Biological Conservation 143 (2010) 1571–1586

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Biological Conservation

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Comprehensive conservation planning to protect biodiversity and ecosystemservices in Canadian boreal regions under a warming climateand increasing exploitation

D.W. Schindler a,*, P.G. Lee b

a Dept. Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9b Global Forest Watch Canada, 10337 146 Street, Edmonton, Alberta, Canada

a r t i c l e i n f o

Article history:Received 24 February 2010Accepted 6 April 2010Available online 5 May 2010

Keywords:Carbon fluxesPermafrost meltingOil sandsWatershed biogeochemistryForest fireCumulative effectsBoreal conservation

0006-3207/$ - see front matter � 2010 Elsevier Ltd. Adoi:10.1016/j.biocon.2010.04.003

* Corresponding author. Tel.: +1 780 492 1291; faxE-mail addresses: d.schindler@ualberta.ca, m.foxcro

ler).

a b s t r a c t

Boreal regions contain more than half of the carbon in forested regions of the world and over 60% of theworld’s surface freshwater. Carbon storage and the flood control and water filtration provided by fresh-waters and wetlands have recently been identified as the most important ecosystem services provided byboreal regions, with a value many times greater than current resource exploitation. Ecosystem servicesand sensitive ways of detecting their impairment have so far not been fully included in boreal conserva-tion planning. Climate warming, via its effect on permafrost melting, insect damage, and forest fire,threatens to trigger large positive carbon feedbacks that may enhance the concentrations of greenhousegases in the atmosphere, further amplifying climate warming. In a water-scarce world, there is increasingpressure to divert and exploit boreal freshwaters, and devising conservation plans to protect boreal fresh-waters and their catchments is urgent. We propose a catchment-based approach that includes water andchemical mass-balances as a sensitive means of detecting early degradation of many ecosystem servicesin both catchments and freshwaters, and give some examples of where this has been advantageous in thepast. The necessary modifications to current conservation planning are simple ones, and the advantagesare great.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

The Boreal Biome (hereafter called the Boreal when used as anoun) is Canada’s largest biome, making up 58.5% of the country’sarea. When the primary author began studying Canadian boreallakes, streams and catchments over four decades ago, there werefew concerns about boreal conservation or ecosystem degradation.The threat of global warming was only discussed only among a fewof the world’s leading global biogeochemists. The concepts of nat-ural capital and ecosystem services were not yet known. Except atits southern edge, the Boreal was largely free of roads or otherwidespread disturbances. Clear-cut logging was not pervasive. Itwas mostly done by small companies employing individual loggerswho used primitive chainsaws, and dragged logs from the forestwith horses. Biodiversity loss was scarcely discussed, although itis noteworthy that wolves, woodland caribou, cougars, and grizzlybears had already been extirpated from the extreme southern partsof the Boreal, particularly near the border with the USA.

ll rights reserved.

: +1 780 492 9234.ft@ualberta.ca (D.W. Schind-

That situation has changed rapidly. Today a wide variety ofdevelopments are disturbing boreal lands and waters (Fig. 1, Ta-ble 1), even at high latitudes. Global Forest Watch’s frequently up-dated maps of Canada’s fragmented forest landscape http://www.globalforestwatch.ca show clearly that the Boreal is changingrapidly (Fig. 1). Opportunities for proper conservation planning arediminishing rapidly as the Boreal is carved up and allocated to for-estry, oil and gas exploration, hydroelectric development, miningand other activities. Projections are for even more rapid exploita-tion of the Boreal in the decades ahead.

The Boreal is also predicted to be one of the biomes most af-fected by climate warming in the coming century (Ruckstuhlet al., 2008). In western Canada, temperatures at boreal climatestations have increased by 2–4 �C in the past 40 years. Ice-free sea-sons are longer in boreal lakes, and snowpacks are smaller andmelt earlier. Where glaciers are present in catchments, loss of icehas accelerated (Schindler et al., 1996a; Schindler and Donahue,2006). By 2050, most parts of the Canadian boreal are expectedto have temperatures 3–4 �C warmer than 1961–1990 (Natural Re-sources Canada at http://atlas.nrcan.gc.ca/site/english/maps/cli-matechange/#scenarios). Winter temperatures are predicted towarm even more, an average of 4–6 �C.

Fig. 1. A map of Canada showing fragmentation of the boreal forest (in red). Map from Global Forest Watch.

1572 D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586

In addition to its direct effects on carbon cycling and freshwa-ters, climate warming will amplify the effects of many other hu-man activities in boreal landscapes (Schindler, 2001). Until veryrecently, the boreal carbon cycle and the sensitivity of boreal fresh-waters to small shifts in climate have been poorly understood. Re-cent work shows that there are potential strong positive borealfeedbacks to the global carbon cycle that could greatly amplify cli-mate warming. Recent studies also show that sustainable watersupplies for boreal regions are much lower than the abundanceof lakes and wetlands suggests. As a result, water levels are verysensitive to small changes in the balance between precipitationand evaporation. Conservation planning for the Canadian borealis at least as urgent as for tropical rain forests.

The Boreal is still home to a large number of indigenous peoplewho use water, plants and animals to support their traditional life-styles, relying on the Boreal for food, transportation, and spiritualsustenance. Many of these people have lived in the Boreal for mil-lennia, and are determined to continue to live a lifestyle that in-cludes many traditional elements. Canadian treaties withindigenous people guarantee that such lifestyles will remain possi-ble, but many of these treaties are being violated by resourcedevelopment. In Canada, we are proud of ‘‘multiculturalism,” thediversity of cultures that our society will support and tolerate. Cer-tainly, we must take great pains to include the first peoples of thecountry!

2. Boreal ecosystem services

In recent years, there has been increasing concern about erosionof the ‘‘services” supplied by ecosystems to support human society,and for the ‘‘natural capital” that supplies the services (Daily, 1997;Costanza et al., 1997). Preliminary estimates for the Canadian bor-eal (Tables 2 and 3; Anielski and Wilson, 2009) place the value ofannual ecosystem services at $703 � 109 in 2002. The services in-cluded carbon storage, flood control and water filtering, biodiver-

sity, pest control by boreal birds, and nature-related activities. Ofthese, carbon storage was by far the greatest value, followed byflood control and water filtration.

Early work on the global carbon cycle ignored the Boreal alto-gether. The main focus was first on the oceans, then later on trop-ical forests. This view began to change when Gorham (1991)revealed that the vast peat deposits of the boreal forests were aglobally significant carbon store. During the past two decades,the estimated carbon contained in boreal soils has slowly crept up-ward, as new studies are completed. As recently as a year ago, itlooked as if globally, boreal ecosystems contained roughly as muchcarbon as the temperate and tropical regions combined (Table 4),and these figures that were the basis for Anielski and Wilson’s cal-culations. As we shall discuss later, even such recent boreal carbonvalues now appear to be huge underestimates.

