稻-鱼系统的发展与未来思考

耕地和淡水是保证全球食物可持续供应所必不可少的资源,如何有效利用有限的水土资源、在保障食物供给的同时降低农业生产过程对资源环境的负面影响,是当今世界农业面临的重大挑战。稻-鱼系统(本文的"鱼"是水产生物的统称)是通过有效利用水土资源同时产出稻谷和水产品的重要农业方式,对保障区域食物供给和保护当地资源和环境有重要作用。近几十年来全球稻鱼-系统迅速发展,至目前全球六大洲的稻作区共28个国家都有了稻-鱼系统的分布;在中国稻-鱼系统也正由原来传统、规模小、养殖单一的模式逐渐发展为规模化、专业化、机械化和养殖多样化的模式。大量研究表明,稻-鱼系统可实现水稻产量稳定和获得水产品,稻-鱼系统同时具有化肥农药减量和农业面源污染降低等效应;稻-鱼系统也有助于解决水产单一养殖而产生的面源污染。虽然全球1.63亿hm2稻田面积90%以上具有发展稻-鱼系统的潜力,但目前稻-鱼系统的比例仍很低,我国稻-鱼系统面积也仅占稻田面积的4.48%。因此,保障稳产高效可持续的稻-鱼系统发展,需要对不同稻作区发展稻-鱼系统的生态经济可行性和适应性进行评估,同时必须建立新的技术体系(田间设施、种养结合技术、农业机械等),并适当扩大规模和创建品牌以增加农民收益。

稻-鱼复合生态系统对水田土壤理化性状的影响

2007年和2008年对稻-鱼(泥鳅)复合生态系统的水田土壤理化性状进行了定位定量研究。与对照相比,养鱼稻田土壤容重平均降低0.09 g/cm3,土壤总孔隙度平均提高9.15%,>0.25 mm团聚体平均增加4.64%,土壤碱解氮、速效磷含量高于对照处理,差异均为极显著(p<0.01);土壤分散系数平均减少6.25%,结构系数平均增加8.30%;土壤氧化还原电位平均增加16.5 mV,还原物质总量、活性还原物质含量、Fe2+含量和活性有机还原性物质含量分别平均降低0.42、0.46、0.26和0.21 cmol/kg。养鱼稻田土壤的通气性、结构稳定性和团聚化程度增强,分散性减弱。底栖鱼类有效改善了稻田土壤理化性状。

盐碱化湿地稻-鱼复合生态系统微生物特征

为揭示盐碱化湿地稻-鱼复合生态系统微生物群落结构特征,1994-1995年,对松嫩平原苏打盐碱化湿地稻-鱼复合生态系统水体与土壤中的微生物数量及种群组成进行了初步研究。结果表明,稻-鱼湿地水体中异养细菌数量显著高于稻田湿地(P<0.05),季节变化特点为秋季>夏季>春季。异养细菌的数量分布与鱼产量有显著相关关系(r=0.879)。稻-鱼湿地系统的土壤微生物数量明显高于稻田湿地(P<0.01)。稻-鱼湿地和稻田湿地分别检测出10个和11个属的异养细菌。稻-鱼湿地系统1个生长期细菌的平均生物量为0.973g/m3,生产量为307.5 kg/hm2,所提供的鱼产力为7.0 kg/hm2。

稻-鱼复合生态系统对水田土壤微生物生理群的影响

通过田间试验、采用平板表面涂抹法和稀释法对稻-鱼(泥鳅)复合体系的水田土壤微生物生理群进行了定位定量研究。结果表明,底栖鱼类对水田土壤特殊微生物生理群具有重要影响,促进了土壤固氮菌、纤维素分解菌、硝化细菌、硫化细菌和氨化细菌的生长,抑制了反硝化细菌和反硫化细菌的繁殖,有助于增加土壤N、P、S等养分元素的供给能力、土壤肥力和生化活性,提高水田的养分利用效率。

稻-鱼复合生态系统对水田土壤呼吸的影响

通过野外田间试验，使用土壤碳通量自动测定系统，对稻-鱼（泥鳅）复合生态系统的水田土壤呼吸进行了定位定量研究。试验地水田土壤呼吸速率表现出明显的季节性，在72．9—221．3mgCO2·m^-2·h^-1之间波动。8月达到最高值。养鱼稻田和对照样地的平均土壤呼吸速率分别为139．2mg·m^-2·h^-1和114．2mg·m^-2·h^-1。底栖鱼类提高了水田土壤呼吸强度。不同的水田复合种养方式对土壤呼吸的影响及其机理，有待于进一步研究。

