浙江赋石水库集水区板栗林土壤氮素迁移特征

本研究通过在板栗林地设置径流小区,于2013年1—10月间采集径流水样进行测试,同时结合雨季前后土壤氮素数据,分析了浙江北部赋石水库集水区板栗林土壤氮素迁移特征.结果表明: 板栗林地的10次地表径流事件中,各径流小区径流水量差别较大,最大达0.51 m³;其中氮是主要的流失元素,硝态氮(NO₃^--N)、铵态氮(NH₄⁺-N)、总氮(TN)和化学需氧量(COD_Mn)的浓度分别为0.02～1.87、0.04～3.53、1.69～5.33和5.30～14.07 mg·L^-1,各水质指标受径流水量影响较大,且用一元一次方程可以较好地拟合氮素流失量与径流水量之间的相关关系;雨季前后板栗林地径流场上部、中部和下部3个位置的土壤中,氮素含量差异较大;总的变化趋势是随着海拔升高氮素含量增加,随着土层深度加深氮素含量降低.比较雨季前后4种土壤氮素(NO₃^--N、NH₄⁺-N、TN 和水解性氮Hydro-N)的差异发现,差异较大的为Hydro-N和TN,平均差异值为20.21和307.49 mg·kg^-1.该区氮素随径流流失风险较大,对赋石水库水体富营养化构成潜在压力,需重点关注.     

模拟N沉降下不同林龄马尾松林凋落叶分解-土壤C、N化学计量特征

模拟N沉降对森林生态系统的影响是当今全球变化生态学研究的一个热点问题,土壤碳库对N沉降比较敏感,N沉降增加了凋落叶分解过程中外源N含量,间接影响凋落叶分解的化学过程并改变凋落叶分解速率,因此,研究模拟N沉降下凋落叶分解-土壤C-N关系对预测森林C吸存有重要意义。利用原位分解袋法研究了模拟N沉降下三峡库区不同林龄马尾松林(Pinus massoniana)凋落叶分解过程中凋落叶-土壤C、N化学计量响应及其关系;N沉降水平分对照(CK,0 g m~(-2)a~(-1))、低氮(LN,5 g m~(-2)a~(-1))、中氮(MN,10 g m~(-2)a~(-1))和高氮(HN,15 g m~(-2)a~(-1))。结果表明:分解540 d后,N沉降促进20年生和30年生马尾松林凋落叶分解,46年生马尾松林中仅低氮处理促进凋落叶分解,4种处理均是30年生分解最快,说明同一树种起始N含量低的凋落叶对N沉降呈正响应,N沉降处理促进起始N含量低的凋落叶分解,起始N含量高的凋落叶分解过程中易达到"N饱和"。N沉降抑制20年生和46年生凋落叶C释放(低于对照0.62%—6.69%),促进30年生C释放(高于对照0.28%—5.55%);30年生和46年生林分N固持量均高于对照(高于对照0.15%—21.34%),20年生则低于对照(5.70%—13.87%),说明模拟N沉降处理促进起始C含量低的凋落叶C释放和起始N含量低的凋落叶N固持。N沉降处理下仅30年生马尾松林土壤有机碳较对照增加,且土壤有机质与凋落叶C、N和分解速率呈正相关,与凋落叶C/N比呈显著负相关;土壤总氮与凋落叶分解速率、凋落叶N含量呈正相关,土壤有机碳/总氮比与凋落叶C、N含量呈正相关;对照处理中凋落叶分解指标对土壤养分影响顺序是分解速率凋落物C含量凋落物C/N比凋落物N含量,低、中、高氮处理中则是凋落物C含量分解速率凋落物N含量凋落物C/N比。研究表明低土壤养分含量马尾松林对N沉降呈正响应,N沉降促进低土壤养分马尾松林凋落叶分解并提高土壤肥力;凋落叶质量和土壤养分含量低的生态系统土壤C对N沉降响应更显著。     

