Prof stresses bio­di­ver­sity

Ottawa Citizen - - Front Page - BRUCE DEACHMAN

Imag­ine if we only had one-day week­ends.

That’s how Lenore Fahrig looks at the loss of bio­di­ver­sity that hu­man ac­tiv­ity has caused, not­ing that an es­ti­mated 15 per cent of species, or about one in seven, have become ex­tinct in the last cen­tury and a half.

“I tell my stu­dents, it’s like all the Satur­days for the rest of your life are gone,” says the Car­leton Univer­sity chan­cel­lor’s pro­fes­sor in bi­ol­ogy. “From my per­spec­tive, it’s just a crime that we are de­stroy­ing the bio­di­ver­sity on the planet.”

Stud­ies show that the bird pop­u­la­tion has dropped by al­most 30 per cent since 1970, am­phib­ians are dis­ap­pear­ing at a rate of nearly four per cent per year, while the de­cline of in­sects stands at about nine per cent per decade.

Over most of the past decade, Fahrig has been leading the way in re­search, both in Eastern On­tario and across Europe, to iden­tify ways to slow this en­vi­ron­men­tal purge. In an ar­ti­cle pub­lished last month in the jour­nal The Con­ver­sa­tion, she iden­ti­fied a pair of im­por­tant fac­tors — the sizes of agri­cul­tural fields and crop va­ri­ety — that con­trib­ute to bio­di­ver­sity, and sug­gests ways farm­ers could help ame­lio­rate these losses.

A land­scape ecol­o­gist, Fahrig stud­ies how fac­tors such as de­for­esta­tion, ur­ban buildup and roads af­fect bio­di­ver­sity. Noth­ing, she says, matches the world­wide ef­fects of agri­cul­ture.

“Of course, peo­ple need to eat and we have to have agri­cul­ture, but we were won­der­ing if there was a way to ar­range crop fields in a way that would re­duce the im­pact on bio­di­ver­sity.”

She and her col­leagues ex­am­ined 93 Eastern On­tario land­scapes, each mea­sur­ing one square kilo­me­tre and cho­sen to rep­re­sent va­ri­eties of field sizes and crop di­ver­sity.

They then sam­pled the num­bers of birds, bees, plants, spi­ders, cara­bid bee­tles, frogs, syr­phid flies, bats and but­ter­flies in each, both in the fields and at their edges. Many of these species, Fahrig says, are im­por­tant for pol­li­na­tion and pest con­trol, and their loss could have se­ri­ous con­se­quences.

They dis­cov­ered much greater bio­di­ver­sity where smaller fields were used. Fahrig ad­mits that some of this in­crease can be ac­counted for by the fence lines, ditches and hedgerows sep­a­rat­ing fields, but greater num­bers of fauna were also found where fields of dif­fer­ent types of crops were not oth­er­wise sep­a­rated.

Even ac­count­ing for such non­cropped strips, they dis­cov­ered that as av­er­age field sizes fell from eight to two hectares, bio­di­ver­sity rose by about 50 per cent.

“Even when you have these very nar­row bits be­tween crops, that still rep­re­sents a refuge. So that a species that’s in a crop field when some­thing’s go­ing on — plow­ing, for ex­am­ple — that’s a place they can go to sit out the storm, so to speak, with­out hav­ing to go great dis­tances, which many of them can’t do.

“Peo­ple are wor­ried right now about the cri­sis in the num­bers of pol­li­na­tors,” she adds. “The num­bers of birds, frog and in­sects are all de­clin­ing, and all of these ac­tu­ally do things for us with­out us be­ing aware of it.

They eats pests in the fields, pol­li­nate crops, while plants re­duce soil ero­sion.

“Most of the things we do rely on nat­u­ral species.”

Fahrig sub­se­quently led sim­i­lar field­work in more than 300 land­scapes in seven dif­fer­ent re­gions and cli­mates in Europe, in­clud­ing those in Eng­land, France, Ger­many and Spain, where their re­sults were con­sis­tent with their On­tario data.

Their find­ings go against an in­creas­ing trend to­ward the econ­omy of scale and op­er­a­tional efficiency of hav­ing larger fields on even larger farms, but Fahrig said she be­lieves the ben­e­fits to farm­ers of bio­di­ver­sity have been left out of that eco­nomic equa­tion, and she would like to even­tu­ally in­clude that cal­cu­la­tion in her group’s re­search.

“Many farm­ers re­ally do love nature, so if they could be con­vinced that they could make their fields smaller, have this large ben­e­fit to nature and not re­duce their profit, they would prob­a­bly be pretty amenable to it.” bdeach­


Lenore Fahrig and her col­leagues ex­am­ined 93 Eastern On­tario land­scapes for a re­cent re­port on how bio­di­ver­sity is af­fected by farm-field size and crop va­ri­ety.

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