Summer at Duck Pond, White Memorial Foundation

Wednesday, February 18, 2015

Earthworm Distribution at White Memorial Foundation

Earthworm presence (red points) and abscence (yellow points) at White Memorial Foundation from 2014 survey.
We randomly selected points throughout the property to survey earthworms.  Each point consisted of a total of three 0.25 square meter quadrats with mustard extraction, sampling occurred from late-July to late-September, 2014.  Earthworms are widely dispersed throughout the property.  A couple regions that are noteworthy include the Cathedrals region, which is located south of Cranberry Pond, had few earthworms while the Museum vicinity, located north of Bantam Lake, have abundant earthworm populations.  The factors that could influence the presence of earthworms need further exploration but some appear to be more important than others including soil pH, previous land use practices, and the likelihood of introduction by fisherman, illegal refuse dumping, and proximity to neighboring homes.  It is important to note that we only used one earthworm detection method and this could bias our sampling of populations with very few individuals or species that live deeply below the soil surface where mustard juice could not penetrate effectively.

Wednesday, January 28, 2015

Forest Vegetation Strongly Related to the Earthworm Biomass

Vegetation and earthworm biomass scatterplot.

I investigated the relationship between vegetation and introduced earthworms on the property.  Several important relationships were observed.  Herbaceous vegetation data was collected at 25 randomly selected points on the property within one square meter quadrats.  Native vegetation including tree seedlings in the herbacous layer were negatively correlated with the amount of earthworms in the soil.  Invasive plants were positively correlated with earthworm biomass.  The relative strength of each of these relationships varied.  Invasive plants and  total native plants were the strongests correlations, while native tree seedlings were not as strong.  Tree seedling cover can be influenced by several factors including herbivory, seed production, acid precipitation, as well as many other disturbances.  Neverthess, this data suggests that introduced earthworms are one more important factor that influences our forest ecosystems.

Monday, January 12, 2015

Earthworm Species Inventory and Forest Cover Type Associations

A total of 14 species of earthworms observed in 2014,
of whcih two were native (N) and twelve were exotic (E),
on The White Memorial Foundation, Inc., and associated forest cover types.
Click on table to enlarge.
A totalof the 14 earthworm species were detected during the 2014 survey at White Memorial Foundation.  We randomly selected 82 plots throughout the property and collected 993 specimens.  Juvenile or non-clitellate individuals for Megascolecidae family and certain Lumbricid genus are impossible to identify to species using external and internal characters with currently developed keys.  Some cover types were sampled more than others, nevertheless random sampling insured that the frequency distribution reflects the actual proportion of cover type at White Memorial.  The native species Eisenoides lonnbergi was found in only two cover types, oak and mixed conifer, specifically in plots located near wetlands.  The other native species Dendrodrilus rubidus was were detected in most of the cover types, conifer as well as upland and lowland hardwoods.  The remaining species have exotic origins and were detected in many cover types.  Intially, it appears that the hardwood cover types more species of earthworms than the conifer stands.  Conifer stands tend to have lower soil pH than hardwood cover types, which could influence the species that inhabit the stands.