Influence of Adjuvants on the Efficacy of Tolpyralate plus Atrazine for the Control of Annual Grass and Broadleaf Weeds in Corn with and without Roundup WeatherMAX^®

Tolpyralate is a new HPPD-inhibiting herbicide that is efficacious on annual grass and broadleaf weed species in corn. For maximum herbicide performance of tolpyralate, it is recommended that atrazine is tank mixed with tolpyralate along with the adjuvants methylated seed oil concentrate (MSO) plus urea ammonia nitrate (UAN). A common use pattern of tolpyralate plus atrazine will be in a tank mix with Roundup WeatherMAX®due to the high proportion of corn acres that are seeded to Roundup Ready®hybrids in Eastern Canada. There is no information in the peer-reviewed literature if the adjuvant system in Roundup WeatherMAX®is adequate for optimal herbicide performance of tolpyralate plus atrazine, or if MSO and UAN are still required. Six field trials were conducted over two years near Ridgetown and Exeter, ON, Canada to determine if adjuvants are still required when tolpyralate plus atrazine is tank mixed with Roundup WeatherMAX®in corn. Tolpyralate plus atrazine plus MSO and Roundup WeatherMAX®plus tolpyralate plus atrazine provided excellent control of velvetleaf, pigweed spp, common ragweed, lambsquarters, ladysthumb, wild mustard, flower-of-an-hour, barnyardgrass and green foxtail in this study. Results of this study show that in the absence of Roundup WeatherMAX®, weed control with tolpyralate plus atrazine was improved substantially with the addition of MSO;however, there was little to no increase in weed control with the addition of UAN. When tolpyralate plus atrazine was co-applied with Roundup WeatherMAX®, there was no improvement in weed control with the addition of MSO and/or UAN.

An Evaluation Model for Improving Biodiversity in Artificial Coniferous Forests Invaded by Broadleaf Trees

Increasing attention is being paid to the various functions of forests, especially the conservation of biodiversity. In Japan, 67% of national land is covered by forest, 41% of which is artificial forest (i.e., plantations). Therefore, efforts to conserve forest biodiversity should also target artificial forests. In this study, we investigated the increase in biodiversity resulting from broadleaf tree invasion of artificial coniferous forests. We examined diversity indices and combinations of indices to identify which ones can aid forest managers in evaluating forest diversity. We also studied classification according to the richness of diversity, which corresponded to the growth stages of Chamaecyparisobtusa and Cryptomeria japonica plantation forests. Moreover, we developed a model that will contribute to sustainable forest management and biodiversity over an entire area. The model, based on a specific rotation scenario in a geographic information system, is easy to use and presents spatial and temporal changes at sites visually.

Broadleaf Weed Control with Halosulfuron Tankmixes in White Bean

Six field trials were conducted over a four-year (2017-2020) period near Exeter and Ridgetown, Ontario to determine the efficacy of halosulfuron tankmixes applied postemergence to control broadleaf weeds in white bean. Halosulfuron caused up to 4% injury in white bean at 2 and 4 weeks after treatment (WAT). Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen caused 2% - 16% injury at 2 WAT and up to 3% injury at 4 WAT in white bean. The addition of halosulfuron to the aforementioned herbicides did not accentuate white bean injury. Reduced weed interference with the herbicides evaluated increased white been yield 50% - 90% compared to the weedy control;there was no difference in seed yield among herbicide treatments evaluated. At 4 WAT, halosulfuron at 25, 37.5 and 50 g ai ha-1 controlled velvetleaf 86%, 93% and 97%;redroot pigweed 83%, 85% and 89%;common ragweed 90%, 93% and 94%;common lambsquarters 27%, 28% and 36%;flower-of-an-hour 66%, 76% and 69%;and wild mustard 100%, 100% and 100%, respectively. Bentazon, acifluorfen, fomesafen, bentazon/acifluorfen, and bentazon + fomesafen controlled velvetleaf 73%, 14%, 52%, 42% and 68%;redroot pigweed 40%, 91%, 85%, 75% and 80%;common ragweed 36%, 81%, 92%, 68% and 84%;common lambsquarters 87%, 39%, 48%, 60% and 76%;flower-of-an-hour 90%, 66%, 63%, 73% and 83%;and wild mustard 97%, 97%, 100%, 99% and 100%, respectively. Halosulfuron tankmixed with bentazon, acifluorfen, fomesafen, bentazon/acifluorfen or bentazon + fomesafen controlled velvetleaf 90%, 51%, 68%, 75% and 90%;redroot pigweed 80%, 99%, 95%, 92% and 91%;common ragweed up to 94%, 97%, 93%, 94% and 95%;common lambsquarters 74%, 62%, 43%, 62% and 66%;flower-of-an-hour 92%, 78%, 74%, 82% and 87%;and wild mustard 100%, 100%, 100%, 100% and 100%, respectively. Weed density and dry biomass followed the same trend. This study concludes that the optimal halosulfuron tankmix is broadleaf weed species specific for weed management in dry bean production.

