新疆博尔塔拉河冬季鱼类群落空间分布及其与环境因子的关系

为完善新疆博尔塔拉河流域的渔业生态评估及体系养护,2016年11月在博尔塔拉河流域展开资源调查,于干流设置4个监测断面,对该水域鱼类群落结构进行研究。本调查共采集鱼类1515尾,隶属于3目5科14属,共计15种,均为硬骨鱼类;通过相对重要性指数(IRI指数)获得的博尔塔拉河干流的鱼类优势种共计3种,分别为麦穗鱼(Pseudorasbora parva)、棒花鱼(Abbottina rivularis)和新疆高原鳅(Triplophysastrauchii)。基于Bray-Curtis相似性指数的二维聚类分析结果显示,在60%相似水平上空间聚类,可将博尔塔拉河分为上游及下游2组,物种聚类在50%相似水平上可分为Ⅰ～Ⅳ共计4组。典范对应分析(CCA)表明,影响冬季鱼类群落空间结构的主要环境因子为海拔、温度和溶氧。对照历史资料结果表明,博尔塔拉河流域的土著鱼类种类减少;外来鱼类种类逐年增加;经济鱼种减少;鱼类群落小型化明显。本研究可为该流域生态环境评估、水资源开发利用及渔业资源养护提供基础数据,具有一定的参考价值。     

A histological evaluation of pansteatitis-affected Mozambique tilapia,Oreochromis mossambicus (Peters 1852), from different geographical locations in South Africa

Pansteatitis is the leading cause for the decline in Nile crocodile populations and the sporadic mortality of fish in the Olifants River System, South Africa. To determine the prevalence of this disease in lentic systems, Mozambique tilapia, Oreochromis mossambicus, were collected from Lake Loskop, Lake Flag Boshielo, Phalaborwa Barrage and Lake Luphephe-Nwanedi. The former three impoundments are located within the main stem of the Olifants River, while the latter, which is geographically isolated and situated in the Limpopo River System, served as a reference site. Mesenteric adipose, liver, serosa of the swim bladder, gill and the skeletal muscle of fish sampled were examined for gross and microscopic evidence of pansteatitis. Microscopically observed changes were used to statistically compare pansteatitis prevalence between samples and sites. Based on histopathological evaluation, the adipose tissue in the liver, swim bladder serosa and coelom from severely debilitated individuals showed the most significant pathological changes. Lesions indicative of steatitis were observed in fish collected from Lake Loskop (75%), Lake Flag Boshielo (22%) and Lake Luphephe-Nwanedi (15%). Further investigation is warranted to understand the pervasiveness and mechanisms driving pathological changes of pansteatitis at Lake Flag Boshielo, Phalaborwa Barrage and Lake Luphephe-Nwanedi.     

基于GAM的长江口鱼类资源时空分布及影响因素

根据2006至2017年长江口及其邻近海域鱼类资源调查,运用广义加性模型研究长江口鱼类资源密度与环境因子之间的关系,并对2017年鱼类资源密度的时空分布进行预测。结果显示,春夏秋冬四个季节最佳GAM偏差解释率分别为69.6%、55.9%、51.4%和47.4%,交叉验证回归线斜率的平均效应为0.62～0.88。盐度、水温和溶解氧是影响长江口鱼类资源密度的主要环境影响因子且在不同季节对鱼类资源密度有不同的影响机制。总体上,在春、夏、秋季,盐度与鱼类资源密度之间存在正向相关性;在夏、秋、冬季,水温对鱼类资源密度有显著影响,在秋季与鱼类资源密度之间存在正向相关性;在春、秋、冬季,溶解氧对鱼类资源密度有显著影响,在冬季与鱼类资源密度之间存在正向线性相关。研究表明,2017年夏季鱼类资源密度较高;在长江口南支的自然延伸水域存在鱼类资源密度的相对低值,在崇明岛向海自然延伸方向水域存在鱼类资源密度的相对高值。后续研究将对长江口鱼类资源进行不同生态类型区分,以期更加准确地掌握影响各生态类型鱼类时空分布的环境因素及其时空分布信息。     

控灌改良对黄河三角洲盐碱地玉米生长与产量的影响研究

本文以黄河三角洲盐碱地玉米为研究对象,利用黄河泥沙对盐碱地进行改良试验,分析不同黄河泥沙施用量和不同灌水量水平对玉米株高、叶面积、干物质量和产量的影响,探讨适宜的泥沙施用量和灌水量。结果表明：玉米的生长和产量都随着泥沙施用量和灌水量的增加而增大,泥沙施用量均大于灌水量对其的影响。株高、叶面积指数、干物质量产量均在在泥沙施用量为6cm,灌水量为150mm处理最大,干物质积累量在成熟期最大为20460kg/hm_²；夏玉米产量最大为11220kg/hm_²。     

