Deciduous Woodlands

Paper birch (Betula papyrifera), quaking aspen (Populus tremuloides) and black cottonwood (Populus balsamifera) stands form the canopy over deciduous woodlands at MPG North. Healthy aspen stands propagate multi-aged tree colonies from root sprouts of a single underground clone. Young and middle-aged saplings provide energy for the clone as older trees fade and die. Birch and cottonwood communities arise after disturbance events. Stands of these species comprise many separate individuals that emerged from seeds. Depending on soil composition and disturbance regimes, the understory in healthy deciduous woodlands supports multiple shrub and herbaceous layers or a simple herbaceous layer.

Healthy deciduous woodlands and their shrub understories at MPG North support a diverse avian community, and ungulates depend on young shoots for nutrition. Healthy stands grow fast enough to compensate for ungulate browsing and damage from antler rubbing. Over time, stem density and size further reduces ungulate damage.

Unhealthy conditions arise in deciduous woodlands when disproportionate ungulate browsing reduces sapling recruitment. These conditions produce a "recruitment gap" where all stems belong to a single older age class. Conifer encroachment and increased canopy closure results until the deciduous trees and understory shrubs die out. Alterations to typical disturbance events (fire suppression and flood control, for example) allow closed conifer forests to persist and deciduous woodland habitat declines.

The desired future condition of unhealthy deciduous woodland habitat at MPG North is multi-aged stands of deciduous trees with sufficient density to facilitate expansion despite browsing and other damage by ungulates. We use fences or "exclosures" to keep ungulates out for a time and allow the stands to recover. Hand planting of deciduous species supplements stem numbers in areas with poor recruitment. Managed disturbance events like prescribed fire, soil surface scarification and conifer thinning will encourage deciduous woodland expansion after the exclosures are removed.

Revegetation efforts at MPG North began in 2005. Monitoring data for 2007-2009 comprised two shrub species (Douglas’s hawthorn and chokecherry). We expanded monitoring procedures in 2011 include all planted species. In 2011 and 2012, crews measured about 25% of planted shrubs, conifers, and deciduous trees to estimate the progress of revegetation efforts over the entire property. 

We planted 1325 trees and shrubs at MPG North over the week of September 14th. This map shows all planting locations. Each plant received at least one gallon of water before exclosure installation. The planting crew applied 2.5 gallons of wood chip mulch over plant roots in dry areas (shown in orange) to improve water retention and decrease grass competition. Mulch applications to island plantings depended on experimental treatment.

Our August 2011 invasive weed survey began with the need for baseline data and it being a 'banner year' for growth- thus a good time to collect data. QUsetions we aim to answer with the survey include; What is the current distribution and abundance of three widespread asteraceous species (Canada thistle - CIAR, spotted knapweed - CEMA, oxeye daisy - LEVU) on MPG North? Is weed distribution similar among the target species? What other weeds exist on the property, and where are they? Are weeds invading relatively undisturbed areas? 

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