Contribution of Atmospheric Nitrogen Compounds to N Deposition in a Broadleaf Forest of Southern China

A one-year study in a typical red soil region of southern China was conducted to determine atmospheric nitrogen (N) fluxes of typical N compounds (NH3, NH4-N, NO3-N, and NO2) and contribution of three sources (gas, rainwater, and particles) to N deposition. From July 2003 to June 2004, the total atmospheric N deposition was 70.7 kg N ha-1, with dry deposition accounting for 75% of the total deposition. Dry NH3 deposition accounted for 73% of the dry deposition and 55% of the total deposition. Moreover, NO2 contributed 11% of the dry deposition and 8% of the total deposition. Reduced N compounds (NH4+ and NH3) were the predominate contributors, accounting for 66% of the total deposition. Therefore, atmospheric N deposition should be considered when soil acidification and critical loads of atmospheric deposition on soils are estimated.

Soil C and N Pools in Chinese Fir and Evergreen Broadleaf Forests and their Changes with Slash Burning in Mid-Subtropical China

Soil organic carbon (C) and total nitrogen (N) pools of a Chinese fir (Cunninghamia lanceolate, (Lamb.) Hook.) (CF) forest, and an evergreen broadleaf (EB) forest located in mid-subtropical, southeastern China, were compared before clearcutting, with the effect of slash burning on organic C and total N in the top 10 cm of soil before and after burning also being evaluated. Prior to clearcutting CF forest had significantly lower (P < 0.05) organic C and total N in the soil (0-100 cm) compared to EB forest with approximately 60% of the C and N at the two forest sites stored at the 0 to 40 cm soil. In post-burn samples of the 0-10 cm depth at 5 days, 1 year, and 5 years for CF and EB forests, significantly lower levels (P < 0.05) of organic C and total N than those in the pre-burn samples were observed. Compared to the pre-burn levels, at post-burn year 5, surface soil organic C storage was only 85% in CF forest and 72% in EB forest, while total N storage was 77% for CF forest and 73% for EB forest. Slash burning caused marked long-term changes in surface soil C and N in the two forest types.

Distribution Patterns and Associations of Dominant Tree Species in a Mixed Coniferous-Broadleaf Forest in the Changbai Mountains

In 2012 a plot was established with 1-ha area in a mixed coniferous-broadleaf forest in the Changbai Mountains, northeastern China for examining local forest processes, structure and succession. A method of O-ring statistics(paircorrelation function) was applied to analyze the spatial patterns and associations of the dominant species within different vertical layers. After the evaluation by their importance values, six tree species(or group)(i.e. Abies nephrolepis, Picea jezoensis, Pinus koraiensis, Tilia amurensis, and species group of Betula ssp. and species group of Acer ssp.) were determined as dominant trees species. It was found that some of these species exhibited closely clustered distributions at fine distances. As spatial distance increased, a random or even regular distribution gradually appeared with the exception of the upper layers of A. nephrolepis and P. koraiensis, and the lower layers of P. jezoensis, P. koraiensis and Betula ssp., which were substantially randomly distributed. Intra- and inter-species spatial associations varied in accordance with species, tree height and reciprocal distances. Positive associations were observedbetween the lower and upper height classes of trees of the same species(except for that of P. jezoensis) at fine distances. This may be owing to limited seed dispersal and geological heterogeneity. The aggregation intensity declines with increasing distances and this consistent with the predictions of self-thinning. Some coniferous trees(e.g. Pinus koraiensis) in the lower height class were positively associated with T. amurensis and group of Betula ssp. of the upper height class at some distances, suggesting that saplings of coniferous trees occupy a broader niche and can grow well under the canopy of the adult of broad-leaved trees. Negative associations were observed between upper coniferous trees and lower broad-leaved trees and between upper P. jezoensis and lower P. koraiensis, suggesting that a canopy of these trees might not provide suitable environment for the survival, establishment, and growth of lower individuals, corresponding well to Janzen-Connell hypothesis.

