nutrient cycling Flashcards
what are nutrients
nutrients are chemical compounds that all living organisms require to grow and survive
sources of nutrients
atmosphere
underlying geology
soil
transfer of nutrients
water
rainfall
soil moisture
what happens when these nutrients enter an ecosystem
nutrients are retained by a highly efficient recycling system (rainforest nitrogen recycling is 99% efficient)
nutrients move between biomass, litter and soil in an ecosystem.
some nutrients can be lost (output) from an ecosystem eg washing away the fertile soil or the migration of animals to another area.
nutrients are transferred between these 3 stores in a single cycle.
(go look at diagram)
what is litter
litter is accumulated dead organic material, normally found on soil surface
case study for a deciduous woodland ecosystem
Breen wood, Co Antrim
background of Breen Wood
- small remnant of natural woodland which has been continually wooded since at least 1600
- these areas of woodland cover less than 0.1% of NI
- its a SAC and 36 hectares, 6 miles from ballycastle
the abiotic environment of Breen wood
LOCATION = 400-600ft above sea level
RAINFALL = high annual rainfall 1,600mm
TEMPERATURE = mean monthly temperatures vary from 4 degrees in January, to 15 degrees in July
WEATHER = most days are cloudy and frosts are common during winter
- these climate conditions locally reduce the length of the growing season as to few as seven months
the wood is on a north-facing slope so…
there is limited quality and quantity of sunlight in the winter. the cold soil prevents trees obtaining the light and water they need for growth
- deciduous trees have adapted to the problem by shedding their leaves in autumn to reduce transpiration from there leaves
another factor limiting growth at Breen Wood is..
the poor quality of the soil
- the underlying parent rock is basalt. basalt is low in nutrients and as a result the soil tends to be thin, rocky and acidic, with a pH around 4.5
in addition, the rainfall quickly leaches nutrients from the top soil which precipitates its low nutrient status
- in this upland oak wood, increased leaching produces a podsol, which has a thin surface humus layer and the subsoil below has a bleached appearance.
as a result of this environmental factors…
the diversity of plants and animals is quite limited
- trees grow slowly and have a stunted appearance
- 200 year old oak trees have only reached half the height they would have attained in lower lying areas
the biotic environment of Breen Wood (autotrophs)
DOMINANT TREE SPECIES = oak
ANOTHER COMMON TREE = downy birch
SHRUB LAYER = smaller trees eg rowan, hazel and holly
FIELD LAYER = bilberry, bramble and ferns
SOIL SURFACE = great wood-rush, wood sorrel, mosses and ferns from a blanket cover
- fungi are common eg birch bracket and mosses, lichen and ferns cover the branches and trunks of dead and living trees
what will change the appearance of this deciduous woodland
seasons
early spring = sunlight reaches forest floor and for a few weeks bluebells and anemones flower
summer = complete leaf canopy restricts ground plant cover to grasses and ferns
heterotrophs (breen wood)
the harsh environment limits the amount of animal life
- insect species = 14 species of caterpillars, later butterflies (orange tip and speckled wood)
- herbivore = native red squirrel (larger grey squirrel is also present and threatens its future)
- birds = goldcrest, great blue and coal tits. gold crests are the smallest bird and eat insects from canopy
- carnivores = buzzards and sparrow harks (eat smaller birds)
- largest mammals = badger, stoat and fox. all are nocturnal. stoats are carnivores eating rodents, bird and eggs. foxes and badgers are omnivores. foxes eat birds and small mammals eg squirrels, grass and fruit.
badgers eat earth worms, small birds, fruit, nuts and plant bulbs
nutrient cycling in Breen Wood
- the harsh abiotic habitat of cool temps and acidic soils makes survival difficult from many species of soil organism
- few earthworks are found and so litter, like the autumn leaf fall, may take years to fully decompose and turn to soil
- the nutrient input from the underlying rock is low and so rainfall is the most important of nutrients
- the release of nutrients from litter to the soil store is slow
- due to autumn leaf fall a large flow form the biomass to the litter store does take place
- leaching of the nutrients move them down through the soil beyond the reach of plants. they leave the ecosystem in the small streams that drain the area
