Abstract: The larch plantations at Maoershan Mt.Experimental Forest Farm in eastern mountainous region of northeastern China were studied to characterize the dynamics of soil fertility under the same thinning larch stand at different age stages and the difference of soil physical and chemical properties between the thinning and non-thinning stands, according to the litter amount, the nutrient return from it, the standing litter, as well as the soil physical and chemical properties.The results show that the litter amount and its nutrient return presented an increasing tendency with increased stand ages.After thinning, the introduction of broad leaf trees into the larch plantation made the litter component structure changed, the litter decomposition rate gradually increased, the nutrient material release and return from litter sped up, the contradiction between litter accumulation and decomposition alleviated and the soil fertility of larch plantation increased.On the average, the contents of organic matter, total Nand total P₂O₅ were respectively increased by 352.00%, 225.53% and 34.96% within15 years.The soil physical and chemical properties of larch plantation after thinning were improved in varying degrees.

Key words: Larch plantation, Litter, Nutrient return, Soil fertility, urban heat island, urban green space, field measurement, cooling effect