Effects of Logging Intensity on Structure and Composition of a Broadleaf-Korean Pine Mixed Forest on Changbai Mountains,Northeast China

In order to identify a harvesting model which is beneficial for broadleaf-Korean pine mixed forest(BKF) sustainability, we investigated four types of harvested stands which have been logged with intensities of 0(T0, control), 15%(T1, low intensity), 35%(T2, moderate intensity), and 100%(T3, clear-cutting), and examined the impacts of logging intensity on composition and structure of these stands. Results showed that there were no significant differences between T0 and T1 for all structural characteristics, except for density of seeding and large trees. The mean diameter at breast height(DBH, 1.3 m above the ground), stem density and basal area of large trees in T2 were significantly lower than in T0, while the density of seedlings and saplings were significantly higher in T2 than in T0. Structural characteristics in T3 were entirely different from T0. Dominant tree species in primary BKF comprised 93%, 85%, 45% and 10% of the total basal area in T0, T1, T2 and T3, respectively. Three community similarity indices, the Jaccard′s similarity coefficient(CJ); the Morisita-Horn index(CMH); and the Bray-Curtis index(CN), were the highest for T0 and T1, followed by T0 and T2, and T0 and T3, in generally. These results suggest that effects of harvesting on forest composition and structure are related to logging intensities. Low intensity harvesting is conductive to preserving forest structure and composition, allowing it to recover in a short time period. The regime characterized by low logging intensity and short rotations appears to be a sustainable harvesting method for BKF on the Changbai Mountains.

除草剂不同时期应用对机直播稻田杂草的防除作用

为开发机直播水稻田高效安全的封闭除草剂,采用大田试验,比较了不同时期应用含有乙氧磺隆成分的除草剂对阔叶草和莎草科杂草的防除效果。结果发现,播种时同步喷施五氟·乙氧或混配乙氧磺隆与其他除草剂能够有效抑制机直播稻田阔叶草和莎草科杂草的萌发和生长,且对水稻出苗安全。机直播后10 d或15 d施用对阔叶草防效下降,但播种15 d后撒施0.65%五氟·乙氧控释颗粒剂97.5 g/hm^(2)对杂草防效较好,密度防效达到90%以上。表明采用五氟·乙氧或混配乙氧磺隆与其他除草剂防除机直播稻田阔叶草,越早施药效果越好。但如果因气候条件或其他因素影响错过施药窗口期时,撒施0.65%五氟·乙氧控释颗粒剂97.5 g/hm^(2)或喷施30%氰氟草酯112.5 g/hm^(2)+30%五氟·乙氧90 g/hm^(2)也可以防控绝大部分直播田杂草。

新疆荒漠绿洲区大麦田阔叶杂草化学防除药效评价

【目的】筛选对大麦田阔叶杂草具有较好防效的除草剂,为荒漠绿洲生态区安全高效应用除草剂提供依据。【方法】采用随机区组的方法,调查各药剂处理小区的杂草株数和地上部分鲜质量,评价供试药剂对大麦田阔叶杂草的防除效果及安全性。【结果】药后50 d,20%双氟·氟氯酯WG 19.50 g/hm^(2)、10%双唑草酮OD 37.50 g/hm^(2)、200 g/L氯氟吡氧乙酸EC 210.00 g/hm^(2)、22%氟吡·双唑酮OD 165.00 g/hm^(2)、50%2甲·氯·双氟SC 450.00 g/hm^(2)、87.5%2,4-滴异辛酯EC 577.50 g/hm^(2)、25%辛酰溴苯腈EC 562.50 g/hm^(2)和75%苯磺隆WG 22.50 g/hm^(2)对阔叶杂草灰绿藜和卷茎蓼的株防效和鲜质量防效较好,防效分别为90.87%~96.02%和94.15%~98.08%,各处理株防效和鲜质量防效之间均无显著性差异。【结论】20%双氟·氟氯酯WG、10%双唑草酮OD、200 g/L氯氟吡氧乙酸EC、22%氟吡·双唑酮OD、50%2甲·氯·双氟SC、87.5%2,4-滴异辛酯EC、25%辛酰溴苯腈EC和75%苯磺隆WG可防除大麦田灰绿藜、卷茎蓼等阔叶杂草,且对大麦生长安全,可在大田合理轮换使用。

