基于Farquhar改进模型的北亚热带森林常见树种光合限速因子研究

为探讨北亚热带地区植物的光合限速因子,利用改进的Farquhar模型研究了9种常见树种的光合特性。结果表明,与常绿树种相比,落叶树种枫香(Liquidambar formosana)和乌桕(Sapium sebiferum)的最大净光合速率(Pmax)和表观羧化速率(CE)较大;核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco)活性是他们的光合限速因子。地带性树种青冈栎(Cyclobalanopsis glauca)的Pmax和CE在常绿木本植物中最大,青冈较强的光合能力可能是来源于Vcmax和TPU。耐阴灌木八角金盘(Fatsia japonica)和美人茶(Camellia uraku)的Pmax较小,其光合限速因子是叶肉细胞导度和呼吸速率。低光照下植物较低的光合能力是由于较小的叶肉导度(gm)和TPU导致的;有效光合辐射短时间的降低使得物种的gm平均减少了60.14%。因此,不同树种在不同环境条件下的光合限速因子不尽相同,应根据树种不同的光合生理特性来合理布局,科学育林。     

小蓬NeMT2基因的克隆及其植物表达载体的构建

该研究利用RACE ( Rapid amplification of cDNA ends)技术从小蓬中成功分离编码金属硫蛋白( Metal-lothionein,MT)的cDNA序列,命名为NeMT2,在GenBank中登录号为KT835290。该基因全长590 bp,开放阅读框为237 bp,编码78个氨基酸,编码的氨基酸序列中含有14个半胱氨酸残基( Cys,C),呈C-C,C-X-C,C-X-X-C排列,集中分布在肽链的N端和C端,基因编码蛋白的分子量为7.6036 kD,等电点为4.71。系统发育分析表明,小蓬金属硫蛋白NeMT2与藜科的海蓬子( AEF01492)和盐穗木( AHI62953)同源性最高,其次是甜菜( XP 010667708.1)。生物信息学分析表明,金属硫蛋白NeMT2无信号肽结构,属于非跨膜亲水性蛋白;疏水性分析表明,NeMT2蛋白的35~45个氨基酸之间有较强的疏水性,其中第41位Asp具最强的疏水性(1.444);结构预测分析该蛋白质二级结构的主要元件是无规则卷曲。通过RT-PCR对NeMT2基因的表达分析发现, NeMT2基因在铜矿区和非铜矿区的小蓬叶片中均有表达,但该基因在铜矿区小蓬叶片的表达量明显高于非铜矿区。将小蓬NeMT2基因定向克隆到植物表达载体pCAMBIA1300的35S 启动子下游,构建该基因的植物超表达载体pCAMBIA1300＋NeMT2。该研究结果为进一步研究该基因的功能和小蓬响应重金属胁迫的分子机制提供了一定基础。     

基于SSR标记的新疆野杏群体遗传多样性及遗传结构

利用27对SSR分子标记对新疆4个野杏群体遗传多样性和遗传结构进行分析,评价新疆野杏遗传多样性水平和分化程度,为新疆野杏合理保护与利用提供科学依据。结果显示：（1）27对SSR引物共检测到431个等位基因（N_a）,各位点平均等位基因数（N_a）和多态性信息含量（PIC）分别为15.96和0.84;物种水平上Shannons信息指数（I）和期望杂合度（H_e）分别为2.21和0.78。（2）群体水平上等位基因数（N_a）、有效等位基因（N_e）、Shannons信息指数（I）、期望杂合度（H_e）和观察杂合度（H_o）分别为10.98、5.85、1.92、0.79和0.55;其中新源县野杏群体遗传多样性最丰富,巩留县群体遗传多样性最低。（3）基于F统计量分析的遗传分化系数（F_st）为0.05,基因流（N_m）为5.26;分子方差分析显示新疆野杏群体大部分遗传变异来自群体内（95.4%）,群体间的遗传变异仅占4.6%。（4）新疆野杏群体遗传距离为0.06~0.49,平均为0.24;遗传相似度为0.61~0.94,平均为0.80;遗传相似度的聚类分析和遗传距离的主坐标分析结果一致,均将供试4个群体划分为两组;Mantel检测显示,新疆野杏群体遗传距离与地理距离无显著相关（r=0.332,P＝0.16）。研究表明,新疆野杏资源具有丰富的遗传多样性,群体遗传分化程度较低,群体间遗传距离较小,这与新疆野杏群体的大小和悠久的演化历史以及群体间频繁的基因交流相关。     

