The Study On Biomass And Caloric Value Of Locust Energy Forests In Luoning Hilly Region, Henan

Studies on renewable biomass resources have been emphasized in all the countries of the world with the exhaustion of the traditional resources. The fuel type energy forest is the major part of biomass resources. Locust, a traditional fuel energy tree species, has wonderful development prospect, because it has good features such as strong adaptability, fast growth, feeding nature and nectar with the large-scale cultivation in our country. Locust in the hilly region of Luoning County, Henan Province was researched from the perspectives of the biomass of locust energy forest, thermal equivalent, variation characteristics of the stand caloric values and their influencing factors by investigating the aboveground growth and biomass of locust and by determining and analyzing the matters (ash, volatile matter) and elements (carbon, nitrogen, phosphorus, potassium) of forest-related components for six years. Major conclusions are as follows.(1) Variation characteristics of the harvest thermal equivalent of the locust energy forest are as follows. The thermal equivalent of the coppice type was higher than that of the high forest type. The thermal equivalent value of the coppice type was obviously high at the ages of four to five with the amplitude of18.76～19.16kj·g-1, while the amplitude of the thermal equivalent of the high forest type was18.50～19.06kj·g-1; The thermal equivalent values of organs were different with the sequence of leaf> trunk> branch> bark; The thermal equivalent values of site conditions were also different, for the average value of the shady slope was higher than that of the sunny slope at the age of two or more; The thermal equivalent decreased as the branch diameter enlarged.(2) Variation characteristics of the biomass of the locust energy forest are as follows. The average annual biomass maximum of the high forest type was22years with obvious decrease at the age of34. During one to five years of locust shrub growth of the coppice working circle, the ground diameter and height declined continuously which was manifested as a declining pattern of "W". It was slightly different in these two wavy patterns, for the steepness of the height was larger than that of the diameter. The annual increment and continuous increment of biomass were both manifested as an increasing pattern of "V" and the continuous increment at the age of five was very obvious.(3) The total harvest volume of various species of the locust energy forest had different coefficient conversions on the basis of biomass. The coal equivalent coefficient of the coppice type biomass was0.6401～0.6538, while that of the high forest type was0.6313～0.6505. One kilowatt hour needed320g of standard coal. For example, as for the harvest volume of various species of the unit area of the five-year-old stand of the coppice type, when the biomass was32.1t·hm-2, the converted standard coal was20.6t·hm-2, which could produce about64375kilowatt hour·hm-2; the total thermal value of the stand mainly depended on the biomass of the stand, and the harvest volume and biomass of the coal quality and electric power had the same tendency and similar changes.(4) Site conditions had the same influence on the thermal equivalent value and biomass of the locust forests of the high forest type and coppice type, especially remarkably on the coppice type stand. The biomass of the coppice type in the shady slope was higher than that in the sunny slope at the age of two; the biomass in the shady slope was twice higher than that in the sunny slope at the age of three. The thermal equivalent value and coal equivalent coefficient were higher in the shady slope than those in the sunny slope except at the age of one, which indicated that the thermal equivalent value and biomass in the shady slope were both very high with the high total thermal equivalent value at the ages of four to five. (5)As was shown in the experiment of the tending intensity of the sample plot of the two-year-old coppice, biomass increased by20.64%(P<0.05) at the tending intensity of1/4and by30.25%(P<0.01) at the tending intensity of1/2, which suggested that the proper tending intensity was effective for the biomass increase.(6) The difference of wood fibre structure was one of the influencing factors of the difference of the thermal equivalent value of the coppice type of the locust energy forest. According to the initial judgment, fibre patterns and thickness of locust were positively correlated with the thermal value, while the length and size were negatively correlated.(7) Different comprehensive component was another reason for the difference of the thermal value. The tendency of shrub locust crude ash content was leaf> trunk> branch> bark; the volatile component decreased as the diameter increased; The sequence of shrub locust forest carbon density:2a>4a>3a>1a; crude ash and volatile component content were negatively correlated with the gross caloric value, while the carbon storage of a stand was positively correlated with the total caloric value. The comprehensive correlation analysis of all the factors showed that the thermal value had high correlation with the factors such as ash, pure carbide, nitrogen, phosphorus and potassium, while pure carbide and ash had high correlation with the other factors.The total harvest volume of various species of the locust energy forest, the variation characteristics and regular pattern of various forms such as biomass, coal quality and electric power were obtained, which provided a theoretical basis to make the measures of improving the harvest volume. The study of the short cutting period contributed a lot to the systematic study of the locust energy forest. The study showed that the biomass production and the short cutting period of the energy forest cultivation and the coppice management were of practical significance. The diameter class provided a theoretical basis for the classification of the harvest and a new method of combining theory with practice in the field of energy forests.