土壤温度和含水量变化对南亚热带常绿阔叶林土壤性质的影响

研究森林土壤铵态氮(NH_(4)^(+)-N)和硝态氮(NO_(3)^(-)-N)质量分数的年际动态及其对环境变化的影响,对预测森林生态系统的结构和功能具有重要作用。应用南亚热带常绿阔叶林连续10 a的土壤理化性质监测,揭示土壤有效氮质量分数对土壤温度和水分的影响。结果表明:(1)土壤NH_(4)^(+)-N和NO_(3)^(-)-N质量分数年际间变化对干湿季节性敏感,湿季NH_(4)^(+)-N质量分数为9.41~15.59 mg·kg^(-1)、NO_(3)^(-)-N质量分数为24.50~36.18 mg·kg^(-1),干季NH_(4)^(+)-N质量分数为6.48~10.19 mg·kg^(-1)、NO_(3)^(-)-N质量分数为22.75~30.09 mg·kg^(-1),干湿季差异显著。(2)土壤温度和含水量对NH_(4)^(+)-N质量分数变异解释率为57%,对NO_(3)^(-)-N质量分数变异解释率为28%,NH_(4)^(+)-N质量分数与气温显著正相关,湿季降水量与NH_(4)^(+)-N和NO_(3)^(-)-N质量分数呈负相关关系;干季降水量与NH_(4)^(+)-N质量分数正相关,但与NO_(3)^(-)-N质量分数负相关;干季低温条件下,土壤含水量与NH_(4)^(+)-N质量分数负相关。(3)土壤温湿度、土壤养分质量分数的变化显著影响土壤NH_(4)^(+)-N和NO_(3)^(-)-N累积;湿季全氮和易氧化碳分别是NH_(4)^(+)-N和NO_(3)^(-)-N累积的主导因子;干季土壤微生物生物量碳和微生物生物量氮为主导因子。

缙云山针阔混交林水热通量特征及其影响因子

基于涡度相关技术,对重庆市缙云山观测站内的针阔混交林生态系统的净辐射(Rn)、显热通量(H)、潜热通量(LE)、土壤热通量(G)等进行处理,分析研究区水热通量及各环境因子的变化过程,明确水热通量变化的外在驱动因子,为森林经营及林业可持续发展提供科学依据。结果表明:1)该生态系统能量闭合缺失为0.26。2)各水热通量在日变化上呈现单峰变化趋势,在季节变化上呈现出夏季最大(日均值124.66 W/m^(2)),冬季最小(日均值31.68 W/m^(2));空气温度(Ta)、饱和水气压差(VPD)呈现多峰变化趋势;降水集中于一年的4、7、8,9和10月;叶面积指数(LAI)在生长季(4—10月)呈现单峰变化。3)非雾天情况下显热通量(H)显著大于雾天情况,冠层导度(Gs)表现出多维度的复杂特征。缙云山针阔混交林能量循环损失较小,数据可靠;太阳高度角变化引起的净辐射变化是水热通量变化的主导因素;降水量(Pr)的不规则分布及LAI的变化导致Ta和VPD多峰变化;雾气对土壤热量的导向会造成显热通量下降;较高的空气温度导致了大气与下垫面之间湍流形式的热流显著增加而使显热通量上涨。一般情况下,H主要受到Rn的影响,且分别受到VPD和土壤温度(Tsoil)的次要影响(雾天环境)以及VPD和风速WS的次要影响(非雾天环境)。Rn、Gs、Ta、VPD均对LE产生显著影响,未发现研究区Pr和Tsoil与LE存在显著关系。Gs受多种因素(Rn、VPD、Ta、VWC、P等)综合影响。

