Impact of mining activity on Lake Duparquet shoreline forest dynamics Hugo Asselin (Québec) John Brown (Missouri) Mary Harner (New Mexico) Christina Longbrake (Pennsylvania)

Introduction Typical boomtown Gold mine started its activities in 1932 Ended mining activities by 1955 Mining waste dumped in Lake Duparquet

Questions Did mining activity have an impact on spruce growth? Did mining activity have an impact on aspen growth? Was this different than the effect on spruce? What has colonized the mine waste beach and when?

Questions 1& 2 Did mining activity have an impact on spruce growth? Did mining activity have an impact on aspen growth? Was this different than the effect on spruce?

Question 1 - Methods Two sites were sampled, one upwind and one downwind from the mine At each site, all the trees > 7 in. diameter were sampled (core) and measured (dbh) inside a 15 m radius plot. Cores were prepared, crossdated, and measured.

White Spruce

Question 2 - Methods At previous two sites, three large aspen trees were sampled in or near the spruce sample area. Cores were prepared, crossdated, and measured.

Aspen

Question 3 What has colonized the mine waste beach and when?

Question 3 - Methods A transect was set up, starting from the forest border (former shoreline) and going towards the lake. Total vegetation cover was estimated in 15 feet radius circular plots located every 100 m Number of individuals of all tree and shrub species was counted. The largest individuals of large species were sampled (cookie).

Species Composition

Plant cover from old shoreline

Colonization pattern on the mining waste beach Birch Cottonwood Birch Spruce Birch

Conclusions Trees have been affected by many different human activities (mining, logging, other?). Colonization of the beach area is proceeding but conditions may hamper further succession (salt, freezing). Good news: found an indicator of good water quality on the mine residue area…

Merci !