Agricultural soils have increased amounts of many water soluble nutrients due to fertilizer application, most importantly phosphorus.Concentration of available P=99.7ppm, K=915ppm, Ca=1500ppm, Mg=720ppm. Pasture soils also have elevated levels of many nutrients, however bioavailable phosphorus is not increased. Concentration of K=234 ppm, Ca=3035 ppm, and Mg=334 ppm. These nutrients are lost from the soils by runoff and erosion and can enter Shelburne Pond. Extracts from agricultural soils resulted in an average growth rate of Shelburne Pond algae r=6.9348 ugDWúd-1; pasture treatment, r=0.5222ugDWúd-1; forest treatment, r=-0.1373ugDWúd-1; control, r=-0.3587 ugDWúd-1. Mean chlorophyll a of agriculture treatment=85.26ægúL-1, pasture treatment=22.55ægúL-1, forest treament=4.11ægúL-1, control 1.24ægúL-1. Extracts from agricultural and pasture soils increased algal growth over the time period.
Algal growth was measured in the LaPlatte River in northwestern VT. The site is located in an agricultural basin, and thus phosphorus levels are high enough so as not to be limiting to algal growth. It was hypothesized that algal growth was limited by herbivory. Nutrient diffusing clay flowerpot substrates were used to set up a condition of enriched phosphorus, insecticide, both phosphorus and insecticide, and a control. Pyrethrin, a naturally occurring organic insecticide was used. The growth of algae on the substrates was measured by total dry weight scraped from a standardized sampling area after 21 days in the river. There were no significant effects on growth by the treatments. Caddisflies (O:Trichoptera) found on the substrates indicated that the insecticide was not having a significant effect on the treatments because they were present on almost all of the substrates. Although the mean numbers of caddisflies seen on each treatments were not significant, they suggest a trend of fewer herbivores on the substrates containing pyrethrin. These results lead us to suggest further study with higher concentrations of pyrethrin which should more effectively repel herbivores. Differences in algal growth in the different conditions would then be expected to be significant.
The focus of this study was to investigate relationships between vegetational patterns and pH levels in Colchester Bog. Two parallel transects were established 140 meters into the bog. Various environmental parameters such a pH and nutrients were measured. Vegetation was also identified along these transects. A relationship between Sphagnum sp. and low pH regions was observed. The distribution of Spirea and Alnus rugosa was strongly correlated with high pH levels. Besides these trends, no other significant relationships were noticed between vegetational patterns and pH levels. Vegetational patterns with Acer rubrum, K. angustifolia, and C. calyculata were observed to be pH independent. Factors, such as nutrients(calcium and nitrogen) and morphological adaptions are belived to be responsible for these vegetational patterns. The cause of these patterns was not established due to time and sampling restrictions.
A survey of Gaultheria procumbens and Mitchella repens was conducted to explore niche overlap, co-occurrence and ecological range. Our nich survey consisted of two parts; the exploration of distribution (density) of each species and a brief census of a few environmental factors, including light, soil moisture, nutrients and pH. Our ecological range data conssits of tree association, slope, and general topography. Chi-squared results for co-occurrence show random co-occurrence (0.32). Nutrient availability results indicate that a niche differentiation of an undeterminable extent exists.
This study investigated the occurance of Abies balsamea, and selected soil factors that might affect this occurance. Abies was investigated on an altitudinal grandient on the west slope of Camel's Hump. Abies balsamea was found to occur first as a shrub at 787m, and then as a canopy tree at 909 m. From 909 m to 1151 m Abies increased in numbers of individuals from 6 to 14 per plot in the canopy, and from 12 to 134 in the understory. This trend of increasing Abies with inceasing altitude was the opposite for the trends of several nutrients in the B Horizon. Ca decreased from 93 mg/L to 22 mg/l, Mg decreased from 10 mg/L to 7 mg/L, and K decreased slightly from 10 mg/L to 9 mg/L. Soil acidity also increased with elevation, dropping from pH4 at 545 m to pH 3.4 at 1151 m in the B Horizon. Soil moisture in the O horizon increased with increasing elevation. Soil moisture in the B horizon followed no specific trend but peaked at 666 m in the deciduous forest, and at 1030 m in the subalpine forest. Our hypothesis for increasing fir, decreasing pH and nutrients with elevation was supported by our data. Our hypothesis for soil moisture was disproved by our data.