Synthesizing the Ideas
Forest insect populations are influenced by environmental conditions such as climate change. In some cases, larger and more frequent insect outbreaks may occur, but in other cases recurring outbreaks may be disrupted or diminished. Shifts in temperatures can directly influence insects, as well as reduced host tree resistance caused by changes in precipitation can contribute to forest insect population growth. Rising CO2 can have important effects on insect pest problems. Recently, free air gas concentration enrichment (FACE) technology was used to create an atmosphere with CO2 and O2 concentrations similar to what climate change models predict for the middle of the 21st century. FACE allows for field testing of crop situations with fewer limitations than those conducted in enclosed spaces. During the early season, soybeans grown in elevated CO2 atmosphere had 57% more damage from insects than those grown in today’s atmosphere, and required an insecticide treatment in order to continue the experiment. Researchers have observed that insects sometimes feed more on leaves that have a lowered nitrogen content in order to obtain sufficient nitrogen for their metabolism. Increased carbon to nitrogen ratios in plant tissue resulting from increased CO2 levels may slow insect development.
Insects’ biodiversity is indirectly affected by the water quality too. Many of the rivers and streams have been dammed, had water pumped out, been diverted and waste discharged into them. Some of the rivers have been drained and cleared for agriculture, forestry, and urban development. This all leads to an increase amount of run off entering river and streams which affect water quality. Sewage discharges from town sewage treatment plants (STPs) or household septic tanks can cause diseases. Runoff from roads, roofs, areas popular for dog-walking to be the biggest water quality issues. From domestic households these include washings of cement, vehicles, paint, petroleum products and pesticides. Stream life can also be adversely affected by the altered flow regime in streams due to the high percentage of impervious surface in urban catchments. This causes increased bed and bank disturbance during and after rain, and reduced flows in dry periods.
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