崖柏群落优势乔木树种种间关系

采用样方调查法,对组成崖柏群落的乔木树种进行调查。通过计算重要值确定崖柏群落优势乔木树种,研究优势树种的总体联结性、2物种间的联结性和种间协变。结果表明:崖柏群落内的15个优势树种总体间存在负关联;2物种间具有显著正联结的种对有:高山栎-川陕鹅耳枥、高山栎-华中八角、大叶青冈-乌岗栎、铁杉-华西花楸、华千金榆-青榨槭、华千金榆-大叶青冈、大叶青冈-川鄂山茱萸、川陕鹅耳枥-华中八角;呈显著负联结的种对是高山栎-青榨槭;崖柏与其他优势树种的联结性均未达到显著程度;有26个种对表现出明显的正协变,12个种对表现出明显的负协变;种对正协变的存在是由于这些物种对环境资源的利用具有相似性所致。     

重度砍伐后极小种群野生植物崖柏群落结构动态

砍伐导致濒危植物种群个体数量减少, 群落结构改变, 加剧物种灭绝风险。崖柏(Thuja sutchuenensis)为典型极小种群野生植物, 森林砍伐是导致其种群数量急剧下降的主要原因。但是, 到目前为止, 有关崖柏种群及其群落对砍伐的响应鲜有报道。本研究以重度砍伐后的崖柏群落为研究对象, 基于对崖柏群落固定样地的调查和两次复查, 对比分析了伐后崖柏种群径级结构、种群生存力、物种多样性及其群落结构动态等特征。结果表明: 崖柏残存群落伐后13年崖柏种群个体数量增加了22.58%, 其中幼苗幼树占85.71%, 而崖柏种群生存率下降25.43%, 种群死亡密度和危险率分别增加了24.12%和28.62%。崖柏群落物种丰富度和Shannon-Wiener指数分别增加96.43%和33.35%。研究结果表明, 砍伐使崖柏种群生存力及其在群落中的优势度持续下降, 崖柏占优势的针阔混交林有向阔叶林演替的趋势, 崖柏种群受到严重威胁, 亟需采取紧急保护措施。     

极小种群野生植物崖柏的生殖物候、传粉及胚胎发育研究

以濒危植物崖柏（Thuja sutchuenensis Franch.）为对象,对其生殖物候、传粉机制进行观察,并采用石蜡切片法对其胚胎发育过程进行研究。结果显示：崖柏于8月分化出大、小孢子叶球,次年3月传粉,为花粉无气囊、具传粉滴、胚珠直立型传粉机制,球果于10月开裂;显微观察发现,传粉期花粉进入珠孔后,贮藏在珠心上方的贮粉室内,同时珠心组织中分化出孢原细胞,进入雌配子体发育阶段,5月中旬,花粉管开始萌发,6月初完成受精,进入胚胎发育阶段,10月初,胚胎发育成熟。研究表明崖柏从大、小孢子叶球形成至种子成熟的整个发育过程中均存在败育,而胚珠败育及雌配子体游离核时期至幼胚发育期间的败育是其生殖障碍的主要原因。本研究获得了崖柏生殖生物学的基础资料,为其人工繁育和制定保护策略提供了重要依据。     

干旱和复水对崖柏光合特性及水分利用效率的影响

以4年生崖柏(Thuja sutchuenensis Franch.)盆栽实生苗为材料,试验干旱和复水对崖柏光合特性及水分利用效率的影响。结果显示,在自然干旱处理过程中,叶片相对含水量(LRWC)在土壤相对含水量(SRWC)降至30%之后开始出现下降;净光合速率(P_n)、蒸腾速率(T_r)、胞间CO₂浓度(C_i)、光饱和点(LSP)和最大光合速率(P_max)随着土壤可利用水分的减少而逐渐降低;而表观量子效率(Q)、表观量子需要量(1/Q)及光补偿点(LCP)未发生明显变化;水分利用效率(WUE)则随着SRWC的下降而逐渐提高。在停止浇水50 d后(SRWC下降约95%),叶片萎蔫,净光合速率接近零,复水后3 d,净光合速率(P_n)恢复至对照的88.59%,WUE降至对照的88.63%。通过干旱-复水一系列生理指标的变化分析认为,崖柏为干旱避免型植物。     

桂北岩溶区青冈栎-青檀群落植物叶片比叶面积研究

为揭示岩溶地区植物叶片比叶面积变化规律和叶片形态之间的相关关系,研究了桂北岩溶区青冈栎-青檀群落的叶片长/宽(LL/LW)、叶片厚度(LT)和比叶面积(SLA)及其之间的关系。结果表明:群落中常绿树种的LL/LW和LT显著高于落叶树种,而常绿树种的SLA显著低于落叶树种;乔木和灌木之间的LL/LW存在显著差异,但SLA和LT不存在显著差异。总体上看,SLA与LL/LW、LT之间是显著负相关关系,SLA随着LL/LW、LT的变大而逐渐减小。但LT与SLA负相关趋势比LL/LW与SLA的明显。因此,LT比LL/LW对叶片SLA的影响大,其明显影响了叶片的SLA。SLA的大小是衡量叶片获取光照能力的指标,因此岩溶区植物较厚的叶片对光照的获取能力具有较大的影响,并可导致光合作用效率的降低。     

濒危植物崖柏遗传多样性研究

以重庆市大巴山和雪宝山的崖柏为研究对象,对其鳞叶的形态分化进行了初步研究,并用RAPD分子标记技术探讨了该物种在分子水平上的遗传变异。结果表明:崖柏居群内和居群间均存在着广泛的表型及基因型的变异;基于形态数据建立的崖柏居群之间的关系和基于RAPD数据建立的关系不相符;空间距离和生态因子对崖柏居群进化的影响较小;崖柏居群之间的基因流水平较低;应对崖柏居群采取就地保护的措施。     