Forests are known to play a major part in the water cycle. Theyintercept falling precipitation, changing snow accumulation, subli-mation, radiation and snowmelt. They delay and damp the springfreshet that follows snowmelt, and decrease erosion (Pomeroyand Granger, 1997). Similarly, wetlands retain water on the land,and retain silt, nutrients and toxins, protecting surface water andground water (Johnston, 1991). Depending on their position inthe landscape, wetlands also recharge groundwater supplies. Inshort, many of the services that protect freshwater supplies aresupplied by catchments, rather than by aquatic ecosystems alone.

In contrast to the high value of ecosystem services, the marketvalue of boreal natural capital extraction for 2002 was only$50.9 � 109, from timber harvesting, extraction of minerals, oiland gas, and hydroelectric generation. The estimated gross valuewas $62 � 109, but estimated environmental costs and govern-ment subsidies to industry reduced the value by $11.1 billion (Ta-ble 3). Thus, ecosystem services had a value almost 14 greater thanexploiting boreal resources contributes to the Canadian GrossDomestic Product.

It is important that carbon storage, freshwater and otherecosystem services be added to conservation planning currently

Table 1Threats to boreal catchments with examples of their damage to ecosystems services, and some locations where such threats occur.

Threat Main effects on Boreal catchments Examples

Climate warming Increased insect outbreaks WidespreadIncreased forest fireIncreased carbon emissionIncreased permafrost meltDecreased lake levels and river flows

Acid raina Acidification of soils and lakes Precambrian Shield of eastern CanadaExhaustion of base cations in soils and lakesLoss of biodiversity

Logginga Decreased old growth forest Woodland caribou and warbler habitatsDecreased habitats for large mammals and birds

Dams and river diversionsa Flooded forests and wetlands James Bay, Northern Manitoba and Northern British ColumbiaIncreased GHG emissionsIncreased mercury in fishDeclines in natural fluvial habitats

Eutrophicationa Increased blooms of nuisance algae Lake Winnipeg, Manitoba; Muskoka-Haliburton, Ontario; Lac laBiche, AlbertaOxygen depletion in deep water

Loss of coldwater fishesDeclining water quality

Urbanization and lakeshore development Loss of littoral fish habitat Widespread in southern Boreal and where commercial fishing isallowedIncreased eutrophication

Increased erosionOverfishing

Exploitation of fisheriesa Loss of piscivorous fish WidespreadTrophic cascades exacerbate eutrophicationDecline of food supplies

Oilsands exploitation, and oil and gasdevelopmenta

Habitat loss and fragmentation in catchments Alberta, Parts of British Columbia and SaskatchewanContamination of surface and groundwater

Mining and other toxin sourcesa Releases of toxic metals, cyanide, arsenic, dioxinsand furans

Widespread, including northern Boreal

Biodiversity loss Habitat fragmentation for birds, mammals, fishes Northern AlbertaOverexploitation of fishes

Incursion by agriculture Habitat loss and fragmentation Southern boreal regions, Grand Prairie Alberta area

Peat extraction Removal of carbon sinks Widespread in southern Boreal

a Designates threats that are expected to enhance, or be enhanced by climate warming, as discussed in the text.

Table 2The estimated value of ecosystem services in boreal Canada. Values are in 2002dollars. From Anielski and Wilson (2009).

Ecosystem service Value

Carbon storage $582 � 109

Flood control, water filtering, peatlands $77.0 � 109

Flood control, water filtering, biodiversity,non peatland wetlands

$33.7 � 109

Pest control – boreal birds $5.4 � 109

Nature-related activities $4.5 � 109

Total value of ecosystem services $703 � 109

Table 3The market value of resources extracted from boreal Canadian resources in 2002dollars. Note that the net value is only about 7% that of ecosystem services. ESP/GDP isthe ratio of the value of ecosystem services in Table 2 to the net value as calculatedbelow. From Anielski and Wilson (2009).

Resource Market value

Timber $18.6 � 109

Mining + oil and gas $23.6 � 109

Hydroelectric generation $19.5 � 109

CostsAir pollution $9.9 � 109

Government subsidies $1.0 � 109

Forestry carbon emissions $0.15 � 109

Net value $50.9 � 109

ESP/GDP = 13.8

D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586 1573

focused on biodiversity or individual species, because impendingclimate change and other human-caused stresses threaten theirsecurity, as we will argue below. Also, including both biodiversityand ecosystem services makes the case for boreal conservationmuch stronger.

2.1. The boreal carbon cycle

Late last year, a study by Tarnocai et al. (2009) revealed thatboreal carbon storage had been vastly underestimated. In a de-tailed inventory of global permafrost, they found that permafrostcontained much more carbon than had been estimated. It is stillimpossible to tell how much their results will increase the calcu-lated boreal carbon inventory, because the permafrost study didnot distinguish between boreal, tundra and barren ground sites.It is probably safe to say that estimates of Earth’s below-ground

carbon will at least double once accurate calculations have beencompleted (Table 4).

2.2. Boreal freshwaters

It is also essential that boreal conservation planning explicitlyinclude freshwater ecosystem services. Boreal regions contain atleast 60% of the planet’s surface freshwater (Schindler, 2001). Theycontain over 3 million lakes, including many of the world’s largestlakes, such as Lake Baikal, Great Bear Lake, Great Slave Lake, andthe upper St. Lawrence Great Lakes. Many of the world’s largestrivers also drain boreal catchments. As much as 80–90% ofCanadian freshwater lies in the boreal lakes, rivers and wetlands

Table 4Estimated carbon stores in boreal, temperate and tropical forests. Values fromKasischke (2000).

Biome Area(�106 ha)

Soil carbon(Pg)

Plant biomasscarbon (Pg)

Total carbon(Pg)

Boreal forest 1509 625–1700a 78 703–1500a

Tropical forest 1756 216 159 375Temperate forest 1040 100 21 121

1 Pg [petagram] = 1 billion metric tonnes or 1 trillion kg.a Italicized numbers are my estimates of how much boreal values could increase

as the results of the recently increased estimates of carbon in permafrost by Tar-nocai et al. (2009).

1574 D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586

(Figs. 2 and 3). The Boreal in Canada alone contains 25% of theworld’s wetlands (Natural Resources Canada, 2009). In some partsof the Canadian boreal, they comprise 40–100% of the surface area(Fig. 3). Wetlands are also important in water purification, and inflood control.

