lec 19 & 20- ecosystems II Flashcards
what 3 elements can be limiting for plants?
phosphorous (P), nitrogen (N), and potassium (K)
what forms of nitrogen do plants use?
ammonia (NH3) and nitrate (NO3-)
what changes N into ammonia and other usable forms for plants?
Nitrogen fixing bacteria
where does phosphorus for plants and other organisms come from?
phosphorus comes from phosphorus rock as well as the weathering of rocks over time which results in the phosphorus to end up in soil
what does nutrient cycling help with?
helps with getting nutrients easier, such as nitrogen
what is the difference in distribution of nutrients in temperate and tropical biomes?
temperate = more nutrients in soil due to less detrivores, while less nutrients in plants
tropical = less nutrients in soil due to more detrivores, while more nutrients in plants
warm tropical environment better for detrivores
what is slash and burn agriculture and what are the effects?
in tropical forests, they burn trees and leave the ash on soil so the nutrients that were in the trees enter the soil and act as fertilizer for agriculture, but the nutrients in the soil only last for a few years and can be washed away
what is clear cut forestry and what are the effects?
in temperate forests, they cut the trees down for agricultural space, but this weakens the soil resulting in land slides and erosion
how do plants take up released nutrients from animals?
plants take up released nutrients in the form of poop from animals, recycling the overall nutrients
why are decomposers important to ecosystems?
they decompose organic matter which helps release nutrients into the environment
how do mycorrhizae (fungi) help plants?
-secrete enzymes into soil, mobilizing nutrients
- extend the volume of soil from which nutrients can be extracted
when is mycorrhizae fungus the most important for plants?
when a limiting element is absent, it can help it grow better
where does nutrient recycling in oceans come from?
- regeneration from sediments and deep-water layers
- consumer-based recycling (zooplankton)
what is the difference in nutrient cycling in lakes when compared to oceans?
lakes and ocean nutrients cycling is the same, apart from regeneration from sediments and consumer-based recycling depending on thermal stratification in lakes
what is thermal stratification of lakes and where does nutrient mixing work best?
the layers of lakes by decreasing depth where the top layer is warmer, middle is in-between and the bottom is the coolest, nutrient mixing works best at different temp gradients rather than one solid temp throughout
what drives the distribution of primary producers in aquatic ecosystems?
thermal stratification
what elements control primary productivity in grassland, forest/shrubland, and tundra?
grassland: both nitrogen and phosphorus are limiting, both are needed
forest/shrubland: nitrogen is a limiting factor, but both are best
tundra: phosphorus is most limiting then nitrogen, both are needed
what elements control algal NPP in oceans?
nitrogen is needed for the best NPP (silicon and iron can also be needed)
what element is needed for best NPP at bottom of lakes?
phosphorus
how much NPP from terrestrial ecosystems go to aquatic ecosystems?
50%
