Life on Earth References

• Illustrates the relationship that human activities have a profound contribution to species extinction

• As the human population grows, species extinction advances in a similar trend

Umesh Babu & Nautiyal, 2015

• The financial system underpins our engagement with nature so changing economic models could stop biodiversity loss

• Financial systems act as an extractive force of nature causing ecosystem decline

• There should be an effort to integrate nature and the financial system to stop species extinction

Atkins & Macpherson (eds.), 2022

• Land use is becoming a global issue driven by needs to provide food, water and sheller to the growing population

• Expansion of croplands and pasture associated with expansion of fertiliser and irrigation lead to salinisation, overgrazing, soil erosion and loss of habitats

• The water balance and water cycle is being disrupted causing droughts, a falling water table, oxygen depletion, blooms and waterborne diseases

• Forests are being lost, net radiation is changing to impact climate as well as transmissions of infectious diseases

• We must assess tradeoffs between human welfare and ecosystems to inform policy action

Foley et al., 2005

• As global agriculture and urban areas hit 5 million hectares, habitat sizes decrease by nearly 20% due to the expansion of human activities

Beyer & Manica, 2020

• There is now an argument for the sixth mass extinction event driven by humans with habitat loss being the biggest problem for biodiversity

• Human predation is an issue as well as introduced species becoming predators, disrupting food webs, pollination, outcompeting native species, hybridisation and genetic dilution

• Disease is also a threat and all are exacerbated by globalisation

Whittaker & Fernandez-Palacios, 2007

• Steep declines are seen in wildlife populations with habitat loss driven by the food system as the main threat

• There is little progress in delivery of global agreements or urgency when we must work collaboratively to transform food, energy and financial systems

• Cumulative impacts of biodiversity loss can trigger larger, faster changes that become self-perpetuating when they reach a tipping point

• Food production is causing habitat loss, unsustainable water usage in land and oceans; energy use is also a main driver of climate change and air pollution

• Economic activities are having large impacts

WWF & ZSL, 2024

• The UK is now one of the most nature-depleted countries on Earth with huge threats on land, oceans and in peatlands

• Agriculture is seeing fertiliser use peak along with overfishing and disease becoming bigger threats

• In Wales, vascular plants show consistent declines due to conversion of grasslands and ammonia emissions kill lichens

• In Scotland, warmer summers and more frequent droughts see species become intolerant of new climates, herbicides see vascular plants decline ad sea pressure put pressure on plankton communities

State of Nature, 2023

• A behaviourally mediated trophic cascade in Yellowstone theorised that as wolves were reintroduced the elk would avoid the risky foraging areas and allow the aspen to regenerate

• The data found that the risk of woolf predation alone was unlikely to alter the degree to which the elk limited aspen, the elk population would have to decline in order to allow the aspen to regenerate

Kauffman et al., 2010

• Ecosystems regulate the Earth’s biogeochemical processes and are key to it’s survival, but human impacts are causing declines in biodiversity and subsequent shifts in the assembly and functioning of ecosystems

• Higher levels of biodiversity act as insurance against environmental fluctuation as they act as a buffer

• The effects of losses on productivity are most felt on small-intermediate scales

• The impacts of diversity loss can impact multiple trophic levels

• A larger number of species is required within ecosystems to ensure stability and biogeochemical stability

Loreau et al., 2001

• Consensus that biodiversity loss reduces efficiency of ecosystems, reduces stability, leads to accelerating change, loss of productivity and can be seen across multiple trophic levels to see extinctions more probable

• Multi-functionality of ecosystems is also threatened by biodiversity loss

• Biodiversity has strongly been correlated with provisioning and regulating services such as fishing yields in the past, we must build on what we know to reduce uncertainties and better serve policy and management

Cardinale et al., 2012

• Biodiversity encompasses all living things currently existing on Earth and is useful as it provides food, materials, medicines and support systems to humans

• It can also be seen as an aesthetic thing for enjoyment

• The defining characteristic of the Anthropocene is enormous species loss and habitat degradation caused by human activities

Cox et al., 2016

• Large wild herbivores are crucial to ecosystems but face dramatic population declines as they are threatened by hunting, land use charges and resource deprivation; their loss can have cascading effects so conservation is key in stalling losses

• Large herbivores act as ecosystem engineers, sources of food, facilitators of life for other herbivores, seed dispersers, nutrient cyclers, control the fire regime, allow small animals to exist as well as being important for human food supplies and tourism related jobs and incomes

Ripple et al., 2015

• The effect of decreasing species richness is to decrease the abundance of the focal group leading to less complete depletion of the resources used by that group

• This influences fluxes of energy within ecological processes so can decrease productivity

• Some species exert stronger controls than others, in very diverse ecosystems this is hard to identify

