Reconciling food production and biodiversity conservation: land sharing and land sparing compared

The question of how to meet rising food demand at the least cost to biodiversity requires the evaluation of two contrasting alternatives: land sharing, which integrates both objectives on the same land; and land sparing, in which high-yield farming is combined with protecting natural habitats from conversion to agriculture. To test these alternatives, we compared crop yields and densities of bird and tree species across gradients of agricultural intensity in southwest Ghana and northern India. More species were negatively affected by agriculture than benefited from it, particularly among species with small global ranges. For both taxa in both countries, land sparing is a more promising strategy for minimizing negative impacts of food production, at both current and anticipated future levels of production.     

农村土地流转中的粮食安全问题研究

为了深入了解粮食产出与农地流转的协同关系,应用回归分析和问卷调研相结合的方法,从土地流转促进粮食生产的规模化和不规范流转会造成粮食安全风险两个方面,分析我国农村土地流转与粮食安全的现状和存在问题,并提出在加强土地流转的同时,应建立相应的监督机制,合理控制土地流转的非粮化规模等政策建议,防范由于农地流转的非粮化造成的粮食安全风险.     

广西耕地保有量与粮食安全分析

从调研广西的耕地面积不断减少、质量不断降低、粮食播种面积及粮食总产量逐年减少出发,分析人口增长、社会经济发展以及粮食增产的制约因素,利用多种数学模型以及人口土地承载力方法预测广西未来耕地保有量、广西粮食安全对耕地保有量的需求,提出在符合土地利用总体规划前提下,对农业生产结构进行适时调整,通过土地开发整理增加耕地面积,加强农用地和基本农田管理,制订鼓励农民种粮的政策等措施,确保广西的粮食安全。     

粮食安全视角下省际耕地生态补偿的标准量化与机制构建

为促进全国耕地利用布局优化,保障粮食安全与生态服务的持续供给,立足粮食安全视角,在厘清省际耕地生态补偿的理论逻辑和补偿标准的测算思路基础上,运用机会成本损失与生态外溢价值法对2019年受偿区粮食安全保障的耕地生态补偿标准进行了量化研究。结果表明:1)研究区有17个省份处于粮食安全保障的耕地生态赤字区(支付区),14个省份为盈余区(受偿区),后者在满足自身粮食需求后,平均约有超过30%的耕地承载的粮食产量和生态服务供给了各生态赤字区;2)受偿区的受偿标准总额约为24 673.4亿元,其中最高的3个省份是河南、山东、安徽,最低的3个省份是宁夏、甘肃、新疆。为此,提出要构建包括补偿主体—目标责任—补偿方式—资金来源构成的补偿机制和配套体系,进一步保障生态补偿的长效实施。     

福建省耕地资源与粮食安全

分析了福建省耕地资源状况,指出了耕地数量减少、质量下降、粮食生产能力受限、粮食播种面积不稳等问题的存在使粮食安全和耕地保护的压力加大,提出了福建省粮食安全与耕地资源保护的对策：（1）强化耕地用途管制,确保基本农田数量;（2）促进耕地制度创新,构建种粮激励机制;（3）加快耕地质量建设,提高粮食生产能力;（4）加大粮食产区投入,提高产粮基地功能。     

基于食物安全的耕地需求分析与预测

为在耕地资源短缺与食物消费结构改变的大背景下合理分析用地需求,保障食物安全,以河南省居民的食物消费情况为研究对象,采用构建时间序列预测模型的方法,基于经济发展和食物结构对河南省未来15~30年的食物需求进行分析,并结合推算结果对不同食物类型所需土地分别计算,得出基于食物安全的耕地需求量。结果表明:1)2000—2019年河南省居民食物消费结构变化显著,植物类食物始终占据较大比重,动物类消费的所占比例呈增长趋势;2)河南省城乡居民耕地需求变化存在一定差异,农村居民的人均耕地需求由城镇居民的1.2倍下降至占城镇居民人均耕地需求的82%。耕地总需求变化趋势为缓慢减少后逐步上升且保持上升趋势,最高约508万hm²;3)河南省人口规模、作物单产水平和食物消费结构均对河南省耕地需求产生着重大影响。其中,主要影响因素是食物消费结构的改变,单产水平提高对缓解人口增长带来的耕地需求压力有重要作用;4)预测发现河南省现有耕地虽能够满足2035—2050年该省人民食物需求,但是河南省作为食物输出大省,无法在满足本省人民食物需求的同时,保持现有的食物供应比例。最后,根据预测结果与河南省耕地保护现状,基于食物安全以市场需求为导向提出相关建议。     

济南市粮食安全与耕地数量变化的相关分析

分析了济南市耕地数量变化与粮食生产的相关关系,结果表明,耕地数量变化对粮食生产具有持久的约束作用,保持一定数量的耕地面积是保障粮食安全的先决条件。在当前耕地面积持续减少、后备耕地资源稀缺、质量差、开发成本高、开垦潜力极其有限的情况下,保护现有耕地就是保护农业生产的基础,就是保护我们的生命线。     

Small phytoplankton and carbon export from the surface ocean

Autotrophic picoplankton dominate primary production over large oceanic regions but are believed to contribute relatively little to carbon export from surface layers. Using analyses of data from the equatorial Pacific Ocean and Arabian Sea, we show that the relative direct and indirect contribution of picoplankton to export is proportional to their total net primary production, despite their small size. We suggest that all primary producers, not just the large cells, can contribute to export from the surface layer of the ocean at rates proportional to their production rates.     