从江侗乡稻-鱼-鸭复合系统的土壤微生物种类

贵州省从江侗乡稻鱼鸭系统被列为首批全球重要农业文化遗产,具有1 200年的历史。为更好地保护和传承该系统,并深入发掘该系统作为全球重要农业文化遗产的意义,也为稻鱼鸭高产技术在该系统保护区域内实施和推广提供科学依据,采用GC-MS方法测定土壤脂肪酸的组成和相对含量,对侗乡稻鱼鸭复合系统土壤微生物的种类组成进行研究。结果表明：1）代表细菌的16∶0和19∶0脂肪酸含量,非稻-鱼-鸭复合系统（以下简称＂非系统＂）土壤比稻-鱼-鸭复合系统（以下简称＂系统＂）土壤的分别高7.97~5.16倍和425.13~43.60倍;代表细菌的11∶0、12∶0和13∶0脂肪酸含量,系统土壤比非系统土壤的分别高80.90~63.17倍、1.90~1.65倍和5.86~5.26倍;代表细菌的其他脂肪酸含量,系统土壤和非系统土壤的差别不大。代表真菌的18∶1ω9c和18∶1ω9t脂肪酸含量,非系统土壤比系统土壤的分别高9.36~7.17倍和8.28~7.19倍;代表真菌的18∶2ω6,9脂肪酸含量,系统土壤比非系统土壤的高4.38~1.87倍。代表放线菌的10Me18∶0脂肪酸含量,系统土壤比非系统土壤的略高。代表线虫的20∶0脂肪酸含量,非系统土壤比系统土壤的高2.82~2.47倍。2）系统土壤和非系统土壤均以细菌为主。其中,主要是G-,放线菌次之,真菌、线虫和G＋含量相对较低,G-丰度较高是稻鱼鸭复合系统的主要特征。结论：系统土壤中微生物丰度的大小依次为细菌〉G-〉放线菌〉真菌〉G＋〉线虫,非系统土壤的依次为细菌〉真菌〉G-〉放线菌〉G＋〉线虫。

稻—萍—鱼系统中红萍氮素吸收利用及有效性研究

本文报道以红萍为饵料,鱼类对红萍氮素消化吸收、转化情况。试验结果表明:草鱼和尼罗罗非鱼对红萍氮素的消化和吸收率约为60％,其中30％红萍氮素转化为鱼体动物蛋白,另外约30％氮素排出体外。在田间条件下,尼罗罗非鱼摄食红萍,每季平均增长率约为41—40％。稻田养鱼,以萍喂鱼,鱼粪肥田,萍体氮素得以吸收利用,效益明显。在稻萍鱼体系中,当季红萍氮素的总利用率可达45—50％,而红萍单作肥料处理其利用率仅为30—36％,第二季作物对红萍残留氮素回收率可达7.83—9.64％,比红萍单作肥料处理高3.33—4.11％。第二季残效明显优于红萍压施处理,晚季稻谷产量的增产率可达13—25％,比压施红萍作肥料处理高7—8％。

稻—萍—鱼—畜(禽)生态系统技术经济效益评价

稻—萍—鱼—畜(禽)生态系统是种植业和养殖业有机结合的生产。采取绿萍的耐寒耐热品种搭配,鱼沟的一字形宽边式和双季养鱼,克服了稻萍鱼共生体系鱼类饵料单一,绿萍利用层次少的不足,延长绿萍繁殖时间,解决协调稻与鱼对水的要求不同及绿萍繁殖与鱼生长不一致的矛盾,有很好的经济、生态效益。

稻鱼复合种养对水田土壤酶活性的影响

通过田间试验，采用分层取样法对稻-鱼（泥鳅）复合种养水田的土壤酶活性进行了定位定量研究。结果表明，稻鱼复合种养水田的土壤酶活性高于对照样地。底栖鱼类增加了水田土壤过氧化氢酶、磷酸酶、脲酶、蔗糖酶及脱氢酶活性，其中时脱氢酶和蔗糖酶活性的影响最为显著。在土壤垂直剖面上，土壤酶活性在0—10cm土层最高，由表层到深层逐渐降低。在稻田中加入底栖鱼类组分，有助于提高水田的土壤肥力和生物学活性。