12种除草剂对花生棉花间作田阔叶杂草防效及安全性评价

为筛选可用于花生棉花间作田的高效、安全除草剂,采用室内生物活性测定法评价了84%氯酯磺草胺水分散粒剂、84%双氯磺草胺水分散粒剂等12种除草剂对花生棉花间作田常见的6种阔叶杂草的防除效果及对花生和棉花的安全性。结果表明,120 g/噁草酮乳油、240 g/L乙氧氟草醚乳油、51%丙炔氟草胺水分散粒剂、40%扑草净可湿性粉剂、330 g/L二甲戊灵乳油在田间推荐剂量下可有效控制供试6种杂草;40%砜吡草唑悬浮剂在棉花和杂草间的选择性指数均大于2,杂草防除效果良好。25%噻吩磺隆可湿性粉剂、84%氯酯磺草胺水分散粒剂、20%乙羧氟草醚乳油等对棉花安全性相对较差。

松阔混交对侵蚀退化地土壤有机碳和微生物群落结构的影响

树种是调控森林土壤有机碳(SOC)积累的重要因子。为明确树种变化对红壤侵蚀退化地表层SOC积累的影响,采用配对实验设计,选择不同恢复年限的马尾松纯林和马尾松+木荷混交林(19和39 a)为研究对象,对比分析表层(0~10 cm)SOC质量分数的差异,并利用相关性分析与结构方程模型探讨其与凋落物特征、土壤氮素水平和微生物群落组成的关系。结果表明:1)恢复19 a的纯林和混交林SOC质量分数无显著差异,而恢复39 a混交林SOC质量分数较恢复19 a纯林、恢复19 a混交林以及恢复39 a纯林分别高39.8%、48.0%和93.6%(P<0.05);2)SOC质量分数与土壤微生物生物量碳、土壤微生物生物量氮、磷脂脂肪酸总量、矿质氮和细菌呈显著或极显著正相关,与凋落物C/N和真菌细菌之比(F/B)呈显著或极显著负相关;3)结构方程模型分析表明,凋落物C/N是松阔混交后表层SOC质量分数变化的触发因子,矿质氮是微生物群落结构变化的关键因子。凋落物C/N可直接驱动SOC质量分数的变化(-0.35*),或通过矿质氮(-0.70***)诱导F/B、丛枝菌根真菌和细菌的变化起间接调控作用,以上因子共解释SOC质量分数变异的86.8%。综上,松阔混交促进侵蚀退化地SOC的积累,且其有效性随恢复年限增强。这个过程主要通过提升凋落物质量、增加微生物养分来源和土壤氮有效性、改变微生物群落结构完成。在我国实施“双碳”战略的背景下,多树种混交对红壤区退化马尾松林SOC提升具有重要意义。

Mercury in leaf litter in typical suburban and urban broadleaf forests in China

To study the role of leaf litter in the mercury （Hg） cycle in suburban broadleaf forests and the distribution of Hg in urban forests, we collected leaf litter and soil from suburban evergreen and deciduous broadleaf forests and from urban forests in Beijing. The Hg concentrations in leaf litter from the suburban forests varied from 8.3 to 205.0 ng/g, with an average （avg） of （49.7 ± 36.9） ng/g. The average Hg concentration in evergreen broadleaf forest leaf litter （50.8 ± 39.4） ng/g was higher than that in deciduous broadleaf forest leaf litter （25.8 ± 10.1） ng/g. The estimated Hg fluxes of leaf litter in suburban evergreen and deciduous broadleaf forests were 179.0 and 83.7 mg/（ha·yr）, respectively. The Hg concentration in organic horizons （O horizons） （（263.1 ± 237.2） ng/g） was higher than that in eluvial horizons （A horizons） （（83.9 ± 52.0） ng/g）. These results indicated that leaf litterfall plays an important role in transporting atmospheric mercury to soil in suburban forests. For urban forests in Beijing, the Hg concentrations in leaf litter ranged from 8.8–119.0 （avg 28.1 ± 16.6） ng/g, with higher concentrations at urban sites than at suburban sites for each tree. The Hg concentrations in surface soil in Beijing were 32.0–25300.0 ng/g and increased from suburban sites to urban sites, with the highest value from Jingshan （JS） Park at the centre of Beijing. Therefore, the distribution of Hg in Beijing urban forests appeared to be strongly influenced by anthropogenic activities.