荒漠草原中间锦鸡儿林土壤养分效应对群落组分和多样性的影响

为系统认识荒漠草原中间锦鸡儿人工林草本植被特征及演变趋势对土壤养分的响应,采用空间代替时间的方法,以天然草地为对照,构建3个中间锦鸡儿林龄(16a、25a、37a)研究序列,调查不同中间锦鸡儿林灌丛内外土壤植被并分析二者之间的关系。结果表明:(1)随林龄增加,不同功能群植物重要值呈不同变化趋势,其中禾本科植物显著增加,豆科植物显著降低,杂草类植物先减小后增加。(2)α多样性分析显示,荒漠草原中间锦鸡儿人工林16a灌丛外物种丰富度(S)、香浓维纳指数(H)最高(P0.01);不同林龄均匀度指数(J)、优势度指数(P)未表现出明显的变化规律。(3)β多样性分析显示,Cody指数(βc)和Morisita-Horn(CMH)相似指数均表现出16a与25a、37a之间的物种差异较大、25a与37a之间物种差异相对较小、37a中间锦鸡儿林与天然草地物种组成相似,βws指数在25a中间锦鸡儿林最大。(4)人工中间锦鸡儿林存在显著的土壤碳氮"肥岛效应",其中土壤有机碳是不同林龄植物群落组成差异的显著性影响因子,土壤速效氮为不同林龄灌丛外植物多样性差异的显著性影响因子,但灌丛内植物多样性对土壤养分的响应并不显著。研究认为,中间锦鸡儿林土壤养分演替正效应提高了植物多样性,增强了植物物种的更替程度,但建植后期(37a)植物群落存在向天然草地演替趋势。     

江西金盆山自然保护区种子植物区系研究

江西金盆山自然保护区位于江西省龙南县、全南县与信丰县的交汇处,为武夷山脉与南岭山脉之间的过渡区域,保护区植物种类丰富、区系地理成分复杂。经野外实地调查、查阅相关文献资料,对保护区内种子植物的科、属、种分布区类型进行统计分析。结果表明：（1）金盆山保护区共有野生种子植物161科659属1 474种,其中裸子植物6科7属7种,占江西裸子植物总种数（83种）的8.43%,被子植物155科652属1 467种,占江西被子植物总种数（4 369种）的33.58%。（2）区系分析显示,金盆山保护区内科的分布区类型中热带分布和温带分布分别占总科数（除去世界分布）的64.22%和35.77%,热带分布占优势地位;属的分布区类型中热带分布和温带分布分别占总属数（除去世界分布）的50.95%和47.55%,二者接近平衡;种的分布区类型中热带分布种和温带分布分别占总种数（除去世界分布）的33.98%和37.15%,而且中国特有种419种,占总种比的28.88%。（3）金盆山保护区种子植物具有单种属、寡种属多,植物区系起源古老的特点,其中有寡种属212属,占总属比的32.17%;单种属374属,占总属比的56.75%;其中寡种属所含种数537种,占总种比的36.43%。（4）与邻近6个保护区的植物区系比较表明,金盆山保护区与武夷山脉的联系较南岭山脉更近,而且金盆山保护区表现出比邻近的阳际峰等武夷山脉地区热带性质更明显。     

西藏维管植物新记录

本研究首次发现西藏新记录属云实属(Caesalpinia Linn.)植物——见血飞(Caesalpinia cucullata Roxb.),另外报道了11个新记录种和2个变种:瓶尔小草科(Ophioglossaceae)薄叶阴地蕨(Botrychium daucifolium Wall.),凤尾蕨科(Pteridaceae)华中凤尾蕨(Pteris kiuschiuensis var.centrochinensis ChingS.H.Wu),毛茛科(Ranunculaceae)尾叶铁线莲(Clematis urophylla Franch.),椴树科(Tiliaceae)刺蒴麻(Triumfetta rhomboidea Jacq.),锦葵科(Malvaceae)拔毒散(Sida szechuensis Matsuda),中华地桃花[Urena lobata var.chinensis(Osbeck)S.Y.Hu],柳叶菜科(Onagraceae)草龙[Ludwigia hyssopifolia(G.Don)Exell]、卵叶丁香蓼(Ludwigia ovalis Miq.),唇形科(Lamiaceae)小鱼仙草[Mosla dianthera(Buch.-Ham.)Maxim.],玄参科(Scrophulariaceae)石龙尾[Limnophila sessiliflora(Vahl)Bl.],爵床科(Acanthaceae)白接骨[Asystasia neesiana(Wall.)Nees],桔梗科(Campanulaceae)卵叶半边莲(Lobelia zeylanica Linn.),天南星科(Araceae)百足藤[Pothos repens(Loureiro)Druce]。研究结果进一步丰富了西藏的植物区系,并为研究与相邻地区植物区系的联系增加了新内容。     

To what extent can and should revegetation serve as restoration?

