陕北毛乌素沙地生物结皮的土壤水分效应及其人工培育技术初探
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摘要
对于生物结皮在干旱、半干旱地区陆地生态系统中的功能,研究者已经给予了充分的肯定。大量的试验研究已经证明了生物结皮在养分循环过程、土壤水文过程、以及土壤侵蚀等过程中有着重要的功能。本论文在前人研究的基础上,针对陕北毛乌素沙地这一特殊地域存在的生物结皮层进行全面踏查,分析了不同发育程度的结皮的理化性质,为进一步研究毛乌素沙地生物结皮的防风固沙效应奠定基础；通过野外小区试验,进行长期定位监测沙地土壤水分含量变化及防风蚀效应研究,比较不同植被及生物结皮的组合对毛乌素沙地水分的影响,寻求从根本上能够治理沙地荒漠化的途径；同时对于毛乌素沙地生物结皮进行了一系列的室内培育试验及野外培育试验,探索该地区苔藓植物人工培养最佳适宜的温度、土壤含水量以及最适培养液,旨在为毛乌素沙地土壤生物结皮人工修复提供实验基础。
本论文通过试验研究,主要得到以下研究成果：
(1)通过野外采样和室内分析相结合,掌握了陕北毛乌素沙地不同地块生物结皮层的理化性质及其发育特征,为进一步研究毛乌素沙地生物结皮的防风固沙效应奠定了基础。踏查发现,苔藓结皮主要分布在沙丘底部、背风坡处、海子旁等地,尤其是在沙地植被下；由于毛乌素沙地地下水位浅,含水量相对较多,故水量充足地区,生物结皮极易发育成苔藓结皮,仅在杨树林迎风坡处采集到藻结皮；随着生物结皮的发育时间的延长,结皮层厚度不断增加,最大值可达11.82mm；土壤颗粒逐渐细化,0.02-0.05mm之间的颗粒含量为7.3-27.7%,均高于流沙(5.7%)；结皮层容重增加,抗剪强度明显提高,且抗剪强度与厚度和容重之间存在一定的正相关性。生物结皮层pH值为7.23-7.81,低于流动沙地的pH值,原因是生物结皮层的生物成分能够腐植酸以及地面植被根系在其生长过程中能够分泌酸类物质；有机质、N、K含量明显高于流沙的含量；P含量略有增加。
(2)通过长期对野外小区沙地水分的动态监测,比较6个不同处理下的水分含量,结果表明：单纯的结皮处理对于沙地的水分保持未能起到积极作用,而从植被来看,沙蒿根系能够很好的涵养水分,为保持沙地水分起到了积极的作用。沙蒿与结皮组合的小区内水分含量不及单纯沙蒿小区的含水量高,但高于单纯的结皮小区。然而沙蒿与生物结皮组合的小区在涵养水分方面却不是最好的,实验证明,紫穗槐与生物结皮组合的小区的沙层含水量要高于沙蒿+结皮小区的含水量。
经过13个月的风蚀观测,发现这6个处理中,裸沙地处理下沙土流失量为788 t／hm2,而结皮处理的防蚀效应要比紫穗槐以及沙蒿的防蚀效果明显,而结皮与沙蒿的共存真正起到防风固沙的效果,固沙量达到了27.51 t／hm2,紫穗槐与结皮的组合未能起到理想的防蚀效应,沙土流失量约为55t／hm2,可能与其植被盖度低有关。
(3)根据对毛乌素沙地不同发育程度的苔藓结皮N、P、K含量的分析结果,修正了Knop培养液,按照正交试验设计方法进行室内培育实验,探讨最适合毛乌素沙地藓类植株茎叶碎段生长发育的温度、培养液浓度、以及培养液使用量。结果表明：当温度为15℃,培养液为low Knop,加液体量为12ml时,藓结皮的生长发育状况最好,其株密度为329株／皿,平均株高为4.5mm 25℃时处理间差异不显著,生长情况不及15℃理想,而35℃高温下的所有处理均没有茎叶碎段生长繁殖。根据所有处理株高随时间的变化,得出藓类植株生长拟合曲线为y=-0.0018x2+0.1367x。
(4)在室内成功培育试验基础上,按照前期方法准备相关试验材料,在野外进行培育实验。野外试验主要考虑到遮荫以及营养液两个因素,水分含量根据室内试验的最适量,统一按每个小区1.1L加营养液。经过半年多的培育,试验表明,遮荫处理下的藓类植株得到很好的生长发育,与室内结果略有不同的是,在High Knop培养液处理下的藓类植株生长最佳,其次为low Knop。但野外试验不及室内培育时藓类植株生长发育快,主要是野外环境中不可控因素较多,需要进一步对野外培育的研究。
About the functions of biological soil crust (BSC) in terrestrial ecosystem in arid and semi-arid region, researchers have given full recognition. A large number of experimental studies have demonstrated that, BSC has an important function in the nutrient cycle, soil hydrological processes and soil erosion process. Based on previous studies, this paper comprehensively investigates the BSC in the special region of Mu Us Sandy Land in Northern Shaanxi, analysis physical and chemical properties of crust in different developmental levels, and lays a foundation for the further research on BSC's effect of sand-fixing in Mu Us Sandy Land. Through field plot experiments, monitoring the change of water content and study the effect of defending wind erosion in a point long term, comparing the affect of combination of vegetations and crust to water content to find a way to control Sandy desertification fundamentally. Meanwhile, we did some indoor and field cultivation experiment to explore the best temperature, soil moisture, and medium for the cultivation of bryophytes.
Through experiment research, this paper gets the following results:
