Showing papers by "Ernst Detlef Schulze published in 1967"

Wintertime Photosynthesis of Bristlecone Pine (Pinus Aristata) In the White Mountains of California

Abstract: Winter rates of photosynthesis and respiration in bristlecone pine were measured at controlled temperatures at 3,094 m elevation. Following the onset of severely cold temperatures in autumn, net photosynthesis declined sharply. By midwinter net photosynthesis became zero and remained there through early spring; during this time only low gross photosynthesis could be measured. Respiration rates remained high until late winter and then dropped significantly in early spring when temperatures increased and the soil thawed. The absence of net photosynthesis and the continued high respiration results in a large negative CO2 balance by the end of the winter. Approximately 117 hr of photosynthesis during summertime at peak rates are needed to equalize the winter loss of 140 mg CO2 per gram dry weight of photosynthetically active tissue. These findings are related to the growth of bristlecone pine at timberline. See full-text article at JSTOR

Soil Respiration of Tropical Vegetation types

Abstract: Soil respiration rates, measured during the dry season of 1966 in Costa Rica by absorption of CO2 through KOH followed by titration with HCI, were lowest in the savanna and the decidous forest (300—400 mg CO2/m2/hr); they were between 1,000 and 2,000 mg CO:2/m2/hr in the gallery forest and the wet forest; and were highest in the secondary growth vegetation (2,556 mg CO2/m2/hr). The results were related to the climatic conditions in these habitats. The climate limits the development of organisms in the soil and the primary production in the vegetation. Comparisons of European, Canadian, and tropical soil respiration rates show the limitation of soil respiration through limitations of primary productivity. See full-text article at JSTOR