Cardinale et al., 2006

• Ecosystem ecology addresses the interactions between organisms and their environments as an integrated system to realise the true role of species and ecosystem functioning in supporting human welfare

• Globalisation is seeing biological invasions increase to see Earth’s biota homogenising to alter ecosystems

• Human activities can introduce novel chemicals into the environment which shift feedbacks and often the services human communities depend on

• We must manage and protect ecosystem functions to continue to extract human services from them

Chapin et al., 2002

• The advantage of species diversity has long been seen in improving stability of yields

• There are functional characteristics in ecosystems that are particularly important such as nitrogen fixing legumes

• Within ecosystems there is the idea of the trophic cascade which can make the impacts of losses hard to predict

• Biodiversity allows for multi-functionality as well as stability through the buffer concept, portfolio effect or compensatory dynamic effect

Wilby & Hector, 2008

• The loss of apex predators is a cascading problem due to the impact of top-down forcing on global ecosystems

• The new extinction event is characterised by humans and sees the loss of larger bodied apex predators globally

• It is now understood that there is much connectivity within ecosystems and the trophic cascade has been documented in almost all the world’s major biomes

• The loss of apex predators will have impacts on wildfires, disease, physical and chemical natures of the biosphere, soils, water, the atmosphere, species invasion and further biodiversity loss

• The loss of native apex predators can be understood as the ultimate driver of ecological change

Estes et al., 2011

• Food webs have undergone steep regional declines in complexity through loss of links after the expansion of humans in the Late-Pleistocene

• Extinctions have been the main driver of food web complexity loss as well as participatory species

• In areas where food webs are threatened, endangered species loss would decrease links further as they are often key to food web preservation

• It is possible to recover food web complexity through natural recolonisation and reintroduction of historic ranges

Fricke et al., 2022

• There is evidence humans began playing a role in extinctions in the Late-Pleistocene around 10,000-50,000 yeas ago

• In this time hominins first appeared in Africa but had very little impact on large herbivores

• Expanding grasslands, declining CO2, fires, pathogens and competing species seem to have played major roles in African megafaunal decline; the role of humans is unclear

Bobe & Carvalho, 2018

• Plant and fungal research is key to achieving many of the SDGs

• Documenting and describing them is key in protecting these species, they can also be seen as possible sources of food and medicine as well as possible losses being projected into the future

• We can alter traits of plants to improve efficiency and identify overlooked sources of food, energy and healthcare

• There are efforts to decolonising similar research and encourage more collaboration and equitable implementation of policy

Antonelli et al., 2020

• The 30×30 target is key to ensuring survival of the planet against biodiversity loss

• The right areas must be chosen and this should come from understanding the importance of all species

• Monitoring should be focused and to core standards as well as all stakeholders being involved to see collaboration fight biodiversity loss

Antonelli, 2023

• Identifying priority areas for biodiversity is key for directing conservation resources, there is a need to reassess global allocation of these resources as knowledge on global patterns of biodiversity improves

• Species richness is globally uneven in all species including those with small range sizes, there are broad similarities but the most effective efforts would focus on specific land parcels

• Birds and mammals are generally concentrated in moist tropical forests with small ranged species being more specific 

• Areas of priority for conservation do not overlap, the most effective conservation would rely on small ranged species centres of diversity as they are very concentrated and many are endemic so face large risks of extinction

Jenkins et al., 2013

• The tropics contain many more species of plants and animals than higher latitudes, this may be due to the diet of animals

• For plants, they need sunlight so the energy hypothesis shows that species richness is correlated by to how much energy is captured by the vegetation; this is in terms of sunlight and evapotranspiration

• For animals higher productivity and greater structural complexity resulting from higher biomass is key as this supports many smaller species

• Aphids provide an anomaly to the latitudinal biodiversity gradients and some argue this is simply due to the tropics having a higher land area

Cox et al., 2016

• Hotspots must be protected as they have endangered habitats that are home to numerous endemic species; there are 25 hotpots covering 2% of Earth’s surface but representing 50% of terrestrial species diversity 

• The Tropical Andes Hotspot has the most diverse vascular plants, the Mesoamerica Hotspot the greatest diversity of amphibians, the most important island hotspot is Cuba and the California Floristic Province Hotspot is one of the few located within the borders of a developed country

• Across all sites, the Caribbean, Philippines and Madagascar are considered priority hotspots due to high levels of endemism but have lost many natural forests in recent years

• The majority of hotspots are located in countries where poverty is rampant and human density is expanding complication efforts to preserve habitats

Mittermeier et al., 2002

• The species-area relationship states that larger areas tend to support more species due to having greater habitat diversity and lower extinction rates

• More isolated areas tend to have lower species richness due to lower immigration rates to the island

