Soil respiration associated with plant succession at the meadow steppes in Songnen Plain, Northeast China

Aims Soil CO_(2) emission from steppes is affected by soil properties and vegetation in different successional stages.Primary and secondary succession of plants frequently occurred at the meadow steppe in Songnen Plain,Northeast China,which indicates the large uncer-tainty associated with CO_(2) emission in this environment.This study aims to investigate the temporal variations of soil respiration(Rs)and the effect of plant succession on cumulative soil CO_(2) emission during the growing season.Methods Using a LI-6400 soil CO_(2) flux system,Rs of five vegetation types which represented different stages of plant succession in meadow steppes of Songnen Plain,China,was investigated during the grow-ing seasons of 2011 and 2012.Important Findings Soil temperature(Ts)was the dominant controlling factor of Rs,which could explain~64%of the change in CO_(2) fluxes.The Q10 values of Rs were ranged from 2.0 to 6.7,showing a decreasing trend with the plant successional stages.The cumulative CO_(2) emis-sion increased with the degree of vegetation succession and it aver-aged to 316±6 g C m^(−2)(ranges:74.8±6.7 to 516.5±11.4 g C m^(−2))during the growing season.The magnitude of soil CO_(2) emission during the growing season was positively correlated with above-ground plant biomass,soil organic carbon content and mean soil water content,while negatively linked to mean Ts,pH,electrical conductivity and exchangeable sodium percentages.The results implied that soil CO_(2) emission increased with the development of plant communities toward more advanced stages.Our findings pro-vided valuable information for understanding the variations of CO_(2) emission in the process of vegetation succession.

Floral trait variation across individual plants within a population enhances defense capability to nectar robbing

Floral trait variation may help pollinators and nectar robbers identify their target plants and,thus,lead to differential selection pressure for defense capability against floral antagonists.However,the effect of floral trait variation among individuals within a population on multi-dimensional plant-animal interactions has been little explored.We investigated floral trait variation,pollination,and nectar robbing among individual plants in a population of the bumble bee-pollinated plant,Caryopteris divaricata,from which flowers are also robbed by bumble bees with varying intensity across individuals.We measured the variation in corolla tube length,nectar volume and sugar concentration among individual plants,and evaluated whether the variation were recognized by pollinators and robbers.We investigated the in-fluence of nectar robbing on legitimate visitation and seed production per fruit.We found that the primary nectar robber(Bombus nobilis)preferred to forage on plants with long-tubed flowers,which produced less nectar and had lower sugar concentration compared to those with shorter corolla tubes.Individuals with shorter corolla tubes had comparatively lower nectar robbing intensity but higher visitation by legitimate visitors(mainly B.picipes)and higher seed production.Nectar robbing signifi-cantly reduced seed production because it decreased pollinator visits.However,neither pollination nor seed production differed between plants with long and short corolla tubes when nectar robbers were excluded.This finding suggests that floral trait variation might not be driven by pollinators.Such variation among individual plants thus allows legitimate visitors and nectar robbers to segregate niches and enhances population defense against nectar robbing in unpredictable conditions.

Effects of soil nitrate:ammonium ratio on plant carbon:nitrogen ratio and growth rate of Artemisia sphaerocephala seedlings

Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.

Unit 1 of Ling’ao Nuclear Power Plant phase II underwent hot functional test successfully

On February 25, the Unit 1 of Ling’ao Nuclear Power Plant phase II underwent a 41-day-long hot functional test successfully with its major systems satisfying the requirements for

西部采煤沉陷地微生物复垦植被种群自我演变规律

菌根真菌可以与陆地上80%以上的植物形成菌根共生体,促进植物在逆境的生长。采煤沉陷地在人工接种菌根真菌后复垦植被种群进行了自我修复与演变,监测采煤沉陷地复垦植物人工接种菌根真菌复垦后4 a对植被种群的自我演变规律影响。以神东矿区大柳塔采煤沉陷地人工林樟子松、沙棘和文冠果为研究对象,野外原位监测植被种类、生活型组成及植被多样性指数,并利用地统计学方法进行克里金插值,对比接种菌根真菌4 a后(+M)与同期种植的自然状态下(CK),两种处理样地内植被种类、数量及其多样性指标,揭示不同人工林在自然状态和人工接种4 a后,区域内物种个体种类、数量和群落多样性差异。研究结果表明:接菌提高樟子松人工林灌木层物种多样性,而降低草本层物种多样性;接菌提高沙棘和文冠果人工林的草本植物群落稳定性和物种多样性及其均匀度,抑制灌木层物种多样性增加。3种人工林微生物复垦4 a后多年生草本占优势地位。接菌组进入多年生草本+灌木的生态组成结构阶段,而对照组则相对滞后,处于一年生草本+多年生草本+灌木的组成结构阶段,接菌促进了生态的演变进程。综合分析植物分布特征,发现植物的最优拟合模型以高斯模型居多,阿尔泰狗娃花、地肤、猪毛蒿、白花草木樨、牛心朴子、野樱桃、油蒿及柠条的预测值精度较好。接菌可促进地稍瓜、阿尔泰狗娃花、牛心朴子、达乌里胡枝子和柠条频度和数量的增加,可能使绳虫实、糙隐子草、苦苣菜和花棒的频度和数量下降。本文为煤矿沉陷区采用微生物修复人工林促进生态群落自我演变进程奠定了初步的研究基础。