苏打盐碱地养鱼稻田水体微生物区系研究

对松嫩平原苏打盐碱地养鱼稻田水体微生物数量及种类组成进行了初步研究。结果表明,养鱼稻田异养细菌数量为0.280万～30.716万mL-1,高于未养鱼稻田(P<0.05),其平均值的时间分布为水稻生长末期>中期>初期;养鱼稻田和未养鱼稻田放线菌和霉菌数量均较少。养鱼稻田大肠菌群数量为403.6～17934.2L-1,显著高于未养鱼稻田(P<0.01),其平均值的时间分布为水稻生长中期>初期>末期。异养细菌数量与鱼产量、总施肥量和有机肥施用量均呈极显著相关,与化肥施用量相关不显著;大肠菌群数量与鱼产量相关显著,与总施肥量相关不显著,但与有机肥施用量相关极显著。养鱼稻田中检测出10个科(属)异养细菌,优势菌为弧菌属(Vib rion)、气单胞菌属(Aeromonas)和芽孢杆菌属(Bacillus)。

Standards of Ecological Compensation for Traditional Ecoagriculture:Taking Rice-Fish System in Hani Terrace as an Example

Traditional eco-agriculture provides many ecosystem services which are important for the local environment, especially in mountain areas. In order to encourage the farmers to engage in coo-agriculture, it is necessary to establish an eco-compensation mechanism for them. As the compensation standard is one of key issues in establishing eeo-compensation mechanism, this paper calculated the standard based on the farmers＇ willingness to accept （WTA） and the input-output analysis of eco-compensation. We took the traditional rice-fish eco-agriculture as the research object, conducting field surveys in Hani Terrace of Honghe County. Through the questionnaires in 2o11, we obtained the farmers＇ willingness to accept government compensation and market compensation. Then, the research evaluated the output of eco-compensation, the economic value of rice-fish paddy ecosystem services. Finally, under different market compensation standards, we compared the input and output of government compensation. The results show that, in 2011 the government should to pay farmers 7462 yuan.ha^-1·a^-1 to meet their willingness, but the output （ecological benefit） was only 7393 yuan.ha^-1·a^-1. However, whenthe rice price increases 1 yuan·kg-1 because of the limited use of chemicals in the next year, the government just has to pay farmers 4062 yuan.ha^-1·a^-1 and the surplus will be 3331 yuan.ha^-1·a^-1.

Rice ＋ Fish Farming in Homesteads： Sustainable Natural-Resource Management for Subsistence in Arunachal Pradesh, India

Understanding the attributes of traditional, location-specific land-use systems will provide insights for improvement of such systems and design of new ones for wider applicability. The integrated rice ＋ fish system developed by the Apatani tribe of Ziro valley, Arunachal Pradesh, Northeastern India is such a unique system. Faced with shortages of their staple food items （rice and fish）, these subsistence farmers developed this ingenious system--in preference to the wide-spread shifting cultivation in the region--by capitalizing on the good water supply （from rainfall supplemented by natural flow from hills surrounding the valley）. Two rice crops are grown annually and fish is reared in paddy fields during the main rainy season. Crop residues and animal wastes are the sources of nutrients to crops, chemical fertilizers and insecticides are not used. Over the years, rice yield has been stable at about 3,700 kg.ha-1.year-1. Recently, UNESCO has tentatively added the valley as a ＂world heritage site＂ recognizing its ＂extremely high productivity＂ and ＂unique＂ ecological preservation. The resilience and the sustainability of the system could be attributed to efficient nutrient cycling and nutrient input through water seeping in from surrounding hills, which have not been, but deserve to be, quantified.

Conceptual Framework for Economic Evaluation of Globally Important Agricultural Heritage Systems (GIAHS): Case of Rice-Fish Co-Culture in China

The Globally Important Agricultural Heritage Systems （GIAHS） initiative was launched by the Food and Agriculture Organization （FAO） of the United Nations in 2002 with the aim of establishing the basis for the global recognition,dynamic conservation and adaptive management of outstanding traditional agricultural systems and their associated landscapes,biodiversity,knowledge systems and cultures.There is anecdotal evidence that designated GIAHS are economically better than non-GIAHS sites.However,there have not been done an economic analysis to prove this.Nor are any sophisticated economic performance criteria for GIAHS in place for a continuously monitoring of the functioning.Therefore,the main objective of this study is to conduct an economic valuation for a GIAHS system versus a similar non designated GIAHS system.For this,a Cost-Benefit Analysis （CBA） is chosen.The major constraint is the data availability.Therefore,a framework for economic analysis shall be developed with the intention to provide directions,assumptions,and data requirement to carry out an economic analysis and so give guidance on future inclusion of economic valuations of GIAHS.Theconceptual framework for economic assessment will use the Rice-Fish pilot site in China as a case study.The example calculations on the rice-fish co-culture （RFC） have to be taken cautiously due to data availability on different activities （tourism,marketed products on local and international markets） as well as comparison to similar systems.