(1) By sampling in fields in Mu Us Sandy Land in Northern Shaanxi and analysis in laboratory, physical and chemical properties and development characteristics of biological soil crust in different sampling points were mastered. This lays a foundation for the further research on soil crust's effects of windbreak and sand fixation. It was found that moss crust mainly distribute in the bottom and Leeward slope of sand and around the lake, especially below the sand vegetations. Because ground water is lower and water content is larger relatively in this region, BSC is easily to be moss crust, algal crust is only found in windward of a poplar forest. With the development of biological soil crust, its thickness growth to 11.82mm; Soil particles in biological soil crust refined, contents of particles whose diameter ranges from 0.02～0.05mm are 7.3-27.7%, higher than in sand(5.7%); Because of the refinement, bulk density of biological soil crust rises and shear strength increases apparently. PH in biological soil crust is from 7.23 to 7.81, lower than in sand; The contents of organic matter, N and K are higher in crust than in sand apparantly, but the content of P increase a little. In this research there are differences among all physical and chemical properties of biological soil crust in different sampling points. Reasons of the differences are mainly the degree of crust's development, vegetation coverage and topography and geomorphology in different sampling points.
(2) Through long-term field plot on the dynamic monitoring of Soil Water, comparing water content in 6 different treatments, result indict that:pure BSC treatment can not play a positive role for water conserve in sandy land, but,as vegetation, artemisia can do this whose root system can hold water perfect. Water moisture in the treatment of combining BSC and artemisia is lower than pure artemisia treatment, higher than pure BSC treatment. However, water moisture in the treatment of combining BSC and another kind of vegetation amorpha is higher than combination of BSC and artemisia.
By monitoring wind erosion in 6 treatment for 13 months, the amount of sand loss is about 788 t/hm2 in the treatment of pure sand, and the effect of wind prevention in the treatment of BSC is better than in the treatment of artemisia and amorpha. The combination of BSC and artemisia serve the effect of sand-fixing really and the mount of sand fixing reach 27.51 t/hm2, better than The combination of BSC and amorpha, whose sand loss is 55 t/hm2. Maybe it has the relation to the lower vegetation coverage.
(3) Based on the nutrient analysis of moss crusts in different growing time in Mao US sandy land, modified the Knop culture medium according to the contents of N、P、K. By the method of orthogonal experimental design, did the laboratory cultivated experiment to find the optimum conditions for the growth of moss plants' tatter leaf sections. The results indicated:the best moss plants' density was 329 strains/dish, and mean height was 4.5 mm in the conditions of 15℃, low Knop as the culture medium and adding 12 ml culture medium; There was no significant difference among the treatments in the condition of 25℃and the growth was worse than in the condition of 15℃;Moss plants' tatter leaf sections did not grow in the high temperature of 35℃; According to all the plants height with the change of time, drew a growth fitting curve of moss plants:y=-0.0018x2+0.1367x. This research provided certain experimental basis on the field cultivation of moss crust, especially for the artificial recovery of biological soil crust in Mao US sandy land.