Globally, human populations are acutely short of freshwater(Millennium Assessment, 2005, IPCC 4th assessment, 2007). It fol-lows that there will be extreme societal and industrial pressure toexploit boreal freshwaters, either by diversion, or by using their‘‘virtual water” values as described below.

The abundance of boreal water is deceptive, giving the impres-sion that we can exploit it lavishly. But it is renewed very slowly.Boreal water is rather like a large bank account with a very lowinterest rate. If we wish to preserve the principle (i.e. our lakesand wetlands) for posterity, we must live off the low interest,which for water is represented by annual runoff. In this regard,Canada’s sustainable water supply is no greater than some other

Fig. 2. Lakes >10 km2 in Canada’s boreal region. The area contains over 2 million lakes, mcovered by water. Figure from Global Forest Watch Canada.

countries that are regarded as water-poor, such as the USA andChina (Sprague, 2006; Table 5). Evaporation and low precipitationlimit the water renewal rate of larger, deeper lakes to less than apercent, and in some cases less than half a percent, each year. Evenvery small changes to precipitation or temperature can shift waterbalances from slightly positive to negative, as studies of past con-ditions show.

As lake levels decline, eventually they drop below the thresholdfor outflow, and the lakes become closed basins. As a result, salinityincreases, causing gradual changes to more salt tolerant taxa ofplants and animals. Nutrient retention becomes 100%. Eventually,lakes can dry up completely. Even now, several lakes that borderthe western Boreal are well along in this salinization process,declining several meters since the mid-20th century. This is at leastin part result of recent climate warming (van der Kamp et al.,2008). In the distant past, such events have occurred in some bor-eal areas that have had ample supplies of water in the 20th cen-tury, under climatic conditions differing only slightly fromcurrent ones. For example, in the mid-Holocene, Lake Manitobawas almost dry. Lake Winnipeg was a closed basin of much smallersize than today. Some of the St. Lawrence Great Lakes were alsoclosed basins. At the Experimental Lakes Area in northwestern On-tario, lake levels at that time were several meters below those re-corded in the 20th century, and they were closed basins. Wetlandson the prairies were much less abundant than they are today (re-viewed by Schindler (2009)).

In wetter regions, increased temperatures and the resulting in-creases in evaporation and evapotranspiration may not be suffi-cient to cause lake levels to decline, but they will still lead tolower flows into and out of lakes, increasing retention of nutrients

ost of them small. Some parts of the Boreal have as much as 40% of their surface area

Fig. 3. The proportion of surface area covered by wetlands in boreal Canada. Figure from Canadian Boreal Initiative.

Table 5Average annually renewed water, based on runoff from land. Modified from Sprague(2006).

Country % of global supply

Brazil 12.4Russia 10.0Canada 6.5Indonesia 6.5USA 6.4China 6.4Columbia 4.8

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and other chemicals. These principles, expressed in a variety ofmass-balance models, have been the basis for predicting retentionin lakes of eutrophying nutrients (Dillon and Rigler, 1974; Vol-lenweider, 1976; Schindler et al., 1978), strong acid anions (Kellyet al., 1987) and other chemicals (Ahlgren, 1978; Schindler et al.,1987). For example, Schindler et al. (1996a) found that an increasein annual temperature of less than 2� caused water retention timein lakes to increase by over four fold, greatly increasing the concen-trations of most chemicals.

2.3. Virtual water

An often forgotten threat to freshwater is the export of ‘‘virtualwater,” in the form of hydroelectric power, oil extraction, irrigatedcrops, livestock, and other commodities that require considerablewater to produce. Ecosystem services and biodiversity are dam-aged in the process. Canada is the world’s second largest exporterof virtual water, with 95 Gm3 yr�1 used to produce the abovementioned commodities, and little thought given to water conser-vation (Schendel et al., 2007). An increasing amount of this virtualwater is coming from boreal catchments. There has recently beenmuch discussion of the human ‘‘carbon footprint” on planet Earthbut little discussion of our ‘‘water footprint,” although the latter isprobably a much more urgent problem (Gerbens-Leenes et al.,2009).

3. Potential positive boreal feedbacks to the carbon cycle couldamplify climate warming

Positive feedbacks from the biosphere to the atmosphere haverecently been of increasing concern, because they could amplifythe effects of simply burning fossil fuels, which have been the maindrivers incorporated in widely known climate models (IPCC, 2007).For example, fears have been expressed that melting of methanehydrates in the coastal ocean could greatly increase the rate ofwarming (Kennett et al., 2000). The collapse of major polar icesheets could significantly increase rates of sea level rise over thosepredicted by the IPCC (Kennett et al., 2000; Vermeer and Rahm-storf, 2009; Overpeck and Weiss, 2009). Acidification and carbondioxide saturation could reduce the efficiency of the oceans as asink for atmospheric carbon, as well as causing the decline inorganisms with calcareous parts (Raven et al., 2005; Lenton et al.,2009). The result of decreasing ocean CO2 uptake efficiency wouldleave more carbon in the atmosphere, increasing rates of globalwarming.

3.1. Boreal carbon feedback loops

Clearly, the magnitude of carbon stores in boreal regions haspotential for important positive feedbacks to atmospheric green-house gases. One such feedback is the melting of permafrost. Manypapers have documented recently increased permafrost melting inmany areas of Canada (Halsey et al., 1995), Alaska (Hinzman et al.,2006), and Siberia (Walter et al., 2006; Christian et al., 2008). As aresult, decomposition of organic matter releases methane directlyto the atmosphere. This can be a surprisingly important source ofgreenhouse warming (Bastviken et al., 2008). Such melting willchange the vegetation, topography and hydrology of large areasof the northern boreal region (Turetsky et al., 2002; Walter et al.,2006; Christian et al., 2008; Schuur et al., 2009). Turetsky et al.(2007) found that as permafrost melts, new species of mosses ap-pear, which over time may help to mitigate the carbon losses.However, more recently Schuur et al. (2009) found that as perma-frost continued to melt, carbon released eventually exceeded thecapacity of plants to replace it. Calculations indicate that melting

1576 D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586

permafrost could add 80 ppm of CO2 to the atmosphere, enough toincrease warming by an additional 0.7 �C (Schuur et al., 2009).

A second potentially large boreal carbon feedback is increasedforest fire. Already, the average area burned by Canadian forestfires annually has almost doubled since 1970. In a bad fire year,forest fires release almost as much carbon as all of Canadian indus-try (Amiro et al., 2002). Concerns about increased forest fire wereexpressed by IPCC (2007), but the estimates at the time did notfully account for the huge extent that increases in mountain pinebeetle Dendroctonus ponderosae and spruce beetle D. rufipenniswould damage western boreal forests in North America in the past10 years. This increase is thought to be the result of a succession ofwarmer winters caused by climate warming (Carroll et al., 2006).

