The role of daytime cues in the development of magnetic orientation in a night-migrating bird

To assess the role of celestial rotation during daytime in the development of the magnetic compass course, pied flycatchers (Ficedula hypoleuca Pallas, Muscicapidae) were handraised in Latvia under various celestial and magnetic conditions. Tests were performed during autumn migration in the local geomagnetic field (50 000 nT, 73° inclination) in the absence of celestial cues. A group of birds that had never seen the sky showed a bimodal preference for the migratory southwest-northeast axis, whereas a second group that had been exposed to the natural sky from sunrise to sunset in the local geomagnetic field showed a unimodal preference for the seasonally appropriate southwesterly direction. A third group that had also been exposed to the daytime sky, but in the absence of magnetic compass information, also oriented bimodally along a southwest-northeast axis. These findings demonstrate that observing celestial rotation during daytime enables birds to choose the right end of the migratory axis for autumn migration at the Latvian test location. This transformation of axial behavior into appropriate migratory orientation, however, requires the birds to have simultaneous access to information on both celestial rotation and the geomagnetic field. Received: 19 September 1997 / Accepted after revision: 22 November 1997     

Estimating Watershed Level Nonagricultural Pesticide Use From Golf Courses Using Geospatial Methods1

Abstract: Limited information exists on pesticide use for nonagricultural purposes, making it difficult to estimate pesticide loadings from nonagricultural sources to surface water and to conduct environmental risk assessments. A method was developed to estimate the amount of pesticide use on recreational turf grasses, specifically golf course turf grasses, for watersheds located throughout the conterminous United States (U.S.). The approach estimates pesticide use: (1) based on the area of recreational turf grasses (used as a surrogate for turf associated with golf courses) within the watershed, which was derived from maps of land cover, and (2) from data on the location and average treatable area of golf courses. The area of golf course turf grasses determined from these two methods was used to calculate the percentage of each watershed planted in golf course turf grass (percent crop area, or PCA). Turf‐grass PCAs derived from the two methods were used with recommended application rates provided on pesticide labels to estimate total pesticide use on recreational turf within 1,606 watersheds associated with surface‐water sources of drinking water. These pesticide use estimates made from label rates and PCAs were compared to use estimates from industry sales data on the amount of each pesticide sold for use within the watershed. The PCAs derived from the land‐cover data had an average value of 0.4% of a watershed with minimum of 0.01% and a maximum of 9.8%, whereas the PCA values that are based on the number of golf courses in a watershed had an average of 0.3% of a watershed with a minimum of <0.01% and a maximum of 14.2%. Both the land‐cover method and the number of golf courses method produced similar PCA distributions, suggesting that either technique may be used to provide a PCA estimate for recreational turf. The average and maximum PCAs generally correlated to watershed size, with the highest PCAs estimated for small watersheds. Using watershed specific PCAs, combined with label rates, resulted in greater than two orders of magnitude over‐estimation of the pesticide use compared to estimates from sales data.     

农作物秸秆综合利用的研究进展综述

通过对农作物秸秆的研究现状、处理方法及综合应用情况进行综述,归纳出了目前农作物秸秆综合利用领域、主要处理方法及需要突破的关键技术.明确了突破农作物秸秆外表面物质结构实现完全降解和完成内部纤维素、半纤维素等高分子化合物降解转化是综合利用农作物秸秆研究的重点和难点.同时指出了解决农作物秸秆综合利用的技术层面、法律层面和人文认知理念等方面的发展趋势,为高效利用农作物秸秆及开展关键技术攻关提供参考.     

随机价格下杉木人工林的碳汇收益及最优轮伐期确定

发展林业碳汇是应对全球气候变化及实现中国2060年碳中和的重要举措。基于改进的Faustmann-Hartman模型,以中国南方浙江、福建和江西三个省份杉木人工林为研究对象,使用时间序列模型拟合并预测中国碳排放权交易市场的碳汇价格,通过蒙特卡洛模拟确定最优轮伐期及碳汇收益。研究结果表明：（1）依次纳入木材收益、地上生物量碳汇收益和死亡有机质碳汇收益时,杉木人工林的最优轮伐期分别为21.85年、22.98年和22.88年;（2）上述三种情景下,林地期望价值的净现值分别为20408.20元/hm²、24587.29元/hm²和28101.11元/hm²;（3）全面考虑包含死亡有机质碳库在内的林业碳汇效益,能够稳定提高林地所有者收益约7.02%~21.61%。此外,应进一步考虑多轮伐期下税收政策及自然风险等因素对碳汇营林的影响,这是确定最优轮伐期和碳汇收益后续研究值得重视的问题。     