桂西北喀斯特地区植被不同演替阶段生态化学计量特征（英文）

【目的】探讨桂西北喀斯特地区植被不同演替阶段生态化学计量特征,为进一步了解植被演替过程中的养分循环和喀斯特生态系统的稳定性提供参考。【方法】通过野外样地设置、取样及室内试验,采用方差分析和相关性分析等经典统计方法对桂西北喀斯特地区四个演替阶段(草丛、灌丛、次生林和原生林)植物、凋落物和土壤的碳(C)、氮(N)和磷(P)含量、化学计量比及其相关性进行分析。【结果】植物C、N和P含量随植被正向演替呈增长趋势,凋落物的养分含量均低于植物。植物N和P再吸收率表现为原生林>灌丛>次生林>草丛。次生林中0~10 cm土壤以C和N含量最高,但灌丛以P含量最高。养分化学计量比C∶N、C∶P和N∶P在各层次中表现出一定的规律:凋落物>植被>土壤。在草丛中,植物C∶N、C∶P和凋落物C∶N最高,植物和凋落物的N∶P最低;凋落物C∶P、N∶P和植物N∶P分别出现在原生林和次生林;土壤C∶P、N∶P沿植被正向演替而增加。植物、凋落物和土壤中C、N和P含量及其化学计量比间存在显著相关(P<0.05)。【结论】土壤养分对植物养分含量影响不明显,但在植物生长过程中发挥重要作用;植物叶片N∶P受土壤N和P含量的影响;植物生长在演替阶段早期易受土壤养分限制。

哀牢山4类植物群落叶面积指数比较

采用演替阶段的划分方法，把哀牢山人工灌木林、次生落叶阔叶林、次生常绿落叶阔叶混交林及原始常绿阔叶林4种群落划分为演替较早期、演替早期、演替中期和演替后期4个时期，利用植物冠层仪测定了4种群落的叶面积指数。结果表明：从演替较早期到晚期，物种多样性和树种密度逐渐增加，叶面积指数值也逐渐增大，演替较早期叶面积指数最小（2．27），演替晚期叶面积指数最大（5．60）。各个演替阶段的叶面积指数间差异极显著（P〈0．01），各演替阶段内测定的叶面积指数也有较大的标准差（0．35—0．73），说明各群落之间甚至同一种群落内，林冠结构都有较大差异。演替晚期乔木层叶面积指数最大，早期最小；演替中期灌木层叶面积指数最大，早期最小；4个阶段草本层叶面积指数差异不大。

Tree diversity effects on forest productivity increase through time because of spatial partitioning

Background: Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment(as of2018) in Japan.Results: I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages(≤ 3 years), the positive complementarity effect was explained by enhanced growths of early-and mid-successional species in the mixture. Later on(≥ 15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e. alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer.Conclusions: The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.

浙江天台山常绿阔叶林次生演替序列群落物种多样性

应用物种丰富度和物种多样性指数及群落均匀度等指标对浙江省天台山常绿阔叶林次生演替序列物种多样性进行研究。结果表明 :天台山次生森林从针叶林到针阔混交林到常绿阔叶林的演替过程中 ,物种多样性呈先变大后变小的趋势。在群落的垂直结构中 ,次生演替序列 3种群落类型的物种丰富度和物种多样性指数的大小顺序均为灌木层 (包括幼苗及幼树 ) >乔木层 >草本层。在 3种群落类型中 ,木本植物的物种多样性均大于草本植物。表 4参

Effect of pine wood nematode invasion on pine community functions in the Pinghu region, Zhejiang Province, eastern China

In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.