持续淹水对河竹器官养分元素分配格局的影响

为探明持续淹水对河竹器官养分元素分布格局的影响,揭示竹子耐受水淹胁迫的养分适应机制,以2年生河竹(Phylllostachys rivalis)盆栽苗为试材,设置不同深度的淹水处理(水位高出栽培基质5 cm(Ⅰ)、10 cm(Ⅱ)和正常供水(CK)),测定了持续淹水90、180 d和360 d河竹叶、枝、秆、鞭和根中养分元素C、N、P、K、Ca、Fe和Mg的含量,分析了淹水条件下河竹器官营养元素分布格局的变化。结果表明:1)淹水深度和时间显著影响河竹器官C含量,与对照比较,淹水90 d时,叶、枝和根C均显著增加(P0.05),随着淹水时间的延长(180 d),C含量维持稳定状态,至淹水360 d,植株C含量降低,尤其淹水Ⅱ显著降低。2)淹水显著影响河竹器官的N、P、K、Ca、Fe和Mg含量(P0.05),且处理时间、处理水平和器官间存在显著交互作用(P0.001),处理90 d时,河竹叶片N、P、Ca、Fe和Mg含量均显著升高,而根的N、P含量则显著降低,淹水180 d和360 d时,除根部的K、Fe和Mg含量升高外,其它器官中各元素均显著降低。3)水位深度对元素之间的关系产生明显影响,在淹水Ⅰ叶片的CK、N-K、P-K、Fe-Ca和Fe-Mg的相关系数升高,元素间协同性增强,而在淹水Ⅱ中这些相关系数则降低,说明元素间的协同性减弱。4)淹水Ⅱ河竹叶片C/N、C/P较对照显著增加(P0.05),而N/P变化不显著(P0.05),说明河竹在淹水条件下具有较高内稳定性。综上,淹水影响河竹根系矿质元素吸收能力,促进其向顶运输,以维持碳同化能力和元素内稳性,这可能是河竹适应持续水淹胁迫的重要机制。     

Effects of light intensity variation on nitrogen and phosphorus contents,allocation and limitation in five shade-enduring plants

Aims To enhance the understanding on nitrogen (N) and phosphorus (P) physiological responses to different light environments in shade-enduring plants and provide references to improve the stand structure and ecosystem functions of plantation forests.Methods We selected seedlings of five shade-enduring species with high ecological and economic value in subtropical area of China to study the effects of light intensity on leaf N and P contents, allocation and nutrient limitation in shade-enduring plants. A light intensity gradient of five different levels was set to simulate the varying understory light environment.Important findings With decreasing light intensity, the total biomass and total N and P accumulation of five shade-enduring plants all showed a decreasing trend, but N, P contents in different organs increased. Among them, Gardenia jasminoides (GJ) had the highest while Illicium henryi (IH) had the lowest N content; The P contents of Quercus phillyraeoides (QP) and GJ were significantly higher than Elaeocarpus sylvestris (ES), Ardisia crenata (AC) and IH. QP and GJ had the highest N, P contents under extremely low light intensity (6% natural light intensity) condition (LIC), while AC and IH had the highest N and P contents in low (15% natural light intensity) and moderate (33% and 52% natural light intensity) LIC. ES demanded differently for LIC on N and P, which were 52% and 6% natural light intensity, respectively. N and P allocation of ES, AC and IH followed leaf > root > stem, but for QP and GJ were root > leaf > stem. Decreasing LIC significantly affected N and P allocation. N content variations shown good consistency among different organs under higher LIC (100% natural light intensity) while distinct variability under lower LIC (15% and 6% natural light intensity) in all five species. Phosphorus contents exhibited good consistency in IH, QP and GJ but varied in ES and AC. Decreasing LIC significantly affected organ N/P ratios of shade-enduring plants, but the fundamental growth restriction patterns remained. Light intensity variation and tree species co-regulated N, P utilization and allocation in shade-enduring plants, and then affected the total biomass and total N, P accumulation, which might result from the change of N and P utilization strategy. Therefore, light intensity preference and N, P nutrient balances in shade-enduring plants should be taken into account when constructing multiple layer and uneven-aged forests.     

