黄淮平原不同多熟模式生产力特征与资源利用效率研究

对黄淮平原一麦三玉米、一麦二玉米和一麦一玉米三种多熟模式的产量、资源利用及经济效益状况进行了比较分析。结果表明，三种模式年亩产均超过吨粮，说明在集约栽培条件下黄淮平原亩产吨粮的现实性。三种模式产量梯度差异表明，在水肥供应基本充足的情况下，通过集约多熟种植并配合以合理调控技术是在高产基础上进一步提高产量的有效途径。一麦三玉米最高产量达２２０１ｔ／ｈm₂（亩产１４６７ｋｇ），是在现有技术条件下接近与突破亩产吨半粮的有效种植模式之一。全年玉米总穗数增加是增产的关键。一麦三玉米模式通过接茬移栽等综合措施的有效配合，能维持较高的同化功能，光热资源利用效率提高。经济效益上表现为高投入高产出，但部分产投经济指标有下降的趋势。从综合考虑公顷产量与公顷纯收入及物质费用、用工等因素上综合评判，一麦三玉米模式总体上表现优势。     

废弃物基水热炭改良对水稻产量及氮素吸收的影响

生物炭农田回用是实现农林废弃物资源化利用和碳封存的有效手段.近年来,水热碳化技术由于在炭产率、能耗及生产过程中的烟气排放等方面显著优于常规热解碳化技术而受到关注.为实现农林废弃物的资源化利用,明确水热炭农田应用对作物生产力的影响,本研究通过原状土柱模拟试验和表征分析,研究了4种不同类型改良水热炭对两种典型土壤的水稻产量和氮素吸收的影响及可能的驱动因素.结果表明,锯末水热炭和秸秆水热炭经物理或生物改良后,在两种类型土壤上均能够增加水稻产量和氮素吸收,减少氮素损失,且其效应不受水热炭添加量影响(5‰,15‰;质量分数).与对照相比,水热炭添加处理的产量和氮素吸收量分别提高9.2%～20.7%和7.7%～17.0%.高C/N比的锯末水热炭更有利于高肥力土壤水稻氮素吸收量的增加;而低肥力土壤由于限制性因子较多,受水热炭类型的影响较小.通过对水热炭的表征分析发现,其表面养分元素丰富;水洗或生物改良后其表面孔隙结构有较大改善,C元素相对含量明显降低,N和O元素相对含量明显增加,这对养分的固持/供应可能产生影响.因此,水热炭改良后孔隙结构的改变和N、O元素含量的增加可能是其施用后水稻产量和氮素吸收增...     

PHYTOPLANKTON PRODUCTIVITY AND BIOMASS IN THE CHARLOTTE HARBOR ESTUARINE SYSTEM,FLORIDA1

ABSTRACT: Phytoplankton carbon-14 productivity at a depth of 50 percent of surface light and chlorophyll-α concentrations were measured every other month from November 1985 through September 1986 at 12 stations in the Charlotte Harbor estuarine system. Maximum productivity and chlorophyll-α concentrations occurred during summer or early autumn near the mouths of tidal rivers. Most of the variability in light-normalized productivity and chlorophyll-α could be attributed to two factors derived from Principal Component Analysis of ambient water-quality characteristics. One factor related to seasonal variability and the other to spatial variability. The seasonal factor incorporated the interaction of temperature and nutrients. The spatial factor incorporated the interaction of salinity, nutrients, and water color that resulted from the mixing of freshwater inflow and seawater. Although freshwater inflow increased the availability of nutrients in low salinity (less than 10‰) waters, the highly colored freshwater restricted light penetration and phytoplankton productivity. Maximum productivity and biomass occurred where color associated with the freshwater inflow had been diluted by seawater so that light and nutrients were both available. Concentrations of inorganic nitrogen were often at or below detection limit throughout most of the high salinity (greater than 20‰) waters of the estuary and was probably the most critical nutrient in limiting phytoplankton productivity.     

