5。沙荒地干旱处理的种子库发生密度与调查的地上植被密度相近,而对照区中种子储量远大于其实地植被密度。(8)南山嘴沙荒地具备一定的自然恢复潜力。且经过短期封育,沙荒地植被状况好转,稳定性提高,出现了物种演替现象——豆科种增多。因此。建议在封育过程中人工补植豆科植物,以加速演替进行和土壤的恢复。更多还原

【Abstract】 Locating in an arid and semi-arid area, Nanshanzui Sandland is in Weichang county in northern of Hebei province. It has been seriously desertificated because of the unmanaged human activities and the dry and windy climate exerting on the frail ecological environment. So Nanshanzui sandland becomes one of the typical regions in land desertification research. In this paper, three site types were selected. They are enclosure and non-enclosure area of Nanshanzui sandland and Nanshatuozi tabulaeformis control zone which is in the climax stage of the local vegetation succession. Soil physical and chemical characteristics and vegetation characteristics of the three site types were investigated and the effect of short-term enclusion in the recovery process of the soil and vegetation was analyzed. While the water control test of the soil seed bank has been taken, the natural recovery potential of vegetation the constraints characteristics of water has been studied in the sandland, with main conclusions being achieved as follows:(1)After being fenced for 5 years, infiltration coefficient of 0～10cm soil layer signifacantly decreased in fenced region of sandland than those in non-exclosure region, while organic matter content of 10～20cm soil layer in fenced region has significantly increaced. But soil porosity, soli bulk density, moisture indexes and the content of available P and available K of 0～40cm soil layers are not significantly better in fenced region of sandland than those in non-exclosure region. The indexes indicate that soil conditions of both fenced region and non-exclosure region of sandland are at the level of tight medium or coarse sand with bad ability of moisture and fertilizer retention and the low level of nutrient supply. The soil physical and chemical characteristics of sandland still have great differrence with the control region which is in the climax stage of the local vegetation succession.(2)After short-term fenced, the number of legume plants increaces and the number of compositae plants reduces, Lespedeza floribunda is predominate instead of Artemisia scoparia, Boehmeria gracilis and Setaria viridis.(3)Vegetation condition has become much better after short-term fenced. Vegetation coverage of exclosure region has a significant increase of more than 42%, while biomass of herb layer and the litter dry weight increase more than 60%. Species richness, Shannon-Wiener index and Simpson index of herb layer also increase. (4)The effects of precipitation on niche distribution of sandland plant and proportion of dominant species has decreased by short-term fenced, so that community stability increased. At the same time, by being short-term fenced niche overlap among dominant species has a marked increase, which increases competition and coexistence among dominant species and promotes full utilization of resources.(5) In different water treatments, the soil seed bank occurrence density and species diversity of sandland are much lower than that of control region. Soil seed bank occurrence densities of sandland and the control region both reach the maximum in the good water condition. Among them, the occurrence densities of sandland was 2608 grains/m2, which shows a considerable restoration potentiality.(6) The C4 species would predominate in terms of number of species and density in drought condition. So that it more adaptes to the sandland environment which is droughty and windy. While C3 plant is significantly affected by water restrictions, particularly in the soil seed bank below surface soil.(7) Species similarity of seed banks and investigated vegetation were low both in sandland and its control region, less than 0.5. The seed bank density of drought treatment of sandland was similar to the investigated vegetation density. While in the control region, seed storage was much larger than its investigated vegetation density.(8) On the whole, Nanshanzui sandland possesses a considerable restoration potentiality. And by short-term fenced, the vegetation condition had become much better, its stability had increased, the phenomenon of species succession had appeared--number of leguminous species had increased. So that we suggest to cultivate legumes in order to speed up the process of vegetation succession and the restoration of soil.更多还原