松嫩平原盐碱地不同植物种植对土壤理化性质、肥力指标与细根生长的影响及在不同土壤深度的表现差异

he effects of different land uses on soil properties and its functioning depth are prevailing hotspots in soil ecology, but few researches is available in saline-alkaline soil, in Songnen Plain, northeastern China. Taking the Zhaodong Experimental Forest Farm as the research site, three soil layers (0-20cm, 20-40cm, 40-60cm) from 8 vegetation types (grassland, farmland, plantations of ash, elm, poplar, mongolian pine, amur corktree, larch ) were sampled and 13 soil parameters (root density, root water, soil moisture, pH, electrical conductance (EC), soil bulk density, soil organic carbon (SOC), alkaline-N, total N, available-P, total P, available-K , total K) were measured. By using vegetation types and soil depths as independent factors, a MANOVA (multivariate analysis of variance) was used for finding the effects of different plants cultivation on soil properties and fine root growth and their differences in different soil depths. Most parameters (root density, pH, bulk density, SOC, alkaline-N, total N, total P, available-K, total K) showed significant change with soil depths. Seven out of the 13 parameters (root density, pH, available-P, soil moisture, EC, SOC, total N) were significantly influenced by different plants. Of the seven parameters, interspecies differences of the first three parameters varied at different soil layers, while the other 4 parameters showed similar interspecies differences among whole soil profile. Peak soil moisture was found in grassland, followed by farmland and ash plantation, and soil moisture in grassland was 1.8 times higher than that in larch plantation; soil pH in grassland (8.75) was significantly higher than those in the most woodland and farmland; EC in grassland (503.4μS/m) was significantly greater than those in all the other vegetation types. Root density in ash plantation was respectively 1.27 and 1.75 times higher than those in grassland and plantations of larch and mongolian pine. SOC in plantations of poplar, mongolian pine were significantly lower than those in plantations of amur corktree, elm, ash and grassland ; Both results of root density and SOC indicate that afforestation in saline-alkalization grassland can neither increase soil carbon input by fine roots, nor in SOC accumulation. Soil total N in grassland, 1.12g/kg, was significantly higher than those in farmland, plantations of larch, poplar and mongolian pine; available-P in amur corktree plantation (3.39mg/kg) and grassland (2.27mg/kg) were significantly higher than those in ash plantation (1.24mg/kg) and larch plantation (1.01mg/kg). No differences were observed in all the other nutrients (total P, total K and available-K) among different plants; these nutrient differences suggest that no differences on soil nutrients depletion were observed among different plants (farmland, grassland and afforestation). A further interaction analysis (vegetation types * soil depths) found that interspecific differences of root water were different in different soil layers (p<0.05). All above mentioned results manifest that afforestation with proper species in Songnen Plain could reduce soil salinity-alkalinity with the expense of more water consumption and similar soil nutrients depletion. Our findings provide guidance both for local afforestation and researches of comparison of region interspecies differences, evaluation of soil fertility, soil nutrient balance in the future.