Effects of glyphosate on interspecific competition between Solidago canadensis and Imperata cylindrica

Aims The extensive use of herbicide to control invasive plants would change the relationship between alien and neighboring plants. In order to provide data for rational use of herbicide and a theoretical reference for further studies on the ecological effects of glyphosate, we explored the variation of the relationship between an invasive plant Solidago canadensis and a native plant Imperata cylindrica when they were sprayed glyphosate.
Methods A replacement series experiment was conducted from June to August 2016 in Wetland Ecosystem Research Station of Hangzhou Bay, State Forestry Administration, to examine the effects of glyphosate at seven concentration levels (0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 mL·L^-1) on the growth and interspecific competition of S. canadensis and I. cylindrica.
Important findings (1) Glyphosate treatment significantly inhibited the growth of S. canadensis and I. cylindrica (p < 0.05). During the test, cumulative growth of height and leaf number of S. canadensis were apparently reduced with the increase of glyphosate concentration, but the leaf number of S. canadensis treated with 0.3- 1.5 mL·L^-1 glyphosate was re-growing with time, while the one treated with 1.8 mL·L^-1 was mostly dead. The withering rate of tiller and green leaf of I. cylindrica also significantly increased with the increase of glyphosate concentration, and the growth indices of this plant treated with 0.3-0.6 mL·L^-1 were also re-growing with time. (2) Glyphosate treatment significantly affected interspecific competition (p < 0.05), which diminished as the glyphosate concentration increased. (3) Interspecific competition has significant influence on the biomass allocation of S. canadensis (p < 0.05). When facing competition, S. canadensis would allocate more organic matter to root and thus increase the ratio of root to shoot. Competition only inhibited the tiller number and total biomass of I. cylindrica, but insignificantly affected its ratio of root to shoot. (4) The interaction between glyphosate treatment and S. canadensis-I. cylindrica interspecific relationship also significantly influenced the biomass of S. canadensis and I. cylindrica (p < 0.05), but insignificantly affected the root/shoot ratio of two plants. Different plants have different tolerance to glyphosate stress. Compared with native plant I. cylindrica, S. canadensis has stronger tolerance to glyphosate. Low-concentration glyphosate could decrease the competitive intensity between S. canadensis and I. cylindrica, which may disturb the structure and dynamics of plant communities.     

芦苇(Phragmites australis)抑制四种植物扩散的化感潜力研究

为评估湿地芦苇植物通过化感抑制非芦苇湿地植物扩散的能力, 运用实验室生物活性测试的方法, 比较了杭州湾湿地围垦区芦苇(Phragmites australis)与其他6 种主要禾本科植物的化感潜力。以加拿大一枝黄花(Solidago canadensis)、田菁(Sesbania cannabina)、小飞蓬(Conyza canadensis)和苣荬菜(Sonchus brachyotus)等研究区域扩散植物种为受体, 研究了芦苇水提取液对上述物种种子萌发影响。结果表明: (1)除白茅(Imperata cylindrical)外, 7 种本地禾本科植物水提液浓度(0-2.50 g·100mL–1)均和萝卜幼苗胚根长呈极显著的负相关(p<0.001); 芦苇具有较强的化感潜力;(2)芦苇根、茎和叶水提液 (0、2.5、5.0、10.0 g·100mL–1)作用下, 不同物种和不同浓度处理下种子萌发指数差异显著(p<0.001), 其中加拿大一枝黄花、苣荬菜和小飞蓬3 种植物对芦苇水提液较为敏感, 而田菁敏感程度较弱。种子萌发指数表现出低浓度(2.5 g·100mL–1)促进和高浓度(5.0 g·100mL–1 和10.0g·100mL–1)抑制的“低促高抑”效应特征。除田菁外, 种子胚根长一般随浓度增加而降低。芦苇不同组织部位水提液对4 种植物抑制程度按大小依次为叶>茎>根, 叶片可能是芦苇化感物质主要来源。芦苇具有较强的化感潜力, 其化感作用可能是抑制其他植物扩散的重要机制之一。     

