Jon E. Sanger

Quantitative Investigations of Leaf Pigments From Their Inception in Buds Through Autumn Coloration to Decomposition in Falling Leaves

Pigments in hazel (Corylus americana), aspen (Populus tremuloides), and pin oak (Quercus ellipsoidalis) leaves were measured from their inception in buds to development of a summer maximum, and through the autumn coloration period to decomposition in dry falling leaves. Leaves contained generally high but varyingconcentrations of chlorophyll and carotenoid pigments throughout the summer months. The summer pigment variations among the three species are discussed in the light of the usefulness of chlorophyll content as an index of net primary productivity. During the autumn coloration period, preceding leaf desiccation and fall, chlorophyll decays rapidly, producing low levels of pheophytin with only occasional faint traces of pheophorbide and chlorophyllide during the period of most rapid chlorophyll breakdown. The levels of carotenoids begin declining at the same time as chlorophyll, but at a much slower rate. Violaxanthin disappears most rapidly, followed closely by neoxanthin. Lutein and Beta—carotene a...

Plant pigments in woodland soils

Low concentrations of carotenoids and chlorophyll derivatives and present in the organic matter of surface horizons of woodland soils. Before leaf fall chlorophyll breaks down more rapidly than carotenoids, while the reverse is true in soils. This suggests that the contribution of woodland litter and humus to the organic matter in such sediments is outweighed by contributions from aquatic macrophytes and phytoplankton. See full-text article at JSTOR

Caloric Values of Organic Matter in Woodland, Swamp, and Lake Soils

Caloric values were determined on an ash—free dry—weight basis for organic matter in woodland, swamp, and lake soils and in certain plants. Mean values in kilocalories per gram are: 11 woodland soils, 5.04; 20 swamp soils, 4.87; 9 lake sediments, 5.24; 10 tree—leaf samples, 5.22; 9 samples of aboveground parts of the ground flora, 4.65; 4 aquatic algae, 5.23; and 4 aquatic macrophytes, 4.31. See full-text article at JSTOR

The Visible Albedo of Surfaces in Central Minnesota

Incident and reflected visible radiation under clear skies was measured in summer 1960 over surfaces in central Minnesota. Measurements were made with Weston photometers, model 756, on the ground, from ladders, and from a Bell 47—G2 helicopter. Percent albedo over natural upland surfaces at 60—65° solar altitude decrease from 12.0 for inorganic sand to 6.1 for organic sand, to 5.3 for short grassland, and to 2.2 for forest; lowland surfaces decreased from 4.0 for water to 2.3 for forest. Albedo decreased with an increasing chlorophyll a + b content of vegetation, but the decrease was negligible above a chlorophyll content of around 1.0g/m2. Urban surfaces were more reflective than agricultural surfaces, which had a higher mean albedo than natural vegetation. The mean albedo of an aerial transect from Bethel to St. Paul was 6.5% and was estimated to have increased around 15% the settlement of the area by European man. Percent albedo over a Quercus forest increase from 2.4 at 65—70° solar altitude of 11.6 at 8—10° and the decreased to 3.8 at 0° altitude. A similar albedo pattern was found for a pioneer (short) grassland which increased from 5.2 to 13.2 and then decreased to 4.6%. Changes in albedo with solar were attributed to changing proportions of diffuse and direct radiation and to Fresnels Law. Light penetration into the Quercus forest decreased most rapidly in the lower tree canopy layer and decreased with increasing solar altitude. Albedo within the Quercus forest increased with increasing forest depth and with increasing solar altitude, reaching a maximum of 12.7% at a forestheight of 0—3 m and a solar altitude of >60°.

A Comparison of the Abundance and Diversity of Fossil Pigments in Wetland Peats and Woodland Humus Layers

The abundance and diversity of fossil pigments (chloraphyll derivatives and carotenoids) in woodland humus layers and in circumneutral to moderately acid swamp peats are shown to increase with degree of soil waterlogging. The swamp peats are distinctly richer in pigments than are the highly acid peats from a Sphagnum bog, especially as regards carotenoids. However, the bog and swamp peats exhibit equal pigment diversity. Although the semi—aquatic swamp peats are richer and more diverse in fossil pigments than terrestrial humus layers, they are much poorer and much less diverse than profundal lake sediments. A combination of low pigment concentrations, moderate pigment diversity, and high ratios of chlorophyll derivatives to carotenoids has shown utility as an indicator of swamp invasion in the course of lacustrine evolution. See full-text article at JSTOR

Identification and Quantitative Measurement of Plant Pigments in Soil Humus Layers

Pigments in soil organic matter layers of an oak forest, a spruce—cedar woodland, and a prairie have been identified and measured quantitatively. In all cases lutein was the dominant carotenoid accompanied by smaller amounts of Beta—carotene. Phenophytin a and chlorophyllide a commonly present in the L and F organic layers. Pigment ratios were examined and compared in all three humus types. See full-text article at JSTOR