Trees with anisohydric behavior as main drivers of nocturnal evapotranspiration in a tropical mountain rainforest.

This study addresses transpiration in a tropical evergreen mountain forest in the Ecuadorian Andes from the leaf to the stand level, with emphasis on nocturnal plant-water relations. The stand level: Evapotranspiration (ET) measured over 12 months with the Eddy-Covariance (ECov) technique proved as the major share (79%) of water received from precipitation. Irrespective of the humid climate, the vegetation transpired day and night.

Biodiversity and ecosystem functions depend on environmental conditions and resources rather than the geodiversity of a tropical biodiversity hotspot.

Biodiversity and ecosystem functions are highly threatened by global change. It has been proposed that geodiversity can be used as an easy-to-measure surrogate of biodiversity to guide conservation management. However, so far, there is mixed evidence to what extent geodiversity can predict biodiversity and ecosystem functions at the regional scale relevant for conservation planning.

A research framework for projecting ecosystem change in highly diverse tropical mountain ecosystems.

Tropical mountain ecosystems are threatened by climate and land-use changes. Their diversity and complexity make projections how they respond to environmental changes challenging. A suitable way are trait-based approaches, by distinguishing between response traits that determine the resistance of species to environmental changes and effect traits that are relevant for species' interactions, biotic processes, and ecosystem functions.

Accounting for multiple ecosystem services in a simulation of land-use decisions: Does it reduce tropical deforestation?

Conversion of tropical forests is among the primary causes of global environmental change. The loss of their important environmental services has prompted calls to integrate ecosystem services (ES) in addition to socio-economic objectives in decision-making. To test the effect of accounting for both ES and socio-economic objectives in land-use decisions, we develop a new dynamic approach to model deforestation scenarios for tropical mountain forests.

Access and benefit sharing--The perspective of basic research.

Background: With the adoption of the Convention on Biological Diversity (CBD) the 196 member countries have agreed that organisms and their derivatives are the property of the country of their origin (CBD Art.3, Art 15). While the spirit of the CBD is generally acknowledged, the ownership causes considerable problems, last not least for research which by the CBD is considered as "use of genetic (=biological) resources" (GR).

Who will win where and why? An ecophysiological dissection of the competition between a tropical pasture grass and the invasive weed Bracken over an elevation range of 1000 m in the tropical Andes.

In tropical agriculture, the vigorously growing Bracken fern causes severe problems by invading pastures and out-competing the common pasture grasses. Due to infestation by that weed, pastures are abandoned after a few years, and as a fatal consequence, the biodiversity-rich tropical forest is progressively cleared for new grazing areas. Here we present a broad physiological comparison of the two plant species that are the main competitors on the pastures in the tropical Ecuadorian Andes, the planted forage grass Setaria sphacelata and the weed Bracken (Pteridium arachnoideum).

Compositional diversity of rehabilitated tropical lands supports multiple ecosystem services and buffers uncertainties.

High landscape diversity is assumed to increase the number and level of ecosystem services. However, the interactions between ecosystem service provision, disturbance and landscape composition are poorly understood. Here we present a novel approach to include uncertainty in the optimization of land allocation for improving the provision of multiple ecosystem services.

Afforestation or intense pasturing improve the ecological and economic value of abandoned tropical farmlands.

Increasing demands for livelihood resources in tropical rural areas have led to progressive clearing of biodiverse natural forests. Restoration of abandoned farmlands could counter this process. However, as aims and modes of restoration differ in their ecological and socio-economic value, the assessment of achievable ecosystem functions and benefits requires holistic investigation.

Influence of root-bed size on the response of tobacco to elevated CO2 as mediated by cytokinins.

The extent of growth stimulation of C3 plants by elevated CO2 is modulated by environmental factors. Under optimized environmental conditions (high light, continuous water and nutrient supply, and others), we analysed the effect of an elevated CO2 atmosphere (700 ppm, EC) and the importance of root-bed size on the growth of tobacco. Biomass production was consistently higher under EC.

Model parameterization to simulate and compare the PAR absorption potential of two competing plant species.

Mountain pastures dominated by the pasture grass Setaria sphacelata in the Andes of southern Ecuador are heavily infested by southern bracken (Pteridium arachnoideum), a major problem for pasture management. Field observations suggest that bracken might outcompete the grass due to its competitive strength with regard to the absorption of photosynthetically active radiation (PAR). To understand the PAR absorption potential of both species, the aims of the current paper are to (1) parameterize a radiation scheme of a two-big-leaf model by deriving structural (LAI, leaf angle parameter) and optical (leaf albedo, transmittance) plant traits for average individuals from field surveys, (2) to initialize the properly parameterized radiation scheme with realistic global irradiation conditions of the Rio San Francisco Valley in the Andes of southern Ecuador, and (3) to compare the PAR absorption capabilities of both species under typical local weather conditions.

Specific and unspecific responses of plants to cold and drought stress.

Different environmental stresses to a plant may result in similar responses at the cellular and molecular level. This is due to the fact that the impacts of the stressors trigger similar strains and downstream signal transduction chains. A good example for an unspecific response is the reaction to stressors which induce water deficiency e.

Soil-plant hydrology of indigenous and exotic trees in an Ethiopian montane forest.

Fast-growing exotic trees are widely planted in the tropics to counteract deforestation; however, their patterns of water use could be detrimental to overall ecosystem productivity through their impact on ecosystem water budget. In a comparative field study on seasonal soil-plant water dynamics of two exotic species (Cupressus lusitanica Mill. and Eucalyptus globulus Labill.

Plant resistance to cold stress: mechanisms and environmental signals triggering frost hardening and dehardening.

This introductory overview shows that cold, in particular frost, stresses a plant in manifold ways and that the plant's response, being injurious or adaptive, must be considered a syndrome rather than a single reaction. In the course of the year perennial plants of the temperate climate zones undergo frost hardening in autumn and dehardening in spring. Using Scots pine (Pinus sylvestris L.

The extra loop distinguishing POR from the structurally related short-chain alcohol dehydrogenases is dispensable for pigment binding but needed for the assembly of light-harvesting POR-protochlorophyllide complex.

We have recently discovered a protochlorophyllide (Pchlide)-based light-harvesting complex involved in chlorophyll a biosynthesis. This complex consists of the two previously identified NADPH:protochlorophyllide oxidoreductases (PORs), PORA and PORB, their natural substrates (Pchlide b and Pchlide a, respectively), plus NADPH. These are all held together in a stoichiometry of five PORA-Pchlide b-NADPH complexes and one PORB-Pchlide a-NADPH complex in the prolamellar body of etioplasts.

Microclimate and ecophysiological significance of the tree-like life-form of Lobelia rhynchopetalum in a tropical alpine environment.

The microclimate and the adaptive significance of the tree-like plant life-form for growth in a tropical alpine environment was investigated with the pachycaul arborescent giant rosette plant, Lobelia rhynchopetalum (Hochst. A. Rich.