Giant amphipod from the abyssal pacific ocean

A baited camera has recorded a lysianassid amphipod that is twice as large as the largest amphipod previously recorded. The locality for this mobile omnivore is the sterile bottom of the eastern North Pacific Ocean, at a depth of 5304 meters.     

World ocean tides synthesized from normal modes

Sixty oceanic normal modes are used to synthesize the M(2) and K(1) (principal lunar semidiurnal and declinational diurnal) tides. The ten most energetic modes in the M(2) synthesis account for 87 percent of the energy; the corresponding figure for K(1) is 93 percent, two-thirds of which is contributed by a single mode whose natural period is about 29 hours. Model calculations indicate that the quality (Q) of the ocean response to tidal forcing resembles that of a frictionally controlled oscillator. In particular, for M(2) the global Q is about 10.     

Oils and rubber from arid land plants

In this article the economic development potentials of Cucurbita species (buffalo gourd and others), Simmondsia chinensis (jojoba), Euphorbia lathyris (gopher plant), and Parthenium argentatum (guayule) are discussed. All of these plants may become important sources of oils or rubber.     

基于农地征用制度视角下的土地发展权探析

我国的土地征用制度虽然不断完善,但仍然存在一定的缺陷。农民围绕土地权益发生大量纷争,为解决其中的一些尖锐矛盾,我国应积极地创设土地发展权制度,显化土地发展权。     

Fossil land mammal from antarctica

A fossil land mammal, apparently the first found in Antarctica, belongs to the extinct marsupial family Polydolopidae. The fossils were recovered from rocks about 40 million years old on Seymour Island, in the northern Antarctic Peninsula. The newly discovered marsupials support theories that predicted their former presence in Antarctica and strengthen proposals that Australian marsupials perhaps originated from South American species that dispersed across Antarctica when Australia still was attached to it, prior to 56 million years ago.     

非农就业、所有权认知与农户承包地退出

为探究非农就业与所有权认知对农户承包地退出的影响,以国内9省1 006份农户抽样数据为基础,在综合分析农户承包地退出成本收益的基础上,利用Probit模型和分组回归方法,考察其对农户承包地退出意愿的作用机制。结果表明：农户的承包地所有权认知与制度规定存在错位,有39.07%的农户认为承包地所有权归农户个人所有,承包地所有权的私有认知降低了农户承包地退出意愿;非农就业程度的升高会降低农户对土地的依赖,这不仅有助于提高农户承包地退出意愿,还在一定程度上缓解了承包地所有权私有认知对承包地退出意愿的负面影响。控制内生性后,非农就业对承包地退出意愿的促进作用增强。因此,要提升农户承包地退出意愿,应从引导农户形成正确的承包地所有权认知及提高农户非农就业水平两方面入手,并在此过程中完善城乡社会保障体系,解除退地农户后顾之忧。     

粮食安全视角下的东北黑土区耕地生态补偿研究

从粮食安全视角出发,在理论分析的基础上,运用基于碳足迹和产量因子修正的生态足迹模型,结合生态服务价值,量化2011—2018年东北黑土区部分城市的耕地生态补偿标准和迫切程度。结果发现:在粮食安全视角下,研究区均为耕地生态盈余区,约有54.1%的耕地生态承载的粮食产量供给到了耕地生态赤字区。受耕地生态盈余面积、单位耕地生态服务非市场价值和支付能力影响,研究区内各市的耕地生态补偿标准总量在研究期初有所提高,但随后均出现明显降低趋势,2018年的耕地生态补偿标准分别为哈尔滨市19.50亿元、绥化市23.60亿元、大庆市10.95亿元、长春市13.05亿元、四平市25.95亿元、铁岭市9.19亿元。考虑各市的经济发展水平,应当率先向四平市、绥化市支付耕地生态补偿。     

Bacterial taxa that limit sulfur flux from the ocean

Flux of dimethylsulfide (DMS) from ocean surface waters is the predominant natural source of sulfur to the atmosphere and influences climate by aerosol formation. Marine bacterioplankton regulate sulfur flux by converting the precursor dimethylsulfoniopropionate (DMSP) either to DMS or to sulfur compounds that are not climatically active. Through the discovery of a glycine cleavage T-family protein with DMSP methyltransferase activity, marine bacterioplankton in the Roseobacter and SAR11 taxa were identified as primary mediators of DMSP demethylation to methylmercaptopropionate. One-third of surface ocean bacteria harbor a DMSP demethylase homolog and thereby route a substantial fraction of global marine primary production away from DMS formation and into the marine microbial food web.     

Fluids from aging ocean crust that support microbial life

Little is known about the potential for life in the vast, low-temperature (<100 degrees C) reservoir of fluids within mid-ocean ridge flank and ocean basin crust. Recently, an overpressured 300-meter-deep borehole was fitted with an experimental seal (CORK) delivering crustal fluids to the sea floor for discrete and large-volume sampling and characterization. Results demonstrate that the 65 degrees C fluids from 3.5-million-year-old ocean crust support microbial growth. Ribosomal RNA gene sequence data indicate the presence of diverse Bacteria and Archaea, including gene clones of varying degrees of relatedness to known nitrate reducers (with ammonia production), thermophilic sulfate reducers, and thermophilic fermentative heterotrophs, all consistent with fluid chemistry.