基于CA-Markov模型的锡林河流域土地利用变化及预测分析

研究土地利用变化特征及预测未来土地利用变化的趋势，对经济平衡发展、提高生态环境质量、实现土地资源合理利用具有重要意义。以锡林河流域为研究区，对Landsat 2000、2005、2010年和2015年4期遥感数据进行目视解译，采用土地利用结构分析方法、重心迁移模型和CA-Markov模型，分析研究区16 a间土地利用演变特征，并对2030年土地利用情况进行预测。结果表明:1)2000-2015年，草地、林地和耕地呈波动变化，水域面积缓慢增加，建设用地不断扩张，未利用地面积在不断减少。建设用地、耕地和未利用地重心具有明显的方向性移动，耕地先向南后向北移动，建设用地主要向西北方向扩张，未利用土地重心持续向北移动。2)研究区综合土地利用动态度为5.70％，变化速率较快；锡林浩特市和各苏木土地利用变化速率差异较大，总体表现为中游＞下游＞上游；不同土地利用类型动态度为建设用地＞水域＞林地＞耕地＞未利用土地＞草地，即建设用地变化最快。3)研究区土地利用变化的主要方向为草地和未利用地的相互转换、耕地和草地的互相转换以及建设用地的不断扩张。4)2030年预测结果表明，耕地面积继续增加，速率有所下降，重心向西南方向移动；林地延续之前变化趋势，稳中有升；草地和未利用地面积继续减少，且未利用地重心持续向北移动；建设用地扩张明显，重心向锡林浩特市中心移动，速度减缓；水域有少量增加。CA-Markov模型与土地利用重心迁移模型相结合，实现了对未来耕地、建设用地和未利用土地的迁移方向的预测，可以为研究区提高草地退化防治效果、土地管理政策的制定和实施、城乡建设、土地利用规划等提供理论指导。     

Investigation of crop evapotranspiration and irrigation water requirement in the lower Amu Darya River Basin,Central Asia

High water consumption and inefficient irrigation management in the agriculture sector of the middle and lower reaches of the Amu Darya River Basin(ADRB)have significantly influenced the gradual shrinking of the Aral Sea and its ecosystem.In this study,we investigated the crop water consumption in the growing seasons and the irrigation water requirement for different crop types in the lower ADRB during 2004–2017.We applied the FAO Penman–Monteith method to estimate reference evapotranspiration(ET0)based on daily climatic data collected from four meteorological stations.Crop evapotranspiration(ETc)of specific crop types was calculated by the crop coefficient.Then,we analyzed the net irrigation requirement(NIR)based on the effective precipitation with crop water requirements.The results indicated that the lowest monthly ET0 values in the lower ADRB were found in December(18.2 mm)and January(16.0 mm),and the highest monthly ET0 values were found in June and July,with similar values of 211.6 mm.The annual ETc reached to 887.2,1002.1,and 492.0 mm for cotton,rice,and wheat,respectively.The average regional NIR ranged from 514.9 to 715.0 mm in the 10 Irrigation System Management Organizations(UISs)in the study area,while the total required irrigation volume for the whole region ranged from 4.2×109 to 11.6×109 m3 during 2004–2017.The percentages of NIR in SIW(surface irrigation water)ranged from 46.4%to 65.2%during the study period,with the exceptions of the drought years of 2008 and 2011,in which there was a significantly less runoff in the Amu Darya River.This study provides an overview for local water authorities to achieve optimal regional water allocation in the study area.     

滇西北退耕还林后续政策分析及发展对策

滇西北是云南省最为贫困的少数民族聚集地区之一,实行退耕还林政策10多年来取得了巨大的成效,随着退耕还林政策补助陆续到期,部分退耕农户生计将出现困难。对退耕还林后续政策进行分析,认为退耕还林补偿标准与现有物价水平不符,套种的规定过于保守,针对政策上的不足与实施过程中存在的作业设计不够规范、监管不力、档案管理不够规范等问题提出相关对策和建议。     

Spawning movements of humpback whitefish in interior Alaska rivers

This study was conducted to describe the spawning movements and identify spawning areas for humpback whitefish Coregonus pidschian in the Minto Flats–Chatanika River complex, Alaska, during 2008 and 2009. Radio transmitters were surgically implanted in humpback whitefish in 2008 (N = 60) and 2009 (N = 100), and fish positions were determined through a combination of boat and aerial surveys and fixed receiving stations. Two spawning areas were identified: one in the Chatanika River downstream of the Elliot Highway Bridge and the other in the Tanana River near Fairbanks. Humpback whitefish dispersed from the wetland complex of Minto Flats in June, moved upstream through late August, arrived at the spawning areas in early September and began moving downstream in early October. In 2009, spatially segregated movements were observed when approximately 40% of the radio‐tagged humpback whitefish moved to the Tanana River, suggesting that humpback whitefish in Minto Flats are comprised of mixed spawning stocks. These study results provide a complete account of humpback whitefish movements and their associated spawning habitats, which will allow for better‐informed management strategies.     

加强国家农业重大科技基础设施建设刍议

国家重大科技基础设施是国家为在科学技术前沿取得重大突破、解决经济社会发展和国家安全中的战略性、基础性和前瞻性科技问题而投资建设的科学技术研究设施。加强农业领域国家重大科技基础设施建设,对提升我国农业科技创新能力,强化科技对现代农业的支撑与引领作用等具有战略意义。     

特大型沼气工程温室气体减排效益分析——以“海南澄迈日产3万Nm3车用沼气项目”为例

根据国际通用的温室气体减排计算方法，对海南澄迈日产3万Nm3车用沼气工程所带来的主要温室气体减排量和减排效益进行了估算分析。结果表明：项目每年可减少温室气体排放53 560 t(CO2当量)，以上海碳交易市场近年平均交易价格(39.23元/t CO2)计算，可带来210.12万元的经济效益。