作物种植专业化与化肥减量来源——兼顾经营规模的影响

以作物种植横向专业化和纵向专业化为切入点,运用中国13个粮食主产省份1980—2018年的面板数据,考察了作物种植专业化对农业化肥减量的影响及其作用机制。研究主要发现：（1）基础回归分析表明,作物种植横向专业化和纵向专业化均对化肥施用强度具有显著的削减效应,对化肥的利用效率有显著的增效作用。且作物种植纵向专业化或社会化服务卷入程度加深,能够增强横向专业化对化肥的减量增效作用。（2）影响路径分析表明,作物种植横向专业化通过扩大农地经营规模,进而增强了作物种植纵向专业化对化肥施用强度的削减效应和利用效率的增效作用。但也应警惕,通过扩大农地经营规模以增强作物种植纵向专业化的减量效应可能存在临界水平。此外,当作物种植横向专业化和纵向专业化积极配合时,可能推移临界点的到来。据此,通过发展作物种植横向专业化,鼓励农户通过服务外包卷入农业的纵向专业化分工以及发展农业适度规模经营,进而实现农业领域化肥的减量增效。     

牡蛎壳粉和石灰改良酸性水稻土对磷有效性、形态和酶活性的影响

我国南方粮食主产区土壤酸化治理是提升耕地地力促进粮食增产的重要内容,目的是探究酸化土壤改良剂牡蛎壳粉和石灰对水稻土酸度、磷有效性和形态以及酶活性和相关功能基因的影响.盆栽试验设计2种改良剂的3个施用量（0.05%、0.10%和0.15%）,以水稻为试验作物.结果表明：①牡蛎壳粉和石灰均显著提高土壤pH,降低土壤交换性酸,且改良效果随着改良剂用量增加而提高,相同用量下石灰对土壤酸性的改良效果高于牡蛎壳粉;② 4种有效磷提取剂提取的土壤有效磷测定结果表明,牡蛎壳粉和石灰显著提高H₂SO₄-P、Bray-1 P和Olsen-P含量,其中Olsen-P含量随改良剂用量的增加而提高.③土壤中不同形态无机磷含量表现为：Fe-P>Al-P>Ca-P,石灰和牡蛎壳粉显著提高Al-P和Fe-P含量,分别提高26.3%~37.4%和7.9%~23.7%;0.15%改良剂显著增加Ca-P含量;④石灰和牡蛎壳粉对土壤DHA、ALP、IPP活性和phoD基因拷贝数具有提高作用,而对土壤ACP活性、phoC和pqqC拷贝数表现为降低;⑤改良剂（0.10%和0.15%）显著提高水稻产量,0.15%用量的石灰和牡蛎壳粉分别提高水稻产量34.2%和46.8%,但对秸秆生物量无显著影响.相关分析表明,土壤无机磷和有效磷含量与pH和ALP活性呈显著正相关,改良剂通过消除土壤酸化和提高土壤磷酸酶活性来改善土壤磷营养状况,这对促进作物产量具有积极作用.     