Cartographic Approach in Studying Landscape Northwestern of Part Western Siberia

The structure and dynamics of geosystems: plant of forest and bogs in the northwestern part of Western Siberia is considered by using the Kazym-Lyamin interfluve, based on the landscape-assessment map for the middle part of the Khanty-Mansi Autonomous District. The study used the landscape structural-dynamical approach and the methods of studying the spatio-temporal dynamics of taiga geosystems. Theoretical and methodological research on the development of the landscape-assessment map for Asian Russia is high on the cartographic agenda of the V. B. Sochava Institute of geography SB RAS. The methodic research is to be used to Landsat-5 TM in GIS Multi-Spec and Qgis. An analysis is also made of the topographic, geomorphologic and forest 1:200,000 maps, the profiles characterize the lithology, field data of geobotanical and soil descriptions, and experimental permanent station operated. The landscape structure of this area and its hierarchical subordination are represented in the map legend in terms of groups of facies which are combined into regional-typological classification units: groups of geoms, classes, and types of natural environment. Landscape mapping and planning will help to timely prevent and forecast the magnitudes of disturbances to natural environment using and be as the basis for a package of optimal nature-conservation measures and target-oriented technogenic and anthropogenic impacts.

长白山不同演替阶段温带森林木本植物菌根类型对林下草本植物多样性的影响

温带森林生态系统草本植物多样性丰富,是植物多样性的重要组分,对森林生态系统功能的调控同样具有重要作用,但却未受到广泛关注。本研究依托长白山地区原始阔叶红松(Pinus koraiensis)林和采伐干扰后形成的次生针阔混交林中共128个1 m×1 m草本植物样方连续两年的调查数据,深入解析了两类森林林下丛枝菌根(arbuscular mycorrhizal, AM)草本植物和非菌根(non-mycorrhizal, NM)草本植物多样性的异同;并运用广义线性混合效应模型分析了AM木本植物和外生菌根(ectomycorrhizal,EcM)木本植物以及环境因子对林下草本植物多样性的影响。结果表明:原始阔叶红松林中群落水平上草本植物和AM草本植物的多度和多样性均显著高于受人类采伐干扰后形成的次生针阔混交林,而NM草本植物无显著差异。林下草本植物多度和多样性受到木本植物邻体的显著影响,但其作用强度受到环境因素的调控。在次生针阔混交林中,群落水平上的草本植物多样性主要受木本植物邻体多样性和林下叶面积指数的直接影响。AM草本植物多度与EcM木本植物邻体密度显著负相关,且这种负作用关系随着土壤含水量的增加而减弱。在阔叶红松林中,土壤含水量直接影响群落水平草本植物和AM草本植物的多度,且土壤含水量的高低调控木本植物邻体对群落水平草本多度和多样性的影响。综上所述,采伐干扰显著降低了温带森林生态系统中草本植物多度和多样性,而上层木本植物邻体的菌根类型和环境因子对林下草本植物群落构建表现出明显的交互作用。

Development of plant communities after restoration of the Antaibao mining site, China

To investigate the dynamic changes in the artificial vegetation in an abandoned mining site,we analyzed the re lationships among community types,environmental variables and community structure in the process of vegetation restoration in the Antaibao mining site,China by survey of the communities and use of biological dating methods.By means of the quantitative classification method(two-way indicator-species analysis,TWINSPAN)and the ordination technique(de-trended correspondence analysis,DCA;and de-trended canonical correspondence analysis,DCCA),the plant communities were classified into seven groups:community I,Robinia pseudoacacia+Pimus tabulaeformis-Caragana kor-shinskii-Agropyron cristatum;community II,Robinia pseudoacacia-Hippophae rhamnoides-Artemisia capil-laries;community II,Ulmus pumila-Elaeagmus angu-stifolia-Artemisia capillaries;community IV,Caragana korshinskii-Agropyron cristatum+Artemisia capillaries;community V,Hippophae rhamnoides-Elymus dahur-icus;community VI,Elaeagnus angustifolia+Hippophae rhamnoides-Brassica jucea;community VII,Hippophae rhammoides+Elaeagnus angustifolia-Salsola collina.We conclude that the community types and diversity are mainly influenced by the succession time and the soil organic matter content.The forest community is more adaptable to the special inhabitation than the shrub community.

High-nitrogen and low-irradiance can restrict energy utilization in photosynthesis of successional tree species in low subtropical forest

