| Populus tomentosa has excellent growth characteristics and high quality wood properties,and is one of the main tree species for fast-growing forests in the western Shandong plain.Intercropping crops under young P.tomentosa is an important cultivation measure for cultivating fast-growing and high-yield plantation.It is of great significance to ensure the survival rate of P.tomentosa,improve the quality of P.tomentosa seedlings,save the cost of young forest tending and increase comprehensive benefits.1-year-old 'Beilin Xiongzhu No 1',a new variety of P.tomentosa was used as the experimental material.The split-plot experimental design was used,the main area was set with two common planting spaces of 2m×3m and 3m×4m,two common intercropping models were set in the sub-zone,P.tomentosa+peanut+spinach(peanut,spinach rotation),P.tomentosa+peanut,with one conventional tending of plantation as control,a total of 6 treatments,repeated 3 times.The effects of different intercropping patterns on the growth of P.tomentosa forest and soil physical and chemical properties,as well as the ecological effects and economic benefits were studied.After one year of afforestation,the main results were as follow:(1)The 2 agro-forestry models(P.tomentosa+peanut+spinach and P.tomentosa+peanut)under different planting densities were more beneficial to the growth of the above-ground(DBH growth,height growth and crown growth)than the conventional tending model of P.tomentosa,and intercropping peanuts under 2 m×3 m planting density was more beneficial to DBH growth than that under 3 m×4 m,the growth rate was 0.11 cm.Intercropping peanut+spinach under P.tomentosa was more beneficial to the increase of tree height growth,which was 6.86cm.(2)The horizontal distribution of fine root was mainly in 0?30 cm,and the vertical distribution was mainly in 0?40 cm,The FRLD and FRBD of 2 agro-forestry models increased by 74.46%?106.30%and 91.16%?102.79%compared with the conventional tending model.The intercropping of agricultural crops after planting could promote the root growth of P.tomentosa trees after one year of afforestation.(3)The 2 agro-forestry models could increased soil water content by 19,82%?32.59%,decreased soil bulk density by 6.62%?15.65%,and increased soil porosity by 6.67%?16.37%.Compared with the conventional tending model,soil nutrient content(total nitrogen,alkali-hydrolyzed nitrogen,available phosphorus and available potassium)of 2 agro-forestry models had increased,the total nitrogen content of soil could be increased by 9.37%?10.83%,the alkali-hydrolyzed nitrogen content could be increased by 21.72%?33.33%,the available phosphorus content could be increased by 51.48%?64.69%,and the available potassium content could be increased by 29.08%?50.05%.(4)In the second year of afforestation,compared with the conventional tending model,the two agro-forestry models can reduce the air temperature and increase the relative humidity of the air between forests to a certain extent,and have a significant cooling effect on the surface temperature in summer,with a cooling range of 1.90%-3.45%,(5)In the first year after afforestation,the input-output ratio of P.tomentosa+peanut+spinach and P.tomentosa+peanut model was 1.65 and 1.27 respectively;in the second year after afforestation,the input-output ratio was 1.38 and 1.09 respectively,while the net profit of conventional tending model was negative within two years of afforestation.The results showed that 2 agro-forestry models under the two planting densities significantly increased the economic benefits,saved the afforestation cost,and helped farmers increase production and income.It was concluded that the 2 models were of great practical value compared with conventional tending models,whether they were the effects on the growth of P.tomentosa trees,the physical and chemical properties of soil after intercropping,or the ecological effects and economic benefits.It was worth popularizing and applying locally. |
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