The pine beetle has already killed huge tracts of lodgepole pinePinus contorta in British Columbia. The resulting stands of dead andfalling trees cause significant increases in fuel loads (McCulloughet al., 1998), causing increased forest fire. This can transform whatwas believed to be a modest carbon sink to a major source. It isestimated that in the period 2000–2020, the affected forests willrelease 270 Mt carbon/y to the atmosphere, equivalent to 75% ofaverage annual forest fire emissions from all of Canada in 1959–1999 (Kurz et al., 2008). The pine beetle is now spreading into Al-berta, where jackpine P. banksiana are thought to be at least as sen-sitive to its attack as lodgepole pine. Together, permafrost melting,insect attack and forest fire could add enough carbon to the atmo-sphere to cause runaway climate change, with rates of warming faroutstripping IPCC predictions.

3.2. Errors in past calculated carbon fluxes caused by ignoringfreshwaters

In addition to the threat of increasing positive carbon feedbacks,several recent studies indicate that boreal carbon fluxes to theatmosphere may have been underestimated, because lakes havebeen ignored. Boreal lakes generally receive 5–10% of terrestrialcarbon production, in the form of dissolved and particulate organiccarbon washed from their catchments. Much of this is either de-graded in lakes and degassed to the atmosphere as CO2 or meth-ane, or is stored in lake sediments. These processes have beenlargely ignored in carbon flux measurements. Tranvik et al.(2009) review several recent studies of the issue. Including fluxesfrom freshwaters will decrease calculated past boreal carbonfluxes, and it seems likely that the Boreal has been a net sourceof carbon to the atmosphere for the past few decades.

4. Catchments as conservation units

In North America, the area that drains to a water body is gener-ally referred to as its watershed. The term catchment is used for thesame designation in UK, where the term watershed customarilymeans the divide between adjacent catchments. The term catch-ment seems more descriptive of how the system actually operates,and we shall use it throughout the rest of this paper. A freshwaterbody’s catchment is defined as the area from which surface andgroundwater flows to the water body, be it a lake or river. Catch-ments can vary widely in size, from a few hectares for first-order(headwater) streams or small ponds to thousands of square kilo-metres for the enormous, dendritic river and lake systems thatdrain a major part of a continent. Stream order is a well-knownconcept in the study of fluvial systems (Vannote et al., 1980), withlarge river basins often containing eight or more stream orders be-fore the river reaches the sea. Flow increases with increasingstream order. In addition, biodiversity is usually greater in higherorder streams, larger lakes and their catchments, due to the inclu-

sion of larger and more heterogeneous areas (Beecher et al., 1988;Schindler, 1990).

It has been recognized for several decades (Likens et al., 1977)that to protect freshwaters, it is necessary to protect the catch-ments that drain to them. Yet until recently, conservation planninghas ignored freshwater, focussing instead on protecting biodiver-sity or habitat of focal species or species groups of birds and mam-mals (Pringle, 2001).

4.1. Advantages of integrating freshwater catchments intoconservation planning

In the past few years, some have recognized the importance ofincluding freshwater in conservation planning from the standpointof protecting biodiversity and habitat. Catchments have been pro-posed as the fundamental unit of conservation for linking fisheriesto their habitats (Collares-Pereira and Cowx, 2004; Naiman andLatterell, 2005). Other recent conservation plans for freshwaterhave considered biodiversity as the major issue (Higgins et al.,2005; Moilanen et al., 2008). Amis et al. (2009) found that inte-grated terrestrial-freshwater conservation plans were more suc-cessful at protecting freshwater biodiversity. Pringle (2001)proposed hydrologic connectivity as essential in managing biolog-ical reserves. Leroux et al. (2007) included wetlands and water in abalanced approach to protecting boreal regions. In boreal regionsunderlain by Precambrian Shield rocks, Steedman et al. (2004) elu-cidated how human activities on land can compromise water qual-ity. However, all of the above studies are focussed on aquaticobjectives. We propose that the approach be modified to combinechemical–biological–hydrological factors in both catchments andfreshwaters, with the multiple objectives of protecting freshwatersupplies, detecting changes to ecosystem services in catchments,and preserving biodiversity at catchment scales, as describedbelow.

4.2. Catchment mass-balance approaches to detecting changes toecosystem services and biodiversity loss

There are many good reasons for terrestrial and wetland conser-vation plans to include freshwaters. They are sentinels of changefor both terrestrial and aquatic ecosystems (Schindler, 2009; Wil-liamson et al., 2009). Changes in the water balance and disruptionsto the biogeochemical cycles of terrestrial, wetland and aquaticecosystems are often most easily detected by monitoring inputsand outputs of water and the chemicals dissolved or suspendedin it. Water budgets and biogeochemical mass-balance budgetscan provide an early warning of impending problems ecosystemprocesses in catchments. Accurate measurements of precipitation,surface water levels, surface water flows, and input–output bud-gets of dissolved chemicals to catchments are well developed sci-ences. Most chemical substances are now detectable atconcentrations of parts per billion or even parts per trillion.Groundwater measurements are less precise, but a number of re-cent isotopic, GIS, or remote-sensing based diagnostic tools haveimproved our abilities to gauge underground flows and the sourcesof chemical constituents (Krabbenhoft et al., 1994; Webster et al.,1996; Hinton et al., 1997; Buttle et al., 2009).

Changes to the water balance of catchments can be used to pre-dict impending changes to community types in the catchment. Forexample, lower precipitation or higher evaporation can be re-flected in lower streamflows and groundwater levels, heraldingthe transition of mesic to xeric communities, from minerotrophicto ombrotrophic wetlands, of higher outputs of hydrogen ion andsulphate from wetlands (Bayley et al., 1992a; Lazerte, 1993) or ofmore frequent or more intense forest fires.

D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586 1577

There are also numerous examples of where chemical mass-bal-ances have shown that the ecosystem services of terrestrial oraquatic ecosystem services are being compromised. Examples in-clude acid rain, insect outbreaks, disruption of biogeochemical cy-cles, fire, and eutrophication. These will be described in detail later.

4.3. Using paleoecology to evaluate past changes to catchments

Another good reason to include lakes in catchment-scale con-servation planning is that they assist in interpreting changes thatoccurred to catchments before contemporary monitoring began.Lake sediments contain records of past changes to all ecosystemswithin the catchment, in the fossil remains and geochemical indi-ces that are deposited chronologically. Using these biological andgeochemical signals, it is possible to deduce in some detail howcommunities and ecosystems reacted to and recovered from paststresses (Smol, 2008). For example, it has been possible to predictthe frequency and duration of past droughts and associatedchanges in algal communities (Fritz et al., 2000; Laird et al.,2003), and of forest fires and the terrestrial species succession thatfollowed them (Campbell and Campbell, 2000; Weir et al., 2000). Insome cases, records span several millennia. This knowledge of howan ecosystem has responded to, or recovered from past stresses isuseful for evaluating the likelihood that future stresses will causecatastrophic ecosystem shifts, or estimating the time required fora community to recover after stress.