Responses of photosynthesis and the partition of energy utilization to high-nitrogen importation and high-light intensity in leaves of three dominant tree species of subtropical forest,including sun plant or early-successional species Schima superba,mesophyte or intermediate-successional species Canstanopsis hystrix,and shading-tolerant plant or late-successional species Cryptocarya concinna were studied by using the CO2 exchange system and chlorophyll fluorescence method.Our results showed that,regardless of plant species,net photosynthetic rate(Pn)was higher in high-nitrogen supply and high irradiance(HNHL)plants than in low-nitrogen supply and high irradiance(LNHL)plants,implying that low-nitrogen importation would limit Pn of plants grown under high irradiance.However, high-nitrogen supply and low irradiance(HNLL)plants had a lower Pn.Insignificant change of quantum yield(Fv′/Fm′)in opened PS II was found in leaves of HNHL,LNHL or HNLL plants of S.superba and C. hystrix,while a higher Fv′/Fm′occurred in HNHL plants of C.concinna in comparison with LNHL or HNLL plants.The HNHL plants of C.concinna also had a higher photochemical quantum yield(△F/Fm′) than LNHL or HNLL plants,however no similar responses were found in plants of S.superba and C. hystrix(P<0.05).In the irradiance range of 0―2000μmol photon·m -2·s -1,the fraction of energy consumed by photochemistry(φ PSII )was 18.2%in LNHL plants of S.superba which was higher than that in HNHL plants(P>0.05)and it was significantly higher than in HNLL plants(P<0.05).C.hystrix also had a similar response inφ PSII to nitrogen supply and irradiance.Regardless of species HNLL plants had a significantφ PSII and higher heat dissipation in light,and this effect was more severe in C.concinna than in S.superba or C.hystrix.The results may mean that high-nitrogen importation by nitrogen deposit and low irradiance caused by changing climate or air pollution would more severely restrict photosynthetic processes in the late-successional species C.concinna than in the early-successional species S.superba and intermediate-successional species C.hystrix.The continuous high-nitrogen precipitation in the future and the over cast mist or pollution smoke could induce late-successional species to degrade,however,early-successional species would be more adapted to competition for more resources to keep their dominance in ecosystems.In this sense,the zonal vegetation may accelerate degradation caused by high nitrogen precipitation and low irradiance,while the early-successional and mesophytic vegetations can remain longer.Thus,nitrogen precipitation may play an important role in plant community succession.

浙东常绿阔叶林植物功能性状对土壤含水量变化的响应

研究群落演替过程中植物功能性状与土壤含水量的关系,揭示植物对水分供给变化的响应策略,具有重要的生态学意义。该研究以浙江东部天童山、南山和双峰山的3个常绿阔叶林演替系列为对象,旨在探索不同演替阶段常见植物的功能性状与森林群落土壤含水量的相互关系。研究结果显示:森林演替中后期的树木高度、树冠面积、叶片干物质含量显著大于演替前期植物;相反,叶片净光合速率和蒸腾速率随演替进程而降低。随森林演替,表层土壤(0–20 cm)的含水量显著增加,深层土壤(20–40 cm)含水量随演替进程增加但不显著。表层土壤含水量与树木高度、树冠面积和叶片干物质含量显著正相关,与叶片净光合速率和蒸腾速率显著负相关;深层土壤含水量与树冠面积显著正相关,与叶片净光合速率、气孔导度和蒸腾速率显著负相关。树木高度、树冠面积、叶片干物质含量、叶片净光合速率、气孔导度和蒸腾速率均可解释土壤含水量随演替进程的变化趋势,而冠长比对土壤水分变化的响应最为敏感。

Changes in the soil microbial communities of different soil aggregations after vegetation restoration in a semiarid grassland,China

Soil aggregate fractions can regulate microbial community composition and structure after vegetation restoration.However,there has been less focus on the effects of soil aggregate fractions on the distributions of microbial communities.Here,we used phospholipid fatty acid(PLFA)analysis to explore the effects of different years of vegetation restoration(a 35-year-old Thymus mongolicus community(Re-35yrs)and a 2-year-old nongrazing grassland(Ug-2yrs))on microbial communities within different soil aggregate sizes(<0.25 mm,0.25–1 mm,1–2 mm,2–3 mm,3–5 mm and>5 mm).The results indicated that the amount of total PLFA in Re-35yrs was 10 times greater than that in Ug-2yrs.The soil aggregate stability increased with increasing duration of vegetation restoration.In Re-35yrs,the total PLFA shown an increase as the soil aggregate size increased,and the highest values were observed in 3–5 mm.Ug-2yrs differed from Re-35yrs,the soil microbial diversity was higher in medium particle sizes(1–2 mm and 2–3 mm)and lower in microaggregates(<0.25 mm and 0.25–1 mm)and macroaggregates(3–5 mm and>5 mm).Soil microbial diversity was highest in large particle size aggregates,which resulted in low environmental stress and strong stability.The same tendency was observed in the high values of cyc/prec,S/M and soil organic matter,which indicated a lower turnover speed(F/B)of fungal energy utilization and a higher fixation rate.After years of natural restoration,the soil microbial community generally transformed from nutrient-rich to heterotrophdominant,especially in microaggregates(reflected in the G^(+)/G^(–)ratio).