Classification of life cycle form spectrum of artificial community of Pinus svlvestris var. mongolica

The plant life cycle form and its spectrum features of different plants in the artificial community of Pinus svlvestris var. mongolica at the botanical garden of Northeast Forestry University were classified by PCA method. For canopy layer plants, the vegetative growth (V) accounted for 46%, the sexual growth (S) accounted for 35%, and the clonal growth (C) accounted for the rest 19%. For succession layer plants, V accounted for more than 50%, and C accounted for a little higher than S did. For herbaceous layer plants, V accounted for nearly 47%, which was only 4% higher than that of S, and C only accounted for 11%. These findings indicate that the plant life cycle forms of canopy layer plants and herbaceous layer plants were VS transition form with V form as the main form, while the succession layer plants were V form. At the viewpoint of artificial community, the life cycle form can be described as V_0.49S_0.33C_0.18, a typical VS transition form, indicating that most of the species studied in this community are in a healthy status with the V form. Moreover, the relatively high (33%) percentage in the S form indicates that the community also tends to sexual growth for offspring, although it will be steady within a period of time for the vegetative growth of bodies.     

Classification of life cycle form spectrum of artificial community of Pinus svlvestris var. mongolica

The plant life cycle form and its spectrum features of different plants in the artificial community of Pinus svlvestris var. mongolica at the botanical garden of Northeast Forestry University were classified by PCA method. For canopy layer plants, the vegetative growth (V) accounted for 46%, the sexual growth (S) accounted for 35%, and the clonal growth (C) accounted for the rest 19%. For succession layer plants, V accounted for more than 50%, and C accounted for a little higher than S did. For herbaceous layer plants, V accounted for nearly 47%, which was only 4% higher than that of S, and C only accounted for 11%. These findings indicate that the plant life cycle forms of canopy layer plants and herbaceous layer plants were VS transition form with V form as the main form, while the succession layer plants were V form. At the viewpoint of artificial community, the life cycle form can be described as V_0.49S_0.33C_0.18, a typical VS transition form, indicating that most of the species studied in this community are in a healthy status with the V form. Moreover, the relatively high (33%) percentage in the S form indicates that the community also tends to sexual growth for offspring, although it will be steady within a period of time for the vegetative growth of bodies.     

樟子松（Pinus svlvestris var. mongolica）人工群落生活史型谱

以东北林业大学植物园内的樟子松人工群落为研究对象,应用主成分分析方法在对群落内不同种的生活史型进行划分的基础上,对松科樟子松和白扦、槭树科糖槭、豆科紫穗槐、木犀科暴马丁香、蔷薇科毛果绣线菊和托盘、红豆杉科东北红豆杉、菊科飞廉和线叶旋覆花、禾本科扁穗草、罂粟科白屈菜、唇形科夏至草、十字花科荠菜14种植物生活史型及谱特征进行了定量化分析,以此为依据对群落演替和健康水平进行评价的可行性进行了探讨。结果发现此群落中主林层植物(樟子松和白扦)营养生长(Vegetationgrowth,V)达到46%,有性生长(Sexualgrowth,S)在35%,无性生长(Clonegrowth,C)约为19%;演替层植物(糖槭、紫穗槐、暴马丁香、毛果绣线菊、托盘和东北红豆杉)营养生长超过50%,无性生长略高于有性生长;草本层植物(飞廉、扁穗草、线叶旋覆花、白屈菜、夏至草和荠菜)营养生长接近于47%,有性生长只比营养生长少了4%,无性生长只占到11%。这些发现说明了主林层的生活史型是以营养生长为主的VS过渡生活史型,演替层植物应为V生活史型而草本植物为VS过渡类型。群落的生活史型是V0.49S0.33C0.18,属于VS过渡生活史型,在样地调查的14种植物中,生活史型大部分以营养为主,综合评价此群落处于以营养生长为主(49%)的健康群落水平,此群落中有性生长占总生活史型得分的33%,有向有性生长发展的趋势,但在一段时间内该群落应为稳定群落。     

Environmental Drivers and Spatial Prediction of the Critically Endangered Species <i>Thuja sutchuenensis</i> in Sichuan-Chongqing,China

Identifying the ecological environment suitable for the growth of Thuja sutchuenensis and predicting other potential distribution areas are essential to protect this endangered species. After selecting 24 environmental factors that could affect the distribution of T. sutchuenensis, including climate, topography, soil and Normalized Difference Vegetation Index (NDVI), we adopted the Random Forest-MaxEnt integrated model to analyze our data. Based on the Random Forest study, the contribution of the mean temperature of the warmest quarter, mean temperature of the coldest quarter, annual mean temperature and mean temperature of the driest quarter was large. Based on MaxEnt model prediction outputs, the potential distribution map not only identified areas that originally recorded T. sutchuenensis, such as Xuanhan County, Kai County and Chengkou County, but also identified highly suitable distribution areas where T. sutchuenensis may exist, including Wanyuan County, Sichuan Province, and the junction of Chongqing and Hubei Province. This provides a more explicit geographic range for ex situ conservation and reintroduction of T. sutchuenensis. Our results also indicate that, in addition to climate factors, topography and soil factors are also important environmental factors that affect distribution. This provides a theoretical basis for subsequent laboratory construction to simulate the indoor growth of T. sutchuenensis.