In summary, in order to fully utilize the unique hydrological,chemical and paleoecological properties of aquatic ecosystems inconservation planning, it is necessary to include catchments as ba-sic units of planning. In the remainder of this manuscript, we firstelucidate some of the direct and indirect (i.e. via catchments)threats to boreal catchments and give some examples of whereaquatic studies have proved useful in interpreting changes to ter-restrial and wetland ecosystems. We will then discuss the fewchanges that are necessary to include freshwaters in existing con-servation plans.

5. Threats to boreal catchments where hydrology andhydrochemistry are useful diagnostic tools

5.1. Climate change

The Boreal Biome is among the regions of Earth being most rap-idly affected by climate change (Schindler, 1998a,b; Chapin et al.,2006; Ruckstuhl et al., 2008). It is obvious from what we have writ-ten above that the potential positive feedback cycles to the globalcarbon cycle would cause great changes to the character of borealforests, including loss of old growth and associated biota. In morexeric parts, the Boreal could become transformed to aspen park-land, or even to grasslands as the fire cycle intensifies. As we haveshown with studies of boreal catchments in northwestern Ontarioof a 20 year drought and two forest fires, hydrological and hydro-chemical cycles in catchments, streams and lakes reveal a numberof critical changes that affect the health of ecosystems for manyyears (Schindler et al., 1990, 1996a; Parker et al., 2009).

5.2. Threats to the Boreal that are likely to be amplified by changingclimate, or vice versa

Many of the current threats to the Boreal are viewed in isola-tion. In reality, climate change can amplify the effects of many.In other cases, the threat can amplify the effects of climate change,as we have seen for permafrost melting and forest fire. The follow-ing are some examples.

5.2.1. Insect outbreaks and forest fireThe severe outbreaks of spruce beetle and mountain pine beetle

discussed above have been large enough to cause changes to thequality and quality of runoff (Natural Resources Canada at http://mpb.cfs.nrcan.gc.ca/archive/projects/8-30_e.html). Other speciesthat have caused damage severe enough to change hydrologyand biogeochemistry include tent caterpillar Malacosoma disstria,European gypsy moth Lymantria dispar, and spruce budwormChoristoneura fumiferana.

Fire causes several changes that affect the chemistry andhydrology of soils and lakes. Runoff from burned catchments in-creases for a few years after fire, carrying with it increased loadsof nutrients, base cations, strong acid anions, and silt (Bayleyet al., 1992a,b; Beaty, 1994; Schindler et al., 1996a). Decreasedheight of the protective forest canopy causes increased wave actionand increased thermocline depth in small lakes (Schindler et al.,1996a; Parker et al., 2009). Wetlands and wet soils are known tosequester mercury that falls with precipitation (St. Louis et al.,1994), and when these systems burn, mercury is released to runoff.When mercury reaches lakes, it can be microbially methylated,then biomagnified by food chains, causing methyl mercury in fishto increase. The process can be complicated by simultaneous re-lease of nutrients from fire, because increased mercury in fish is di-luted to some degree by their increased growth (Kelly et al., 2006).

The changes to watershed vegetation and soils by fire also causereductions in the flow of dissolved organic carbon to lakes. Thischanges some key properties of the aquatic ecosystem, such ashigher water transparency to solar insolation, which causes in-creased UV exposure and thermocline depth (Schindler et al.,1996a,b), increased incidence of transient thermoclines (Xenopou-los and Schindler, 2001) and greater photosynthesis at depth (Kar-lsson et al., 2009). It also allows increased penetration of UVradiation, which has harmful consequences for aquatic biota(Leech and Williamson, 2001; Xenopoulos and Schindler, 2003).Organic carbon of terrestrial origin is now known to be a criticalenergy source for aquatic organisms, particularly in small boreallakes (reviewed by Tranvik et al. (2009)).

Fire can also alter stream habitats. Increased runoff followingfire can cause changes to stream morphology that can persist formany years. Warmer stream temperatures result from lost canopycover, affecting distributions of fish and amphibians in streams(Dunham et al., 2007). Typically, runoff of strong acid anions ex-ceeds that of base cations after fire, so that streams in burnedcatchments become more acidic (Bayley et al., 1992a).

In addition to altering biotic communities (Ward et al., 2007),burning also causes decreased albedo, which exacerbates earlierspring snowmelt and permafrost melting in northern areas, as wellas increasing surface temperatures.

5.2.2. Acid rainAcid rain is caused by anthropogenic emissions of oxides of sul-

phur and nitrogen, which are transformed to strong acids in theatmosphere. If the resulting rain and snow has pH values less than4.9–5.0, it can cause acidification of poorly buffered lakes, streamsand soils, resulting in considerable loss of aquatic biodiversity(Minns et al., 1990). The parts of the boreal region underlain byigneous rocks, such as the Precambrian Shield of eastern Canada,are very susceptible to acid rain.

Legislation in most western countries now requires some con-trol of emissions of sulphur oxides that are the precursors of sul-phuric acid. In North America, sulphur oxide emissions arecurrently about half of values 30 years ago. As a result of these con-trols, coverage of acid rain by the popular media has dwindled, andmost funding for scientific study has disappeared. But the acid rainproblem has not gone away. Although many lakes have recovered

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somewhat as a result, many more have not, due largely to the con-tinued emission of acidifying nitrogen species.

Very little has been done to control nitrogen oxide emissionsfrom high-temperature combustion in industrial sources and auto-mobiles, or ammonia released from agriculture. Both continue tocause acidification of lakes and soils. Roughly half of the nitrogenin rain falls as nitric acid, the result of the oxidation in the atmo-sphere of anthropogenic nitrogen oxide emissions. The other halfof the nitrogen falls as ammonium ion. In an ecosystem, both up-take of ammonia by plants and nitrification of ammonium to ni-trate are strongly acidifying reactions (Kelly et al., 1982) thatrelease hydrogen ion to soils and waters. Some of the most insidi-ous effects of acid rain are currently via damage to terrestrial soilsand saturation of terrestrial ecosystems with nitrogen.

