Suchergebnisse

Assessment and documentation of the status of ecosystem health and analysis of the effects of human-induced changes on a Kenyan montane natural forest, characterized by a human-dominated landscape, were done. A socioeconomic assessment of the perceptions and attitudes of the inhabitants about the importance, status and causes of degradation was carried out between August 2006 and September 2007. The provisional capacity of the reserve for goods and services was also evaluated. In order to assess individual local actions at the household level and their effects on the overall health dynamics in the forest reserve, information about the direct and indirect drivers of forest degradation at the forest reserve level was sought from the time of inhabitation until the time of study. The perceptions and attitudes of the inhabitants regarding supply of ecosystem goods and services at the forest reserve scale were evaluated. This was executed using a household survey where one hundred and fifty household heads were interviewed using a semi-structured questionnaire. An integrated approach to defining the health of the ecosystem at the local level was attempted. Results indicated a chronological degradation in the condition of the forest over time. A continued reduction in the number and density of once dominant tree species as well as structural physiognomy was shown. Households in the South-western Mau experience an increasing decline in the supply of once abundant important goods, including fuelwood, timber, medicinal plants and poles. Disappearance of abundant and common wildlife species was also recorded. In the forest reserve, solutions to issues and problems related to encroachment on forestland and related disturbance activities lie in clear land use policy and legislation designating particular uses to particular land categories. This is urgently required to deal with the issues related to unsustainable land use.

Model development is of vital importance for understanding and management of ecological processes. Identifying the complex relationships between ecological patterns and processes is a crucial task. Ecological modelling - both qualitatively and quantitatively - plays a vital role in analysing ecological phenomena and for ecological theory. This textbook provides a unique overview of modelling approaches. Representing the state-of-the-art in modern ecology, it shows how to construct and work with various different model types. It introduces the background of each approach and its application in ecology. Differential equations, matrix approaches, individual-based models and many other relevant modelling techniques are explained and demonstrated with their use. The authors provide links to software tools and course materials. With chapters written by leading specialists, 'Modelling Complex Ecological Dynamics' is an essential contribution to expand the qualification of students, teachers and scientists alike. Editors: Fred Jopp (University of Miami, USA) Hauke Reuter (Leibniz Center for Tropical Marine Ecology, Bremen, Germany) Broder Breckling (University of Bremen, Germany) Authors: Esther M. Borell (The Interuniversity Institute (IUI) for Marine Sciences, Eilat, Israel) Broder Breckling (University of Bremen, Germany) Donald L DeAngelis (University of Miami, USA) Marko Debeljak (Jozef Stefan Institute, Ljubljana, Slovenia) Carsten F. Dormann (Helmholtz Centre for Environmental Research, Leipzig, Germany) Saso Dzeroski (Jozef Stefan Institute, Ljubljana, Slovenia) Alejandro Gallego (Marine Scotland, Aberdeen, UK) Robert H. Gardner (University of Maryland, Frostburg, USA) Aurélie Garnier (Office National de la Chasse et de la Faune Sauvage, Nantes, France) Fred Jopp (University of Miami, USA) Sven Erik Jørgensen (University of Copenhagen, Denmark) Dietmar Kraft (University of Oldenburg, Germany) Andreas Kubicek (Leibniz Center for Tropical Marine Ecology, Bremen, Germany) Winfried Kurth (University of Göttingen, Germany) Christoph Lange (Fraunhofer MEVIS, Bremen, Germany) Dirk Lanwert (University of Göttingen, Germany) Jane Lecomte (Université Paris-Sud 11, France) Horst Malchow (University of Osnabrück, Germany) Agnese Marchini (University of Pavia, Italy) Yiannis G Matsinos (University of the Aegean, Grecce) Felix Müller (University of Kiel, Germany) Søren Nors Nielsen (Copenhagen, Denmark) Guy Pe'er (Helmholtz Centre for Environmental Research, Leipzig, Germny) Hauke Reuter (Leibniz Center for Tropical Marine Ecology, Bremen, Germany) Michael Sieber (University of Osnabrück, Germany) Dagmar Söndgerath (TU Braunschweig, Germany) Marc Taylor (Alfred Wegener Institute, Bremerhaven, Germany) Joel C. Trexler (Florida International University, Miami, USA) Gerd Weigmann (FU Berlin, Germany) Matthias Wolff (Leibniz Center for Tropical Marine Ecology, Bremen, Germany)

Abstract
About 20 years after the market introduction of the first GM plants, we review whether or not uncontrolled spread occurred. We summarise cases documented in the scientific literature and derive conclusions for the regulation of the authorisation of new events. Several cases documented in North and Central America and Japan show that transgenes have spread beyond cultivation areas. Important examples are bentgrass (Agrostis stolonifer a), oilseed rape (Brassica napu s) and cotton (Gossypium hirsutum). Several factors can be identified as relevant for transgene dispersal in the environment. Grasses (Poaceae), in particular, show a high potential for persistence and invasiveness, and wild relatives that can cross with the crop plants are a major factor in the unintended spread of the transgenes. There are significant uncertainties in predicting which transgenes will escape and how they will interact with the environment. For example, climate change is likely to have a major impact on the invasive potential of some plant species. The uncontrolled spread of transgenes is therefore a remaining challenge for regulators. We discuss some of these issues in the context of EU regulations since these regulations explicitly refer to the precautionary principle in the assessment of uncertainties. We found the that the precautionary principle as established in EU Directive 2001/18 can only be applied where efficient measures are available to remove genetically engineered organisms from the environment should this become necessary. If a removal from the environment would not be practically feasible, undesirable developments could not be mitigated.

Africa has deep contentions on the use of GM crops in agriculture, similar to those found in Europe and elsewhere. However, it is apparent that the debate is most protracted on the continent with two entrenched viewpoints i.e. the pro-GMO and anti-GMO groups. The challenge for an acceptable consensus is attributable to a complexity of issues relative to the introduction of GM maize into small-scale farming systems that fundamentally relies on open pollinated varieties (OPVs) with broad genetic backgrounds and tolerance to diverse biotic stresses, and which is usually produced for the informal seed market. Other factors relate to the generally low capacity of African states and weak mechanisms for assessing the potential risks posed by GM crops. The lack of public awareness, participation and information sharing are additional limiting factors. These issues have weakened government and policy responses to the potential deployment of GM crops on the continent. This review draws on research-based evidence as a basis to comment on some key issues to inform the development of biosafety standards in African countries. We conclude that the potential introduction of GM crops into small-scale farming would lead to huge consequences from emerging ecological, economic and trade impacts if these issues raised are not taken into account in decisionmaking processes.