异质低磷胁迫下马尾松家系根构型和磷效率的遗传变异

以7个马尾松(Pinus massoniana)一代种子园自由授粉家系为材料, 设置同质低磷(P)胁迫和异质低P胁迫模拟的盆栽试验, 系统研究马尾松家系对不同类型低P胁迫的适应机制和P效率变异规律。结果表明, 参试马尾松家系的苗高、地径和生物量等P效率指标均表现出显著的家系变异, 主要P效率指标的家系遗传力均较高, 干物质积累量的广义遗传力大于0.80, 揭示了马尾松P营养效率的较大遗传改良潜力。马尾松对不同类型低P胁迫的适应机制有所差异。在同质低P胁迫下, ‘3201’、‘1217’等高P效率家系的根系主要参数均高于低P效率家系, 表明整体根系参数的适应性变化是P效率和生物量形成的决定因素。在异质低P胁迫下, 高P效率马尾松家系在表层富P介质的根系分布量、分布比例均显著增加, 表层根系参数与马尾松家系P效率呈显著正相关, 揭示根系空间构型的适应性变化是决定马尾松高P效率的重要生物学基础。表层根系生物量、表层根相对比例的家系遗传力达0.88和0.72, 证实了以马尾松根构型的适应变化为突破口, 选育具有理想根构型和较高P效率的马尾松家系。     

樟树种子休眠和萌发的初步研究

樟树(Cinnamomum camphora)为亚热带常绿阔叶林的代表种,是珍贵用材树种之一。它生长快、寿命长、抗性强。木材可供造船、制作家具和雕刻之用,为上等材;樟脑是重要的出口物资,因此它在林业生产上占有重要的地位。但樟树以种子育苗时,发芽迟缓,发芽期长达二个月之久,而且极不整齐;其品质检验方法,至今亦未很好解决。我们于1981—1983年,对此进行了试验研究,得到一些初步结果,报道如下。     

高复种指数区成都市郫都区农田土壤养分特征及其空间变异研究

成都平原属典型的水田农业区,复种指数高,农作物一年两熟或三熟。为探究高土地利用率地区农田土壤养分特征及其空间分布格局,基于成都市郫都区2015年测土配方施肥数据,运用经典统计学和地统计学方法揭示该区域农田土壤养分的描述性统计特征及其空间变异。结果显示:郫都区农田土壤有机质(SOM)、总氮(TN)、碱解氮(AN)、速效磷(AP)、速效钾(AK)含量均值分别为22.35 g·kg^-1、1.15 g·kg^-1、95.38 mg·kg^-1、21.01 mg·kg^-1和104.58 mg·kg^-1,不同土壤类型及不同种植模式农田土壤养分差异总体较小,表明高强度的人类活动使郫都区土壤养分含量变得均一;半方差分析显示,SOM和AK的块金系数分别为0.39和0.62,其空间变异由土壤母质、地形、气候条件等结构性因素和耕作制度、施肥条件等随机性因素共同作用引起;TN、AN和AP的块金系数分别为0.87、0.94和0.97,其空间变异性主要受耕作制度、施肥条件等随机性因素影响;结合已有研究来看,郫都区农田SOM块金系数呈下降趋势而TN、AN和AP块金系数呈增加趋势,表明随着郫都区作物产量与作物复种指数的不断提高,以蔬菜为主的旱作模式代替传统的水旱轮作模式、复合肥代替农家肥等生产方式的改变正在影响着郫都区农田土壤养分的空间分布格局。     

钱江源国家公园体制试点区水稻田土壤微生物群落的格局及其驱动机制

建立健全国家公园体制对于保护自然生态系统的完整性与生物多样性具有重要意义。作为首批试点单位之一,钱江源国家公园体制试点区(以下简称“钱江源”)率先开展了集体林地地役权改革,并取得了良好效果。然而地役权改革是否以及如何影响钱江源土壤及其微生物,目前还缺乏系统评估。本研究对钱江源4个片区中不同改革模式下的水稻田表层土壤进行取样,每个片区内均采集4种模式的水稻田:公园内改革、公园内弃耕地、公园内未改革以及公园外未改革。利用高通量测序研究土壤微生物群落的组成与结构,并利用多元统计分析等剖析塑造微生物群落空间格局的驱动因素。结果发现,与其他3类土壤相比,弃耕地具有更低的氮磷等营养元素含量和重金属元素含量;其他3类土壤的理化性质则较为相似。在微生物方面,细菌群落以变形菌门(48.57%)和酸杆菌门(31.62%)为主;真菌群落以子囊菌门(78.31%)和担子菌门(16.38%)为主。不同模式下的细菌群落差异较大,尤其是弃耕地与其他3类均具有显著性差异,其他3类则较为相似。真菌群落的变异相对较小,仅公园外未改革和弃耕地间具有显著差异。细菌群落组成的空间变异与土壤环境因子显著相关,其中具有主要影响的前...