Does Land Tenure Security Promote Manure Use by Farm Households in Vietnam?

Facing widespread poverty and land degradation, Vietnam started a land reform in 1993 as part of its renovation policy package known as “Doi Moi”. This paper examines the impacts of improved land tenure security, via this land reform, on manure use by farm households. As manure potentially improves soil fertility by adding organic matter and nutrients to the soil surface, it might contribute to improving soil productive capacity and reversing land degradation. Random effect regression models are applied to a panel dataset of 133 farm households in the Northern Uplands of Vietnam collected in 1993, 1998, and 2006. The results confirm that land tenure security has positive effects on manure use, but the levels of influence differ depending on whether the land has been privatized or whether the land title has already been issued. In addition, manure use is also influenced by the number of cattle and pigs, the education level and ethnicity of household heads, farm land size and non-farm income. The findings suggest that speeding up land privatization and titling, encouraging cattle and pig rearing, and improving education would promote manure use in farm production. However, careful interpretation of our research findings is required as land privatization, together with economic growth and population pressure, might lead to overuse of farm inputs.DF

Nutzerverhalten in elektronischen Medien : theoretische Grundlagen und eine Analyse am Beispiel des Lufthansa InfoFlyway

Der Einsatz elektronischer Medien im Marketing hat in den letzten Jahren stark an Bedeutung gewonnen. Neuere technische Anwendungen wie das Internet, kommerzielle Online-Dienste oder das interaktive Fernsehen bieten Unternehmen die Möglichkeit, sich gegenüber ihren Wettbewerbern zu differenzieren. So können bspw. Kunden direkt und individuell angesprochen, neue Märkte erschlossen sowie effizientere Organisationsformen realisiert werden. Unternehmen fast aller Branchen setzen neuere elektronische Medien zunehmend als Kommunikationsmittel und/oder Vertriebskanal ein. Gemeinsames Merkmal der Nutzung dieser Medien ist die Interaktivität, die Dialogfähigkeit der Anwendungen, welche die Rolle des Konsumenten im Kommunikations- und Informationsprozeß in entscheidender Weise verändert. Im Gegensatz zu der eher passiven Rolle des Rezipienten bei traditionellen Massenmedien verfügen Konsumenten bei interaktiven Medien über die Möglichkeit, den Kommunikationsprozeß zu steuern und aktiv mitzugestalten. Relevante Informationen können gezielt ausgewählt, individuell kombiniert und nicht erwünschte Informationsangebote umgangen werden. Grundlage einer erfolgreichen Integration interaktiver Medien in den Marketing-Mix von Unternehmen ist daher ein umfassendes Verständnis der Entscheidungsprozesse und -mechanismen des Konsumenten bei der Auswahl des Mediums und der Selektion von Informationsinhalten. Die Konsumentenverhaltensforschung leistet hierfür einen wichtigen Beitrag. Für die Erklärung des Konsumentenverhaltens spielt die Analyse von Motiven, die der Mediennutzung zugrunde liegen bzw. ihre Befriedigung durch Medien- und Informationsangebote eine wichtige Rolle. In Anlehnung an die von Csikszentmihalyi entwickelte Flow-Theorie können in diesem Zusammenhang intrinsische Motive, d.h. der für Flow charakteristische Aspekt der Freude bzw. des Vergnügens an der Ausübung einer Aktivität als wesentliche Determinante der Nutzung elektronischer Medien betrachtet werden

Evidence for alternative trapping strategies in two forms of the pitcher plant, Nepenthes rafflesiana.

Nepenthes pitchers are specialized leaves that function as insect traps. Several pitcher components may contribute to trapping, including the pitcher fluid, slippery wax crystals and downward-pointing epidermal cells on the inner pitcher wall, and the wetness-dependent pitcher rim (peristome), but the relative importance of these traits is unclear. Mechanisms of prey capture and retention in the field were investigated by quantifying the effect of 'knock-out' manipulations of individual pitcher structures, and by testing the ability of pitcher fluids and water to retain insects. Two forms of Nepenthes rafflesiana Jack ('elongate' and 'typical') with contrasting combinations of pitcher traits were compared. Wax crystals on the inner pitcher wall were found to be the most important trapping structure in the elongate form, whereas the typical form relied primarily on the peristome. The pitcher fluids of both forms, differing markedly in the degree of viscoelasticity, retained significantly more ants than water. The present results show that pitcher plants utilize several mechanisms for prey capture and retention, varying in efficiency and relative importance between forms. It is proposed that these differences represent alternative prey capture strategies that may provide a mechanism to reduce competition and facilitate species co-existence in nutrient-limited habitats

Disentangling the role of surface topography and intrinsic wettability in the prey capture mechanism of Nepenthes pitcher plants.

