First-Principles Study of Effect of Strain on the Band Structure of ZnO Monolayer

采用基于密度泛函理论的第一性原理计算对单层znO薄膜能带结构的应变调控进行了研究.计算结果表明:沿着之字形方向的压缩应变和扶椅形方向的拉伸应变对薄膜带隙的调控都是线性的,而且带隙调控的范围最大;相反地,在沿着之字形方向的拉伸应变和扶椅形方向的压缩应变的调控下,带隙则呈现出非线性的变化.对于双轴应变的拉伸与压缩,带隙的变化都是非线性的.这种通过不同的应变加载方式来实现对带隙不同程度的调控,对znO薄膜在光学和催化等领域的应用具有重要的指导意义.The effect of strain on the band structure of the ZnO monolayer has been investigated by firstprinciples calculations based on density functional theory.The results reveal that the band structure of the ZnO monolayer presents different dependences on three types of strain.The band gap linearly and steeply varies under uniaxial zigzag compressive strain and armchair tensile strain, while it shows nonlinear dependence on the other types of strain.Therefore, uniaxial zigzag compressive strain and armchair tensile strain should be the most effective to tune the band gap.This work has significant implications for application of strain to tune the optical and catalytic properties of ZnO nanofilms.国家自然科学基金(10702056;11204252); 四川省教育厅(12ZA072)资助项目~

Carbon and Nutrient Pools of Coarse Woody Debris in a Natural Forest and Plantation in Subtropical China

福建三明格氏栲天然林及在其采伐迹地上营造的33年生格氏栲人工林和杉木人工林粗木质残体现存量与季节动态、C库及养分库的研究表明,格氏栲天然林、人工林和杉木人工林粗木质残体现存量分别为1 32、0 4 6和0 2 3t·hm- 2 。3种林分粗木质残体现存量的季节变化模式均为夏季>冬季>秋季>春季。格氏栲天然林粗木质残体C贮量为0 78t·hm- 2 ,分别是格氏栲人工林和杉木人工林的4 1 1倍和7 0 9倍;格氏栲天然林粗木质残体C库与2种人工林间差异显著(P <0 0 5)。格氏栲天然林、人工林和杉木人工林粗木质残体养分贮量分别为1 4 1 6、2 90和0 95kg·hm- 2 ;格氏栲天然林粗木质残体中各种养分贮量均最高。与人工林相比,天然林粗木质残体现存量、C和养分贮量均最大。 【英文摘要】 During the past decades, large scale natural forests had been converted to fast growing and high yield commercial plantations to meet the demands for timber, fuel material, and other forest products. Some silvicultural measures, such as planting pure stands, clear cutting and slash burning, were widely applied during this conversion. Yield decline and land deterioration in such disturbed ecosystems had become serious. In this context, the ecological comparisons between natural forests and plantations have...福建省重大基础研究项目 (2 0 0 0F0 0 4 ) ;; 高等学校优秀青年教师教学科研奖励计划资助

Distribution of Fine Roots in a Mixed Cunninghamia lanceolata-Tsoongiodendron odorum Plantation

