Editing Botany (section)

== Plant ecology ==
{{Main|Plant ecology}}
[[File:Medicago italica root nodules 2.JPG|thumb|left|alt=Colour photograph of roots of Medicago italica, showing root nodules|The [[root nodule|nodules]] of ''[[Medicago italica]]'' contain the [[nitrogen fixation|nitrogen fixing]] bacterium ''[[Sinorhizobium meliloti]]''. The plant provides the bacteria with nutrients and an [[hypoxia (environmental)|anaerobic]] environment, and the bacteria [[nitrogen fixation|fix nitrogen]] for the plant.{{sfn|Campbell|Reece|Urry|Cain|2008|p=794}}]]
Plant ecology is the science of the functional relationships between plants and their [[habitat]]s&nbsp;– the environments where they complete their [[Biological life cycle|life cycles]]. Plant ecologists study the composition of local and regional [[flora]]s, their [[biodiversity]], genetic diversity and [[Fitness (biology)|fitness]], the [[adaptation]] of plants to their environment, and their competitive or [[mutualism (biology)|mutualistic]] interactions with other species.{{sfn|Mauseth|2003|pp = 786–818}} Some ecologists even rely on [[Empirical evidence|empirical data]] from indigenous people that is gathered by ethnobotanists.<ref name="TeachEthnobotany-2012">{{Citation|last=TeachEthnobotany|title=Cultivation of peyote by Native Americans: Past, present and future|date=2012-06-12|url=https://www.youtube.com/watch?v=xK5ZjSiIEGE| archive-url=https://ghostarchive.org/varchive/youtube/20211028/xK5ZjSiIEGE| archive-date=2021-10-28|access-date=2016-05-05}}{{cbignore}}</ref> This information can relay a great deal of information on how the land once was thousands of years ago and how it has changed over that time.<ref name="TeachEthnobotany-2012"/> The goals of plant ecology are to understand the causes of their distribution patterns, productivity, environmental impact, evolution, and responses to environmental change.{{sfn|Burrows|1990|pp = 1–73}}

Plants depend on certain [[edaphic]] (soil) and climatic factors in their environment but can modify these factors too. For example, they can change their environment's [[albedo]], increase [[Surface runoff|runoff]] interception, stabilise mineral soils and develop their organic content, and affect local temperature. Plants compete with other organisms in their [[ecosystem]] for resources.{{sfn|Addelson|2003}}{{sfn|Grime|Hodgson|1987|pp = 283–295}} They interact with their neighbours at a variety of [[spatial scale]]s in groups, populations and [[Community (ecology)|communities]] that collectively constitute vegetation. Regions with characteristic [[Holdridge life zones|vegetation types]] and dominant plants as well as similar [[Abiotic component|abiotic]] and [[Biotic components|biotic]] factors, [[climate]], and [[geography]] make up [[biomes]] like [[tundra]] or [[tropical rainforest]].{{sfn|Mauseth|2003|pp = 819–848}}

[[Herbivore]]s eat plants, but plants can [[plant defence against herbivory|defend themselves]] and some species are [[parasitic plant|parasitic]] or even [[carnivorous plant|carnivorous]]. Other organisms form [[mutualism (biology)|mutually]] beneficial relationships with plants. For example, [[mycorrhiza]]l fungi and [[rhizobia]] provide plants with nutrients in exchange for food, [[ant]]s are recruited by [[myrmecophyte|ant plants]] to provide protection,{{sfn|Herrera|Pellmyr|2002|pp = 211–235}} [[honey bee]]s, [[bat]]s and other animals [[pollinate]] flowers{{sfn|Proctor|Yeo|1973|p = 479}}{{sfn|Herrera|Pellmyr|2002|pp = 157–185}} and [[seed dispersal#Humans|humans]] and [[seed dispersal#Dispersal by animals|other animals]]{{sfn|Herrera|Pellmyr|2002|pp = 185–210}} act as [[dispersal vector]]s to spread [[spore]]s and [[seed]]s.

=== Plants, climate and environmental change ===
Plant responses to climate and other environmental changes can inform our understanding of how these changes affect ecosystem function and productivity. For example, plant [[phenology]] can be a useful [[proxy (climate)|proxy]] for temperature in [[historical climatology]], and the biological [[effects of climate change|impact of climate change]] and [[global warming]]. [[Palynology]], the analysis of fossil pollen deposits in sediments from [[geologic timescale|thousands or millions of years ago]] allows the reconstruction of past climates.{{sfn|Bennett|Willis|2001|pp = 5–32}} Estimates of atmospheric {{CO2}} concentrations since the [[Palaeozoic]] have been obtained from [[stomatal]] densities and the leaf shapes and sizes of ancient [[land plants]].{{sfn|Beerling|Osborne|Chaloner|2001|pp = 287–394}} [[Ozone depletion]] can expose plants to higher levels of [[Ultraviolet|ultraviolet radiation-B]] (UV-B), resulting in lower growth rates.{{sfn|Björn|Callaghan|Gehrke|Johanson|1999|pp = 449–454}} Moreover, information from studies of [[community (ecology)|community ecology]], plant [[systematics]], and [[taxonomy (biology)|taxonomy]] is essential to understanding [[climate change#Vegetation|vegetation change]], [[habitat destruction]] and [[endangered species|species extinction]].{{sfn|Ben-Menahem|2009|pp = 5369–5370}}