生长光强对亚热带自然林两种木本植物稳定碳同位素比、细胞间CO2浓度和水分利用效率的影响

生长于１００％、４０％和１６％自然光下的荷木和黧蒴幼苗叶片稳定碳同位素比（δ１３Ｃ,－‰）,细胞间ＣＯ２浓度（Ｃｉ）和水分利用效率（ＷＵＥ）有一定的差别。１６％和４０％弱光下,δ１３Ｃ的负值增加－０．５４Ｊ‰到－０．８９‰。Ｃｉ增大８．１－１３．２μｉＬ－１,ＷＵＥ则下降６－２４％。结果表明,叶片的水分和气体交换特性受生长光强的调节,叶片的δ１３Ｃ值可反映其生长过程中受光的强弱状况。     

格氏栲幼苗叶绿素荧光和非结构性碳水化合物积累对种子散布位置的响应

植物种子从母树掉落形成土壤种子库时,凋落物或土壤是其最初接触的物理环境,种子所处位置(种子在凋落物上层、土壤表层或凋落物下层)影响了幼苗天然更新进程。模拟格氏栲种子在凋落物上层(种子下层铺垫2和4 cm凋落物)、土壤表层(无凋落物)及凋落物下层(种子上层覆盖2、4、6和8 cm凋落物)等3种不同散布位置,探讨种子散布位置对幼苗叶绿素荧光特性、非结构性碳水化合物、比叶面积、叶干物质含量和养分含量的影响。结果表明:不同散布位置的幼苗单位面积的叶氮含量与可溶性糖、非结构性碳水化合物含量呈显著正相关,与比叶面积呈显著负相关。适宜凋落物覆盖(2和4 cm)的幼苗通过提高叶绿素相对含量、可溶性糖含量、非结构性碳水化合物含量、叶干物质含量和单位面积的叶氮含量和叶磷含量,降低比叶面积等的资源获取策略来实现自身快速生长需求。无凋落物和深层凋落物覆盖(6和8 cm)的幼苗采取高单位重量的叶氮含量和比叶面积,低叶干物质含量和非结构性碳水化合物含量的资源保守型策略以截获更多有效光资源,进而弥补深层凋落物带来的郁闭环境,降低幼苗因“碳饥饿”而死亡的几率。下层铺垫凋落物的幼苗通过在叶片储藏淀粉,降低叶片光合组织消耗能量(低PSⅡ最大光化学效率)等维持幼苗生长。熵值法综合分析表明,浅层凋落物覆盖(2 cm)对格氏栲幼苗生长的促进作用最为显著,未来可通过调节天然林凋落物层厚度以促进格氏栲幼苗生长与更新。     

米槠与杉木细根凋落物是否在自身群落中分解得更快?

本研究应用网袋法对福建省万木林自然保护区米槠（Castanopsis carlesii）、杉木（Cunninghamia lanceolata）细根在米槠林群落和杉木林群落交叉分解进行了为期2年的研究。结果表明,0-1mm、1-2mm米槠细根在米槠群落比在杉木群落分解速率快,而相同径级杉木细根在两群落分解差异较大。0—1mm杉木细根在杉木群落的分解速率高于米槠群落,而1—2mm杉木细根在杉木群落的分解速率只及米槠群落的48％。米槠、杉木细根在两群落分解的差异表明,群落立地条件对细根分解存在较大的影响。     

Superoxide anion burst and taxol production induced by Ce in suspension cultures of Taxus cuspidata

Generation of reactive oxygen species (ROS) induced by Ce⁴⁺ in suspension cultures of Taxus cuspidata was investigated. The burst of superoxide anions (O₂√⁻) occurred rapidly after the addition of Ce⁴⁺ and reached maximum at 4.3 h, while the total level of the cellular reactive oxygen species maintained unchanged. The intracellular superoxide dismutase (SOD) and catalase (CAT) were activated while the intra/extracellular peroxidases (PODs) were inhibited accompanying the O₂√⁻ burst. The pretreatment of the suspension cultures with diphenylene iodonium (DPI), a suicide inhibitor of the NADPH oxidase, blocked the O₂√⁻ burst, inhibiting the cell apoptosis and taxol production induced by Ce⁴⁺. These results show that NADPH oxidase played a key role in O₂√⁻ burst and O₂√⁻ served as a mediator of Ce⁴⁺ for cell apoptosis and taxol production. The pretreatments of the suspension cultures with anthracene-9-carboxylate, an ion-channel blocker, nifedipine, a Ca²⁺-channel blocker, neomycin, a phospholipase C (PLC) inhibitor, or suramin, a G-protein inhibitor, decreased O₂√⁻ burst induced by Ce⁴⁺. It is thus inferred that Ce⁴⁺-induced O₂√⁻ burst, which mediated cell apoptosis and taxol production by activating the ion-channels, PLC, G-proteins and NADPH oxidase.     