对27年生混交比例为2行杉木和1行观光木的混交林和杉木纯林群落细根分布的研究表明,杉木和观光木行间的杉木细根密度虽比杉木与杉木行间的低8.5％,但观光木细根密度则高152.09％,其细根总密度比杉木与杉木行间的大10.43％。混交林中杉木各径级活细根密度呈单峰型分布,均以5-10cm土层最大,而观光木各径级活细根主要分布在0-10cm土层内。纯林杉木各径级活细根密度亦基本呈单峰型分布,但峰值出现在10-20cm或20-30cm土层。不同树种不同径级死细根的分布均与其各自的活细根分布相似。混交林中灌木细根密度在30-40cm的土层最大,而纯林中的灌木细根集中于0-10cm的表土层;混交林和纯林中的草本细根均集中在0-5cm土层。与纯林的相比,混交林中杉木细根主要分布的土层明显上移,表层土壤细根所占比重增大,有利于更好利用土壤养分和提高群落生产力。Fine roots were measured by soil core sampler in a mixed plantation of 27-year-old Cunninghamia lanceolata (C) and Tsoogiodeudron odorum (T) in Fujian Province. Fine root density of C at interrow between C and T was lower by 8.5% than that between C and C, but fine root denstiy of T and total fine root density were higher by 152.09% and 10.43%, respectively. High density of living fine roots with different thickness of C in mixed plantation appeared at 5-10 cm soil depth, whereas that of T at 0-10 cm. Compared to mixed plantation, living fine root density in pure C plantation appeared at 10 -30 cm of soil depth. The distribution of dead fine roots had the same pattern. In mixed plantation, upward trend of soil layer with maximum fine roots of C was obvious, showing that mixed plantation had an advantage over pure plantation in nutrient absorption.中国博士后科研基金项目（1999-10）;;福建省科委重大基础研究项目（2000-F-004）;; 高等学校骨干教师资助计划项目;;福建省自然科学基金项目（B0110025

PRODUCTION, DISTRIBUTION AND NUTRIENT RETURN OF FINE ROOTS IN A MIXED AND A PURE FOREST IN SUBTROPICAL CHINA

研究了福建三明 2 7a生杉木观光木混交林和杉木纯林群落细根 (d <2mm)的生产力、分布和养分归还 .结果表明 ,混交林细根生物量、N、P养分现存量分别为 5 .381thm-2 、4 8.0 85kghm-2 和 4 .174kghm-2 ,分别比杉木纯林增加17.4 %、2 7.2 %和 2 0 .0 % .混交林细根的年净生产力达 4 .12 4thm-2 a-1,比纯林高出 16 .9% .混交林杉木和观光木细根均在表层土壤富集 ,而在较深层土壤两者分布具镶嵌性 ;与混交林杉木相比 ,纯林杉木土壤表层细根量较少 ,最大分布层次下移 .混交林中观光木细根的周转速率为 1.16 ,杉木为 0 .96和 0 .95 ;而林下植被层细根周转速率 (1.4 6～ 1.5 2 )均高于相应的乔木层 .混交林细根的年死亡量、N和P养分年归还量分别达 2 .119thm-2 、18.5 5 9kghm-2 和 1.5 6 5kghm-2 ,分别是纯林的 1.2 1倍、1.2 3倍和 1.14倍 ,其中林下植被细根占有较为重要位置 .对细根分布与土壤性质的相关分析表明 ,细根的垂直分布与土壤全N的相关性最强 (0 .87～ 0 .89) .图 1表 4参 32The studies on production, distribution and nutrient return of fine roots ( d <2 mm) in a mixed Chinese fir ( Cunninghamia lanceolata ) Tsoong' tree ( Tsoongiodendron odorum ) forest and a pure Chinese fir forest at age 27 were carried out in Sanming of Fujian, China. The standing crops of dry matter, N and P in fine roots of the mixed stand were 5.381 t hm -2 , 48.085 kg hm -2 and 4.174 kg hm -2 , 17.4 %, 27.2% and 20.0% higher than those of the pure stand, respectively. The fine root production in the mixed forest was up to 4.124 t hm -2 a -1 , 16.9% higher than that in the pure stand. Fine roots of Chinese fir and Tsoong' tree in the mixed forest both concentrated in the surface soil, and showed a vertical stratification in the subsoil. Compared with those in the mixed forest, fine roots of Chinese fir in the pure forest had a deeper rooting zone, with a lower root density in the superficial soil. The turnover rates of fine roots for Tsoong' tree and Chinese fir in the mixed stand, and Chinese fir in the pure stand, were 1.16, 0.96 and 0.95, respectively. The undergrowth species had higher root turnover rates than their respective tree layers (1.46 in the mixed forest and 1.52 in the pure stand). The annual mortality, annual return of N and P of fine roots in the mixed forest amounted to 2.119 t hm -2 , 18.559 kg hm -2 and 1.565 kg hm -2 , 1.21, 1.23 and 1.14 times as much as that in the pure forest respectively. Bulk density, moisture content, total N and humic C were strongly correlated with fine root density along the soil profile in the two forests, with total N giving the highest coefficients of determination. Fig 1, Tab 4, Ref 32中国博士后科研基金;; 福建省科委重大基础研究项目 (2 0 0 0F0 0 4 );; 高等学校骨干教师资助计划;; 福建省自然科学基金 (B0 1 1 0 0 2 5)资助