土地生产潜力评价中土壤修正系数模型的研究──以河北省涿鹿县为例

为了方便、准确地分析土壤条件（包括部分地理条件，如坡度、地下水位等，下文同）对土地生产潜力的影响，本文提出土壤修正系数的概念，即：在一定的气候和投入水平条件下，某种土壤能够满足作物生长的生理、生态要求的程度称其为该土壤对这种作物的土壤修正系数。以河北省涿鹿县为例探讨了定量计算土壤修正系数的理论和方法，并采用相对权重模糊距离法设计了土壤修正系数的计算模型。专家计算结果。（２）土壤修正系数模型的理想检验方法是在土地利用、气候等条件一致的情况下，将土壤修正系数与实际产量进行对比分析。但由于气候等条件不好控制，因此该方法在实践中很难实现。事实上，“土地评价的结果如果能够准确地反映土地评价专家的正确判断，那么它就是有效的；检验结果正确性的一个方法就是通过比较不同专家分析评价的结果。”（Ｎ．Ａ．Ｊ．ＶａｎＬａｎｅｎ，１９９１）笔者认为，这是对目前土地评价结果检验的一个比较客观的认识，本文的检验方法就是基于此。表７相关分析和均方差分析参考文献     

中国旅游业全要素碳生产率动态演进及其影响因素

为探清中国旅游业全要素碳生产率（total factor carbon productivity,TFCP）增长演化特征及影响因素,运用Malmquist-Luenberger指数测算2000—2017年中国30个省（自治区、直辖市）旅游业TFCP及其分解（不含港澳台及西藏自治区数据,下同）,借助核密度估计揭示其动态演进趋势,并建立面板数据模型探究影响旅游业TFCP的关键因素.结果表明:①2000—2017年,中国旅游业TFCP平均增长率为6.2%,呈现中部高于东部、东部高于西部的空间增长格局,且技术进步是其增长的主要驱动力.②中国共有28个省份的旅游业TFCP呈现正增长,其中吉林省的增幅最高,而青海省、宁夏回族自治区旅游业TFCP出现下降;旅游业碳排放技术“创新者”主要为天津市、河南省、山西省、上海市和内蒙古自治区.③旅游业累积TFCP和累积技术进步均存在明显提升,但二者省际差距有所扩大;而累积技术效率虽然省际差距在缩小,但效率提高幅度不明显,且呈一定倒退趋势.④全国范围内,旅游业经济规模、产业结构和对外开放程度分别在1%、1%和10%的显著性水平上正向促进旅游业TFCP,旅游业能源强度、旅游业碳排放结构及城镇化水平在1%的显著性水平上负向影响旅游业TFCP,环境规制对其影响不显著.研究显示,中国旅游业TFCP虽波动性较大,但整体呈增长趋势,技术进步的贡献高于技术效率的贡献,今后在依靠技术进步提升旅游业TFCP的同时,更要注重改善技术效率.      

Characterization and acid-mobilization study for typical iron-bearing clay mineral

In this study, iron speciation in five standard clay samples was characterized. Iron mobilization from these clays was then measured in acidic media. For comparison, a commercially available Arizona test dust (ATD) was also observed. The results showed that the free-Fe contents of clays were commonly lower than that of dust aerosols. The components of clays were dominant by the structural Fe held in the aluminosilicate lattice. The iron solubility of the clays were in the order of KGa-2?>?SWy-2?>?CCa-2?>?IMt-2?>?NAu-2. Based upon the Mössbauer spectrum and transmission electron microscopy (TEM) analysis, the Fe(II) fraction and the Fe/Si ratio of clay particles changed after dissolution, suggesting the total Fe solubility depended on the Fe atom states existing within the aluminosilicate lattice. The Fe in KGa-2 and SWy-2 was most likely substituted for alkaline elements as the interlayer ions held by ionic bonds in the aluminosilicate, which are more liable to dissolution. However, the Fe in NAu-2 was more likely to be bound by strong covalent bonds in aluminosilicate mineral, which is less soluble. The much highly soluble Fe in ATD was not only linked to the dissolution of an appreciable fraction of Fe(II), but also could be attributed to the fact that the Fe bonds in the clay fraction of ATD were mainly present as ionic bonds. The TEM images showed that reacted clay particles displayed less aggregate particles, with nanoparticle aggregates and the Fe/S-rich tiny particles attached to the remains.     

