Effects of Fire on Factors Controlling Plant Growth in Adenostoma Chaparral

摘要: In the first few years following fire, burned chaparral areas are typified by a flush of seed germination and seedling growth not seen in unburned chaparral. The effects fire on factors potential importance to this plant response were examined recently long chaparral, dominated Adenostoma fasciculatum, Santa Ynez Mountains near Barbara, California. Measurement soil moisture, texture, light indicated that changes these had little direct effect postfire growth. Bacteria fungi more abundant than soil. Thus, hypothesis microbial depletion oxygen inhibits appears untenable. Changes organic matter content, pH, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium upper layers both during 18 mo fire. Mineral addition as ash—fall was also evaluated. Burning increased levels most mineral elements significantly. Furthermore, large reservoir readily available nutrients added ash. Causes low nutrient investigated. Additions greenhouse field resulted species common areas. Bioassays aqueous A. fasciculatum leaf washings performed against 10 Significant depression observed. Rain throughfall collected under shrubs inhibitory. Efforts isolate identify toxins described. Numbers small herbivorous mammals greatly reduced This factor is shown have marked survival. Applications various heat treatments fresh seeds several released from dormancy heat. Insolational heating cleared, but unburned, sufficient stimulate germination.