NET PRODUCTIVITY AND TURNOVER RATE OF FINE ROOTS IN MIXED FOREST OF CUNNINGHAMIA LANCEOLATA AND TSOONGIODENDRON ODORUM

本文系统地研究了 2 7a生杉木观光木混交林和杉木纯林群落细根 (<2mm)的生物量、净生产力和年周转率。结果表明 ,混交林和纯林群落活细根现存量分别为 3 872和 3 315t·hm- 2 ,活细根现存量变化呈双峰型 ,在 3月和 9月出现两次高峰 ;死细根现存量为 1 5 0 9和 1 2 6 9t·hm- 2 ,数量变化呈现单谷型 ,在 5月或 3月出现最低值 ;细根净生产力分别为 4 12 4和 3 5 2 8t·hm- 2 a- 1 ,分别占各自群落净第一性生产力的 2 2 9%和2 0 9% ;细根年死亡量分别为 2 119和 1 894t·hm- 2 ,相当于各自群落地上部分凋落物量的 31 4%和 2 7 8% ;细根周转率分别为 1 0 7和 1 0 6 ,观光木、混交林杉木、纯林杉木的细根周转速率依次降低 ,而林下植被层细根周转率高于乔木层。表明细根周转是群落有机质归还的重要途径 ,对维持和改良地力有重要作用Studies on biomass, net productivity and annual turnover rate of fine roots in mixed forest of Cunninghamia lanceolata and Tsoongiodendron odorum and in pure stand of Cunninghamia lanceolata at 27 years old were carried out. The existing amount of living fine roots in both stands were up to 3 872 and 3 315?t·hm -2 , and their seasonal changes showed two peaks in March and September, and those of dead fine roots amounted to 1 509 and 1 269?t·hm -2 , being lowest in May or March. The net productivity of fine roots in both stands totaled to 4 124 and 3 528?t·hm -2 a -1 , accounted for 22 9% and 20 9% of total net primary productivity of community, respectively. In both stands, annual mortality of fine roots were 2 119 and 1 894?t·hm -2 , respectively, amounted 31 4% and 27 8% of annual aboveground litterfall. Annual turnover rate of fine roots was 1 07 in mixed stand and 1 06 in pure stand, which decreased successively from Tsoongiodendron odorum, Cunninghamia lanceolata in mixed forest to the pure stand, and that of undergrowth were higher than that of tree stralum in both stands. It was concluded that annual turnover of fine roots was an important way for organic matter in communities returning to forest floor.中国博士后科研基金;; 福建省科委重大基础研究项目 ( 2 0 0 0 -F -0 0 4);; 高等学校骨干教师资助计划资

