【作者】 叶彦辉；

【导师】 宋西德；

【作者基本信息】 西北农林科技大学 ， 森林培育， 2007， 硕士

【摘要】 在陕西省咸阳市永寿县马坊林场,采用标准地调查的方法,对黄土高原农林复合系统四种景观界面(刺槐林地—草地,刺槐林地—农田,刺槐林—草地—刺槐林,刺槐林带—农田)土壤的养分(有机质、氮、磷、钾和pH)含量、微生物(细菌、真菌和放线菌)数量和酶活性(蔗糖酶、脲酶、过氧化氢酶)进行测定。通过分析比较其养分、微生物和酶活性的分布特征,揭示黄土高原区坡地典型农林景观格局一刺槐林景观边界上各种生物因子、非生物因子的影响机制,阐明小尺度范围内林地与农田、林地与草地互相作用的强度与范围,为我国西部土地优化利用模式选择、退耕还林还草工程建设、构建西部黄土区森林复合景观的优化配置模式提供科学依据。研究的主要结论如下:1.土壤养分1.1林-草界面及相邻区域土壤养分分布特征:OM值在0~40 cm土层的平均含量为草地>边缘>林地;AN则为边缘>林地>草地;TN为林地>草地>边缘;TP、TK和pH为边缘>草地>林地,差异不明显;AP和AK为草地>林地>边缘,差异也不明显。林地系统、草地系统内的OM、AP、AK含量在生长季末期(9月)含量相对最高,在生长季或生长季前期(6月或4月)含量较低;而AN含量在生长季前期(4月)含量最高。1.2林-农界面及相邻区域土壤养分分布特征:OM、TN、AK和pH在0~40 cm土层的平均含量为边缘>林地>农田;AN为林地>边缘>农田;TP为林地>农田>边缘,差异不明显;AP和TK为农田>边缘>林地;差异也不明显。林地系统、农田系统内的OM、TN、AP、TP在生长季(6月)含量相对最高,而在生长季前期(4月)含量最低;TK、AK在生长季末期(9月)含量最高,在生长季或生长季前期(6月或4月)含量较低。1.3林-草-林界面及相邻区域土壤养分分布特征:OM、TN和AK在0~40 cm土层的平均含量为林地>草地,AN、TP、AP和TK为草地>林地,差异也都不明显;pH值为林地>草地。1.4林带-农界面及相邻区域土壤养分分布特征:OM、TN、AN和AK值在0~40 cm土层的平均含量为边缘>林地>农田;TP为农田>林地>边缘,AP为农田>边缘>林地,差异不明显;TK为林地>农田>边缘,pH为边缘>农田>林地,差异不明显。1.5不同类型农、林、草边界土壤养分沿林地—边缘—农田、林地—边缘—草地水平分布特征表现为呈“V”、倒“V”或近线性;沿样带梯度分布特征表现为“V”“W”、波浪状等。2.土壤微生物2.1四种景观界面下土壤中各种微生物数量存在明显差异,在总体数量上均以细菌为主,放线菌次之,真菌较少。林地微生物总数量0~20 cm土层的远大于20~40 cm土层,而农田20~40 cm土层的远多于0~20 cm土层的。细菌在林地和草地上都是0~20 cm土层大于20~40 cm土层。在农田上是20~40 cm土层的远多于0~20 cm土层的。2.2真菌在林地和农田上是0~20 cm土层的小于20~40 cm土层,在草地上不同景观界面数量分布不一样,在林草景观界面的草地上是0~20 cm土层的小于20~40 cm土层,但在林草林景观界面的草地上是0~20 cm土层的大于20~40 cm土层,这是因为0~20 cm土层的pH小于20~40 cm土层,真菌在酸性环境条件下生长旺盛。2.3放线菌在林草界面的林地中是0~20 cm土层的大于20~40 cm土层,在其它3中景观界面的林地中是0~20 cm土层的小于20~40 cm土层;在草地上是0~20 cm土层的大于20~40 cm土层,农田中林农界面上是0~20 cm土层的小于20~40 cm土层,林带农田界面是0~20 cm土层的大于20~40 cm土层。3.土壤酶活性3.1在垂直层次上,三种酶的活性都是0~20 cm土层高于20~40 cm土层;蔗糖酶活性在土层间差异性较小,脲酶和过氧化氢酶活性在土层间差异性较大。3.2在景观界面上,蔗糖酶活性最强,脲酶和过氧化氢酶活性较弱。蔗糖酶活性在景观界面上林地>草地>农田;脲酶活性在景观界面上农田>林地>草地;过氧化氢酶活性在景观界面上变化不大,在林地、农田、草地活性基本一样。4.土壤肥力相关性4.1土壤细菌、真菌、放线菌对土壤pH值成相关性,除了在林草景观界面呈正相关外,在其它三个景观界面呈负相关。对其他养分指标相关性不显著。4.2土壤蔗糖酶、脲酶和过氧化氢酶与土壤pH值均呈负相关关系,对有机质、全氮、速效钾呈显著或极显著相关性。通过研究黄土高原不同土地类型上土壤养分、微生物和酶活性变化特征,给土地优化利用模式提供参考,对西部退耕还林还草工程实施以来的生态效益以及土壤质量的研究提供参考依据,为复合景观模式配置研究提供参考依据。更多还原

