Mean while, many new characteristic parameters such as litter equilibrium index and soil nutrient equilibrium index have been proposed and the calculation tenet of Deanglis's nutrient recycling index applied in forestland has been elaborated.

Eco-network is a structural model which simulates the flow of material and energy in ecosystem, CI (Cycling Index) reflects the recycling feature of material flow.

The sensitivity Analysis of Recycling Indices of Nitrogen,Phosphorus and Potassium in an Agroforestry Ecosystem of the Populus euramericana-Triticum sativum-Zea mays

The sensitivities of recycling indices of nitrogen, phosphorus and potassi-um(N,P,K)in the agroforestry ecosystem of Populus euramericana-Triticum sativum-Zea mays were analyzed.

Sensitivinty analysis of Recycling Indexes of Nitrogen,Phosphorus and Kalium in an Agroforestry Ecosystem of the Populus euramericana- Triticum aestivm-Zea mays Community

According to the complexity of food chain and the nitrogen recycling indexes in different microecosystems, it is considered that the maturity and stability of the ecosystem were higher in treatments 1:0,0.5:0.5, and 0.3:0.7, but lower in the treatment 0:1 which consists of rice plantation and relaying on inorganic fertilizers only.

In the present paper, a computational method about CI is given on the basis of stochastic process in detail, and the sensitivity of CI about the state variable of econetwork is formulated.

A cycling index of 44% indicated a fairly closed system where most components were important in determining the overall structure of the system.

The proposition of the compartment model method brings us bopes that with this method We can solve she problem of matter cycling in agroecosystem quantitatively. In this paper based on data collected in our experiments and surveys a compartment model Was built, and the behavior of agroarosystem in nutrient cycling was simulated and predicted using computer for Doudian village in Beijing suburb, With the model tested in different decisions. It Was proved mathematically that the system Was tending lottfards a...

The proposition of the compartment model method brings us bopes that with this method We can solve she problem of matter cycling in agroecosystem quantitatively. In this paper based on data collected in our experiments and surveys a compartment model Was built, and the behavior of agroarosystem in nutrient cycling was simulated and predicted using computer for Doudian village in Beijing suburb, With the model tested in different decisions. It Was proved mathematically that the system Was tending lottfards a steady state and was observable as Well as coutrolable. Sensitivity of the system to perturbation Was highest with N and decreasing with P and K respectively. Recycling indicis of NPK in the system Were computed as a scientific basis provided for Ihe system management. The method of building a compartment model Was discussed in the paper, which suggests an improved modification of syslem analysis, with its shortcomings and limitations indicated.

~(15)N labelled technique was used for understanding the transferring and cycling of nitrogen in micro-agroecosystems with soil-ryegrass-rabbits-rice compartments and soil rice compartments. Preliminary results showed that the utilizational rate of (NH_4)_2SO_4 by ryegrass was 59.36% for the above ground portion and 9.79% for roots. As ~(15)N labelled ryegrass was comsumed by rabbit,the ~(15)N labelled recovery rates in feces and urine collected were 11.78% and 17.95% respectively. Rabbit excrement-nitrogen...

~(15)N labelled technique was used for understanding the transferring and cycling of nitrogen in micro-agroecosystems with soil-ryegrass-rabbits-rice compartments and soil rice compartments. Preliminary results showed that the utilizational rate of (NH_4)_2SO_4 by ryegrass was 59.36% for the above ground portion and 9.79% for roots. As ~(15)N labelled ryegrass was comsumed by rabbit,the ~(15)N labelled recovery rates in feces and urine collected were 11.78% and 17.95% respectively. Rabbit excrement-nitrogen was integrated with inorganic fertilizer nitrogen in different proportions as 1:0, 0.5:0.5, 0.3:0.7 and 0:1 for rice culture. Results showed that the uptake of nitrogen by rice plant was 67—70% from the soil and 30—33% from fertilizers.The utilizational rates by rice plant were increased with the proportion of inorganic nitrogen. They were 36.94%, 40.52%, 40.73% and 43.91% for treatment 1—4. The yield of rice grain decreased with the proportion of inorganic nitrogen, however. The functional effects of organic fertilizer on the ecosystems were:(l) promoting the ear and root development of rice plant;(2) increasing the transferring ability of nitrogen from straw to rice grain, especially in 0.5:0.5; (3)maintaining inorganic fertilizer nitrogen in soil; (4)decreasing losses of nitrogen to air and waters. In treatment 0.3:0.7, the utilizational rate of organic fertilizer nitrogen was enhanced, and no considerable increment of utilizational rate of inorganic fertilizer nitrogen was found in the study. According to the complexity of food chain and the nitrogen recycling indexes in different microecosystems, it is considered that the maturity and stability of the ecosystem were higher in treatments 1:0,0.5:0.5, and 0.3:0.7, but lower in the treatment 0:1 which consists of rice plantation and relaying on inorganic fertilizers only.

In this paper, the authors analysed the macroscopic characteristics of circulation of N, P, K of the agroecosystem in Taihu Lake area, Jiangsu province by using the compartment model theory. 1. The agroecosystem is stable and N, P, K will reach the stable point in the years of 2020, 2007 and 2566 respectively. 2. At present, the recycling index of N, P, K is, respectivlely, 27.92％, 48.79％ and 46.62％. In their stable points that will be 27.65％, 49.33％ and 47.55％. 3. In the present situation, the storage and...

In this paper, the authors analysed the macroscopic characteristics of circulation of N, P, K of the agroecosystem in Taihu Lake area, Jiangsu province by using the compartment model theory. 1. The agroecosystem is stable and N, P, K will reach the stable point in the years of 2020, 2007 and 2566 respectively. 2. At present, the recycling index of N, P, K is, respectivlely, 27.92％, 48.79％ and 46.62％. In their stable points that will be 27.65％, 49.33％ and 47.55％. 3. In the present situation, the storage and output of N, P are increasing and those of K are decreasing year by year. 4. The effect of input of N on the system funciton is the most important and that of P is the next. 5. Husbandary subsystem is the most sensitive part to the input of the system.