4) Based on the successful laboratory cultivated experiment, the field experiment was done according to the same preparation. It contains 2 factors (shade or not, culture medium), every treatment add culture medium 1.1 L. After seven months, moss plant in the shade treatment developed well, the best is in the treatment of High Knop culture medium, the better is low Knop. Growth speed in yield is not fast, because there are some uncontrolled factors. We need do further yield cultivation research.
本论文通过试验研究,主要得到以下研究成果：
(1)通过野外采样和室内分析相结合,掌握了陕北毛乌素沙地不同地块生物结皮层的理化性质及其发育特征,为进一步研究毛乌素沙地生物结皮的防风固沙效应奠定了基础。踏查发现,苔藓结皮主要分布在沙丘底部、背风坡处、海子旁等地,尤其是在沙地植被下；由于毛乌素沙地地下水位浅,含水量相对较多,故水量充足地区,生物结皮极易发育成苔藓结皮,仅在杨树林迎风坡处采集到藻结皮；随着生物结皮的发育时间的延长,结皮层厚度不断增加,最大值可达11.82mm；土壤颗粒逐渐细化,0.02-0.05mm之间的颗粒含量为7.3-27.7%,均高于流沙(5.7%)；结皮层容重增加,抗剪强度明显提高,且抗剪强度与厚度和容重之间存在一定的正相关性。生物结皮层pH值为7.23-7.81,低于流动沙地的pH值,原因是生物结皮层的生物成分能够腐植酸以及地面植被根系在其生长过程中能够分泌酸类物质；有机质、N、K含量明显高于流沙的含量；P含量略有增加。
(2)通过长期对野外小区沙地水分的动态监测,比较6个不同处理下的水分含量,结果表明：单纯的结皮处理对于沙地的水分保持未能起到积极作用,而从植被来看,沙蒿根系能够很好的涵养水分,为保持沙地水分起到了积极的作用。沙蒿与结皮组合的小区内水分含量不及单纯沙蒿小区的含水量高,但高于单纯的结皮小区。然而沙蒿与生物结皮组合的小区在涵养水分方面却不是最好的,实验证明,紫穗槐与生物结皮组合的小区的沙层含水量要高于沙蒿+结皮小区的含水量。
经过13个月的风蚀观测,发现这6个处理中,裸沙地处理下沙土流失量为788 t／hm2,而结皮处理的防蚀效应要比紫穗槐以及沙蒿的防蚀效果明显,而结皮与沙蒿的共存真正起到防风固沙的效果,固沙量达到了27.51 t／hm2,紫穗槐与结皮的组合未能起到理想的防蚀效应,沙土流失量约为55t／hm2,可能与其植被盖度低有关。
(3)根据对毛乌素沙地不同发育程度的苔藓结皮N、P、K含量的分析结果,修正了Knop培养液,按照正交试验设计方法进行室内培育实验,探讨最适合毛乌素沙地藓类植株茎叶碎段生长发育的温度、培养液浓度、以及培养液使用量。结果表明：当温度为15℃,培养液为low Knop,加液体量为12ml时,藓结皮的生长发育状况最好,其株密度为329株／皿,平均株高为4.5mm 25℃时处理间差异不显著,生长情况不及15℃理想,而35℃高温下的所有处理均没有茎叶碎段生长繁殖。根据所有处理株高随时间的变化,得出藓类植株生长拟合曲线为y=-0.0018x2+0.1367x。
(4)在室内成功培育试验基础上,按照前期方法准备相关试验材料,在野外进行培育实验。野外试验主要考虑到遮荫以及营养液两个因素,水分含量根据室内试验的最适量,统一按每个小区1.1L加营养液。经过半年多的培育,试验表明,遮荫处理下的藓类植株得到很好的生长发育,与室内结果略有不同的是,在High Knop培养液处理下的藓类植株生长最佳,其次为low Knop。但野外试验不及室内培育时藓类植株生长发育快,主要是野外环境中不可控因素较多,需要进一步对野外培育的研究。
About the functions of biological soil crust (BSC) in terrestrial ecosystem in arid and semi-arid region, researchers have given full recognition. A large number of experimental studies have demonstrated that, BSC has an important function in the nutrient cycle, soil hydrological processes and soil erosion process. Based on previous studies, this paper comprehensively investigates the BSC in the special region of Mu Us Sandy Land in Northern Shaanxi, analysis physical and chemical properties of crust in different developmental levels, and lays a foundation for the further research on BSC's effect of sand-fixing in Mu Us Sandy Land. Through field plot experiments, monitoring the change of water content and study the effect of defending wind erosion in a point long term, comparing the affect of combination of vegetations and crust to water content to find a way to control Sandy desertification fundamentally. Meanwhile, we did some indoor and field cultivation experiment to explore the best temperature, soil moisture, and medium for the cultivation of bryophytes.
