Dataset 242
Lac Croche understory vegetation data set (1998 to 2006)
Realm: Terrestrial
Climate: Temperate
Biome: Temperate broadleaf and mixed forests Central latitude: 45.993278
Central longitude: -74.001571
Duration: 7 years, from 1998 to 2006
Climate: Temperate
Biome: Temperate broadleaf and mixed forests Central latitude: 45.993278
Central longitude: -74.001571
Duration: 7 years, from 1998 to 2006
1030 records
12 distinct species
Across the time series Acer rubrum is the most frequently occurring speciesMethods
Abstract: The Lac Croche data set covers a nine-year period (1998?2006) of detailed understory vegetation sampling of a temperate North American forest located in the Station de Biologie des Laurentides (SBL) Qu?bec Canada. After having been submitted to logging in the late 19th and early 20th centuries followed by a major fire in 1923 the forest is currently in a transition state dominated by pioneer canopy tree species. The sampling design is based on the annual re-sampling of 43 permanent 400-m2 plots along five transects running parallel to an elevation gradient from a lake (Lac Croche) to the top of a hill. Abundances of all understory vascular plants (tree seedlings herbs and shrubs) are included in the data set and are expressed either as absolute densities or cover classes depending on life form. The location and elevation of each plot as well as some key environmenatl descriptors such as slope rockiness canopy openness age of the largest tree basal area of mature trees and a number of soil variables are also available. The Lac Croche data set should prove useful for testing hypotheses about forest vegetation dynamics at different sacles as well as to test new statistical tools developed for the analysis of the spatio-temporal variation of plant distributions. Sampling is ongoing and new data will be added every year ________ Site description: The study site is located within the SBL (Fig. 1) which is located north of Montr?al in St-Hippolyte Qu?bec Canada. The SBL was acquired in 1963 by the D?partement des Sciences biologiques (Universit? de Montr?al) as a long-term research facility. Located at the foot of the Laurentides geological formation (part of the Canadian Shield) it is part of the sugar maple - yellow birch ecological region. The territory is mostly forested with several lakes and bogs typical of the region. The SBL (46?58? ? 46?01?N 73?57? - 74?01?W) covers 16.5 km2 of mountainous irregular ground with much evidence of the Wisconsinian glaciation (e.g. erratic boulders). Bedrock is primarily composed of anorthosite. Altitude varies from 270m to 450m. Mean annual temperature is 3.9?C and annual precipitations average 1153 mm of which 26% falls as snow (1970-2000 averages; SIMAT 2000). While the climax forest type on mesic sites in the region is typically Acer saccharum - Betula alleghaniensis forest a large number of mesic sites are currently in transition states that are dominated by A. rubrum and pioneer tree species such as B. papyrifera and Populus grandidentata (Savage 2001). This is likely due to perturbations such as logging episodes early in the 19th and 20th century as well as a fire which occurred in 1923 (Lortie 1979). Conifers are dominant on hydric and xeric sites. On August 1st 2006 a windstorm with 100 km/h winds created gaps in the canopy where patches of large pioneer species were still present.Sampling design: The data were collected during a plant ecology field course (BIO3753) given each summer in mid-August by the D?partement de sciences biologiques Universit? de Montr?al. Five permanent transects were established in 1998 at the north-eastern tip of Lac Croche (Fig. 1). Transects are separated by about 50 m. The transects which run more or less parallel to each other at an azimuth of 074? start at the edge of the lake and follow an elevation gradient uphill. Along the transects 43 permanent plots were established (1998) approximately every 50 m. Their location is marked by permanent steel rods in their center. Plots are 20 ? 20 m (400 m2). Sampling of the Lac Croche transects takes approximately three days to complete; the dates given in the data set is that of the first sampling day each year.Within each plot the cover of herbaceous and shrub species was assessed every year usinga modified Braun-Blanquet (1932)semi-quantitative cover scale (Table 1) (Barbour et al. 1999). Tree seedlings (DBH < 1 cm) were also inventoried within two classes according to height (smaller or taller than 30 cm) (Table 2) using ten 1 m x 1 m sub-plots that were established every 2 m along the center of each plot following the transect axis. Within each sub-plot all tree seedlings were counted and identified to species. Data from those ten sub-plots were then pooled and multiplied by 40 to give an estimate of tree seedling abundance over the whole 400 m2 plot. In 1998 2000 and 2001 the two classes of seedlings were joined. Tree seedlings were not inventoried in 1999.A number of abiotic and biotic environmental variables were also evaluated. In 2005 all mature trees (DBH > 10 cm) were identified to species and their diameter at breast height (DBH) measured. The total basal area (BA) per species was then calculated for each plot. A pedon was dug just outside each plot (in order not to disturb the area for subsequent years). From this pedon the following edaphic variables were evaluated: thickness of the organic (O) horizon thickness of horizon A presence of eluviation (E horizon) (Soil Survey Division Staff 1993) and maximum root depth. Pedons were as deep as necessary to collect all variables. Slope was measured using a clinometer (PM-5 model Suunto Vantaa Finland) and slope orientation was measured using a compass. Slope shape was judged on a qualitative scale (concave convex or regular). Surface rockiness (including exposed bedrock) was evaluated on the modified Braun-Blanquet cover scale (Table 1). Canopy openness was measured with Gap Light Analyzer (Frazer et al. 2000) from hemispherical photographs of the canopy taken in the middle of each plot at one meter above ground. Geographic coordinates as well as elevation were measured with a differential GPS receiver (Trimble Navigation Ltd. Sunnyvale CA USA) with estimated 2-m accuracy. Abundances of all understory vascular plants (tree seedlings herbs and shrubs) annual re-sampling of 43 permanent 400-m2 plots Unit of abundance = IndCountInt, Unit of biomass = NACitation(s)
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