| The high and sustainable primary production of artificial pasture, which in accordance with community stability, provided a fundamental base for intensive pasture-based animal husbandry. A 17-year long term trial has been conducted in Shuopu Demonstration Farm in Weining County, Guizhou Province, in which a set of improved methods employed as following: 1) Analyze average DM yield by statistical and regression method, 2) Interpreted the interspecific relations and community stability by analyzing population ratio dynamic changes, 3) Study the relations between species diversity and primary production and stability by regression and analyze different number species mixture, 4) Principal Components Analysis method employed to ordinate different temporal community of each mixture so to analyze and compare community develop stages, 5) Shannon-Wiener Index was calculated to indicate and compare the complex mixtures for species abundance and evenness. The results proved that the methods are reasonable and applicable.The results are as followings:1. The yields and stability of complex mixtures were significantly greater than that of a simple mixture. The three high DM in 17-year duration on top list are complex mixtures: red clover + white clover + perennial ryegrass + red fescue 739.7 gDM/m2, red clover + white clover + orchardgrass + red fescue 659.8 gDM/m2, red clover + white clover + blackspiked lovegrass + red fescue 630.6 gDM/m2. For simple cutting mixtures: red clover + perennial ryegrass 579.2 gDM/m2, red clover + orchardgrass 529.1 gDM/m2; grazing: white clover + perennial ryegrass 509.5 gDM/m2, white clover + red fescue 504.5 gDM/m2.2. DM yield and community stability are increasing while species diversity increasing, although the scope of DM between years increasing also. However, the simple mixture white clover + red fescue shown great stability and DM, it's obviously that compatibility is the prerequisite to the diversity-stability relation.3. There are two different patterns of the species DM in the 17-year duration: red clover and perennial ryegrass are very high at beginning years following rapid decrease, while white clover and red fescue are relatively lower at beginning then increase to a stable range.4. Same species shown different DM yield in different mixes, therefore, its ability of interspecific competition to relative component can be speculated. 5. Any mixture with red fescue has a lower weed DM, although different mixtures shown different resistance to weeds invasion. The lower ones are : white clover + red fescue, red clover + white clover + orchardgrass + red fescue, red clover + white clover + perennial ryegrass + red fescue. 6. Among the mixtures with same number of species, only one species different, can vary the community evenness. The Shannon-Wiener Indexes of the three complex mixtures are: red clover + white clover + perennial ryegrass + red fescue 1.43, red clover + white clover + orchardgrass + red fescue 1.33, red clover + white clover + blackspiked lovegrass + red fescue 1.30. The index is varying due to the one different grass. 7. If ecological lifetime of a species has matched its physiological life-span and has a normal DM yield, it could be regarded as with normal stability and primary production. In the mixtures of red clover + perennial ryegrass and red clover + orchardgrass, red clover yield a high DM and reasonable ratio within 5 years, --its physiological life-span, those mixtures can be regarded as stable communities.8. The Principal Components Analysis of all mixtures has shown that most mixtures are relatively unstable at beginning years but with high DM yields; when they reach a stable stage, the primary production become lower.9. From all results above, the mixtures with higher primary production and stable community are red clover + white clover + perennial ryegrass, red clover + white clover + orchardgrass + red fescue, red clover + white clover + blackspiked lovegrass + red fescue. The best one among the simple mixtures is white clover...
|
PDF Full Text Request