Plant ecology Flashcards
Plant ecology
The plant in its environment
Plants of the same species may have different fates depending on biotic and abiotic env
Typically grow as part of a population, populations of different species grow together in plant community
Each plant is affected by all other aspects of its immediate environment
- Landscape = continent, island, aspect
- Climate = temperature, rainfall
- Latitude and longitude = day length, seasons
- Soil = pH, nutrient status, salinity
- Other organisms = competitors and predators
Longer scale, periods of global warming alternate w ice ages, continents drift across surface of planet
Earth’s surface composed of rich and changing mosaic of diverse habitats, natural selection produced a wealth of species of plants, animals, fungi, protists and prokaryotes
Various adaptations for particular environmental aspects determines where they will survive and where they will be outcompeted by organisms that are better adapted
Plant populations
Plants growing together in population are synergistic
Populations can undertake sexual reproduction, individuals cannot – some plants reproduce vegetatively (asexually)
Individuals may produce pollen but not enough to sustain a pollinator unless growing in population
Do not exist in isolation
Coexist w populations of other plants, animals, fungi, protists and prokaryotes
All populations together = community
Community = characteristic of habitat
Community + physical, non-living environment = ecosystem
Plant habitat
Set of conditions in which an organism completes its life cycle
Abiotic and biotics
For migratory organisms, the winter and summer areas, and migration routes = habitat components
No plant migratory but portions of plants are including spores, pollen, fruits and seeds
Abiotic habitat components
Climate = critically important to all organisms, most species restricted to certain regions because of climatic conditions, climate has many components
- Temperature
- Rainfall
- Wind
- Humidity
Soil factors = soils formed by breakdown of rock, young soils are n deficient and sandy, most minerals locked in the rock matrix, little water holding capacity, variations in bedrock type result in varying soil pH e.g limestone = calcareous, sandstone = acidic
Pioneer species must tolerate severe conditions = usually associated w n fixing prokaryotes, pioneers improve soil quality, addition of dead material, after many years a thick soil results, distinct soil profile of 3 layers or horizons
Latitude contributes many factors = regions at high altitudes on mountain tops are similar to those at high latitude, high winds and poor soil, much or all of year is cold, short growing season, intense UV light
Disturbances such as fire, landslides, avalanches, floods = quickly produces significant change in ecosystem, affects biotic factors, fire natural and common component of many dry ecosystems, many plants of these regions are fire resistant as result of natural selection, thick bark or cones that only open after fire
Human disturbances increasing
Biotic habitat components
Plant itself influences habitat = in woodlands tress modify habitat by growing dense canopy of leaves, reduces light regime on woodland floor, early flowering spring plants must complete their life cycle before the canopy closes
Other plant species may be beneficial = mutualism, or disadvantageous = competition, sharing a limited amount of available light and nutrients leads to comp. in stable ecosystem comp is reduced since each species is specifically adapted to fill particular niche, many species overlap in their tolerance ranges
Organisms other than plants = animals, fungi, bacteria
Mutualism = animal receives nectar, pollen or fruit and plant benefits from their transfer e.g ants, acacias and herbivores
Commensalism = one species benefits, other unaffected e.g birds building nest
Predation = one species benefits, other suffers e.g herbivory
Many interrelationships between plants and fungi or bacteria are detrimental – pathogenic, also mutualistic
Ecosystems extremely complex, interactions between plants and other organisms are many and varied
Water voles = rodents that engineer their riparian and wetland habitats by creating
- Feeding stations of veg
- Latrines of faecal pellets
- Underground burrows
- Runways in bankside veg
Predation structure plant ecology
Geographic distribution of a plant species depends on its ability to disperse and ability to tolerate biotic and abiotic conditions in the new area
Many factors determine plant health at any one time = one can be limiting factor
Local geographic distribution
- Random = no obvious pattern
- Clumped = small or large spacing between individuals e.g seeds deposited in dung grow into localised patch
- Uniform = regular pattern e.g orchard or tree plantation. Not typical in nature but observed when plants release allelopathic chemicals
Age structure = demography. relative proportions of young, middle-aged and old individuals, affected by generation time and intrinsic rate of natural increase
Ecosystem structure plant ecology
Physiognomic structure = physical size and shape of the plants and their relation to each other and the physical env. Trees, shrubs, herbs
Raunkiaer’s life forms = classified according to their means of surviving stressful seasons
Species competition = number and diversity of species that coexists in an ecosystem. Depends on climate, soil, tolerance range: broad or narrow
Competition can be intense, but natural selection has resulted in habitat and niche partitioning. Each species occupies narrow portion of various resource gradients
Niche partitioning overcomes competition
Trophic levels = plants/algae base of food web
Plant biome
Earths land surface is covered w biomes; extensive groupings of many ecosystems characterised by the distinctive aspects of the dominant plants
Biomes vary from simple arctic tundra and deserts to complex grasslands, temperate forests and tropical rainforests
Complexity and physiognomy are most strongly influenced by 2 abiotic factors = climate and soil
A particular type may occur in various regions of earth – the same set of climatic and soil factors occur in these regions
Physiognomy is similar, but species composition varies greatly
Temperate grasslands = central plains of America, steppes of Russia, pampas of argentinia and veldt of Africa. All dominated by grasses and large animals and devoid of trees (except along rivers), each area has characteristic suite of species adapted to grassland niche, convergent evolution, independent development od beneficial traits
Geographic locations of earths biomes are determined by world climate and positions of continents, if either were different locations of biomes would be different. Both do change = cycles of cooling and warming and continental drift, past conditions different and likely to change in future
Plant biome and world climate
Effect of earths tilt – axis rotation tilted
Atmospheric distribution of heat, atmosphere develops convection currents, distributes heat from tropics to temperate regions and poles, hot air rises and draws in cold air underneath = wind
Continental climate = size of land mass influences the weather it receives, continents cause air to rise, cool and drop precip. If topography flat rain is evenly distributed, presence of mountains also important as causes rain shadow = decreased rain on landward side
Water flows in giant circular currents driven by air circulation patterns, ocean currents distribute heat from tropics to poles, as warm tropical surface water evaporates it increases air humidity
Regional climate determined by latitude = warm and humid at equator, cooler and drier towards poles, present position of todays continents determines biomes
Plant world biomes
- Moist temperate
- Dry temperate
- Polar
- Tropical
Regional extent determined by climate, classified according to physiognomy
