基于MODIS NPP的2006—2015年三江源区产草量时空变化研究

草地既是高原地区重要的生态屏障,也是维系当地人民生产生活的自然资源,准确估算本区域的产草量,可为区域资源开发利用、社会经济可持续发展决策提供科学参考。论文基于MODIS遥感影像获得不同分辨率的NDVI、EVI和NPP产品,结合三江源区监测点的产草量地面实测数据,利用统计分析方法分别建立多种产草量遥感估算模型。利用择优选取的估产模型进行区域适用性评价和模型反演,研究三江源区产草量在2006—2015年的时空分布情况。研究结果表明,基于MOD17A2H NPP的一元线性模型的估算精度相对较高,三江源区的产草量（单产）呈东多西少、自东南向西北逐渐减少的空间分布特点。2006—2013年的产草量（总量）整体呈上升趋势,2013年的产草量（总量）达到3 869.43×10⁴ t,产草量（总量）自2014年开始降低,2015产草量（总量）为2 069.07×10⁴ t。     

北方旱农区玉米自然降水生产潜力研究

针对我国北方水资源匮乏日益严重的状况,利用CERES-Maize作物模型模拟分析了北方旱区玉米自然降水生产潜力及其时空分布规律。研究表明,我国北方旱区玉米的水分生产潜力大小排序依次是半湿润区>半干旱区>干旱区,半湿润区的玉米自然降水生产潜力大约为11000kg/hm₂,干旱区大约在5000kg/hm₂,但同时半湿润区潜力的年际间波动性也最显著,干旱区则相对较为稳定。我国北方旱区东部的玉米生产潜力高于西部,但南北方向潜力差异不明显。     

磁化处理对水体的复氧速率及生物效应影响的研究

通过试验证明，磁化处理不仅可引起水体物理、化学性质的异常变化，而且还强烈影响水体的生物性质（刺激藻类生长、抑止异养菌数等）。磁化处理引起藻类生产力显著提高的特殊生物效应，对加速水体的复氧能力，提高自净效率，有着重要的意义。     

黄土高原旱地农业自然生产力潜势评价——兼论旱地农业的出路

本文运用系统工程理论,从理论与实践的结合上,对黄土高原旱地农业自然生态系统的土地、光、热、自然降水等各主要因子的生产潜力进行了评价。从而为开发该地区旱地农业的自然生产力潜势提供了科学依据。本文还通过对旱地农业生态经济系统可控制因素与非可控制因素的分析,以及从人类经济再生产行为方式等角度,对旱地自然生产力蕴藏着巨大潜势和“越穷越垦、越垦越穷”这一历史事实构成的悖论作出了科学解释,否定了“十年九旱”是旱地农业增产的主要制约因素的传统观点,为开发旱地农业资源提供了一条现实的、可供选择的思路。     

黄河上中游流域植被净初级生产力空间特征及驱动因素分析

植被净初级生产力（NPP）在陆地生态系统中扮演着关键角色,深入研究年均NPP及其驱动因子对于促进区域生态建设和可持续发展具有重要意义.本文利用2000~2020年的MOD17A3 年均NPP数据,采用趋势分析、Hurst指数、随机森林模型、偏依赖模型、地理加权回归以及偏最小二乘-结构方程（PLS-SEM）模型等方法,分析黄河上中游地区年均NPP年度变化特征及其与驱动因子的关系.结果显示： ①在2000~2020年期间,黄河上中游地区年均NPP总体呈逐年增长趋势,其中79.25%区域年均NPP表现出显著改善,0.25%区域年均NPP则呈现严重退化趋势. ②影响黄河上中游年均NPP变化的主导因子为降雨量、NDVI、干旱和相对湿度. 适宜年均NPP增加的降雨量范围为400~650 mm,相对湿度范围为40%~70%,NDVI与年均NPP呈线性正相关,干旱指数与年均NPP呈显著负相关关系,当干旱指数超过阈值8时,年均NPP趋于平稳. ③极端降雨通过影响植被生长状况间接影响流域年均NPP变化,极端降雨指数中对流域年均NPP影响程度由高到低依次为：R10>R95P>PRCPTOT>SDII>Rx5day>R99P. ④黄河上中游在生态建设方面的下一步应重点关注黄河北部的干旱和严重干旱区域,因地制宜,提升区域生态环境水平.     