In the early days of acid rain research, it was believed that depo-sition of nitrogen would not be harmful, because nitrogen-limitedcatchment vegetation would utilize the nitrogen, with the resultsof uptake of ammonium and nitrate roughly cancelling each other.But soon after, it was discovered that catchment vegetation andsoils became nitrogen saturated at moderate levels of nitrogendeposition. Also, ammonium as nitrified, a strongly acidifying reac-tion. Excess nitrogen was released as nitrate into surface waters(Emmett et al., 1998). As a result, modern critical loading modelsfor acidifying substances consider both inputs of sulphur and nitro-gen. Such limits are exceeded in the southeastern boreal regions ofCanada (Fig. 4).

Nitrate losses from catchments must be balanced by cations.Valuable calcium and other base cations are leached from forest

Fig. 4. A map of calculated exceedances of critical loads of sulphur and nitrogen for uplanAURAMS model. The map is based on a base cation/aluminum ratio of 10, which was estareas where forest soils and lakes are particularly damaged. The additional effects of fo

soils into streams and lakes. At high critical loads of acid, calciumlevels in soils eventually become low enough to impair forestgrowth (Watmough and Dillon, 2003), particularly where both acidrain and clear-cut logging are removing calcium (Watmough et al.,2004).

Eventually, as calcium stores in catchments become depleted,less calcium enters lakes, and lacustrine concentrations of the ele-ment decline. Such declines cause a loss of sensitive mollusc andcrustacean species (Jeziorski and Yan, 2006; Jeziorski et al.,2008). Declining calcium concentrations and increasing acidity ofreceiving waters also cause the permanent loss of other key organ-isms such as the fathead minnow (Pimephales promelas) (Schindleret al., 1985), the opossum shrimp (Mysis relicta) (Nero and Schin-dler, 1983), the boreal crayfish (Orconectes virilis) (France, 1985),and a host of molluscs (Øklund and Øklund, 1980) from manypoorly buffered lakes. It also means that lakes will not recover totheir original pH values for centuries, because the base cations insoils must be replaced by chemical weathering of igneous bedrock.Also, the loss of critical base cations prevents lakes from fullyrecovering if acid deposition is reduced, so that biodiversity willnever recover entirely.

In summary, increased loss of critical nutrients and bufferingbase cations in runoff from catchments can be used as an earlywarning of impending damage to forest health and biodiversity,as well as to the health and biodiversity of lakes and streams.

Climate warming exacerbates the effects of acid rain by dryingof wetlands that under wetter conditions reduced sulphate to sul-phide, which was then stored as organic sulphur or iron sulfides,

d forest soils of Canada, based on preliminary estimates of 2002 deposition from theimated to maintain base cation saturation in soils >20%. Areas in red and orange arerest harvesting are not shown. From Carou et al. (2008).

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effectively neutralizing sulphuric acid in precipitation. As the wet-lands dry, these deposits are oxidized and decayed, re-releasingsulphuric acid. The result can be the release of acid pulses to lakesand streams following rainstorms (Bayley et al., 1992a; LaZerte,1993). This has delayed the recovery of many lakes from acid rain(Stoddard et al., 1999; Keller et al., 2007).

5.2.3. LoggingApproximately 1/3 of the Canadian boreal forest has been allo-

cated to logging companies. About one million hectares of forest islogged in Canada each year, most of it in the Boreal. Almost all of itis in areas not previously harvested (Global Forest Watch, 2000).Clearcutting continues to be the dominant harvest practice. Inaddition to the well-known damage to and disturbance of habitatsfor terrestrial wildlife, logging of catchments causes many prob-lems associated with biogeochemical cycles and ecosystem ser-vices. Some or these are identical to those described for fireabove, such as increased losses of silt, nutrients and base cations(Wright, 1976; Steedman et al., 2004). As noted above, loggingcan also accelerate the base cation losses caused by acid rain(Watmough et al., 2004) and multiple forest rotations (Duchesneand Houle, 2006). Climate warming, via its effect on acid rain,would further accelerate base cation loss from logging.

5.2.4. Dams and diversionsHydroelectric power is still regarded as ‘‘green” by many sectors

of society. This view is very misguided. Large dams flood terrestrialand wetland ecosystems, releasing large quantities of the green-house gases methane and CO2 (St. Louis et al., 2000; IRN, 2006).In boreal regions the release of greenhouse gases is generally lessthan that from generating the same amount of energy by burningfossil fuels, but it is still substantial (Duchemin et al., 1995; St.Louis et al., 2000). In Canadian boreal regions, the combined areaof hydroelectric reservoirs is roughly equal to the area of Lake On-tario. The area affected in Quebec alone is the size of New YorkState (Ruckstuhl et al., 2008). Dams in boreal regions cause manyother problems, disrupting fish passage and navigation, destabiliz-ing shorelines, causing siltation of spawning beds, increasing mer-cury burdens in fish, changing nutrient loading and retention, anddisplacing indigenous people (Newbury et al., 1984; Legault et al.,2004). When all environmental and social factors are considered,hydroelectric power is probably one of the least sustainable of allenergy options.

Some have advocated small-scale, run of the river hydroelectricgeneration as the path to green power. But an experiment withlicensing small-scale hydroelectric stations in British Columbia re-veals that such plans require many sites to be developed in order togenerate significant power, resulting in many adverse environmen-tal and social impacts (Calvert, 2007).

Climate warming is expected to increase demands for hydro-electric power, especially in the summer months. In addition,dwindling river flows and reservoir levels will require more damsto be built and more rivers diverted to generate the same amountof hydroelectric power.

Disruption of the timing of flows to sensitive ecosystems com-monly results from dam building. For example, the construction ofBennett Dam on the Peace River caused spring high flows to de-cline, and winter flows to increase below the dam. Climate warm-ing has caused snowpacks to dwindle, and spring melt to occurearlier than in the past (Peters and Prowse, 2001). The result hasbeen fewer of the huge ice jams that occurred near the river’smouth in earlier years, causing the flooding of the Peace-AthabascaDelta, a RAMSAR site that is a key staging area for migrating water-fowl and home to several thousand indigenous people. Before theriver was dammed, the flooded area supplied subsistence and anincome from trapping to many families. The combined effects of

climate warming and damming have caused less frequent flooding,allowing the shallow, periodically flooded lakes that supported thiseconomy to dwindle.