Ecological Benefit Evaluation of Agricultural Heritage System Conservation——A Case Study of the Qingtian Rice-Fish Culture System

In order to better understand the developmental conditions and trends of the biodiversity at agricultural heritage sites,the structure and function of the ecosystem and ecological environment in Qingtian Rice-Fish Culture System is examined in the decade since the implementation of the GIAHS project.Through the collection of historical data and sample-plot survey,this study collates the data from 2005 to 2013 related to the heritage site to evaluate the ecological benefit of the Agricultural Heritage System conservation.The results show that:(1)Since the implementation of heritage conservation,the variety of traditional rice grown at the heritage sites basically remains stable,the varieties of other crops basically remain unchanged and the varieties of fruit trees and medicinal plants have developed at faster rates.As the ecological environment at the heritage sites gradually improved,the species and richness of the biodiversity in the ecosystem have increased,especially the increasing growth of egrets and boars.(2)From 2005 to 2013 in the Fangshan Town of Qingtian County,the ecosystem areas identified as river,forest,urban and bare land have increased.The increased area of the urban ecosystem is the largest one of them,which is up to 20.30 ha;while the area of the forest ecosystem has increased to 7.29 ha.The areas of wetland,reservoir,farmland and grassland have been reduced,and the area of grassland ecosystem has been reduced the most with a reduction of 28.87 ha.From the changes in the values of the ecosystem services of different ecosystem types,the values of forest ecosystem services have achieved the most growth,reaching up to 92000 yuan yr-1 and the growth of the river and bare land ecosystem service values are not obvious.(3)Over nearly a decade,the soil nutrients and the water quality of rice fields at the heritage site have not obviously changed and the plant diseases and insect pests in the rice fields have not been aggravated.The monitoring indexes are far better than the standard values.With the great support of the local government,the production and living conditions and the living environments of farmers in the villages of the heritage sites have been greatly improved through road reconstruction,water improvement,toilet enhancements and the greening,brightness and beautification of the villages.

Design and Application of the Annual Report of Globally Important Agricultural Heritage Systems(GIAHS)Monitoring

Scientific and effective heritage monitoring can not only realize the conservation of the heritage itself and the maintenance of its values,but it can also realize the sustainable development of the heritage site.In order to promote the conservation and management of Globally Important Agricultural Heritage Systems(GIAHS),this study proposed a design for the annual report of GIAHS monitoring under the overall framework of the GIAHS monitoring system,and explored the application of the annual report in the first GIAHS site in China:the Qingtian Rice-Fish Culture System.In the design scheme of this study,the GIAHS annual monitoring report is composed of 24 monitoring items,with each of them logically related.It is to be filled in by the bureaus of the heritage site and reported through the GIAHS dynamic monitoring system.The results of an analysis of the annual reports of Qingtian Rice-Fish Culture System for four years showed that Qingtian County has taken a series of conservation and development measures which have reduced the area of abandoned paddy,enhanced the unit benefit of agri-products,and increased the farmers’income.At the same time,the heritage site is faced with various challenges and threats,such as the weakening of the tourism attraction,the aging of the heritage practitioners,and the limitation of the heritage-themed agri-products and tourism income,which need to be addressed with proper measures.The results can also provide guidance for other GIAHS based on indications that heritage sites should improve the development of cultural products,the construction of social organization and the cultivation of spontaneous publicity,and an exchange and learning mechanism should be established among them in the future.The design and application of the GIAHS annual monitoring reports can not only provide specific guidance for conducting the GIAHS monitoring,but also lay the foundation for evaluating the effectiveness of GIAHS conservation and management.This study is expected to help enrich the theory of GIAHS monitoring,further promote China’s GIAHS monitoring work,and also provide China’s experience for the benefit of international GIAHS monitoring efforts.