Environmental Engineering Reference
In-Depth Information
extinctions of local populations, or their reduction to functionally extinct, can
dramatically affect regulating and supporting ecosystem services [
71
].
Species Loss and Extinction
It is clear that as more species and/or the variability within species disappears,
significant loss of ecosystem function, and hence ecosystem goods and services,
may occur. While the evolution of species and the extinction of others is a natural
process, current extinction rates are estimated to be between 100 and 1,000 times
greater than they were in the distant past and future rates may be 10-100 times what
they are today [
10
,
34
]. Even among lesser threatened taxa, for example, birds,
current extinction rates are several orders of magnitude higher than the natural or
background rate. Roughly one-fifth of the world's vertebrates and plants are
threatened with extinction [
38
,
72
], and in addition to individual species, entire
lineages or ecosystems are threatened [
45
,
73
]. Current rates of population extirpa-
tion are probably at least three orders of magnitude higher than species extinction
rates [
74
]. In addition, changes in the relative abundance among species are also
capable of causing important changes in ecosystem function [
75
].
The main cause of extinction across all vertebrate groups is habitat loss or
degradation - primarily driven by agricultural development and logging - followed
by invasive species and human overexploitation [
38
,
72
]. However as the impacts
of climate change increase, it will likely be the greatest driver of extinctions
this century. Climate change has already been proven as a cause of species
extinction [
76
] and may likely be the greatest driver of extinction this century. As
more distributions shift, it is predicted based on midrange climate warming
scenarios for 2050 that 15-37% of species will be committed to extinction, with
the most severe impacts resulting from synergistic interactions among a range of
threats [
77
,
78
].
Conservation of Species and Ecosystems
Invasive species and human-caused extinctions are already altering ecosystems;
there are few places left on the planet that have not been affected by human impacts
[
79
,
80
]. Even minor losses may reduce the capacity of ecosystems to adjust to
changing environments. As it is often difficult, expensive, or impossible to fix or
reverse these changes with technological solutions [
64
,
81
], it is crucial that the
diversity of our planet's species and ecosystems is conserved. There are several
levels of approach and the appropriate one will depend on the specific goals and
resources available. The species level has been the traditional focus of conservation
planning and action. Common frameworks include IUCN Species Action Plans and
Species Conservation Strategies, which focus on assessing species and making