Spectral vegetation indices as the indicator of canopy photosynthetic productivity in a deciduous broadleaf forest

Aims Understanding of the ecophysiological dynamics of forest canopy photosynthesis and its spatial and temporal scaling is crucial for revealing ecological response to climate change.Combined observations and analyses of plant ecophysiology and optical remote sensing would enable us to achieve these studies.In order to examine the utility of spectral vegetation indices(VIs)for assessing ecosystem-level photosynthesis,we investigated the relationships between canopy-scale photosynthetic productivity and canopy spectral reflectance over seasons for 5 years in a cool,temperate deciduous broadleaf forest at‘Takayama’super site in central Japan.Methods Daily photosynthetic capacity was assessed by in situ canopy leaf area index(LAI),(LAI×Vcmax[single-leaf photosynthetic capacity]),and the daily maximum rate of gross primary production(GPPmax)was estimated by an ecosystem carbon cycle model.We examined five VIs:normalized difference vegetation index(NDVI),enhanced vegetation index(EVI),green–red vegetation index(GRVI),chlorophyll index(CI)and canopy chlorophyll index(CCI),which were obtained by the in situ measurements of canopy spectral reflectance.Important Findings Our in situ observation of leaf and canopy characteristics,which were analyzed by an ecosystem carbon cycling model,revealed that their phenological changes are responsible for seasonal and interannual variations in canopy photosynthesis.Significant correlations were found between the five VIs and canopy photosynthetic capacity over the seasons and years;four of the VIs showed hysteresis-type relationships and only CCI showed rather linear relationship.Among the VIs examined,we applied EVI–GPPmax relationship to EVI data obtained by Moderate Resolution Imaging Spectroradiometer to estimate the temporal and spatial variation in GPPmax over central Japan.Our findings would improve the accuracy of satellite-based estimate of forest photosynthetic productivity in fine spatial and temporal resolutions,which are necessary for detecting any response of terrestrial ecosystem to meteorological fluctuations.

雅鲁藏布大峡谷植物叶片碳氮磷化学计量特征

为了解雅鲁藏布大峡谷区域植物的生态适应性及N、P养分利用特征,该研究在墨脱不同森林植被区选取6个采样点,对每个采样点优势植物进行了植物叶片C、N、P化学计量特征分析。结果表明,研究区植物叶片碳含量均值为452 g kg^(-1),在不同采样点之间差异未达到显著水平,其余指标在部分采样点之间则存在一定的差异;从生活型看,研究区木本植物叶片碳含量要高于草本植物,氮含量差异不显著,磷含量则低于草本植物;在不同采样点之间木本植物叶片碳氮磷含量差异不显著,木本植物碳氮差异也不显著,但草本植物部分采样点之间磷差异达到显著水平;相关性分析显示,植物叶片C与N、C与P相关性均不显著,但N、P相关性达到极显著水平;墨脱常绿阔叶林区植物叶片C含量略低于我国南方其它常绿阔叶林区植物叶片碳含量,氮含量略高于其他区域,但P含量显著高于其他区域的植物叶片P含量,因此C/N,C/P及N/P均较低,N/P的均值为11.4。本研究结果支持植物叶片氮磷在不同生境中均存在明显正相关关系,结合生长速率假说,墨脱常绿阔叶林区的植物生长速率可能远高于我国其他常绿阔叶林区,因此研究区森林生态系统的碳汇以及面对全球N沉降背景下的响应值得进一步研究。

