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| The experimental concept of SFB 607 |
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The experimental concept is being pursued on economic plants from forestry and agronomy, namely Norway spruce, European beech, apple, grass and legume species, potato and barley. This selection of contrasting plant species is gathering disciplines from basic and applied biological sciences like molecular biology, biochemistry, ecophysiology, phytopathology, mycology, zoology, soil ecology, climatology, pasture and silvicultural yield sciences as well as modeling. By this, scientists from agricultural and forest sciences are collaborating, within an interdisciplinary cooperation of 20 projects (cf. Fig. 1), on the investigation of a basic research question of common interest, i.e., the control of resource allocation as a central feature of individual plant fitness. This kind of collaboration within a large-scale research initiative represents - world-wide - a novum in the field of applied, biological research. The selection of plant species provides, in addition, the scientific perspective of examining the regulatory mechanisms of resource allocation for the extent of general validity, regardless of the plant life form - i.e., the herbaceous or woody growth habit.
For achieving this latter aim, the individual plant is the focal point in the research of SFB 607, with the internal process integration reaching from the molecular through the organ up to the whole-plant level. This kind of scaling is extended towards the external scale of the stand level, where the individual plant is regarded as the determinant of the resource fluxes involved in competitive interactions. Hence, the individual plant forms an 'interface' in linking internal to external resource partitioning.
Experimental scenarios are being created to induce 'conflicts' in resource allocation, given through contrasting levels, in particular, of light and nutrient supply as well as chronic exposure to elevated ozone and/or CO2 regimes. These latter gases are not being regarded as agents of forest decline or global-change scenarios, but as driving forces (together with light and nutrition) to perturb, in antagonistic or synergistic ways, the control in resource allocation. Such an approach is expected to facilitate the unraveling of the underlying, regulatory mechanisms. These abiotic settings provide the stage for analyzing the biotic interactions, given through intra and inter-specific competition and impacts by fungal pathogens, phytophagous insects, mycorrhizospheric organisms and biomass removal through grazing.
The experiments are being performed both under controlled and field conditions, in phytotrons and glasshouses, 'open-air' lysimeters and field plantations as well as managed pasture systems and old-growth forest stands. In the latter case, a novel 'free-air' ozone fumigation system has been developed (HÄBERLE et al. 1999; KARNOSKY et al. 2001; WERNER & FABIAN 2002; NUNN et al. 2002) to impose ozone as a disturbant, at the canopy level, on the competitive interactions between 10 neighboring, mature forest trees (with other trees in unchanged air serving as a 'control'). Therefore, two further kinds of scaling - besides that mentioned above between the molecular and stand level - are being achieved by SFB 607, i.e., from controlled to field conditions, and across different stages in plant ontogeny (in particular, young and old trees).
The experiments are designed in a complimentary way to each other:
(1) analysis of forest and pasture plants (including interactions with the mycorrhizosphere) under their corresponding stand conditions in order to gain mechanistic, resource-related insight into competitiveness;
(2) analysis of host/parasite relationships in fruit trees (apple) and agricultural plants for deriving hypotheses to be tested in pasture and forest systems; and
(3), analysis of experimental settings with pasture or forest systems in which pathogenic impact (or herbivory) interferes with the competitive relationships between the plants.
This latter integration is being backed by both modeling and findings from the former two kinds of analysis on mechanisms which are relevant in resource sequestration and retention. By means of this complementary experimentation, the cost/benefit balances for conceiving individual plant fitness in mechanistic terms become accessible.
There are three main lines of analysis and integration in SFB 607 (cf. Fig. 1 ):
(1) clarification of central mechanisms in the control of resource allocation as reflected by molecular, biochemical and physiological processes - representing the common basis of resource sequestration and retention. Processes at this basis may directly control the efficiency parameters in plant competitive behavior as defined above, being of relevance for the understanding of the 'plant-plant interactions' in a mechanistic way. Plant competitiveness (i.e., capacity and efficiency in resource sequestration) may be influenced, in addition, by interactions with
(2) the mycorrhizosphere and
(3) parasites (pathogens, herbivory) - two kinds of biotic impact linked in-between the basic mechanisms in resource allocation and the competitive performance of the plant.
The resource-based clarification of mechanisms in 'plant-mycorrhizosphere' and 'plant-parasite' interactions are, therefore, inherent aims of SFB 607, altogether with the analysis of their functional cross-links which may be mediated - again - through the basic regulatory mechanisms. Both of these latter kinds of interactions need to be understood in terms of their relevance for the competitive behavior of plants.
It is the 'plant-parasite' interactions which, in particular, determine the capacity in resource retention and, thus, the second major component in individual plant fitness. Linked in-between these lines of integration is modeling (together with projects of coordination and central data management; cf. Fig. 1). Two modeling concepts are being pursued in SFB 607 - one for the analysis of processes reflecting the competition for resources within the plant ('Division A'), and one for analyzing the competition for resources of plants in stands ('Division B'). These concepts interact with the experimental approaches in a way to examine and further develop the guiding hypotheses of SFB 607 and to locate missing experiments for clarifying 'black boxes' in the 'cost/benefit' balances of resource allocation. Thus, modeling is being regarded as an analytical rather than prognostic tool in relation to plant responses that assists in mathematically depicting, testing and further developing the functional understanding of allocation.The experimental concept is being pursued on economic plants from forestry and agronomy, namely Norway spruce, European beech, apple, grass and legume species, potato and barley. This selection of contrasting plant species is gathering disciplines from basic and applied biological sciences like molecular biology, biochemistry, ecophysiology, phytopathology, mycology, zoology, soil ecology, climatology, pasture and silvicultural yield sciences as well as modeling. By this, scientists from agricultural and forest sciences are collaborating, within an interdisciplinary cooperation of 20 projects (cf. Fig. 1 ), on the investigation of a basic research question of common interest, i.e., the control of resource allocation as a central
feature of individual plant fitness. This kind of collaboration within a large-scale research initiative represents - world-wide - a novum in the field of applied, biological research. The selection of plant species provides, in addition, the scientific perspective of examining the regulatory mechanisms of resource allocation for the extent of general validity, regardless of the plant life form - i.e., the herbaceous or woody growth habit. For achieving this latter aim, the individual plant is the focal point in the research of SFB 607, with the internal process integration reaching from the molecular through the organ up to the whole-plant level. This kind of scaling is extended towards the external scale of the stand level, where the individual plant is regarded as the determinant of the resource fluxes involved in competitive interactions.
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