Effects on community structure –
Work package 3

The multiple stress factors and seasonal patterns will affect the physiology of organisms and species in the ecosystem (WP 2). This may translate into changes in ecosystem functions e.g. the ability to compete for resources (WP4). The direct and indirect results of changes in physiological processes may be changes in spatial and temporal distribution of species, timing of phenological events, growth rates and consequently changes in community structure depending on the vulnerability of species. Hence, work package 3 is expected not only to give result of treatment and temporal effects on the structures per se, but also to form a functional link between the responses of individuals and the ecosystem responses as an aid for the synthesis in work package 5.

The objectives of WP3 are:

• To improve our understanding of how multiple stress factors e.g. warming, CO₂- enrichment and/or water availability will affect the relative abundance and growth patterns of individuals and the structure of plant, microbial and soil fauna functional groups and whole ecosystem communities.
   
  
• Determine the seasonal pattern in nutrient distribution in plant, soil, micro-organisms and soil fauna and how this is affected by multiple stress factors and changes in length of the growing season
   
  
• Link changes in plant, microbial, micro- and meso fauna community structure and biomass to climate changes. Link recovery rate of community structure following an extreme weather event to different climatic conditions.
  
  
• Determine resource allocation between growth and defense compounds in plants in response to multiple stresses.

Work package 3 consists of two major types of activities:

1. analyses of treatment and temporal effects on the relative abundance and growth patterns of individuals, the structure of plant, microbial and soil fauna communities, chemical structure of the ecosystem and on tissue and substrate chemical quality.
    
   
2. analyses of the “natural” temporal dynamics in the structures across the year and following discrete weather events, and how these characteristics are affected and modified by the changes we impose on the system.

The data of all analyses will be available in a common database so all measurements can be related to primary productivity and plant biomass, nutrient availability, ecosystem C, N and P pools and plant tissue and litter chemistry.