LITTER DECOMPOSITION AND NUTRIENT RELEASE IN A MIXED FOREST OF CUNNINGHAMIA LANCEOLATA AND TSOONGIODENDRON ODORUM

通过福建省中亚热带杉木观光木混交林 (CunninghamialanceolataandTsoongiodendronodorummixedforest)和杉木纯林 (PureC .lanceolataforest)凋落物的分解和养分释放动态试验研究表明 ,凋落物各组分分解过程中干物质损失速率随时间而减小 ,分解 1年时以观光木叶的干重损失最大。各组分分解过程中N、P元素浓度增加而K和C元素浓度下降。混交林中各组分的养分释放速率大小为观光木叶 >混合样品 (等重量的观光木叶和杉木叶混合 )>杉木叶 >杉木小枝。不同元素的释放速率与干重损失速率大小为 :K >C >干重 >N≈P。混交林凋落物的年养分释放量 (kg·hm-2 ·a-1)为N 17.92 1,P 0 .715 ,K 10 .315 ,分别是纯林的 2 .0 3倍、1.73倍和 1.34倍。与纯林相比 ,混交林较高的年凋落物养分归还量和养分释放量有利于促进养分的再循环 ,这对维持混交林的地力有重要作用。Rate of litter weight loss and release of nutrient elements were investigated in a mixed forest of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) and Tsoong' tree (Tsoongiodendron odorum Chun) and a pure stand of Chinese fir in Sanming, Fujian. Chinese fir needle, branch, Tsoong' tree leaf and the mixture of Chinese fir needle and Tsoong' tree leaf were involved in the 510 day period of litter bag studies. Rate of weight loss slowed with time for all litter components, with the highest percent initial weight loss of 74.54% for leaf litter of Tsoong' tree at the first year. Concentrations of N and P appeared to increase and concentrations of K and C appeared to decrease during the decomposition. The four litter components could be arranged with respect to nutrient release rate in this sequence: leaf of Tsoong' tree > the mixed leaves > needle of Chinese fir > branch of Chinese fir. Nutrient elements and weight loss followed the release pattern: K >C >dry weight> N≈P. The total annual nutrient release of litter fall was N,17.921 kg·hm -2 ·a -1 ; P, 0.715 kg·hm -2 ·a -1 and K,10.315 kg·hm -2 ·a -1 respectively in the mixed forest, being 2.03, 1.73 and 1.34 times as much as that in the pure forest. It was concluded that the higher yield of litter production and the greater amount of nutrient release from litter in mixed forest were beneficial to nutrient cycling. Thus, a higher level of soil fertility would be expected for mixed forest than for pure forest.ThePost_doctorResearchFoundationofChina,theFoundationforUniversityKeyTeacherbytheMinistryofEducation,andtheResearch ProjectofBasicTheoryofFujianProvince ( 2 0 0 0F0 0 4

~(31)P NMR与HPLC联用筛选高效有机磷降解细菌

从有机磷农药污染地区分离到 14株具有高效甲胺磷降解活力的细菌 ,并用HPLC对其降解效率进行分析 ,发现一周内降解率最高达 74 % .采用3 1PNMR对其降解产物进行了同步监测 ,发现其降解产物不同 ,其中有三株可以把甲胺磷代谢成磷酸 .这三株降解细菌可以从环境中有效的清除有机磷的污

Nutrient dynamics of decomposing leaf litter in natural and monoculture plantation forests of Castanopsis kawakamii in subtropical China

