ISSUES WITH PLANTS

Monocultures A monoculture where a large areas is planted with a single crop. This is required for industrial agriculture Planting in monocultures makes planting and harvestinf more efficient Monocultures have some drawbacks Reduce biodiversity over large areas All plants are genetically similar, they are vulnerable to the same diseases and pests

Pests We call organisms pest when it damages plants that are valuable to us We call a plant a weed when it competes with our plants

Chemical Pesticides To prevent crop losses people have developed thousands of chemical pesticides Since the 1900’s pesticide use has risen fourfold worldwide The ability of a pesticide to reduce a pest population often declines over time as the population evolves resistance to it As a result chemists are caught up in an “evolutionary arms race” with the pests they battle

Biological Pest Control Because pesticide resistance and health risks from some pesticides agricultural scientists increasingly battle pests and weeds with organisms that eat or infect them Bt Bacillus thuringiensis is a naturally occurring soil bacterium that produces a protein that kills many caterpillars and the larvae of some flies and beetles Introduced Predators and Parasites While this practice can be effective, it is sometimes unknown how the introduced species will interact with the ecosystem Benefits and Costs If the control works it will be permanent, require no maintenance and is environmentally harmless If the introduced species is invasive there will be many wide-ranged ecological impacts

Integrated Pest Management (IPM) Because both chemical and biological pest control approaches have their drawbacks, agricultural scientists and farmers have developed more complex strategist that combine the most useful aspects of each IPM may include biological pest control, close monitoring of populations, habitat alterations, crop rotation, reduced soil tillage, mechanical pest removal and chemical pest removal

Parasitic wasp larva feeding on a tomato hornworm caterpillar.

Pollinators Pollination is the process by which male sex cells of a plant (pollen) fertilize female sex cells of a plant. With out it plants can’t reproduce Some plants including corn and wheat are fertiltized by chance when male pollen lands on the female parts of the plant Plants with flowers, including fruiting plants are typically pollinated by animals such as insects, hummingbirds, and bats. These animals are referred to as pollinators The pollinator population is declining because of pesticide use, which threatens the yields in crops which require pollinators

Individual grains of pumpkin pollen hitch a ride on a honeybee

Pollinator Decline The term pollinator decline refers to the reduction in abundance of insect and other animal pollinators in many ecosystems worldwide during the end of the twentieth century. The value of bee pollination in human nutrition and food for wildlife is immense and difficult to quantify. 60 to 80% of the world’s flowering plant species are animal pollinated, and 35% of crop production and 60% of crop plant species depend on animal pollinators. It is commonly said that about one third of human nutrition is due to bee pollination. This includes the majority of fruits, many vegetables (or their seed crop) and secondary effects from legumes such as alfalfa and clover fed to livestock.

Genetically Modified Organisms (GMO’s) Scientist manipulate an organisms DNA is recombined with other DNA code for desired traits such as rapid growth, pest resistance and frost tolerance in plants Potential Risks Might be dangerous for people to eat Might create ‘superpests’ as pests become resistant to the modifications GM genes might ‘escape’ pollinating non-GM plants and harming them Potential Benefits Supporters believe GM crops have no ill effects on health, and are in fact beneficial for people and the environment Reduce the amount of pesticides and herbicides need to support the crop, thereby reducing emissions

Locally Supported Agriculture In developed nations, increasing numbers of consumers are supporting local small-scale agriculture, using farmers markets to interact. The average food product sold travels 2400km to market and is often chemically treated to preserve it during the long trip At farmers markets consumers can buy product from local farmers and support their local economy

Timber Harvest Timber companies use one or more of the following methods, clear cutting, the seed-tree approach, the shelterwood approach, or a selection system These methods fall into two categories: Even Aged Stands: result from the regrowth of trees cut down at the same time Uneven-aged: results from the regrowth of trees that were cut at different times

Clear-Cutting All the trees in an area are cut down Generally the most cost-efficient method, but has the greatest impact of forest ecosystems Results in even-aged stands of regrowth Can sometimes mimic natural disasters, but destroys or displaces entire communities, causes soil erosion

Seed-Tree and Shelterwood Approaches Seed-tree approach: small numbers of mature and healthy seed producing trees are left standing so they can reseed the area Shelterwood approach: small numbers of mature trees are left in place to provide shelter for seedlings as they grow Both methods are less harmful to forest communities Both lead to mostly even-aged regrowth

Selection Systems Only some of the trees are cut at once Single tree selection: trees spread widely apart are cut at one time Group selection: small patches of trees are cut Selection systems are not ecologically harmless Results in uneven-aged stands of trees

Deforestation Deforestation is the clearing of a forest and the replacement of it by another land use The negative effects are greatest in tropical regions because of the potential massive loss of biodiversity It adds carbon dioxide to the atmosphere in two ways: When plant matter is burned or decomposed Less vegetation remains to use CO 2

Sustainable Forestry Products Many organizations offer sustainable forestry certifications to products produced using methods they consider sustainable. Certified wood products carry logos of the certifying organizations Some national home-improvement stores now carry certified wood to consumers