Nepenthes pitcher plants capture prey with leaves specialised as pitfall traps. Insects are trapped when they 'aquaplane' on the pitcher rim (peristome), a surface structured with macroscopic and microscopic radial ridges. What is the functional significance of this hierarchical surface topography? Here, we use insect pad friction measurements, photolithography, wetting experiments and physical modelling to demonstrate that the ridges enhance the trap's efficacy by satisfying two functional demands on prey capture: Macroscopic ridges restrict lateral but enhance radial spreading of water, thereby creating continuous slippery tracks which facilitate prey capture when little water is present. Microscopic ridges, in turn, ensure that the water film between insect pad and peristome remains stable, causing insects to aquaplane. In combination, the hierarchical ridge structure hence renders the peristome wettable, and water films continuous, so avoiding the need for a strongly hydrophilic surface chemistry, which would compromise resistance to desiccation and attract detrimental contamination.BBSRC (BB/I008667/1

An ecological perspective on water shedding from leaves

UB is funded by a Royal Society University Research Fellowship (UF150138) and Anne-Kristin Lenz is supported by a Royal Society Enhancement Award (RGF/EA/180059) held by UB.Water shedding from leaves is a complex process depending on multiple leaf traits interacting with rain, wind and air humidity, and with the entire plant and surrounding vegetation. Here, we synthesise the current knowledge of the physics of water shedding with implications for plant physiology and ecology. We argue that the drop retention angle is a more meaningful parameter to characterise the water shedding capacity of leaves than the commonly measured static contact angle. The understanding of the mechanics of water shedding is largely derived from laboratory experiments on artificial rather than natural surfaces, often on individual aspects such as surface wettability or drop impacts. In contrast, field studies attempting to identify the adaptive value of leaf traits linked to water shedding are largely correlative in nature, with inconclusive results. We make a strong case for taking the hypothesis-driven experimental approach of biomechanical lab studies into a real-world field setting to gain a comprehensive understanding of leaf water shedding in a whole-plant ecological and evolutionary context.Publisher PDFPeer reviewe

Disentangling the role of surface topography and intrinsic wettability in the prey capture mechanism of Nepenthes pitcher plants.

Nepenthes pitcher plants capture prey with leaves specialised as pitfall traps. Insects are trapped when they 'aquaplane' on the pitcher rim (peristome), a surface structured with macroscopic and microscopic radial ridges. What is the functional significance of this hierarchical surface topography? Here, we use insect pad friction measurements, photolithography, wetting experiments and physical modelling to demonstrate that the ridges enhance the trap's efficacy by satisfying two functional demands on prey capture: Macroscopic ridges restrict lateral but enhance radial spreading of water, thereby creating continuous slippery tracks which facilitate prey capture when little water is present. Microscopic ridges, in turn, ensure that the water film between insect pad and peristome remains stable, causing insects to aquaplane. In combination, the hierarchical ridge structure hence renders the peristome wettable, and water films continuous, so avoiding the need for a strongly hydrophilic surface chemistry, which would compromise resistance to desiccation and attract detrimental contamination.BBSRC (BB/I008667/1

How to catch more prey with less effective traps: explaining the evolution of temporarily inactive traps in carnivorous pitcher plants.

Carnivorous Nepenthes pitcher plants capture arthropods with specialized slippery surfaces. The key trapping surface, the pitcher rim (peristome), is highly slippery when wetted by rain, nectar or condensation, but not when dry. As natural selection should favour adaptations that maximize prey intake, the evolution of temporarily inactive traps seems paradoxical. Here, we show that intermittent trap deactivation promotes 'batch captures' of ants. Prey surveys revealed that N. rafflesiana pitchers sporadically capture large numbers of ants from the same species. Continuous experimental wetting of the peristome increased the number of non-recruiting prey, but decreased the number of captured ants and shifted their trapping mode from batch to individual capture events. Ant recruitment was also lower to continuously wetted pitchers. Our experimental data fit a simple model that predicts that intermittent, wetness-based trap activation should allow safe access for 'scout' ants under dry conditions, thereby promoting recruitment and ultimately higher prey numbers. The peristome trapping mechanism may therefore represent an adaptation for capturing ants. The relatively rare batch capture events may particularly benefit larger plants with many pitchers. This explains why young plants of many Nepenthes species additionally employ wetness-independent, waxy trapping surfaces

With a flick of the lid: a novel trapping mechanism in Nepenthes gracilis pitcher plants.

Carnivorous pitcher plants capture prey with modified leaves (pitchers), using diverse mechanisms such as 'insect aquaplaning' on the wet pitcher rim, slippery wax crystals on the inner pitcher wall, and viscoelastic retentive fluids. Here we describe a new trapping mechanism for Nepenthes gracilis which has evolved a unique, semi-slippery wax crystal surface on the underside of the pitcher lid and utilises the impact of rain drops to 'flick' insects into the trap. Depending on the experimental conditions (simulated 'rain', wet after 'rain', or dry), insects were captured mainly by the lid, the peristome, or the inner pitcher wall, respectively. The application of an anti-slip coating to the lower lid surface reduced prey capture in the field. Compared to sympatric N. rafflesiana, N. gracilis pitchers secreted more nectar under the lid and less on the peristome, thereby directing prey mainly towards the lid. The direct contribution to prey capture represents a novel function of the pitcher lid