Response of soil enzyme activities to litter input changes in two secondary Castanopsis carlessii forests in subtropical China

酶在土壤有机质分解中起重要作用。为深入了解全球变化背景下森林凋落物产量的改变对森林生态系统过程的影响, 以亚热带米槠(Castanopsis carlesii)人促更新次生林(米槠人促林)和米槠次生林为研究对象, 设置凋落物加倍(DL)、凋落物去除(NL)和对照(CT) 3种处理, 探讨土壤6种胞外酶活性的变化。研究结果表明: 米槠次生林中土壤纤维素水解酶(CBH)、β-N-乙酰氨基葡萄糖苷酶(NAG)、酚氧化酶(PhOx)和过氧化酶(PerOx)活性高于米槠人促林, 而酸性磷酸酶(AP)和β-葡萄糖苷酶(βG)活性没有差异; NL和DL处理均降低了两种不同更新方式森林土壤的AP、βG和NAG活性, CBH和PerOx活性均无显著变化, 而PhOx活性仅在DL处理后降低; 除NAG活性外, 米槠人促林的AP、βG、PhOx活性在凋落物处理后下降的幅度均高于次生林; Pearson相关分析和冗余分析表明, 土壤酶活性与土壤含水量、碳(C)、氮(N)含量和微生物生物量碳(MBC)、氮(MBN)含量显著相关。因此, 凋落物输入的改变(无论增加和减少), 引起了土壤含水量、C、N以及MBC和MBN含量的下降, 进而可能会导致亚热带米槠次生林和米槠人促林土壤某些胞外酶(如AP、βG和NAG)活性降低。从土壤酶活性角度看, 米槠次生林比米槠人促林更有利于亚热带森林生态系统C、N养分循环。     

武夷山自然保护区不同海拔甜槠天然林土壤有机碳变化特征及影响因素

为揭示中亚热带常绿阔叶林建群种--甜槠天然林不同海拔土壤有机碳含量垂直分布差异及影响机制,以武夷山自然保护区甜槠天然林单一植被类型为研究对象,在其集中分布的5个海拔梯度（540、700、850、1022、1200 m）范围内设置固定样地,测定每个海拔梯度不同深度土层土壤因子（土壤全氮、全磷、土壤pH值、容重、土壤有机质、粉粒、砂粒、粘粒）、气候因子（土壤温度）、植被因子（细根生物量）及土壤有机碳含量等指标,分析了土壤有机碳沿海拔及垂直土层分布特征,并在主成分分析基础上构建了基于主控因子的线性回归模型。结果表明：（1）同一海拔高度,土壤有机碳含量在土壤垂直剖面分布具有明显的"表聚性"现象;同一土层深度,随着海拔升高,土壤有机碳含量逐渐增加,但增幅随土层深度增加而减小,高海拔地区有助于土壤有机碳的固存;（2）不同土层土壤有机碳含量与海拔、土壤全氮、土壤含水量、土壤粉粒呈极显著正相关（P<0.01）,与土壤温度、土壤容重、土壤粘粒、砂粒呈极显著负相关（P<0.01）;土壤细根生物量、土壤有机质与土壤有机碳含量在土壤表层（0-10、10-20 cm）呈极显著（P<0.01）或显著正相关（P<0.05）;土壤pH值、土壤砂粒与土壤有机碳含量在20-30 cm土层呈显著负相关（P<0.05）,但与其他土层关系不显著（P>0.05）;海拔因素是影响土壤有机碳含量分布的主要因素,其次为土壤因素,植被因素主要影响土壤表层有机碳含量分布。（3）海拔因素能通过影响与土壤有机碳形成和转化的因子及改变土壤有机碳的累积和分解速率,对土壤有机碳的分布产生影响。（4）多元线性回归模型拟合R²高于一元线性回归模型拟合R²,能解释土壤有机碳含量变异的82.1%-98.1%。由此可见,不同环境因子组合可以更好的解释不同土层土壤有机碳含量随海拔梯度的变异。     

Taxusecone,a Novel Taxane with an Unprecedented 11,12-Secotaxane Skeleton,from Taxus cuspidata Needles

Taxusecone, 2α,7β,9α,10β-tetraacetoxy-5α,12-dihydroxy-11,12-secotax-4(20)-ene-11,13-dione (1), a novel taxane with an unprecedented skeleton, was isolated from the needles of Taxus cuspidata.     

栲树种群生态位动态研究

用Levins生态位宽度及重叠、Feinsing等生态位宽度和Petraitis生态位重叠计测方法 ,处理缙云山森林群落演替系列取样 ,分析栲树种群的生态位特征及动态 .结果表明 ,栲树种群为缙云山森林群落演替顶极群落常绿阔叶林的优势种群 ,其生态位宽度随群落演替过程基本呈增长趋势 ,而资源利用程度却呈“∧”形 ;对于栲树种群和缙云山森林群落其它 1 4个优势种群间在所有 5类群落中的生态位重叠 ,仅栲树种群与典型针阔混交林中的小叶栲、光叶灰木、川灰木、薯豆、白毛新木姜子、广东山胡椒、大头茶、虎皮楠、杉木、马尾松种群上和针叶林中小叶栲、光叶灰木、杉木种群上 ,表现出显著完全特定重叠 .     

