【作者】 沈章军；

【导师】 孙庆业；

【作者基本信息】 安徽大学 ， 生态学， 2013， 博士

【摘要】 作为世界广布的植物类群,禾本科植物的多数种类对不良物理化学性质、极端pH值与营养贫瘠等特征的尾矿基质具有较强耐受性,成为铜尾矿原生演替草本植物阶段的主要优势植物类群。本研究试图以铜尾矿自然生态恢复草本植物阶段的优势植物白茅(Imperata cylindrica(Linn.)Beauv.)为主要实验材料,探究其成为该阶段优势植物种群的营养生态学策略及其生长代谢过程对尾矿基质营养状况的改良作用机理。主要的研究结果如下：1、样地调查与植物形态构件特征分析表明,铜尾矿基质的养分及其它理化性质均存在较大的空间异质性,白茅的地上克隆分株的数量和地下茎长度随微生境中的总氮(r=0.513,p<0.05；r=0.687,p<0.01)和有效磷(r=0.695,p<0.01；r=0.486,p<0.05)含量增加而显著增加。然而,不同营养条件微生境中的白茅根茎内养分却并不存在显著差异(p>0.05)。这说明根状茎型植物白茅可通过牺牲其生理可塑性为代价来增加其形态可塑性,将更多的幼根分布在远离母株的不同的生境中,以提高对环境选择压力的生态适应性,实现其在贫瘠尾矿生境中对养分及其它生存必需条件的寻觅和吸收。2、白茅根系活动对根际磷动态影响研究表明,白茅及其它5种常见伴生植物的生长活动能有效降低根际pH值约0.16-1.40个单位,根际中各形态无机磷和有机磷含量与无植被尾矿之间存在显著差异(p<0.05),根际中碱性磷酸酶活性显著高于无植被尾矿(p<0.05)。根际中2钙结合态、铝结合态和铁结合态无机磷的含量均被显著提高86.56%-147.58%、5.46%-88.86%和49.22%-214.20%。2钙结合态、铝结合态和铁结合态无机磷的含量与pH值均表现为显著负相关性(r=-0.586,p<0.01；r=-0.487,p<0.05；r=-0.417, p<0.05).在本研究中,豆科植物马棘表现出最强的增加根际有效磷含量的特性,禾本科植物中白茅对根际有效磷相对含量的提高效率最高。3、白茅根系活动对根际无机氮动态影响研究表明,白茅及其它5种常见伴生植物的生长代谢活动有效的增加了基质氮养分的总量和有效态含量。根际中无机氮和总氮的含量均明显高于无植被尾矿(p<0.05)；白茅等禾本科植物根际中各形态无机氮所占总氮的比例均高于其常见伴生植物,其中硝态氮所占总氮的比例显著高于豆科植物马棘(p<0.05)和两种菊科植物(p<0.05),铵态氮也显著高于菊科植物(p<0.05)。这说明白茅等禾本科植物可以通过根系活动增加有效态氮在总氮中的比例,以提高植物对根系周围氮营养的吸收效率。4、以铜尾矿同区域农田中生长的白茅居群为对照,对不同生长时期的白茅体内氮(N)、磷(P)营养浓度、叶片硝酸还原酶和酸性磷酸酶活性动态等的研究表明,在萌芽期,两居群白茅体内的N、P均主要集中于根状茎。到花蕾期、成熟期时,两居群白茅体内的N、P均向成熟叶片迁移,浓度均达到最高。但在衰败期,铜尾矿白茅体内的N主要迁移到根状茎中,P在根状茎中的浓度也达到生长期中的最高值,而农田白茅成熟叶片内N、P浓度依然最高。铜尾矿白茅叶片N、P的再吸收效率分别为49.54%-65.22%和74.71%-98.71%,衰老叶片中N的再吸收效率显著大于农田居群(p<0.05),P达到完全再吸收的程度。铜尾矿白茅叶片硝酸还原酶活性在生长旺盛期显著高于农田居群(p<0.05),是白茅加强对自身氮养分代谢活动调节作用的表现；同一生长时期白茅叶片酸性磷酸酶活性在两种生境间差异性并不明显(p>0.05),但随着生长期的延长,白茅叶片酸性磷酸酶活性表现出不断升高的趋势,这有利于生长后期衰老叶片中有机P的水解再吸收。总之,铜尾矿中生长的白茅可通过对N、P养分的适时分配,提高营养成分的再吸收效率和调节N、P代谢相关调节酶活性等方式来减轻生境的营养胁迫。5、以同一尾矿中的禾本科植物白茅和中华结缕草(Zoysia sinica Hance)群落、隐花植物木贼(Hippochaete ramosissmium L.)群落和藻类植物结皮中的土壤和植物衰败组织为实验材料,研究了土壤和植物组织中的有机碳氮含量、13C和15N的同位素相对丰度值(δ13C和δ15N),以分析植物组织对尾矿土壤有机质碳氮的影响。结果表明,植物群落土壤内的δ13C和δ15N值低于无植被尾矿土壤,禾本科植物群落中植物组织和土壤之间的有机碳含量具有显著相关性(r=0.998,p<0.01),但这种相关关系在隐花植物群落中没有被发现。白茅和藻类植物结皮的生长代谢活动有效的影响了土壤中δ13C,且土壤的含水量(r=0.716,p<0.01)、土壤微生物碳含量(r=0.729,p<0.01)和pH值(r=0.529,p<0.05)也显著的影响了土壤δ13C。相对而言,仅土壤微生物的氮含量对土壤中δ1SN值表现出显著的相关关系(r=0.935,p<0.01)。更多还原

【Abstract】 Gramineous plants are considerable distributed in the whole world. They can tolerate some extreme physical and chemical conditions in the copper tailings wasteland, such as the droughty conditions, extremely changed temperature, extreme pH, high salinity and high concentrations of harmful substances. They are also commonly survived from the nutrition stress in the barren habitat of the copper tailings. According to these ecological adaptive characteristics, gramineous plants become the mainly dominant vegetation group in the copper mine tailings. In this study, the nutritional strategy of Imperata cylindrica (Linn.) Beauv living in the copper tailings wasteland was explored. And the effect of Ⅰ. cylindrica growth metabolic process on nutrient level of copper tailings soil ecosystem was studied. The main