Net primary productivity of China's terrestrial ecosystems from a process model driven by remote sensing

The terrestrial carbon cycle is one of the foci in global climate change research. Simulating net primary productivity (NPP) of terrestrial ecosystems is important for carbon cycle research. In this study, China's terrestrial NPP was simulated using the Boreal Ecosystem Productivity Simulator (BEPS), a carbon-water coupled process model based on remote sensing inputs. For these purposes, a national-wide database (including leaf area index, land cover, meteorology, vegetation and soil) at a 1 km resolution and a validation database were established. Using these databases and BEPS, daily maps of NPP for the entire China's landmass in 2001 were produced, and gross primary productivity (GPP) and autotrophic respiration (RA) were estimated. Using the simulated results, we explore temporal-spatial patterns of China's terrestrial NPP and the mechanisms of its responses to various environmental factors. The total NPP and mean NPP of China's landmass were 2.235 GtC and 235.2 gCm(-2)yr(-1), respectively; the total GPP and mean GPP were 4.418 GtC and 465 gCm(-2)yr(-1); and the total RA and mean RA were 2.227 GtC and 234 gCm(-2)yr(-1), respectively. On average, NPP was 50.6% of GPP. In addition, statistical analysis of NPP of different land cover types was conducted, and spatiotemporal patterns of NPP were investigated. The response of NPP to changes in some key factors such as LAI, precipitation, temperature, solar radiation, VPD and AWC are evaluated and discussed.     

Sexual dimorphism in amphipods: the role of male posterior gnathopods revealed in Gammarus pulex

In the mate-guarding amphipod, Gammarus pulex, the enlarged male posterior gnathopods have been variously suggested to function to grasp and subdue the female, to be used as weapons in fights between males, to signal to the female the male presence and stimulate moult accelaration, egg development or egg extrusion. These hypotheses were tested in a series of experiments, the results of which reveal an unexpected function. Ablation of the posterior gnathopods of males showed that they were neither necessary for, nor advantageous in, establishment and/or maintenance of precopula mate guarding, with or without competition with intact males. Furthermore, these appendages do not function to advance female moult, or stimulate egg development or extrusion. However, only males with intact posterior gnathopods were able to copulate. We also show that females require a full copulation of several bouts to extrude eggs. We conclude that the function of the posterior gnathopods is to facilitate copulation and suggest future studies focus on the selective pressures acting on copulating males.     

Irrigation quotas for high water use efficiency and economic water productivity of typical crops in Shiyang River Basin北大核心CSCD

Water consumption in agricultural activities is the main water use in inland oases in Northwest China. Research on water conservation in agriculture is of great significance to alleviate the conflict between the use of agricultural and ecological water and is of great importance to local farmers’ livelihoods. This study, based on traditional irrigation practices (flood irrigation and fixed irrigation frequency) of Minqin County in Shiyang River Basion, was designed to reveal the impacts of five irrigation quotas (1 800, 1 440, 1 080, 720, and 360 m3/hm2) on crop yield, biomass, irrigation water use efficiency (IWUE), and economic water productivity (EWP) to determine the optimal irrigation for five crops and guide local irrigation practices. The results showed that: (1) Under the five irrigation quotas, IWUE of corn, with the highest of 12.27 kg/m3, was higher than the other four crops; (2) The average EWP of cotton with a 2-year-average of 8.0 yuan/m3 was higher than the other four crops. Thus, the economic output of cotton is the best under the same irrigation quota; (3) Considering the yield, IWUE, EWP, and biomass, corn was better than the other four typical crops; and (4) 1 080 m3/hm2 was the optimal irrigation quota for sunflower in local planting practices. In addition, 720 m3/hm2 was suitable for corn, pepper, wheat, and cotton as their irrigation quota. This study shows that reducing the amount of irrigation quota in the Shiyang River Basin can effectively improve local IWUE and EWP. © 2022 Authors. All rights reserved.     

至2050年中国生态高值农业体系建设特征与目标

2010年6月7日,国家主席胡锦涛在两院（中国科学院、中国工程院）院士大会上针对农业科技明确指出：构建我国生态高值农业和生物产业体系,建成农业高值转化的产业体系。本文对＂生态高值农业＂进行论述。所谓生态,就是要体现农业既能为社会提供安全优质的农产品又能实现农业资源的永续利用,将农业纳入可持续发展的道路;所谓高值,就是要体现农业有很高的土地产出率、投入产出率、劳动生产率。因此,＂生态高值农业＂是集约化经营与生态化生产有机结合的现代农业。它以健康消费需求为导向,以提高农业市场竞争力和可持续发展能力为核心,兼有高投入、高产出、高效益与可持续发展的双重特性,是转变农业增长方式、提高农业综合生产能力的集中体现。