不同施肥措施对热带地区稻菜轮作体系土壤CH4和N2O排放的影响

研究稻菜轮作模式下土壤甲烷（CH₄）和氧化亚氮（N₂ O）排放对不同施肥措施的响应,对补充我国热带地区CH₄和N₂ O排放研究的不足具有重要的指导意义.在辣椒季设置4种施肥处理：磷钾肥（PK）、氮磷钾肥（NPK）、等氮条件下50%有机肥替代化肥（NPK+M）和100%有机肥替代（M）,水稻种植季未设置施肥处理,研究辣椒季不同施肥条件下CH₄和N₂ O的排放规律以及对早稻生长季水稻产量、CH₄和N₂ O排放的后续影响.采用密闭静态箱-气相色谱法测定稻菜轮作土壤CH₄和N₂ O,同时测定作物产量,并估算全球增温潜势（GWP）和温室气体排放强度（GHGI）.结果表明：①辣椒季和早稻季4种施肥处理下土壤CH₄的累积排放量分别为0.9~2.7 kg ·hm^-2和5.5~8.4 kg ·hm^-2,与NPK处理相比,辣椒季NPK+M和M处理CH₄累积排放量分别减少35.3%和7.6%;而早稻季NPK+M和M处理CH₄累积排放量均增加37.5%和55.1%,其中早稻季M处理达到显著水平.②辣椒季和早稻季4种施肥处理下N₂ O的累积排放量分别为0.5~3.0 kg ·hm^-2和0.3~0.5 kg ·hm^-2,相对NPK处理,辣椒季NPK+M和M处理降低33.7%和16.0%的N₂ O累积排放量,其中NPK+M处理达到显著差异,早稻季NPK+M处理N₂ O累积排放量降低23.5%,M处理却增加9.1%,但均未达到显著水平.③ 4种施肥处理下辣椒和早稻的产量分别为3055.6~37722.5 kg ·hm^-2和5850.9~6994.4 kg ·hm^-2,与NPK处理相比,NPK+M和M处理显著增加辣椒产量.各施肥处理GWP为508.0~1864.4 kg ·hm^-2,NPK+M和M处理相对NPK处理分别下降25.7%和5.7%,其中NPK+M处理达到显著差异.辣椒季各处理的GWP对总GWP的贡献率为69.2%~78.1%,N₂ O对总GWP的贡献率为77.3%~85.3%.辣椒季和早稻季GHGI分别为0.03~0.09 kg ·kg^-1和0.04~0.24 kg ·kg^-1,与NPK处理相比,辣椒季M和NPK+M处理使GHGI显著下降71.5%和54.7%,早稻季NPK+M和M处理GHGI值分别下降44.0%和20.8%,其中NPK+M处理达到显著差异.综合作物产量及温室气体减排效果考虑,化肥和有机肥配施（NPK+M）可推荐为海南稻菜轮作模式下一种最优的减排稳产的施肥措施.     

浒苔生物炭与木醋液复配改良碱化土壤效果及提高油葵产量

为探究浒苔生物炭与木醋液复配改良碱化土壤效果及提高作物产量,以龟裂碱土为例,通过田间试验研究不同生物炭施加量(0、1％、2％和4％)与不同木醋液稀释倍数(0、2％)复配对土壤pH、碱化度、全盐、容重、速效磷、有机质、盐分离子、油葵生长和产量的影响,不施加生物炭和木醋液视为对照(CK).结果表明,2％浒苔生物炭+2％木醋液(V2BC2)改良龟裂碱土的综合效果最佳;在最佳处理条件下:①浒苔生物炭与木醋液复配能改善土壤理化性质,具体表现为作物生长期内土壤平均pH、碱化度和全盐含量显著降低,较CK分别降低12.14％、40.63％和42.75％,土壤容重显著减小,较CK减小20.78％;②浒苔生物炭与木醋液复配能显著降低土壤Na+、Cl-和SO42-含量,较CK分别降低47.17％、45.32％和33.33％,提高土壤K+和Ca2+含量,其他离子含量的差异不显著;③浒苔生物炭与木醋液复配显著提高土壤养分含量及有效性,增强土壤酶活性,与CK相比,速效磷提高2.88倍,有机质提高58.76％,土壤脲酶、碱性磷酸酶和蔗糖酶活性分别提高0.92、1.02和2.29倍;④油葵产量在V2BC2处理时最高,为3 546.7 kg-hm-2,较CK增产2 325.3 kg-hm-2.因此,浒苔生物炭与木醋液复配能进一步提高盐碱土改良效果及作物产量.     

氯代苯酚结构与农作物毒性关系的研究

卤代苯酚是一种环境污染物。本文通过水培发芽试验和幼苗土壤盆栽试验,研究了卤代苯酚系列污染物结构与冬小麦、萝卜、油菜等作物毒性的关系。结果表明,氯代苯酚系列污染物都可抑制他们的发芽和幼苗生长,其毒性都大于苯酚,并与浓度成显著性正相关。在浓度相同时,其毒性随苯环上氢原子被氯取代个数的增加而加大。在浓度和取代个数都相同时,不同取代部位的毒性不同,邻位取代毒性最大。不同农作物对它们的抗性不同;在取代个数、浓度和取代部位都相同时,小麦受害程度最轻,油菜最重。     

CO2浓度增加对作物影响的研究动态

大气CO2浓度不断增加将以两种方式影响作物的代谢、生长发育和产量的形成：一是通过温室效应“加热”气候，改变降水类型，进而影响作物；二是浓度变化本身对作物生理过程的影响。介绍了国内外近年来在与CO2浓度有关的作物生理实验方面取得的进展及其主要结果。