Power developments around James Bay and in northern Mani-toba have also caused increased emissions of carbon dioxide andmethane, and large-scale disruptions to boreal ecosystems andindigenous peoples (Duchemin et al., 1995; Rosenberg et al.,1995). While dam building has generally declined in recent yearsas a result of the above impacts, there are plans for dams on thePeace and Slave rivers, to supply power to support oilsands extrac-tion and other human industries. There is also still talk of divertingwater from the Peace River to water-scarce southern Alberta,where the South Saskatchewan River system is now known to be70% oversubscribed. In the eastern Boreal, there are plans to divertand dam more of the rivers that flow to James Bay. Such diversionswould be costly and ecologically disastrous, as channel-formingflows in the diverted rivers would change the morphology of theentire river system below the diversions, including the riparianzones that are home to many birds, mammals and amphibians(Newbury and Gaboury, 1994; Lytle and Poff, 2004). Given thatthe Boreal contains most of the world’s water but a very small pro-portion of human population and industry, in the future there willbe many more attempts to dam and divert major boreal rivers, orto exploit them for hydroelectric power, irrigation or other ‘‘virtualwater” uses to supply more populous regions with food and en-ergy. The role of hydrology and hydrochemistry in assessing theimpacts of dams and river diversions is an obvious one.

5.2.5. EutrophicationEutrophication is also becoming a widespread problem in bor-

eal lakes, particularly in southern regions near to major populationcenters. Increased runoff of phosphorus from land cleared for lake-shore development and agriculture, added to that from septictanks, are generally to blame for the problem (Schindler and Val-lentyne, 2008). Detailed studies of phosphorus ‘‘loading” to lakesfrom non-point sources, and mass-balance studies that includethe rate of water renewal in lakes have greatly enhanced our abil-ity to predict the course of eutrophication.

Climate warming enhances the effect of increased nutrient in-puts to lakes, by reducing outflows. There are now a number ofpractical models that quantitatively relate declines in water qual-ity to changes in inputs of both nutrients and water, for exampleVollenweider (1976), Dillon and Rigler (1974), and Schindleret al. (1978). It is thus clear that where changes to water flowsand water chemistry can be measured precisely, they can beimportant indicators of changes to ecosystem services.

Many of the Cyanobacteria species that form nuisance algalblooms are favored by warmer water and longer ice-free seasons(Paerl and Huisman, 2008). Also, warmer water will cause waterto contain lower concentrations of oxygen, and hasten the deple-tion of oxygen in deep water by decomposition.

5.2.6. Declines in fisheriesMany boreal lakes already have badly degraded fisheries as a re-

sult of overfishing by sport and commercial fishermen and habitatdegradation (Post et al., 2002). Top predators such as walleye (San-der vitreus), lake trout (Salvelinus namaycush), Atlantic salmon (Sal-mo salar) and Pacific salmon (most notably Chinook (Oncorhynchustshawytscha), sockeye (O. nerka) and coho (O. kisutch) are particu-larly affected. Removal of top predators is known to cause trophiccascades that affect many features of aquatic communities and eco-systems (Carpenter et al., 1985; Schindler et al., 1997; Elser et al.,2000). Most investigations have been confined to small lakes atthe southern edge of the Boreal, and much more research is needed,especially in view of the rapidly increasing commercialization of

1580 D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586

northern fly-in sport fishing lodges in the Boreal, in areas where fishrecruitment and growth are very low.

Climate warming is expected to exacerbate declines in manyspecies. Salmon runs are affected by a complicated mix of climatewarming and oceanic events such as the Pacific Decadal Oscilla-tion and ENSO (Beamish et al., 1997). Some lakes and streamsmay get too warm for the coldwater species that are their tradi-tional inhabitants (Poff et al., 2002) or their habitats may becomefragmented as streamflows dwindle and become warmer (Rahelet al., 1996).

5.2.7. Oil sands and other oil and gas developmentsOil sands mining is very energy intensive, emitting far more CO2

per unit of oil extracted than conventional oil extraction. Mining of

Fig. 5. A map of the area underlain by oil sands deposits. The area in orange is surfacesolvents. From Lee and Cheng (2009).

bitumen in northern Alberta has increased greatly in recent yearsas a result of insecure supplies of conventional oil, and energy de-mand by the USA. It has caused increasing release of organic pollu-tants such as naphthenic acids, polycyclic aromatic compounds(PACs; including PAHs and dibenzothiophenes), and toxic tracemetals such as mercury and arsenic to boreal rivers and catch-ments (Timoney and Lee, 2009; Kelly et al., 2009). While increasesin concentrations in rivers are small, i.e. ng/L, such concentrationshave also been shown to cause embryo toxicity in fish (reviewedby Kelly et al. (2009)). Some people believe that elevatedincidences of some types of cancers in downstream humancommunities (Alberta Cancer Board, 2009) have resulted fromcontamination of ecosystems by the oil sands. The problem hascaused much social discord and political controversy.

mineable, and the area in pink can be exploited by in situ processes using heat or

D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586 1581

Oil sands development until the present has been largely bysurface mining (Fig. 5). Needless to say, the ability of mined land-scapes to sequester carbon is destroyed for the foreseeable future.The area damaged by mining and related development is currently4000 km2 and increasing rapidly.

The ability of mined areas to filter and clean water is also im-paired. Whole aquifers are being destroyed with the mining andcannot be replaced (Johnson and Miyanishi, 2008). Little of thewater for the processing of oil sands is returned to the AthabascaRiver, because it is heavily polluted with a wide variety of organic

Fig. 6. (a) The area of Canada exploited by oil and gas activity before 2003 and (b) the aGlobal Forest Watch.

and inorganic toxins (Schindler et al., 2007). Instead, the water issimply confined in large tailings ponds, which now total over130 km2. A tailings pond breach would cause widespread damageto downstream waters.

Even more insidious is the so-called in situ extraction, which isplanned to occur in an area of over 140,000 km2 of northern Alber-ta (Fig. 5). Industries have implied that the technique is benign, butrecent studies have shown that early developments have createdenough surface disturbance to alienate large mammals over largeareas (Schneider et al., 2003). While no studies have been done,

rea projected for exploitation due to oil and gas activity in future years. Maps from

1582 D.W. Schindler, P.G. Lee / Biological Conservation 143 (2010) 1571–1586

the degree of disturbance suggests that carbon sequestration andwater-related ecosystem services will also be impaired over largeareas. As the studies by Kelly et al. (2009) show, such large scaledevelopment leaves significant chemical fingerprints in the Ath-abasca River and its tributaries.

An even larger threat to boreal habitats, and ecosystem servicesis the proposed Mackenzie Valley Pipeline, which would compro-mise a vast area of the western Boreal (Fig. 6). Similar develop-ments are planned for northern Saskatchewan. In the latterprovince, greatly increased uranium mining and exploration havemodified boreal catchments over large areas and increased the re-lease of several radioactive elements.

