Climate Change Affects On Plant-Pest- Natural Enemy Interactions.

Abstract

Climate change will alter the geographic distribution, abundance and relationships of many species in managed and natural systems.  This may prove catastrophic for some species unable to adjust to habitat change and unable to migrate to favorable areas.  In this paper I examine ways to characterize the climatic requirements for growth, survival and reproduction of plant and animal species and to analyze the effects of climate change on their dynamics, geographic distribution, abundance, and interactions with other species. Three approaches are reviewed: long term observations in nature, the climate envelope approach, and the use of physiologically based food web models that include the effects of biotic and abiotic factors on species dynamics and interactions.  The utility and limitations of the approaches are discussed.  

Physiologically based system models for alfalfa, cotton, grape, olive and the noxious weed yellow starthistle are used to examine the effects of observed weather and projected climate change on species in all trophic levels including the economic one. Observed daily weather (max-min temperatures, solar radiation, rainfall, RH, runs of wind) and climate model scenarios of daily weather are forcing variables in the model.  Regional analyses are performed by mapping the data using GIS (geographic information system), and marginal analysis of multi-variate regression model to estimate the major trends in model predictions. The effects of climate change on plant yield and phenology, pest distribution and damage potential, and the efficacy of biological control agents are examined.

 Improvements to enhance further the utility of the model systems include: (i.) refinement of models for soil water and nutrients, (ii.) access to a fine grid of long runs of daily historical and climate model weather data, and (iii.) additional biological data to test and improve the models.