Plant ecology
Photosynthesis is the process of a chemical reactions to create glucose and oxygen, which is vital for plant life.
At the same time, plants began removing carbon dioxide from the atmosphere, thereby initiating the process of controlling Earth's climate.
[1][7] First, most plants are rooted in the soil, which makes it difficult to observe and measure nutrient uptake and species interactions.
Working from herbarium collections, De Candolle searched for general rules of plant distribution and settled on using temperature as well.
[11]: 14–16 Grisebach's two-volume work, Die Vegetation der Erde nach Ihrer Klimatischen Anordnung, published in 1872, saw plant geography reach its "ultimate form" as a descriptive field.
[10]: 29 Starting in the 1870s, Swiss botanist Simon Schwendener, together with his students and colleagues, established the link between plant morphology and physiological adaptations, laying the groundwork for the first ecology textbooks, Eugenius Warming's Plantesamfund (published in 1895) and Andreas Schimper's 1898 Pflanzengeographie auf Physiologischer Grundlage.
Inspired by Warming's Plantesamfund, Arthur Tansley set out to map British plant communities.
[10]: 41 Cowles' students played an important role in the development of the field of plant ecology during the first half of the twentieth century, among them William S. Cooper, E. Lucy Braun and Edgar Transeau.
In order to show up, a species must either have evolved in an area or dispersed there (either naturally or through human agency), and must not have gone locally extinct.
The set of species present locally is further limited to those that possess the physiological adaptations to survive the environmental conditions that exist.
[13] Within biomes, there may be many ecological communities, which are impacted not only by climate and a variety of smaller-scale features, including soils, hydrology, and disturbance regime.
When plants grow in close proximity, they may deplete supplies of these elements and have a negative impact upon neighbours.
In principle, it is possible to examine competition at the level of the limiting resources if a detailed knowledge of the physiological processes of the competing plants is available.
In certain situations, plants may compete for a single growth-limiting resource, perhaps for light in agricultural systems with sufficient water and nutrients, or in dense stands of marsh vegetation, but in many natural ecosystems plants may be colimited by several resources, e.g. light, phosphorus and nitrogen at the same time.
This relationship seems to have its origins in beetles feeding on primitive flowers, eating pollen and also acting (unwittingly) as pollinators.
Although people are often fascinated by unusual examples, it is important to remember that in plants, the main mutualisms are mycorrhizae, pollination, and seed dispersal.
Parasites depend on another organism (their host) for survival in general, which usually includes both habitat and nutrient requirements at the very minimum.
[26] Many parasitic plants are generalists and are able to attack multiple hosts at the same time, greatly affecting community structures.
[28] An important ecological function of plants is that they produce organic compounds for herbivores[30] in the bottom of the food web.
A large number of plant traits, from thorns to chemical defenses, can be related to the intensity of herbivory.
These include removing selected species, creating gaps for regeneration of new individuals, recycling nutrients, and dispersing seeds.
Certain ecosystem types, such as grasslands, may be dominated by the effects of large herbivores, although fire is also an equally important factor in this biome.
Often such long term experiments show that herbivores have a significant effect upon the species that make up the plant community.
Parthenogenesis is defined as "a form of asexual reproduction in which genetically identical offspring (clones) are produced".
[33] Another form of reproduction is through cross-fertilization, which is defined as "fertilization in which the egg and sperm are produced by different individuals", and in plants this occurs in the ovule.