【Abstract】 Based on determination of soil nutrients(organic matter,N,P,K and pH) and soil microoganisms(bacteria, fungi and actinomyces)and activity of the enzyme(invertase,urease, catalase)in four kinds of agroforestry landscape boundaries(forest-grassland,forest-farmland ,forest-grassland-forest and forest belt-farmland boundaries) in gully region of loess plateau,comparative analysis of siol nutrients, microoganisms and enzyme activity statistics were carried out.The main conclusions are as follows:1.Soil nutrient1.1 The soil nutrient distribution characters of forest-grassland boundary and neighboring region were different.The organic matter of average level in 0-40 cm soil layer was grassland > boundary > forestland,Available N was boundary > forestland > grassland ,Total N was forestland > grassland > boundary,Total P,K and pH were boundary > grassland > forestland,the difference was not significant.Available P and Available K were grassland > forestland > boundary,the difference was not significant.The content of organic matter,available P,available K of forestlsnd and grassland were higher in the late growing season (September),than that in early growing season(June or April),But the content of available N was the highest in the early growing season(April).1.2 The soil nutrient distribution characters of forest-grassland boundary and neighboring region were different.The organic matter,Total N,Total K and pH of average level in 0-40 cm soil layer were boundary > forestland > farmland,Available N was forestland > boundary > farmland,Total P was forestland > farmland > boundary,the difference was not significant.Available K and Available K were farmland > boundary > forestland,the difference was not significant.The amount of organic matter,total N,available P,and total P of forestlsnd and farmland were highest in the growing season (June), in early growing season(April)were the lowest.The amount of total K and available K were the highest in the late growing season(Septemper),in early growing season or growing season(June or April)were the lowest. 1.3 The soil nutrient distribution characters of forest-grassland-forest boundary and neighboring region were different.The organic matter,Total N,Available K of average level in 0-40 cm soil layer were forestland > grassland,the difference was not significant.Available N,Total P, Available P and Total K were grassland > forestland,the difference was not significant.pH was forestland > grassland.1.4 The soil nutrient distribution characters of forest belt-grassland boundary and neighboring region were different.The organic matter,Total N,Available N and Available K of average level in 0-40 cm soil layer were boundary > farmland > forestland, Total P farmland > forestland > boundary,the difference was not significant.Available P was farmland > boundary > forestland,Total K was forestland > farmland > boundary,pH was boundary > farmland > forestland,the difference was not significant.1.5 Horizontal distributions of soil nutrient across different boundaries showed“V”shape,inverse“V”shape and line shape along patch gradients of farmland (grassland)-edge-forestland and showed“V”shape,“W”shape and wave shape along belt transect gradients distribution.2. Soil microoganism2.1 Each kind of microoganism quantity exists obvious difference under four kinds of agroforestry landscape boundaries in soil.In the overall quantity,the bacteria was the highest,the fungi took second place,and the actinomyces was the lowest.The amount of microorganism in 0-20 cm soil layer of forestland was significantly much more than that of 20-40 cm.But the amount of microorganism in 20-40 cm soil layer of farmland was significantly much more than that of 0-20 cm.The amount of bacteria in 0-20 cm soil layer of forestland and grassland was more than that of 20-40 cm.But the amount of bacteria in 20-40 cm soil layer of farmland was significantly much more than that of 0-20 cm.2.2 The amount of fungi in 0-20 cm soil layer of forestland and farmland was less than that of 20-40 cm.The amount of fungi in different landscape boundaries was different in the grassland,the fungi in 0-20 cm soil layer of forest-grassland boundary was less than that of 20-40 cm,but the fungi in 0-20 cm soil layer of forest-grass-forestland boundary was more than that of 20-40 cm.This is because pH of 0-20 cm soil layer is smaller than that of 20-40cm, the fungus grows exuberantly under the acidic environmental condition.2.3 The amount of actinomyces in 0-20 cm soil layer of forestland in forest-grassland boundary was more than that of 20-40 cm,but 0-20 cm soil layer was less than 20-40 cm in other boundaries.In grassland were 0-20 cm soil layer more than 20-40 cm.In farmland ,The amount of actinomyces in 0-20 cm soil layer of forest-farmland boundary was less than that of 20-40 cm,the forest belt-farmland boundary was just opposite.3. Soil enzyme activity3.1 In vertical level,The activity of invertase,urease and catalase in 0-20 cm soil layer are more than that of 20-40 cm,The activity of invertase at different level showed small difference,But the urease and catalase showed big difference.3.2 On the landscape boundaries,The activity of invertase was the highest,the urease and catalase were weak.The activity of invertase in landscape boundary was forestland > grassland > farmland ,the urease was farmland > forestland > grassland,The activity of catalase showed little change, There was almost no difference among forestland,farmland and grassland.4. Correlation analysis of soil fertility4.1 The bacteria,fungi and actinomyces have the positive correlation with pH in forest-grassland boundary,But have the negative correlation in other landscape boundary.There was correlation between pH with other soil Nutrients, but the correlation was not significant.4.2 The activity of invertase,urease,catalase showed a negative correlation with pH,and a significant correlation with the organic matter,the total N,Available K.更多还原