Whittaker & Fernandez-Palacios, 2007

• Communities are distributed due to dispersal constraints, environmental constraints and internal dynamics and the results are measured in terms of species richness

• Gradient analysis, classification and ordination can be useful in understand species patterns in spaces but boundaries are not always clear

• Community patterns also occur in time if a species is capable of reaching a location, appropriate conditions exist there and predators do not preclude it; these community changes follow disturbances and can be primary or secondary succession

• Succession can be explained by competition-colonisation trade-off, successional niche mechanisms, facilitation, interactions with enemies, resource-ratio hypothesis, vital attributes, the role of animals and will eventually result in a polyclimax

• Patch dynamics also see a landscape as made up of patches of communities, this is formed by disturbance and migration between patches

Begon et al., 2006

• Passive rewildings refers to spontaneous development of ecosystems without direct intervention such that abandoned land restoration occurs via natural succession

• This has advantages in preserving native plant genotypes, avoiding pests and diseases on imported saplings, better resilience to drought and reduced management costs but will see some species out competed and habitats lost

• Evidence from monitoring passive rewilding in New Wilderness and Old Wilderness in England see that New Wilderness gained 86% vegetation cover after 23 years and Old Wilderness 100% cover averaging 13.1 metres tall after 53 years

• The species compositions different from ancient woodlands and tree colonisation was spatially clustered due to wind-dispersed seeds and clusters of oak resulting from hoarding of birds and animals

• This provides long term reference data to inform predictions of further passive rewilding in temperature Europe as closed-canopy woodlands can readily establish due to natural succession

Broughton et al., 2021

• Ecological release occurs when a species colonising an island encounters a biotic environment in which competition is absent so their niche expands

• This may mean a larger realised niche without changes to the fundamental niche, but can also be character release where an increased variance of genetically coded features such as beak morphology occurs e.g. finch species in Hawaii

• Changes in niche breath can b accompanied by a loss of defensive traits, this may contribute to the demise of an island species as it lacks fear and cannot flee from humans or predators 

• Ecological release may lead to adaptive radiation where the species evolves into multiple new species 

• Density compensation also occurs when a lower area-adjusted species richness raises increased population sizes per area linked to the expansion of niche spaces leading to density overcompensation

Whittaker & Fernandez-Palacios, 2007

• Invasive rats are one of the world’s most successful animal groups causing native species extinctions and ecosystem change particularly on islands

• They have now been introduced by humans to over 80% of the planet’s islands and impact the environments through opportunistic foraging and preying on plants, birds, reptiles and invertebrates

• Rate eradication is often impossible but population control is routinely carried out on many islands as a management tool

• There is a need to expand rat control distribution especially in biodiversity hotspots, improvement of methods is needed as well as regular monitoring to assess short and long term effectiveness

Duron et al., 2017

• Darwin’s travels on HMS Beagle taught him that islands are an important source of evidence for evolution as they are young and have relatively few species, evolutionary adaptation and species proliferation are obvious and easy to study

• They are also isolated allowing evolution to take its own course free of influence resulting in unusual faunas and floras unlike those found anywhere else

• Island research provides valuable insight into speciation and adaptive radiation

Losos & Ricklefs, 2009

• Gendered differences and inequalities mean that women, girls, people living in poverty, rural communities, sexual and gender minorities and Indigenous Peoples are differentially and disproportionately affected by biodiversity loss

• This impacts human rights, health, food, water and sanitation, culture and self-determination

• Often women face higher domestic burdens, loss of income, declining health, exposure to gender-based violence, loss of culture and impacts on wellbeing; girls see reduced access to education

• The negative impacts are often interconnected and perpetuate one another 

• Women’s voices are often not heard or represented in biodiversity policy, there must be better representation of their rights, knowledge and access to benefits in the future

Booker et al., 2022

• A keystone species is one whose effect is large and disproportionately large relative to its abundance, here less abundant species have strong effects on communities and ecosystems 

• Top predators tend to be assumed to be the most important due to having high per capita effects and low collective biomass, but keystone species can also be found at lower trophic levels

• An example of lower trophic level species is soil bacterias or lichens that fix nitrogen and support snails

• The keystone concept is important to identifying the most suitable areas for biodiversity preservation, it may be useful to maintain keystones instead of focusing on endangered local species or hotpots to maintain maximum ecosystem functioning

Power et al., 1996

• The keystone plant resources concept describes certain plant species in tropical forests vital to community stability and diversity dye to providing food resources to vertebrate consumers during a season of scarcity 

• In a lowland western Amazonian rainforest, it was found only less than 5% of plant communities consistently provided fruit for a broad set of consumers during a period of resource scarcity making them keystone plant resources 

• This has implications for conservation and management of Amazonian forests

Diaz-Martin et al., 2014