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21.
Carlos A. Guerra Marc J. Metzger Joachim Maes Teresa Pinto-Correia 《Landscape Ecology》2016,31(2):271-290
Context
Policy decisions form a major driver of land use change, with important implications for socially and environmentally susceptible regions. It is well known that there can be major unintended consequences, especially where policies are not tailored to regionally specific contexts.Objectives
In this paper we assess the implications of 60 years of agricultural policies on soil erosion prevention (SEP) by vegetation, an essential regulating ecosystem service in Mediterranean Europe.Methods
To assess these implications we produced and analysed a time series of land cover/use and environmental conditions datasets (from 1951 to 2012) in relation to changing agricultural policies for a specific region in the southern Portugal. A set of indicators related to SEP allowed us to identify that land use intensification as increased soil erosion in the last 60 years.Results
Particularly in the last 35 years, as a consequence of headage payments for cattle, the agricultural policy had a significant effect in the density and renewal of the tree cover, resulting in drastic effects for the provision of the SEP service. These are more significant after 1986, coinciding with the implementation of several Common Agricultural Policy instruments focused on increasing the modernization and productivity capacity of farm systems.Conclusions
The results show some unintended effects of agricultural policy mechanisms on ecosystem service provision and highlight the need for context-based policies, tailored to the environmental constrains and potentials of each region.22.
Kelly W. Wilcox Joachim Stoss Edward M. Donaldson 《Aquaculture (Amsterdam, Netherlands)》1984,40(1):77-87
Egg content originating from ruptured ova progressively reduced the success of fertilization in coho salmon (Oncorhynchus kisutch) eggs. The salmon egg differs in ionic composition from the ovarian fluid in exhibiting higher K+ and Mg2+ and lower Na+ concentrations. Normal ovarian fluid induced spermatozoan motility whereas ovarian fluid contaminated with egg content progressively lost the ability to induce motility. Loss of motility was related to decreasing ratios in the ovarian fluid, indicating that reduced fertility may be caused by inactivation of sperm cells in the insemination medium. Removal of contaminated ovarian fluid by rinsing ova in isotonic media induced spermatozoan motility and restored fertility completely. The use of an isotonic NaHCO3 solution for rinsing of ova is suggested as a routine procedure for artificial insemination in salmonids where the presence of broken eggs is suspected. 相似文献
23.
Modelling the temperature mediation of growth in larval fish 总被引:1,自引:0,他引:1
Joachim Bartsch 《Fisheries Oceanography》2002,11(5):310-314
24.
Zhang Wantong Kang Xiaoming Kang Enze Audet Joachim Davidson Thomas A. Zhang Xiaodong Yan Liang Li Yong Yan Zhongqing Zhang Kerou Wang Jinzhi Hu Zhengyi 《Journal of Soils and Sediments》2022,22(2):470-481
Journal of Soils and Sediments - Alpine wetland ecosystems can contribute large amounts of methane (CH4) to the atmosphere; however, their emissions vary with environmental conditions. Microbial... 相似文献
25.
Habitat destruction is one of the main threats to environmental integrity. Assessing the consequences of human impacts is crucial both to predict and prevent structural and functional changes of habitats. However, to date almost all studies on marine threats, from regional to global scales, have been entirely qualitative and generally based on little more than expert opinion. We have developed a meta-analytical approach to quantify overall effects of various stressors on different Mediterranean habitat types and to compare the relative importance of different impacts across a range of habitats. We first qualitatively reviewed and synthesized 366 experiments (either manipulative or correlative) collected in the literature. After a selection procedure, we finally quantitatively meta-analyzed 158 experiments. We showed that fisheries (destructive or not), species invasion, aquaculture, sedimentation increase, water degradation and urbanization have negative effects on Mediterranean habitats and associated species assemblages. We also explored the overlap between the impacts identified as important in the Mediterranean and those identified by experts as being important globally, highlighting the inadequacies of relying on expert opinion alone. Finally, we drew attention to the critical lack of empirical knowledge about marine systems in many areas of the Mediterranean, which impedes the implementation of effective conservation measures. Our study is the first to synthesize experimental analyses on human-driven impacts on marine habitats across such a broad geographic scale. 相似文献
26.
田间试验的空间变异性及其统计控制 总被引:6,自引:1,他引:6
利用空间相关模型和传统方差分析模型对小麦和玉米3个田间试验产量数据进行了拟合与分析。结果表明,3个试验都显著存在空间变异,空间变异方差占据剩余变异方差的83.5%~0.4%;相对于传统随机完全区组分析法,空间相关模型法效应比较的标准误平均降低18.4%~14.2%,分析相对效率平均为1.50~1.36,因而比区组控制空间变异更有效;不同空间相关模型分析的结果呈现出一定的差异。建议利用空间相关模型分析田间试验,并利用Akaike信息准则(AIC)进行最佳空间相关模型选择。 相似文献
27.