生产力与生物多样性关系的研究进展

生产力和生物多样性是生态系统两个基本属性。然而,几十年来,人们一直在争论它们之间的相互关系及其潜在机制。论文综述过去有关两者关系的控制实验、meta分析、多点观测研究和潜在机制,发现两者关系主要表现为单峰关系、正相关关系、负相关关系、无关系、“U”型关系,并且关于它们关系的潜在机制也没有普遍共识。同时,两者关系及其潜在机制均对尺度具有很强依赖性。分析其原因,可能生产力与生物多样性的关系不是简单或直接因果关系,而是由相互关联的、多变量过程共同控制。因此,应放弃固定化二元模式,开展多元化驱动因素的生物多样性研究,加强人类对复杂生态系统过程的理解,提供更具意义的生物多样性保护和管理指导。     

宁夏荒漠草原恢复演替过程中物种多样性与生产力的变化

荒漠草原一直是生态学者关注的焦点。文章以宁夏灵武的荒漠草原区为研究对象,对围栏条件下退化群落的物种多样性、生产力和群落演替及其生态机制进行探讨,为荒漠草原的植被恢复和重建提供理论基础。结果表明:群落生产力除受物种多样性的影响外,也受物种本身特征和环境资源的影响。在荒漠草原中功能群盖度与群落初级生产力无显著的相关关系。荒漠植物群落物种多样性指数在时间尺度上的变化表现为随着围栏时间的延续逐渐增加,而生态优势度变化趋势则相反。在不同年份年降水量直接影响植物群落物种数的多少、丰富度和生产力。     

Complexity in an obligate mutualism: do fungus-gardening ants know what makes their garden grow?

Fungus gardening ants make clear choices among fungal substrates (food for their fungus). It has been proposed, but never demonstrated, that these ants are collecting the best for their symbiotic fungus and the production of ant biomass (fitness). The goal of this study was to determine whether preferred substrates lead to higher fitness in the attine, Trachymyrmex septentrionalis. Preferences exhibited by foragers were established. Colonies were fed a single substrate or a mixture of substrates during the entire course of the experiment, which ended when sexual offspring appeared in the nest. The response variables were numbers and weights of ant offspring and the chitin content of fungus gardens. Preference was not strongly related to fitness. The preferred oak catkins produced the highest amounts of ant and fungal biomass, but the ants collected much more material than needed, which indicates that forager activity is decoupled from fitness. The preferred caterpillar feces were rejected shortly after the feedings began. The unpreferred oak leaves were just as effective at producing ant and fungal biomass as catkins. Leaves are possibly unpreferred because they are expensive to cut. The unpreferred huckleberry flowers were inferior but did not cause rejection behavior. The mixed diet was just as productive as catkins or leaves. This study indicates that foragers possess a default mechanism to prefer catkins and frass, which can be quickly changed if substrates are bad. In contrast, there does not appear to be a similar mechanism causing substrates to become preferred quickly.     

Increasing the Accuracy of Productivity and Survival Estimates in Assessing Landbird Population Status

Abstract:  The conservation of species with declining populations requires information on population demography and identification of factors that limit population growth. For landbird species, an understanding of large-scale population declines often requires assessment of local population processes, including the production of offspring, the survival of those offspring, and adult survival. Population growth has been modeled for several species of landbirds to date, and these studies have provided important information on relationships between population status and population-limiting factors. Several recent studies have illuminated field methods and analytical techniques that can aid in increasing the accuracy of productivity and survival estimates for population models. We reviewed these methods and recommend their implementation, including quantification of the season-long productivity of individuals, collection of empirical data on juvenile survival during the postfledging and overwintering periods, and incorporation of adult breeding dispersal into annual adult survival estimates. Such methods will allow for more accurate assessment of population status and provide a better understanding of the factors on which to focus our conservation efforts.