The State of BC’s Forests The Indicators Species diversity — PDF print version

Indicator 4 – Species diversity

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Why is this important?

Changes in species diversity can affect ecosystem productivity and stability. Species at risk, especially culturally important species, have a high public profile.

Overview

• Species diversity encompasses the number of species (species richness) and the distribution of their populations and individuals.
• British Columbia has high species diversity, with more vascular plants than neighbouring provinces and states, and more than 70% of Canada’s bird species.
• Most of B.C.’s forest-associated species have healthy populations. Some populations and distributions are changing, and some are at risk.

STATE

mixed

TREND

deteriorating

INFORMATION

partial

Questions about species diversity

4-1	How many species are forest-associated?
4-2	How many forest-associated species are at risk?
4-3	Are populations of selected forest-associated species changing?
4-4	Are tree species before and after timber harvests similar?
	Ministry of Forests and Range’s assessment

Related indicators

• Pressures on species diversity include land use changes, invasive species, fires and fire suppression, logging, human access and climate change (see Ecosystem diversity, Exotic species, Ecosystem dynamics, Timber harvest, Recreation and Greenhouse gases).
• Changes in species diversity may affect ecosystem services, economic opportunities, enjoyment of nature and cultural traditions (see Ecosystem dynamics, Forest products, Recreation, First Nations involvement).
• Management responses include protected areas (see Protected forests), other habitat protection, recovery programs and ecosystem restoration.

Indicator 4-1

How many species are forest-associated?

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Why is this important?

Forest management changes the habitats that forest-associated species depend on.

State and Trend

• B.C.’s forest ecosystems provide habitats for many plants, vertebrates, invertebrates, lichens and fungi. A forest-associated species is known to either depend on, or make some use of, forest ecosystems.
• Among B.C.’s 3,201 vascular plant and terrestrial vertebrate species, 1,324 (41%) are forest-associated, including 721 vascular plants, 303 birds, 189 mammals, 81 freshwater fish, 20 amphibians and 10 reptiles.
• Of these forest-associated species, 473 (36%) are known to be associated with old growth forests.
• Standing or fallen, dead or dying trees (wildlife trees, coarse woody debris) are used for food, nesting habitat or shelter by 83 birds, 58 mammals, 12 amphibians and one reptile.
• Many streams that support freshwater fish species depend on forested riparian areas and large organic debris in stream channels for channel stability, erosion control and temperature modification.
• Maps: See Indicator 4-3 for range maps of selected species.

Information

• Extensive information is readily available for some taxonomic groups.
• Information is available but incomplete for non-vascular plants, invertebrates, lichens and fungi.
• The Resource Information Standards Committee (RISC) develops standards for field inventory of plants and animals in British Columbia.
• Relatively few species are regularly and systematically inventoried.
• References: MoE’s SEE, IWMS, RISC, CDC; MFR’s WTC; UBC’s E-Flora BC; NatureServe; Wild BC
• Related international and national indicators: MP 1.2.a; CCFM (none)

Indicator 4-2

How many forest-associated species are at risk?

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Why is this important?

Local extirpation of species can affect ecosystem processes and economic opportunities. Global extinction of species is irreversible.

State and Trend

• Ranking the risk of extinction helps to guide conservation efforts. Various provincial, national and international lists of species are based on increasing degrees of scientific scrutiny and data to confirm status.
• The B.C. Conservation Data Centre’s red list includes 400 (12%) vascular plant and terrestrial vertebrate species that are extirpated, endangered or threatened. A further 5 species are extinct.
• Some red-listed species are naturally rare. Some are at the limits of their natural range and rare in B.C., but more abundant outside B.C.
• Further investigation is required after a species is red listed. This may or may not lead to formal designation and explicit management measures.
• Forest-associated species include 106 (27%) of the red-listed species, with the largest numbers in the CWH (42), CDF (30) and IDF (26) biogeoclimatic zones. Timber harvesting is a major threat to 33 or more of these, including coastal giant salamander and spotted owl.
• The provincial Forest and Range Practices Act provides specific habitat protection for “identified wildlife” – 70 species and 15 plant communities.
• The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) lists 91 of B.C.’s forest-associated species as endangered or threatened, and protection is provided for 76 under federal law.
• Maps: See Indicator 4-3 for range maps of selected species.

Information

• Changes in number of species listed and in rankings (greater or lesser risk) do not reliably indicate trends, due to factors other than risk status.
• References: MoE’s CDC, SEE, IWMS, Recovery Planning; MFR’s BEC; Government of Canada’s COSEWIC, SAR; NatureServe; IUCN
• Related international and national indicators: MP 1.2.b; CCFM 1.2.1

Indicator 4-3

Are populations of selected forest-associated species changing?

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Why is this important?

