sustainability

what are keystone species

species that hv an important role in maintaining the structure & function of an ecosystem

presence of absence of keystone species can hv a significant effect on the biodiversity of an ecosystem, as well as its stability

is also a species that helps define an entire ecosystem 

often regulate the population or abundance of other organisms 

could also be understood as a species with a unique niche that has a disproportionately large impact on an ecosystem

what’re some reasons that keystone species are so important in an ecosystem 

control populations to ensure balance in an ecosystem

modify existing habitats in a way that creates new habitats for other organisms, or in a way that allows for increased nutrient accessibility 

influence nutrient cycling & key ecosystem processes

are keystone species only carnivores or top predators

no, any species can be a keystone species

  • ex: bees are often regarded as a keystone species, as they are the world’s most important pollinator in ecosystems. They ensure the reproduction & survival of different plants, and other organisms depend on these plants for food

what happens if keystone species decline or are removed

since keystone species can regulate the abundance of a species (through predation, herbivory, or other interactions) removing the keystone species disrupts the balance in the food web

  • certain species may increase in abundance, which can ruin the delicate interactions between different species & plants

    • ex: sea otters - sea otters feed on sea urchins & control their population size. By controlling their population, sea otters help prevent overgrazing by the urchins, thus maintaining the health of the kelp forests. Kelp forests also capture CO2, so sea otters are indirectly helping mitigate the effects of climate change

      • if sea otters are removed, the population of the sea urchins will rapidly increase, which negatively affects the kelp forests, and thus the amount of CO2 they absorb. the forests also provide a shelter for many organisms, so an unhealthy kelp forest means fewer shelter and protection for organisms

what can keystone species do (in terms of habitat)

they can shape & modify the physical structure of their habitat

  • ex: beavers construct dams that alter water flow, which creates new habitats for other species

loss of keystone species = loss of the habitat modifications they provide, which affects resource availability & the different shelters for organisms

  • removal of beavers can result in decreased water availability during dry periods & increased vulnerability to drought conditions

  • the wetlands that form as a result of their water redirection, are also a habitat for many animals

nutrient cycling & ecosystem processes

example - some marine keystone species, such as sea otters & seagrass, play crucial roles in carbon sequestration & nutrient cycling

decline in the populations of these keystone species = imbalance in nutrient availability & biogeochemical cycles = effects the resilience of ecosystem

note as technology has developed & there’s been an increase in human populations, the act of harvesting from the wild has become complex

  • in some cases, the rate of harvesting has exceeded the natural renewable rate of the source, leading to overexploitation

what should be done to avoid overexploiting renewable natural resources

harvesting should be done sustainably

(the needs of the present generation should be met, but not in a way that compromises the needs of the future generation)

what does sustainable harvesting consider

the stability of ecosystems

if harvesting exceeds the natural renewing rate, then ecosystems will become unstable & less resilient

  • ex: teak trees are often sought after because they hv high durability & aesthetic appeal

    • they were not harvested in a sustainable way, which prevented the natural regeneration of teak trees, leading to the degradation of teak forests & a decrease in their productivity & health

what are the 4 principles of wildlife conservation that the International Union for the Conservation of Nature (IUCN) has proposed

  1. safety factor - a safety factor in terms of population size should be determined, as estimations aren’t perfect

  2. focus on entire community - there should be concern for the entire community of organisms & the renewable resources, not just focus on one species, which would be wasting other resources

  3. maintenance - the ecosystem should be maintained, so that there is minimal risk of irreversible change & long-term damage

  4. continual monitoring, analysis & assessment - application of science & investigation into the wildlife of interest & its ecosystem should be maintained & results should be available to the public

what are some of the most commonly used indicators to assess the sustainability of harvesting from the wild - check kognity for this (the Sustainability section)