research contents and conclusions are as follows:1. The nutrients conditions and other physicochemical properties of the copper tailings had more severe spatial heterogeneity. The number of the ground cloning seedlings and the rhizome length of Ⅰ. cylindrica increase significantly with the rich content of total nitrogen (r=0.513, p<0.05; r=0.687, p<0.01) and effective phosphorus (r=0.695,p<0.01; r=0.486, p<0.05) in the copper tailings. But the difference of the nutrients content in the stems and roots of Ⅰ. cylindrica between barren tailings and rich tailings was not significant. This indicated that Ⅰ. cylindrica was to adapt the barren environment of the tailings by reducing the physiological plasticity and improving its morphological plasticity. To increase the chances of looking for and absorbing nutrients, the roots of I. cylindrica were distributed in different nutrients level microhabitat in the copper tailings.2. P dynamics from rhizosphere of Ⅰ. cylindrica and other five plants in the copper tailings were studied. The results indicated that the plant growth decreased the rhizosphere pH by0.16-1.40pH units significantly. The difference of contents of soil inorganic P (Pi) and organic P between the rhizosphere and no-plant tailings were significant (p<0.05). The alkali-phosphatase activity in the rhizosphere was significant higher than in the no-plant tailings (p<0.05). The mean concentration of Ca2-bound Pi, Al-bound Pi and Fe-bound Pi in all the rhizosphere was significantly enhanced compared with the no-plant tailings, with the increase range from86.56%to147.58%, from5.46%to88.86%and from49.22%to214.20%respectively. All the other forms of phosphorus except Ca8-bound Pi and Caio-bound Pi, were shown to be negatively correlated with pH in the rhizosphere (r=-0.586, p<0.01; r=-0.487, p<0.05; r=-0.417, p<0.05). Among the studied species included the study, this capability of Indigofera pseudotinctoria on enhancing available P content was the most significant. Among three graminaceous plants, the relative content of available P in Ⅰ. cylindrica rhizosphere was the highest.3. The impacts of the roots activities of Ⅰ. cylindrica on its rhizosphere inorganic nitrogen dynamic were studied and with the five associated plants as control in the copper tailings. The results showed that the growth of plants influenced effectively the contents of total nitrogen and bioavailable nitrogen, and the contents of inorganic nitrogen and total nitrogen in all the plants rhizosphere were significantly higher than that in no-plant tailings (p<0.05). The percontages of all the forms inorganic nitrogen in the total nitrogen in the gramineous rhizosphere were slightly higher than that of other plants. The percontage of nitrate nitrogen in total nitrogen was significantly higher than in leguminous and compositae communities (p<0.05). The percontage of ammonium nitrogen in total nitrogen was also significantly