Desertification and climate change are degrading large areas of arid and semiarid habitat in many regions. In response, many countries have implemented revegetation programs, commonly using Atriplex nummularia, native to Australia. Although not intrinsically targeted at habitat restoration, these programs aim to restore (stabilize) erosional processes and provide livestock forage (usually goats, sheep). Few investigators have assessed the utility of these novel habitats for native fauna. In a recent, extensive survey of small mammal communities in lands revegetated with A. nummularia in north‐central Chile, we captured a single animal, the marsupial (Thylamys elegans). We also captured no birds in our live traps and saw numerous darkling beetles in traps. These striking results contrasted with data from a nearby ungrazed park with natural vegetation where 10 small mammal species are known with total abundances ranging from 15 to 80 animals in similar sampling efforts. These revegetated lands provide poor habitat for native mammals, and we argue that revegetation efforts should include proactive risk assessment and cost‐benefit analyses in a structured decision‐making framework. In addition, managers should target increased plant species diversity to support broader biological diversity in addition to the need to control erosion. Although our work has focused on revegetation with Atriplex, numerous other plant species have been intentionally introduced to arid lands, usually for economic reasons; many of these, like Atriplex, have unintended consequences for native biota.     

Overcoming challenges on using native seeds for restoration of megadiverse resource‐poor environments: a reply to Madsen et al.

Madsen et al. (2016) reviewed several major limiting factors to establishment of seedlings in nonforest ecosystems (NFE), and proposed seed enhancement technologies to overcome these restoration barriers. However, biodiverse nutrient‐poor NFE present additional hurdles that preclude landscape‐scale seed‐based restoration and were not mentioned in their review. Here, we discuss issues related to native seed availability and provenance, and shortfalls in knowledge on seed quality testing and dormancy release that severely hamper restoration of degraded nutrient‐impoverished NFE. We present alternatives for overcoming these challenges and highlight the need for investments to find more practical and cost‐effective options for broad‐scale restoration.     

Boundaries of the wolf and the wild: a conceptual examination of the relationship between rewilding and animal reintroduction

Animal reintroduction and rewilding are two widely appealing and frequently connected forms of ecological restoration. However, the critical assumption that animal reintroduction automatically helps to restore formerly wild places is under‐theorized. To fill this void, we identified three common rewilding elements from the literature—ecological functioning, wilderness experience, and natural autonomy—and screened these against a hypothetical wolf reintroduction to Scotland. Each of the rewilding elements was likely to be positively impacted by a wolf reintroduction. Yet, there is a key conceptual difficulty in that the different rewilding elements do not necessarily enforce each other, and at times may even collide. Thus, a reintroduced species like the wolf may obfuscate the clear‐cut, purified nature category to which rewilding often aspires. As a way forward, we suggest that there is merit in actively engaging with the tensions created by rewilding and reintroductions. A reconceptualisation of the nature–culture spectrum as consisting of multiple layers (e.g. ecological functioning, wilderness experience, and natural autonomy) may help to interpret ecological restoration as a tentative, deliberative, and gradual enterprise. This bears some resemblance to the notion of approaching a landscape like a ‘palimpsest’ (i.e. a text built up of different layers written on top of each other), which may support the reconciliation of conflicting views without necessarily making those disappear. When viewed as feeding into a multilayered nature–culture spectrum, animal reintroduction and rewilding can be promoted as inspiring and essentially non‐controlling forms of ecological restoration and human interaction with nature.     

基于提高鸟类多样性的北京城市线性公园绿地植物景观探析

植被覆盖率高的线性公园,可作为鸟类的迁徙途径和栖息之所,并猜测其可作为生态廊道的一部分,适宜的营造植物景观、提升植物种类的多样性对保护鸟类多样性有促进作用。因此,采用标准取样法对北京城市线性公园绿地进行研究,提取可能影响鸟类多样性的植物群落因素、植物生境因素,对提高鸟类多样性提出建设性的意见。研究结果主要表明,在线性公园绿地宽度30~200m内,随着宽度的增加,鸟类的数量有所提高;含有不同类型植物生境的线性公园绿地,对鸟类目标种的吸引力不同,植物生境类型数较多样的线性公园绿地具有较高的鸟类目标种吸引力;不同的鸟类目标种偏好在不同的树种上进行活动。