Through experiment research, this paper gets the following results:
(1) By sampling in fields in Mu Us Sandy Land in Northern Shaanxi and analysis in laboratory, physical and chemical properties and development characteristics of biological soil crust in different sampling points were mastered. This lays a foundation for the further research on soil crust's effects of windbreak and sand fixation. It was found that moss crust mainly distribute in the bottom and Leeward slope of sand and around the lake, especially below the sand vegetations. Because ground water is lower and water content is larger relatively in this region, BSC is easily to be moss crust, algal crust is only found in windward of a poplar forest. With the development of biological soil crust, its thickness growth to 11.82mm; Soil particles in biological soil crust refined, contents of particles whose diameter ranges from 0.02～0.05mm are 7.3-27.7%, higher than in sand(5.7%); Because of the refinement, bulk density of biological soil crust rises and shear strength increases apparently. PH in biological soil crust is from 7.23 to 7.81, lower than in sand; The contents of organic matter, N and K are higher in crust than in sand apparantly, but the content of P increase a little. In this research there are differences among all physical and chemical properties of biological soil crust in different sampling points. Reasons of the differences are mainly the degree of crust's development, vegetation coverage and topography and geomorphology in different sampling points.
(2) Through long-term field plot on the dynamic monitoring of Soil Water, comparing water content in 6 different treatments, result indict that:pure BSC treatment can not play a positive role for water conserve in sandy land, but,as vegetation, artemisia can do this whose root system can hold water perfect. Water moisture in the treatment of combining BSC and artemisia is lower than pure artemisia treatment, higher than pure BSC treatment. However, water moisture in the treatment of combining BSC and another kind of vegetation amorpha is higher than combination of BSC and artemisia.
By monitoring wind erosion in 6 treatment for 13 months, the amount of sand loss is about 788 t/hm2 in the treatment of pure sand, and the effect of wind prevention in the treatment of BSC is better than in the treatment of artemisia and amorpha. The combination of BSC and artemisia serve the effect of sand-fixing really and the mount of sand fixing reach 27.51 t/hm2, better than The combination of BSC and amorpha, whose sand loss is 55 t/hm2. Maybe it has the relation to the lower vegetation coverage.
(3) Based on the nutrient analysis of moss crusts in different growing time in Mao US sandy land, modified the Knop culture medium according to the contents of N、P、K. By the method of orthogonal experimental design, did the laboratory cultivated experiment to find the optimum conditions for the growth of moss plants' tatter leaf sections. The results indicated:the best moss plants' density was 329 strains/dish, and mean height was 4.5 mm in the conditions of 15℃, low Knop as the culture medium and adding 12 ml culture medium; There was no significant difference among the treatments in the condition of 25℃and the growth was worse than in the condition of 15℃;Moss plants' tatter leaf sections did not grow in the high temperature of 35℃; According to all the plants height with the change of time, drew a growth fitting curve of moss plants:y=-0.0018x2+0.1367x. This research provided certain experimental basis on the field cultivation of moss crust, especially for the artificial recovery of biological soil crust in Mao US sandy land.
4) Based on the successful laboratory cultivated experiment, the field experiment was done according to the same preparation. It contains 2 factors (shade or not, culture medium), every treatment add culture medium 1.1 L. After seven months, moss plant in the shade treatment developed well, the best is in the treatment of High Knop culture medium, the better is low Knop. Growth speed in yield is not fast, because there are some uncontrolled factors. We need do further yield cultivation research.
引文
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