The UN launches the International Year of Biodiversity on Monday, warning that the ongoing loss of species affects human well-being around the world.
Eight years ago, governments pledged to reduce the rate of biodiversity loss by 2010, but the pledge will not be met.
The expansion of human cities, farming and infrastructure is the main reason.
Dignitaries including German premier Angela Merkel will speak at the launch in Berlin, with a video message from UN Secretary-General Ban Ki-moon.
Mr Ban is due to say that human expansion is wiping out species at about 1,000 times the "natural" or "background" rate, and that "business as usual is not an option".
The Secretary-General is expected to argue that the failure to protect biodiversity "should be a wake-up call", leading to effective ways of protecting forests, watersheds, coral reefs and other ecosystems.
The UN says that as natural systems such as forests and wetlands disappear, humanity loses the services they currently provide for free, such as the purification of air and water, protection from extreme weather events and the provision of materials for shelter and fire.
The rate of species loss leads some biologists to say that we are in the middle of the Earth's sixth great extinction, the previous five stemming from natural events such as asteroid impacts.
The UN Convention on Biological Diversity (CBD) was agreed at the Rio Earth Summit of 1992, alongside the climate change convention.
But it acquired its key global pledge during the Johannesburg summit of 2002, when governments agreed to achieve a "significant reduction" in the rate of biological diversity loss by 2010.
Conservation organisations acknowledge that despite some regional successes, the target is not going to be met; some analyses suggest that nature loss is accelerating rather than decelerating.
"We are facing an extinction crisis," said Jane Smart, director of the biodiversity conservation group with the International Union for the Conservation of Nature (IUCN).
"The loss of this beautiful and complex natural diversity that underpins all life on the planet is a serious threat to humankind now and in the future."
A large on-going UN-sponsored study into the economics of biodiversity suggests that deforestation alone costs the global economy $2-5 trillion each year.
In his speech at Monday's event, United Nations Environment Programme (UNEP) executive director Achim Steiner is due to highlight problems caused by invasive species, and the potential for ecosystems such as forests and wetlands to absorb and store carbon from the air.
The UN hopes some kind of legally-binding treaty to curb biodiversity loss can be agreed at the CBD summit, held in Japan in October.
One element is due to be a long-awaited protocol under which the genetic resources of financially-poor but biodiversity-rich nations can be exploited in a way that brings benefits to all.
However, given the lack of appetite for legally-binding environmental agreements that key countries displayed at last month's climate summit in Copenhagen, it is unclear just what kind of deal might materialise on biodiversity.
The UN has been pursuing new ways of raising public awareness on the issue, including a collaboration with the Cameroon football team taking part in the African Nations Cup finals.
Many environment organisations will be running special programmes and mounting events during the year.
"The big opportunity during the International Year of Biodiversity is for governments to do for biodiversity what they failed to do for climate change in Copenhagen," said Simon Stuart, a senior science advisor to Conservation International and chair of IUCN's Species Survival Commission.
"They have the chance to make a major difference; and key to this will be halting species extinctions, the most irreversible aspect of biodiversity loss."
WWF is highlighting 10 species it considers especially threatened, ranging from commercially significant ones such as bluefin tuna to the Pacific walrus and the monarch butterfly.
In the UK, the national IYB partnership - hosted from the Natural History Museum (NHM) - is asking every citizen to "do one thing for biodiversity" in 2010.