不同供氮水平对蒙古栎幼苗生物量与光合特性的影响

采用盆栽试验方法,从1、4、8、16、32 mmol·L^-1 5个N素处理对蒙古栎幼苗的生物量、相关生理指标以及光合特性等方面的影响进行研究。结果表明,随着供N水平的提高,蒙古栎幼苗根、茎和全株的生物量均在N_(16)供应下达最高,但与N_8、N_(32)处理间差异不显著,叶片生物量在N_(32)水平达最大,与N_(16)的差异不显著。根冠比随着供N水平的提高呈现降低的趋势。蒙古栎幼苗的光合参数(P_n、T_r、G_s、C_i)随供N量的增加呈现出先增加后减小的趋势,均在N_8水平下达最大。除叶绿素b之外,叶绿素a、叶绿素总量、类胡萝卜素以及可溶性蛋白含量与光合参数的变化一致,同样在N_8水平达最大。试验结果表明,增加N素供应可促进蒙古栎幼苗的生物量,或高或低的供N都会影响蒙古栎幼苗的光合作用。

大兴安岭不同演替阶段土壤呼吸及其组分的动态

土壤呼吸及其组分随森林演替的变化对于长期碳循环模型及其地下碳储量至关重要。为了研究土壤呼吸随森林演替的变化及其影响机制,在2019年大兴安岭地区选取草地(GL)、白桦林(BF)、白桦与落叶松混交林(MF)、落叶松林(LF)4个不同演替阶段并对其进行研究。采用壕沟法测定自养(RA)和异养(RH)呼吸。结果表明,GL、BF、MF和LF的土壤呼吸(RS)分别为3.11,5.68,5.54和4.69μmol·m^(-2)·s^(-1),RH分别为2.37,4.56,4.31和3.50μmol·m^(-2)·s^(-1),RA分别为0.74,1.12,1.23和1.19μmol·m^(-2)·s^(-1),GL、BF、MF、LF去除凋落物后RS值分别为3.01,5.21,5.24和2.88μmol·m^(-2)·s^(-1)。GL、BF、MF和LF中RA对RS的贡献分别为23.79%,19.72%,22.20%和25.37%。演替阶段对RS有显着影响(P<0.05)。回归分析发现,RA与细根生物量呈正相关(P<0.01),RH与森林凋落物质量呈显著正相关(P<0.05)。试验的结果强调了演替阶段对土壤呼吸不同成分的重要性及其对估算森林碳汇潜力的重要性。

Relationship between diversity of forest plant species and environmental gradient in eastern mountainous area of Heilongjiang Province, China

Twenty-three secondary forest communities with different structure were selected in Mao＇er Mountain National Park of Heilongjiang Province, China to study the relationship between diversity of forest plant species and environmental gradient. The forest plant species diversity was analyzed by the diversity index, and the environmental factors was quantified by the method of Whittaker＇s quantification of environmental gradient. Meanwhile, β-diversity indexes of communities were calculated with similar measurements. The results showed that the Shannon-wiener diversity index of forest plant species increased with the increase of the environmental gradient, and the β-diversity indexes of communities showed a liner increase along with the change of environmental gradient.

Relationship between diversity of forest plant and community dynamics in eastern mountain area of Heilongjiang Province, China

The biodiversity was studied in 26 communities with different structures in Maoershan National Park and Liangshui Natural Reserve of Northeast Forestry University in Heilongjiang Province, China. Composition index （CI） was taken as a parameter to quantify the community dynamics, which can nicely describe forest community dynamics, meanwhile, the relationship between diversity and community dynamics were also investigated and analyzed. Results showed that the total number species of community, richness, evenness, and Shannon-Wiener diversity index were obviously different in every community. The richness decreased with the increasing CI of every community, which means richness was in inverse proportion to community dynamics. The Shannon-Wiener index of every community increased from the initial stage to the middle stage of succession, and then decreased in the climax stage. The coverage weighted foliage-height diversity index increased along with the increase of CI, which was similar as the oattem diversity.

造纸废水UMIC反应器中微生物的纵向分布特性

为探明造纸废水UMIC反应器中微生物的纵向分布特性,试验应用16S rRNA基因-Illumina MiSeq高通量测序技术分析和比较了不同高度反应器中的微生物群落结构及多样性。微生物多样性分析表明,在UMIC反应器中,细菌的多样性要高于古菌,且在反应器7.5 m处微生物多样性最高。反应器的顶部拟杆菌门微生物分布较多,而绿弯菌门微生物分布较少。厚壁菌门在反应器中分布较为均匀;在UMIC反应器的1m处,Euryarchaeota丰度相对较低,而Bathyarchaeota丰度相对较高。在5 m和10 m处,Euryarchaeota占绝对优势。

植物入侵机制的主要假说

植物入侵是最严重的全球问题之一,严重破坏生态系统的结构和功能。随着植物入侵现象日益严峻,要控制和解决外来植物入侵问题,了解和掌握植物入侵机制尤为重要。本文概述了植物入侵的多种机制及不同机制间的协同作用,阐述了植物入侵过程中的化感作用、植物-土壤反馈机制、互惠共生关系,以及植物功能性状和表型可塑性对入侵过程的影响,并对多种机制协同与植物入侵轨迹的关系进行综合分析。根据分析结果将外来植物在侵入地的入侵时间轨迹分为引入、定植、建立和侵入4个阶段,把遇到的各种阻碍和促进因素融入其中,提出外来植物入侵曲线图,有助于未来对入侵植物及其影响的研究和管理。对现有的植物入侵研究方法进行分析,提出现阶段研究的不足以及未来的研究方向和目标。