Trade-offs between vegetative growth and acorn production in Quercus lobata during a mast year: the relevance of crop size and hierarchical level within the canopy

The concept of trade-offs between reproduction and other fitness traits is a fundamental principle of life history theory. For many plant species, the cost of sexual reproduction affects vegetative growth in years of high seed production through the allocation of resources to reproduction at different hierarchical levels of canopy organization. We have examined these tradeoffs at the shoot and branch level in an endemic California oak, Quercus lobata, during a mast year. To determine whether acorn production caused a reduction in vegetative growth, we studied trees that were high and low acorn producers, respectively. We observed that in both low and high acorn producers, shoots without acorns located adjacent to reproductive shoots showed reduced vegetative growth but that reduced branch-level growth on acorn-bearing branches occurred only in low acorn producers. The availability of local resources, measured as previous year growth, was the main factor determining acorn biomass. These findings show that the costs of reproduction varied among hierarchical levels, suggesting some degree of physiological autonomy of shoots in terms of acorn production. Costs also differed among trees with different acorn crops, suggesting that trees with large acorn crops had more available resources to allocate for growth and acorn production and to compensate for immediate local costs of seed production. These findings provide new insight into the proximate mechanisms for mast-seeding as a reproductive strategy

Message Passing In A Distributed, Object-Oriented Condition Monitoring And Maintenance Planning System

This paper describes some aspects of a software development toolkit for industrial condition monitoring and maintenance planning applications. The toolkit consists of a graphical Workbench for design and debugging, an Instancer for creating and re-configuring an application and a run-time system for supporting message passing. The software architecture of an application is a distributed system and the object-oriented approach used allows the decoupling of the structure of an application from the implementation of its components, thus promoting object re-use and application re-configurability. The main focus of this paper is on the implementation of the run-time system. 1 Introduction The development of effective maintenance strategies has a high priority in manufacturing and process industries. The need for such a strategy becomes increasingly critical with the continued introduction of advanced technologies in a bid to improve the cost effectiveness of production. Such advanced manu..