2021-2022年广东南岭站日尺度气象数据集

南岭森林生态系统的山地森林及生物多样性生态功能区是我国25个重点生态功能区之一,覆盖包括亚热带常绿阔叶林、针阔叶常绿混交林、山顶常绿阔叶矮林等多种森林植被类型。亚热带常绿阔叶林作为南岭山地最典型植被类型,对其群落气象要素进行监测有助于探索亚热带常绿阔叶林对气候变化的响应机理。本研究依托广东南岭森林生态系统国家野外科学观测研究站(简称“南岭站”)在广东南岭国家级自然保护区开展定位研究。本研究将南岭站2021-2022年亚热带常绿阔叶林区内连续采集的10 min平均风速、降水量、气温、气压、太阳辐射(总辐射、反射辐射、紫外辐射、净辐射、光合有效辐射)、相对湿度的原始数据,经过数据处理、质量控制和评估,以日尺度公开。本数据集的建立和公开共享,可为进一步认识南岭山地森林生态系统提供数据支撑,为森林生态系统修复和保护提供理论参考。

铜仁缬草不同部位药效成分的质量研究

建立铜仁宽叶缬草的质量标准研究。方法:在500 nm波长处采用紫外-可见分光光度法对铜仁宽叶缬草药材中总黄酮进行含量测定。结果标准曲线的回归方程为y=10.6736x+0.0024(r=0.999935,n=5)。结果表明,芦丁进样量在0.008~0.056 mg范围内与吸光度呈良好的线性关系;精密度试验,结果,RSD=0.0011%(n=5),表明仪器精密度良好;稳定性试验,结果,RSD=0.0026%(n=6),表明供试品溶液在120 min内稳定性良好;重复性试验,结果,样品中芦丁的平均质量分数为0.71%,RSD=0.13%(n=6),表明本方法重复性良好;加样回收率试验,结果,RSD=1.66%(n=6)。结论:本方法能准确反映铜仁宽叶缬草不同部位中总黄酮的含量,作为参考只有在符合宽叶缬草叶子、茎部、根部样品中芦丁的平均质量分数分别在11.59%、0.98%、0.71%以上才符合铜仁宽叶缬草的质量要求;本实验在实现资源利用充分的同时,其总黄酮的质量要求范围为铜仁宽叶缬草的质量标准提供了一定的参考价值。

Linking satellite-based spring phenology to temperate deciduous broadleaf forest photosynthesis activity

Satellite-based remote sensed phenology has been widely used to assess global climate change.However,it is constrained by uncertain linkages with photo-synthesis activity.Two dynamic threshold methods were employed to retrieve spring phenology metrics from four Moderate Resolution Imaging Spectro-radiometer(MODIS)products,including fraction of Absorbed Photosyntheti-cally Active Radiation(fAPAR),Leaf Area Index(LAI),Normalized Difference Vegetation Index(NDVI),and Enhanced Vegetation Index(EVI)for three temperate deciduous broadleaf forests in North America between 2001 and 2009.These MODIS-based spring phenology metrics were subsequently linked to the photosynthetic curves(daily gross primary productivity,GPP)measured by an eddy covariance flux tower.The 20% dynamic threshold spring onset metrics from MODIS products were closer to the photosynthesis onset metrics at the date of 2% GPP increase for NDVI and fAPAR,and closer to the date of 5%and 10% increase of GPP for EVI and LAI,respectively.The 50% dynamic threshold onset metrics were closer to the photosynthesis onset metrics at the date of 10%GPP increase for NDVI,and closer to the date of 20% GPP increase for fAPAR,LAI and EVI,respectively.These results can improve our knowledge on the photosynthesis activity status of remotely sensed spring phenology metrics.

紫花苜蓿田春季阔叶杂草除草剂筛选及安全性评价

为明确适用于紫花苜蓿田防除春季阔叶杂草的除草剂,本研究通过室内和田间试验筛选了对紫花苜蓿安全且对春季阔叶杂草防效好的除草剂。室内试验表明,供试的11种除草剂中仅有唑草酮、吡草醚、乙羧氟草醚等3种除草剂对紫花苜蓿具有较好的安全性。通过田间试验发现,40%唑草酮WG 30~66 g/hm^(2)(有效成分用量,下同)和10%乙羧氟草醚ME 75~90 g/hm^(2)处理对春季阔叶杂草具有较好的防治效果,株防效为83.68%~97.32%,鲜重防效为73.18%~95.62%,且对紫花苜蓿有较好的安全性,增产12%以上。综上所述,在紫花苜蓿返青期进行唑草酮和乙羧氟草醚处理可用于紫花苜蓿田春季阔叶杂草防除,具有较好的应用前景。