A study on multidimensional time series model of individual age’s measurement in Castanopsis kawakamii population

Studies on disclosing characteristics and endangered mechanisms of Castanopsis kawakamii population ecology have already become an urgent task of protecting C. kawakamii population. The establishment of the standard life table is one of an important work study on C. kawakamii population ecology, and determining individual ages of the plant is necessary for studying age structures and population dynamics of C. kawakamii. There are three main methods of determining individual age of forest population: (1) by annual ring of tree, (2) by individual growth phase, and (3) by DBH and height of tree. However, the three methods have their shortcomings, such as low precision, worse serviceability, high difficulty for operation and so on. In this paper, a new method for determining plant individual ages more accurately is presented on the basis of the method aboU_t “annual ring–time series”. Based on the stem analysis, the multidimensional time series model of diameter growth at breast height in C. kawakamii population was established by U_tilizing the analY_tical method of multidimensional time series: Y_t = 1.325034Y_t-1 ? 0.4711007Y_t-2 ? 284.5648U_t + 569.4783U_t?1 ? 284.8745U_t?2, where Y_t, Y_t-1, Y_t-2 represent diameter growth in C. kawakamii population at t, t ? 10 and t ? 20 years respectively, and U_t, U_t?1, U_t?2 represent individual age in C. kawakamii population at t, t ? 10 and t ? 20 years respectively, the model coefficient correlation is 0.9994. Based on this model CAR(2), the total increment of individual DBH in C. kawakamii population are simulated and regressively verified at different ages. The mean simulating precision of this model was 98.84%, the maximum relative error was 2.56%, bU_t the next was 2.47% and the minimum relative error was 0.07%, showing that this model was suitable for estimating breast-height diameter of C. kawakamii plant. Using the multidimensional time series model, diameter growth of C. kawakamii population for longer time series was estimated in order to gain data for establishing the relationship model of individual age, diameter growth and to increase its precision in determining individual age is by tree ring analysis. A combination method of determining individual age of C. kawakamii population by integrating annual ring data with its diameter using multidimensional time series model, which can improve precision of individual ages in C. kawakami, was produced: A = 9.966671944 + 1.146011591D + 0.041059628D² ? 0.000211907D³, where A and D represent individual age and diameter at breast height respectively in C. kawakamii population, the model coefficient correlation is 0.9998. The combination model, which shows that the regression relationship is significant and the model can exactly predict the individual age of population, is a valuable tool for determining individual ages in endangered plants.     

A study on multidimensional time series model of individual age’s measurement in Castanopsis kawakamii population

Studies on disclosing characteristics and endangered mechanisms of Castanopsis kawakamii population ecology have already become an urgent task of protecting C. kawakamii population. The establishment of the standard life table is one of an important work study on C. kawakamii population ecology, and determining individual ages of the plant is necessary for studying age structures and population dynamics of C. kawakamii. There are three main methods of determining individual age of forest population: (1) by annual ring of tree, (2) by individual growth phase, and (3) by DBH and height of tree. However, the three methods have their shortcomings, such as low precision, worse serviceability, high difficulty for operation and so on. In this paper, a new method for determining plant individual ages more accurately is presented on the basis of the method aboU_t “annual ring–time series”. Based on the stem analysis, the multidimensional time series model of diameter growth at breast height in C. kawakamii population was established by U_tilizing the analY_tical method of multidimensional time series: Y_t = 1.325034Y_t-1 ? 0.4711007Y_t-2 ? 284.5648U_t + 569.4783U_t?1 ? 284.8745U_t?2, where Y_t, Y_t-1, Y_t-2 represent diameter growth in C. kawakamii population at t, t ? 10 and t ? 20 years respectively, and U_t, U_t?1, U_t?2 represent individual age in C. kawakamii population at t, t ? 10 and t ? 20 years respectively, the model coefficient correlation is 0.9994. Based on this model CAR(2), the total increment of individual DBH in C. kawakamii population are simulated and regressively verified at different ages. The mean simulating precision of this model was 98.84%, the maximum relative error was 2.56%, bU_t the next was 2.47% and the minimum relative error was 0.07%, showing that this model was suitable for estimating breast-height diameter of C. kawakamii plant. Using the multidimensional time series model, diameter growth of C. kawakamii population for longer time series was estimated in order to gain data for establishing the relationship model of individual age, diameter growth and to increase its precision in determining individual age is by tree ring analysis. A combination method of determining individual age of C. kawakamii population by integrating annual ring data with its diameter using multidimensional time series model, which can improve precision of individual ages in C. kawakami, was produced: A = 9.966671944 + 1.146011591D + 0.041059628D² ? 0.000211907D³, where A and D represent individual age and diameter at breast height respectively in C. kawakamii population, the model coefficient correlation is 0.9998. The combination model, which shows that the regression relationship is significant and the model can exactly predict the individual age of population, is a valuable tool for determining individual ages in endangered plants.