通过对中亚热带格氏栲天然林 (natural forest of Castanopsis kawakamii,约 15 0 a)、格氏栲和杉木人工林 (monocultureplantations of C.kawakamii and Cunninghamia lanceolata,33年生 )凋落叶分解过程中养分动态的研究表明 ,各凋落叶分解过程中 N初始浓度均发生不同程度的增加后下降 ;除格氏栲天然林中其它树种叶和杉木叶 P浓度先增加后下降外 ,其它均随分解过程而下降 ;除杉木叶外 ,其它类型凋落叶的 Ca和 Mg浓度呈上升趋势 ;凋落叶 K浓度均随分解过程不断下降。养分残留率与分解时间之间存在着指数函数关系 xt=x0 e- kt。凋落叶分解过程中各养分释放常数分别为 :N (k N) 0 .6 78～ 4 .0 88;P (k P)0 .6 2 1～ 4 .30 8;K(k K) 1.4 0 8～ 4 .4 2 1;Ca (k Ca) 0 .799～ 3.75 6 ;Mg (k Mg) 0 .837～ 3.894。除杉木叶外 ,其它凋落叶分解过程中均呈 k K>k P>k N>k Mg>k Ca的顺序变化。各林分凋落叶的年养分释放量分别为 N10 .73～ 4 8.19kg/ (hm2 · a) ,P0 .6 1～ 3.70kg/ (hm2· a) ,K6 .6 6～ 39.6 1kg/ (hm2· a) ,Ca17.90～ 2 0 .91kg/ (hm2· a) ,Mg3.2 1～ 9.85 kg/ (hm2· a)。与针叶树人工林相比 ,天然阔叶林凋落叶分解过程中较快的养分释放和较高的养分释放量有利于促进养分再循环 ,这对地力?Nutrient dynamics of decomposing leaf litter was studied in two 33-year-old plantations, Chinese fir (Cunninghamia lanceolata, CF) and Castanopsis kawakamii (CK), and compared with that of an adjacent natural forest of Castanopsis kawakamii (NF, ~150 year old) in Sanming, Fujian, China. During the decomposition, varying degree of initial increase followed by decrease of N concentrations was observed in leaf litter, while initial increase and then decrease of P concentration was only found in leaves of other tree species in the NF and Chinese fir needle. The concentrations of Ca and Mg increased in all leaves except for Chinese fir needle, whereas that of K decreased consistently. Using the model x_t=x_0e~(-kt), the decay constants of nutrients ranged from 0.678 to 4.088 for N (k_N), from 0.621 to 4.308 for P (k_P), from 1.408 to 4.421 for K (k_K), from 0.799 to 3.756 for Ca (k_(Ca)) and from 0.837 to 3.894 for Mg (k_(Mg)) respectively. The decay constants of nutrients during leaf-litter decomposition can be arranged in the sequence of k_K>k_P>k_N>k_(Mg)>k_(Ca), except for leaf litter of Chinese fir where k_K>k_(Mg)>k_(Ca)>k_N>k_P. Annual nutrient release from decaying leaf litters in the three forests was N, 10.73～48.19 kg/(hm~2·a); P, 0.61～3.70 kg/(hm~2·a); K, 6.66～39.61 kg/(hm~2·a); Ca, 17.90~20.91 kg/(hm~2·a) and Mg, 3.21～9.85 kg/(hm~2·a) respectively. It was concluded that faster nutrient release of leaf litter and its greater amount in the natural broadleaved forest were beneficial to nutrient recycling and soil fertility maintenance than monoculture coniferous plantations.教育部高等学校优秀青年教师奖资助项目;; 教育部高等学校骨干教师资助计划资助项目 ;; 福建省重大基础研究资助项目 (2 0 0 0 F 0 0 4)~

Carbon and nutrient pools of forest floor in native forest and monoculture plantations in subtropical China

通过对福建三明格氏栲天然林及在其采伐迹地上营造的 33年生格氏栲人工林和杉木人工林枯枝落叶层现存量与季节动态、C库及养分库的研究表明 ,格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层现存量分别为 8.99t· hm- 2 、7.5 6t· hm- 2 和 4 .81t· hm- 2 ;枯枝落叶层中叶占现存量的比例分别为 6 4 .96 %、6 1.38%和 38.0 5 % ,枝占比例分别为 31.5 9%、37.83%和 4 2 .6 2 %。格氏栲天然林与人工林枯枝落叶层现存量最大值均出现在春季 ,而杉木人工林枯枝落叶层现存量最大值出现在夏季。格氏栲天然林枯枝落叶层 C贮量为 4 .0 2 t· hm- 2 ,分别是格氏栲人工林和杉木人工林的 1.2 2倍和 1.77倍 ;格氏栲天然林和人工林枯枝落叶层 C库与杉木人工林的差异均达到显著水平 (P<0 .0 5 )。格氏栲天然林、格氏栲人工林和杉木人工林枯枝落叶层养分贮量分别为 138.4 2 kg· hm- 2 、113.5 6 kg· hm- 2 和 72 .39kg· hm- 2 ;除 Mg外 ,格氏栲天然林枯枝落叶层中各种养分贮量均最高。与人工林... 【英文摘要】 In the last decades, large-scale native forests have been converted to fast-growing and high yield commercial forest plantations to meet the demands for timber, fuel material, and other forest products. Some silvicultural measures, such as planting pure stands, clear cutting and slash burning, are widely applied during this conversion. Yield decline and land deterioration in such disturbed ecosystem has become serious. In this context, the ecological comparisons between native forests and monoculture planta...福建省重大基础研究资助项目 (2 0 0 0 F0 0 4) ;; 高等学校优秀青年教师教学科研奖励计划资助项目~

