This exposure, of course, killed off large numbers of people, but those who survived tended to be much hardier and possessed much stronger immune systems. Therefore, when Europeans came into contact withnative Americans, they were like walking biological warfare weapons. Ultimately, these societies came to dominate their physical environments and excel in the development of technology; hence the “steel” and “guns” in Diamond’s title. It is a fact that after Europeans began arriving in the New World, they killed vast populations without firing a shot, thanks to the microbes they carried with them. Of course, it would be centuries before scientists discovered the existence of microorganisms.

Another important characteristic of ecosystems is total biomass, the dry weight of all the organisms living in it. Rain forests have more organisms per square meter and therefore more total biomass than other ecosystems, more even than the superproductive marshes. Today such places as the American Midwest support abundant agriculture, and one might wonder why that was not the case in the centuries before Europeans arrived. The reason is simple but subtle, and it has nothing to do with Europeans’ “superiority” over Native Americans. The fact is that the native North American ecosystems enjoyed far less biological diversity, or biodiversity, than their counterparts in the Old World. Peoples of the New World successfully domesticated corn and potatoes, because those were available to them.

When organisms die in aquatic systems, they sink to the ocean or lake floor where they are decomposed by bacteria, returning inorganic nutrients to the water for phytoplankton to use in photosynthesis. An ecosystem is the collection of organisms, or the biological community, that lives in a certain area as well as the physical components of the environment. The biological community includes all of the populations of animals, plants, fungi, and bacteria.

The widely spaced, scattered canopy trees allow light to penetrate and reach the ground. Because of that, shrub and herbaceous layers dominated by grasses are able to grow abundantly as well. Thus, the animals commonly found here are the grazers, such as sheep, cattle, and goats. This type of ecosystem often serves as a transition zone between forest and desert or grassland. Decomposers are the last group of organisms through which energy flows through. In essence, the ecosystem definition in biology is that it acts as the fundamental unit of nature.

Perhaps partially for that reason, ecologists have resisted applying the notion of “health” to ecosystems. Yet, ecosystems can become dysfunctional, particularly under chronic stress from human activity. For example, the discharge of nutrients from sewage, industrial waste, or agricultural runoff into lakes or rivers affects the normal functioning of the ecosystem, and can result in severe impairment. Excessive nutrient inputs from human activity was one of the major factors that severely compromised the health of the lower Laurentian Great Lakes and regions of the upper Great Lakes . Unfortunately, degraded ecosystems are becoming more the rule than the exception.

An ecosystem could be an entire rain forest, covering a geographical area larger than many nations, or it could be a puddle or a backyard garden. Even the body of an animal could be considered an ecosystem, since it is home to numerous microorganisms. On a much larger scale, detective pikachu research tasks the history of various human societies provides an instructive illustration as to the ways that ecosystems have influenced civilizations. Ecosystem services are the many and varied benefits to humans provided by the natural environment and from healthy ecosystems.

These activities also disrupt nutrient cycling, and cause the loss of biodiversity. This tutorial deals with the abiotic factors of the freshwater environment that determine what sort of life would be suited to living and adapting to the conditions of the ecosystem… If the balance of nature is left untouched, landscapes can change dramatically over time.