Bio 109 L9 Ecosystems I: Biotic Networks

What are food web.

food web is a series of chains

Exaplin this graph

the rapid is the species that eats most of the vegetation (flowers,fruit,leaves) due to thick lign. And most of the spcies are eaten by Kiore. Thick lines = strong interaction.

What happened after Kiora erradicated.

Lizard introduction into the habitat. rats and rabbit eradication. lizards eating allot. preditory centipied killing invertebrates they are very dangerous. More predotry birds omming to the fore. seabird levels are low. not only preditory of their food competition.

what is light causing

it pervasive throughout the system impacting all species due to inbuilt biological clock being dirupted.

what does ALAN light at night impact (light polution)

chagnges how and when plants flower and grow

reduces food availability for herbitovurs

helps visual predetors detect prey

reduces nutrient cycling by soil digging nocturnal spp

disrupts circadian cycling and reproducitve cycle

Mutualism

both partener benefit from interaction.

example

plant seed disperer

plant pollinators

explain this graph

pollination and pollinators hevily dpepndent on one species which is the silverye bird species. much broader than food webs.

What word do we use know rather than food webs

ecological networks

why

because we study not just consumers but pollination aswell.

What are some disrumptions in biotic networks

Trophic cascade

What does it mean

a predator has a positive effect on primary producer species by reducing the abundance of a herbivore.

example

Wolves (top preditor) killing the primary producer (elk) causing fewer elks and increases the willow, aspen trees. Due to this their are more beavers.

another example

otter fur hunting trade.

humans are preditors reduced otters to low numbers and stopped killing kina. the increase in kinna caused kelp to be utterly destroyed.

What is a good anolagy

Some species are more important than others for biotic networks that if you map them around and if you do something with them and remove them, uh, then the system can collapse

What does this anotmy called

A keystone species.

Definition of key stone species

a species whose removal would produce a significant effect (extinction or large change in density) in 1 or more species).

what kan a keystone species be

a species that is a key food resource

top predator

key herbivore or detritivore

seed disperer/pollinator

An example of a bird and how

Kereu feeding on taraire fruit.

birds that can open their mouth wide and only species to disperse seeds. Karaka tare tawa are haavily relient on keraru. Low density of kereu = very low recruitment (seedling) of these species.

anither example

scale insect. kereu pases exess suger out of bum producing pure tree important for kanuka trees. the sugar causes native fornere to have food.

How else does scale insects help.

some trees infested by scale insects not seen before. Now 30 geckos per tree. it was important for food weBs. scale insects important for mainland but onyl in few places. also beenfitical for birds for sugars.

How much percentage of birds does nz and how much breed here.

39% of birds in new zealand and quater breed in nz

what makes seabirds keystone species

they are bringin marine neutrients into land. Burrowed birds dirtupts soil mixing soiling. pooing and regergitation food for kids. nutrients high and nitrogen ending up in these areas.

examples of where seabirds colonies

so main point

seabirds don’t have to be near the sea but inland aswell such as seaward kaikoura rangs birds colonising inland

what is most forests missing

neutrients from the birds system.

summary

pre human were very common - as far inland as mountains of te urewra and seawards kaikora ranges (still present).

Now due to humans largely confined in isalnds.

What are some threats seabirds are facing

Predatation -introcued mammals

Pollution - sea

CLimate change

declining fish stock

fisheries bycatch.

marin input

“new source” of nutrients from marine ecosystems brought into terrestrial ecosystems - energy flow.

seabirds also

result in rare plants and unsual plant communities. These plants can cope with high disturbance (trampling) and are very neutrient rich.

how does poo of seabird Guano prodvide nutrients

sustain invertebrate populations

this in turn supports reptile populations.

How does seabirds impact leaves

Due to seabirds being present it mean leaves has more nitrogen resulting in the survival of the plant.