NUTRIENT CYCLING OF N AND P BY A MIXED FOREST OF CUNNINGHAMIA LANCEOLATA AND TSOONGIODENDRON ODORUM IN SUBTROPICAL CHINA

通过对福建三明 2 7年生杉木 (Cunninghamialanceolata) 观光木 (Tsoongiodendronodorum)混交林 (混交比例2 :1)及杉木纯林群落N、P养分循环进行为期 2年的研究。结果表明 ,混交林中杉木和观光木地上各组分的N、P含量大小均为叶 >活枝 (或皮 ) >枯枝 >干 ,而根系的则随径级的减小而增大 ,且观光木各组分的N含量均高于杉木的 ;混交林群落的N、P总积累量达 5 85 .2 2 3kg·hm-2 和 12 8.784kg·hm-2 ,分别是纯林群落的 1.5倍和 1.3倍。混交林群落N、P养分年归还量达 75 .740kg·hm-2 和 5 .493kg·hm-2 ,分别是杉木纯林的 113 .0 %和 79.6 %。混交林通过凋落物、降水淋溶和细根枯死 3种途径的N归还量分别占群落总归还量的 6 7.1%、8.4%和 2 4.5 % ,而纯林的则分别为 6 9.3 %、8.1%和 2 2 .6 % ;混交林 3种途径的P归还量分别占群落总归还量的 6 4.0 %、7.5 %和 2 8.5 % ;而纯林则为 74.8%、5 .3%和 19.9%。混交林中林下植被层的N、P归还量分别占群落总归还量的 14.8%和 37.3 % ;而纯林的则为 2 9.5 %和 5 9.4%。混交林群落的N、P富集率和利用系数均低于纯林的 ,而周转期则均大于纯林的。混交林群落的P吸收系数小于纯林的 ,而循环系数则高于纯林的 ,但其两者的N吸收系数和循环系数则相似。A study on the cycling of N and P in a pure forest of Chinese fir ( Cunninghamia lanceolata (Lamb.) Hook. and a Chinese fir_ Tsoongiodendron odorum Chun mixed forest (2 Chinese fir: 1 T. odorum ) over two years was carried out in Sanming, Fujian, China. For both Chinese fir and Tsoongiodendron odorum, the concentrations of N and P in aboveground fractions were in the order of leaves>living branches (or stem bark)>dead branches> stem wood, and those in roots increased with an increase in root diameter. N concentrations in various fractions of T. odorum were higher than their respective values for Chinese fir. The standing crops of N and P in the mixed stand were up to 585.223 kg·hm -2 and 128.784 kg·hm -2 , being 1.5 and 1.3 times as much as that in the pure stand, respectively. The annual return of N and P amounted to 75.740 and 5.493 kg·hm -2 in the mixed forest, respectively, being 113.0% and 79.6% of that in the pure forest. The fractions of annual N return through litterfall, rain leaching and fine root turnover were 67.1%, 8.4% and 24.5% in the mixed forest, respectively, and the corresponding values were 69.3%, 8.1% and 22.6% in the pure forest. These three pathways contributed to 64.0%, 7.5% and 28.5% of total P return in the mixed forest, and 74.8%, 5.3% and 19.9% in the pure forest, respectively. 14.8% of N return and 37.3% of P return in the mixed forest, and 29.5% of N return and 59.4% of P return in the pure forest were derived from the undergrowth vegetation. For both N and P elements, the enrichment ratios and the utilization coefficients were lower, and the recycling periods were higher in mixed forest than in pure stand. For P, the absorption coefficient was lower, and the cycling coefficient was higher, in mixed forest than in pure forest, while there were no significant differences for those of N between the two forests.中国博士后科研基金;; 福建省科委重大基础研究项目 ( 2 0 0 0_F_0 0 4);; 高等学校骨干教师资助计划项