higher than that of compositae rhizosphere (p<0.05). These indicated that Ⅰ. cylindrica could increase the ratio of bioavailable nitrogen in total nitrogen by roots activity in order to improve the absorption efficiency of nitrogen nutrition around the root system.4. N and P distributions, N:P, nutrient resorption rate, nitrate reductase and acidic phosphatase activities of Ⅰ. cylindrica organs in the copper tailings and the farmlands as control were investigated. The results showed that N and P in both populations were mainly in the rhizomes in the growth initial stage. At bud and mature times, N and P concentrations were highest in leaves and lowest in roots and rhizome. At the decay period, N and P concentrations in senescent leaves were9.19±0.80and0.05±0.03mg·g-1,respectively, which were significantly lower than for the control farmlands (p<0.05). The N and P resorption efficiencies of Ⅰ, cylindrica leaves in the tailings were49.54%-65.22%and74.71%-98.71%, respectively, with P in senescent leaves resorbed completely. Nitrate reductase activity of Ⅰ. cylindrica leaves in the tailings was significantly higher than in the farmlands (p<0.05), and this is useful to regulate Ⅰ. cylindrica nitrogen metabolism activities. But with plant growth, the differences gradually disappeared. At the same growth period, acidic phosphatase activity of Ⅰ. cylindrica leaves between the tailings and the farmlands were not significantly significant (p>0.05). With the plant growth, the acidic phosphatase activities increased, which was conducive to decompose organophosphate in senescent leaves and increase P resorption efficiencies. In short,Ⅰ. cylindrica might reduce the nutrition stress from the copper tailings by the timely distribution of N, P in its tissues, the enhancing resorption efficiencies of nutritions and the adjusting nutrition metabolism enzymatic activities.5. The soil and tissue litter of Gramineae (I. cylindrica and Zoysia sinica Hance) and Cryptogam (Hippochaete ramosissmium and algal-moss crusts) in the copper tailings were collected as experimental material. The differences and relationships of C, N contents, carbon isotope ratio (δ13C) and nitrogen isotope ratio (δ15N) between litter and soil were analyzed. The soil δ13C and δ15N in all community areas were lower than those in no-plant tailings. The correlation of C content between the litter and soil was significant in Gramineae community (r=0.998, p<0.01), but the relationship in Cryptogam community was not found. The effects ofⅠ. cylindrica and algal-moss on soil13C enrichment were significant, and the microbial biomass C (r=0.729, p<0.01), water content (r=0.716, p<0.01) and pH (r=0.529, p<0.05) also effectively affected soil813C. In contrast, the significant correlation was observed only between microbial biomass N and soil δ15N (r=0.935, p<0.01), and the other factors had no obvious effects on soil815N in the tailings.更多还原