Changes in populations and ranges may reflect evolutionary change or ecological dysfunction, and can affect economic uses and social traditions.

State and Trend

• From a list of 105 species selected for their ecological, economic or social significance, and to represent a variety of taxonomic groups, 14 species are presented here to illustrate the variety of population trends.
• Among widespread species, caribou, moose, elk, grizzly bear and cougar have locally varying population trends. Some local populations are increasing, or have expanding ranges; others are stable, declining or at risk, and a few have been extirpated.
• Pileated woodpeckers appear to be increasing. The tree cavities created by this keystone species are used by other species for nesting, shelter and feeding.
• Along the coast, all stocks of coho salmon have declining spawning abundance, due to changes in forest and marine conditions.
• Among rare species with limited ranges, Vancouver Island marmot and spotted owl are endangered and populations are decreasing.
• Although few or no population trend data exist for many species such as Pacific water shrew, marbled murrelet, Rocky Mountain tailed frog, rubber boa and tall bugbane, their habitat is known to be declining in quantity and quality due to logging, urbanization and agriculture.
• Maps: Range maps and notes for the above species are in Maps annex.

Information

• Population trends are known for relatively few species. Most vascular plant and vertebrate species have not been systematically inventoried.
• References: MoE’s SEE, IWMS, CDC, Recovery Planning; Government of Canada’s COSEWIC; NatureServe; BBS
• Related international and national indicators: MP 1.3.a, 1.3.b; CCFM 1.2.2, 1.2.3

Indicator 4-4

Are tree species before and after timber harvests similar?

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Why is this important?

Reducing the number of tree species (or changing the species) may decrease biological diversity and ecosystem resilience. Future economic value of forests may be increased or inadvertently decreased.

State and Trend

• Most of B.C.’s forests have a mixture of two or more tree species. About one quarter to one third are dominated by a single tree species that accounts for more than 80% of timber volume before harvest.
• The area dominated by one species before timber harvests can change after harvests and reforestation⁷. The extent of dominance changed after 1987, when the government assigned greater responsibility for reforestation, including selection of tree species, to the forest industry.
• In areas harvested up to 1987, coniferous forests with one dominant tree species decreased from 33% before harvest to 25% after harvest. Broadleaved forests increased from 0% before harvest to 5% after.
• In areas harvested after 1987, coniferous forests with one dominant tree species increased from 25% before harvest to 34% after harvest. Broadleaved forests increased from 1% before harvest to 4% after.
• Tree species after harvest may differ from those before harvest due to natural seeding, or planting species with better success rates and costs.
• Changes in area of predominant species before and after harvest (both time periods combined) include lodgepole pine (35% to 33%), spruces (29% to 23%), true firs (3% to 9%), hemlock (6% to 4%), Douglas-fir (16% to 16%), western redcedar (3% to 2%) and aspen (0% to 2%).
• Maps: Predominant Tree Species (PDF)

Information

• Species data before and after harvest are available for only 57% and 11%, respectively, of the areas harvested 1970–1987 and after 1987.
• References: MFR’s RESULTS
• Related international and national indicators: MP (none); CCFM (none)

 

Indicator 4 – Species diversity Ministry of Forests and Range’s assessment State mixed British Columbia has exceptional species diversity, much of it forest-associated. Among the 1,324 forest-associated vascular plant and terrestrial vertebrate species, 106 (8%) are red-listed (extirpated, endangered or threatened). Timber harvesting is a major threat to 33 or more of these. Management of older forests in and outside protected areas is expected to address concerns about species associated with old growth forests. Reforestation is maintaining a mix of tree species, which helps maintain ecosystem processes and diverse habitats. Trend deteriorating Populations and ranges of some opportunistic species have expanded, while declining habitat quantity and quality has reduced populations of other species, in some cases putting them at risk. The extinction of five species to date was not related to forestry. Forest management is, however, implicated (along with climate change, urbanization and activities relying on road access) in the critical status of a few endangered species. To halt the trend, management responses increased over the past two decades, and include species recovery plans, breeding programs, protected forests (5.7 million ha), protection of other forest habitats (3.4 million ha) and establishment of old growth management areas. Partial data (for 11% of areas harvested) indicate that since 1987 reforestation may be increasing the extent of forests dominated by a single tree species. In some areas, this has been stopped due to concern about ecosystem health and resilience. Information partial Taxonomic cataloguing and description of B.C.’s species and their life cycles is extensive for vascular plants and vertebrate species; less so for non-vascular plants, invertebrates, lichens and fungi. Populations and population trends are known only for the relatively few species that are regularly and systematically inventoried. Inventories of mosses and lichens are generally lacking. Several sources rank the conservation status of B.C.’s species. Changes in conservation status may be due to changes in knowledge, procedures and taxonomy, rather than a species’ actual condition, so trends in the number of species at risk can be misleading.