5.2.8. Mines and other toxic dischargesThere are many sources of toxins to boreal catchments in addi-

tion to oil sands mines. Open pit, underground and placer minesleak toxic trace metals, arsenic, cyanide and other toxins to borealenvironments (Commissioner of the Environment and SustainableDevelopment, 2002). Many toxic sites are mines that have beenabandoned by bankrupt mining companies, leaving a toxic legacyto be cleaned up at public expense (Commissioner of the Environ-ment and Sustainable Development, 2002). Many of these sourcesare difficult and costly to remediate, and the damage they cause isincreased by climate warming. For example, the Giant Mine nearYellowknife, NWT closed recently, leaving 237,000 tonnes of ar-senic trioxide dust in underground chambers, the result of mininggold from arsenopyrite ores. It was once believed that permafrostwould contain the arsenic below ground, but the engineers didnot predict the effects of climate warming on permafrost. Seepageof arsenic now threatens nearby water bodies, including GreatSlave Lake (Fig. 7). Removal of the arsenic would cost an estimated$900 million. Instead, the costly current plan is to use giant ther-

Fig. 7. The location of the Giant Mine near Yellowknife, N.W.T., showing its proximity t

mosyphons to keep the permafrost frozen (Indian and Northern Af-fairs Canada at http://www.ainc-inad.gc.ca/ai/scr/nt/cnt/gm/atg/index-eng.asp).

6. Planning a catchment conservation approach

The numerous examples presented above are convincing evi-dence that a catchment-based approach to conservation planningis urgently needed, and that including water will provide manyadvantages for interpreting threats to both terrestrial and aquaticecosystems. There is also clear evidence that the threats posedby direct perturbations to ecosystems are compounded by climatewarming, and in the southeastern Boreal by continued acid depo-sition. It is the cumulative effects of a cascade of direct and indirectinsults, including airborne stresses, stresses to catchment ecosys-tems, and direct stressors to aquatic ecosystems that are of con-cern. It is thus essential that a conservation plan be broadlyenough based to allow a true assessment of cumulative effects.Schneider et al. (2003) have already advocated the need for sucha plan for northeastern Alberta, based on the cumulative effectsof oil and gas exploration and development plus forestry. TheALCES model that they use is well suited for including aquatic cri-teria. Such an approach would in most cases require little modifi-cation to existing plans. Here are some of the criteria that needto be considered:

6.1. Catchments as conservation units

If catchments designated for conservation are to include all de-sired features, including far-ranging terrestrial species such asbears, woodland caribou, and wolverines, scales of thousands ofsquare kilometres might be needed. This is probably still possible

o Great Slave Lake and other local freshwaters. Indian and Northern Affairs Canada.

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in northern boreal regions of North America, where relatively littleindustrial development has taken place. The Northwest Territoriesgovernment has initiated proactive planning to protect aquatic re-sources (ENR, 2008), and it is considering an approach that in-cludes many of the necessary features for catchment-scaleconservation.

In many catchments, conservation at large catchment scales ishindered by geopolitical boundaries. In this respect, Canada has agreat advantage, with several large boreal catchments containedentirely within the country, although interprovincial politics haveoften been a hindrance to progress.

However, many of the stresses common in the Boreal occur atsmaller scales, affecting the catchments of first or second orderstreams. To detect these, it may be more advantageous to performmonitoring at the scale of multiple small catchments, rather thanone large one. This will be necessary in any case in more southerlyparts of the Boreal, where development has proceeded piecemealwith little thought to cumulative effects or ecosystem services, itis no longer possible to protect such large catchments. Small catch-ments are usually the most sensitive biogeochemical units, wheremany of the early signs of problems with ecosystem services canusually be detected hydrologically or biogeochemically, as clearlyshown by studies at Hubbard Brook and at three boreal sites in On-tario: Dorset, Turkey Lakes, and the Experimental Lakes Area (re-viewed by Parker et al. (2009)).

Extrapolating results to larger areas, or to hydrologically-diffi-cult areas such as those described by Devito et al. (2005) posessome difficulties. In this regard, recent advances in understandingsubsurface water movement using geographical information sys-tems, remote sensing and modelled hydrological patterns showconsiderable promise for estimating water and geochemical bud-gets for large forested areas (reviewed by Buttle et al. (2009)).

To incorporate aquatic studies that can detect both direct andindirect changes to ecosystem processes with the required accu-racy will require some serious upgrading of the monitoring ofmeteorology, hydrology and water chemistry. There are a numberof useful models in boreal or near-boreal regions, at the Experi-mental Lakes Area (Schindler et al., 1996a; Parker et al., 2009), Dor-set (Watmough and Dillon, 2003), at Turkey Lakes (Spoelstra et al.,2001), all in Ontario, and at Trout Lake, Wisconsin (Magnusonet al., 2006). Depending on site location and air mass movement,these have already revealed long-term problems caused by climatechange and other stresses, for example, long-term increases inammonium input, decreases in calcium input (Parker et al.,2009), increased calcium loss (Watmough et al., 2004) and in-creased nitrogen losses (Spoelstra et al., 2001).

It would be useful to a catchment-scale program if changes inwater quality could be linked to standards that designate thresh-olds and concentrations of substances that are detrimental to bio-diversity and ecosystem health services. At present, both theCanadian federal government and provinces have only water qual-ity guidelines, which are not legally enforceable and are often ex-ceeded. With respect to terrestrial ecosystems, it would makesense to have ‘‘loading” similar to the ‘‘critical load” problemdeveloped in Europe for managing the effects of acidifying emis-sions on both terrestrial catchments and receiving waters. The crit-ical load approach has been successfully applied in some systemsin boreal Canada (for example Watmough et al., 2006), but it isnot in widespread use in formulating management policies.

Measuring water and biogeochemical balances in many catch-ments in the Precambrian Shield, including those of several thou-sand square kilometres, is relatively easy, because most areashave little groundwater flow and are underlain by unfracturedbedrock. In most areas, water and biogeochemical balances aredominated by surface flows, because aquifers are generally shallowand well-defined. In contrast, at many sites in the western boreal

ecoregion, lack of relief, few sites for making accurate streamflowand lake level monitoring, thick overburden containing importantaquifers and large areas of wetlands make determining water bal-ances for catchments very difficult.

In summary, a few simple changes to conservation planning toemploy input–output budgets of water and chemicals would allowmany advantages in protecting the health of aquatic and terrestrialecosystems, and evaluating stresses to ecosystem services and nat-ural capital.

Acknowledgements

Reviews of an earlier draft of this manuscript by Suzanne Bayleyand Fiona Schmiegelow much improved it. Matt Hanneman andRyan Cheng from Global Forest Watch prepared several of themaps, and Dinah Roberts and Julian Aherne provided Figs. 3 and4 respectively. Margaret Foxcroft helped to compile the bibliogra-phy and format the manuscript. Much of the primary author’s bor-eal work has been supported for the past 20 years by an NSERCDiscovery Grant.

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