Joachim Schiemann 《Genetic Resources and Crop Evolution》1989,37(1):15-27
Zusammenfassung Durch Übertragung von klonierten Fremdgenen läßt sich die genetische Variabilität der Kulturpflanzen wesentlich erweitern. Insbesondere die Übertragung monogen bedingter Resistenzeigenschaften gelingt bei einer zunehmenden Zahl von Kulturpflanzen. Für die ökonomisch wichtige Zuckerrübe ist ein etabliertes Gentransferverfahren bisher nicht verfügbar. Während Einschleusung, Integration und Expression von Fremdgenen in Zuckerrübenzellen und -gewebe mit einer Vielzahl von Gentransfermethoden erreicht werden können, ist die Regeneration transgener Zuckerrübenzellen zu transgenen Pflanzen bisher nur in wenigen Laboratorien gelungen. Die experimentellen Details wurden bisher nicht publiziert. Die vorliegende Arbeit beschreibt Verfahren, die sich für einen Gentransfer bei der Zuckerrübe eignen sollten. Expression und meiotische Stabilität der transferierten Gene werden behandelt sowie Anwendungsmöglichkeiten des Gentransfers bei der Zuckerrübe kurz diskutiert.
Chances and approaches for gene transfer in sugar beet (Beta vulgaris L.)
Summary The genetic variability of cultivated plants can be extensively increased by the transfer of cloned genes. Especially the transfer of monogeneously coded resistancies is established for an increasing number of cultivated plants. A routine gene transfer method is not available for the economicly important sugar beet. Though transfer, integration and expression of foreign genes in cells and tissues of sugar beet can be achieved by a number of gene transfer methods, only a few laboratories succeeded in the regeneration of transgenic cells of sugar beet to transgenic plants. The experimental details have not been published until now. This paper deals with methods which could be useful for gene transfer in sugar beet. Expression and meiotic stability of transferred genes are described and the aims of gene transfer in sugar beet are shortly discussed.
(Beta vulgaris L.)
. ë . ÿe . . . ë . , . ë , , .相似文献
28.
Dr. Ing. Joachim Wieting 《Water, air, and soil pollution》1986,31(1-2):247-256
In the Federal Republic of Germany (FRG), airborne pollutants are leading to an increased rate of acidification of aquatic systems. In particular, the upper reaches of rivers and obligotrophic lakes in low-carbonate areas are affected. These areas are a minority of the total number of waterways, but are of great importance for environmental protection. Water acidification cannot be viewed as an isolated issue. In forested areas, it is associated with damage to the entire ecosystem. In lakes and streams, one of the most significant effects of water acidification is fish mortality; several bodies of water in which fish were once plentiful are now devoid of fish. With increasing acidification of the ground water, drinking-water supply problems may also be expected, All measures which can be taken to prevent the entry of pollutants into aquatic systems are preferred to those which merely treat the symptoms of acidified aquatic systems (e.g. addition of lime). The Federal Environmental Agency therefore considers the reduction of air pollutants to be the most effective solution to the problem of acidified of aquatic systems. 相似文献
29.
Dr. Jürgen Schultze-Motel Dr. Reinhard Fritsch Dr. Karl Hammer Dr. Peter Hanelt Dr. Joachim Kruse Dr. Helga I. Maass Dr. Harald Ohle Klaus Pistrick 《Genetic Resources and Crop Evolution》1982,30(2):273-291
Summary Important papers on taxonomy and evolution of cultivated plants published in 1980 and 1981 were compiled and briefly discussed.
Herrn Prof. Dr. Dr. h. c. mult. H.Stubbe aus Anlaß der 80. Wiederkehr seines Geburtstages gewidmet. 相似文献
Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1980/1981
Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1980 und 1981 wurden zusammengestellt und kurz kommentiert.
: 1980–1981 .
, 1980 1981 . .
Herrn Prof. Dr. Dr. h. c. mult. H.Stubbe aus Anlaß der 80. Wiederkehr seines Geburtstages gewidmet. 相似文献
30.
Jürgen Schultze-Motel Reinhard Fritsch Karl Hammer Peter Hanelt Joachim Kruse Helga I. Maass Harald Ohle Klaus Pistrick 《Genetic Resources and Crop Evolution》1990,38(3):417-434
Summary Important papers on taxonomy and evolution of cultivated plants published in 1988 and 1989 were compiled and briefly discussed.
Taxonomie und Evolution der Kulturpflanzen: Literaturübersicht 1988/1989
Zusammenfassung Wichtige Arbeiten über Taxonomie und Evolution der Kulturpflanzen aus den Jahren 1988 und 1989 wurden zusammengestellt und kurz kommentiert.
: 1988–1989
, 1988 1989 . .相似文献