Data/hora: 02/06/2024 07:23:33

Biblioteca(s): 	Embrapa Caprinos e Ovinos.	
Data corrente: 	01/08/1992	
Data da última atualização: 	04/12/2023	
Autoria: 	HEADY, H. F.	
Título: 	Changes in a California annual plant community induced by manipulation of natural mulch.	
Ano de publicação: 	1956	
Fonte/Imprenta: 	Ecology, v. 37, n. 4, p. 798-812, Oct. 1956.	
DOI: 	https://doi.org/10.2307/1933071	
Idioma: 	Inglês	
Conteúdo: 	1. Amounts and position of natural mulch were manipulated according to 8 treatments and 8 replications for a period of 4 years. Yearly pro- duction of herbage was oln oven-dry weight basis determined by sampling square-foot plots. Bo- tanical composition, ground coverage and height of plant materials were determined by the point system. 2. A total of 46 species was found in the study area. Sixteen of them were alien and 40 were annual. Six species that were both alien and an- annual contributed between 67 and 84 per cent of the composition during the 4 years of the study. 3. A perennial bunchgrass, Stipa pulchra, in- creased in numbers from none to 612 plants with- in the exclosure between 1952 and 1955. 4. Amounts of mulch in the different treatmenits varied between zero and nearly 5,000 pounids onl an acre basis. Not all of the mulch decomposed each year so there was a gradual accumulation from 1952 to 1955. The percentage increase was relatively greater where a larger proportion of cur- rent growth was left on the plots than where small amounts remained. The increase in percentage of the soil surface covered with mulch in each April from 1953 to 1955 also indicated accumulation of mulch. 5. With increasing amounts of mulch onl the soil immediately before the fall rains, there was an increase in herbage production the following spring. This relationship is expressed by the re- gression equation Y 1214 + 0.354X for pro- dtuction within the 1,200 to 2,400 pound range. 6. Baeria chrysostoma responded quickly to the mulch treatment and after 1953 it was very abun- dant with no mulch and absent where mulch was the heaviest. Aira caryophyllea reacted in a sim- ilar fashion except it did not show significant differences between treatments until 1954 and the trend was still developing in 1955. Several other grasses and broadleaved herbs followed these same trends although to a much less degree. 7. Bron1us niollis was the only plant that in- creased a significant amount in percentage com- position with the heaviest mulch treatments. It is the species which contributed most to the high production. 8. The legumes and several additional grasses including Festuca dertonensis were most abundant on intermediate treatment. However, these dif- ferences were not significant. 9. Differences in the proportions of Erodiuiit botrys due to treatment were not conclusive. However, this species and all others tested showed highly significant differences between years. Studies on the natural vegetation in the California annual type should include a measure of the varia- tion resulting from different yearly environments. Otherwise, these may overshadow or confuse the differences due to treatments. 10. The proportion of the soil surface covered with moss varied significantly between years and to a less extent between treatmients. 11. The height reached by Bromus mollis in the fall after the first effective rain and before cold weather was dependent upon the amount of mulch and the height of stubble (position of the mulch). 12. The average height of plant materials was determined by measuring the height of the first hit of the points above the soil surface. Significant differences in height of vegetation occurred be- tween years and between treatments within 1954 and 1955. Both yearly and treatment differences in height undoubtedly reflect the differences in botanical composition. 13. The total percentage of ground covered by vegetation was related more to differences between years and and between locations than it was to differences in botanical composition between treatments. 14. Soil movement during the first intense fall rains and frost heaving were observed only on the plots where all mulch was removed each year. 15. The use of mulch in the appraisal of proper utilization of the annual range by livestock is dis- cussed.	
Thesagro: 	Matéria Orgânica; Pastagem; Vegetação.	
Thesaurus Nal: 	Community ecology; Community forestry; Organic matter; Pasture plants; Vegetation.	
Categoria do assunto: 	F Plantas e Produtos de Origem Vegetal	
Registro original: 	Embrapa Caprinos e Ovinos (CNPC)	
Exemplares: 	CNPC - (6498-1) - ADD - AP - DD -  -  -  - DIS