Fine Roots Responses Of Manchurian Ash And Korean Larch To Soil Nutrients Heterogeneity

The responses of the fine roots of Manchurian ash (Fraxinus mandshwica Rupr.), and Korean larch (Larix olgensis Henry) to nutrients supply pattern and nutrients heterogeneity were studied by growing seedling in pots under different nutrients supply regime, surveying the spatial distribution pattern of fine roots in the strip mixture sand of ash and larch, patchy nutrients (N,P) enrichment experiment by ingrowth core method in monoculture stands of respective species, and the surveying and analysis of soil nutrients spatial heterogeneity vs. fine root spatial distribution pattern in 13-yr-old monoculture stand of ash.1. Experiment in greenhouse by growing seedling in pots demonstrated (1)the growth of ash seedlings were sensitive to fertilizer supply rate, the total biomass of ash seedlings increased significantly with higher supply rate (true for both balanced and P only slow release fertilizer treatments); the biomass allocation of seedlings between above- and below -ground was also affected, lower root/shoot ratio was found under higher nutrients supply rate, (2)significant morphological differences between the two species were found, indicated by the higher specific root length and fine root length density of ash in relation to that of larch under same fertilizer treatments. (3) the total biomass accumulation of seedlings of the two species was not significant affected by nutrients supply pattern, no significant difference was detected in the total biomass accumulation under homogeneous and heterogeneous fertilization pattern for both tree species. But the biomass allocation of ash seedling was significantly different between different supply pattern of P only fertilizer, more biomass was deployed to below-ground part under heterogeneous P treatment comparing to homogeneous treatment (D proliferation of fine roots of ash in nutrients enriched patches was detected by comparing heterogeneously and homogeneous nutrients supply regimes. Not significant proliferation of fine roots of larch in the enriched patches in contrast.2. The survey of fine roots spatial distribution with in 13-yr-old ash and larch strip mixture stand demonstrated the belowground resources were dominated by ash "trees. The fine root biomass density (FRBD) of larch in soil between larch rows were significantly lower comparing to that of ash fine roots between ash rows. The FRBD and FRLD of ash tree accounted for fairly high proportion even in soil between larch-ash rows, and larch-larch rows zone. In contrast, the FRBL and FRLD of larch in soil between larch-ash rows and ash-ashrows decreased dramatically in comparison to that in soil between larch-larch rows. An obvious trend was found that ash trees placed large amount of fine roots in soil between ash-larch rows and larch-larch rows, suggesting that ash tree may most probably dominating the belowground resources distribution.3. The patchy enrichment of N and P fertilizers conducted by ingrowth core method in monoculture ash and larch stands confirmed that the fine roots of ash were sensitive to patchy fertilization under nutrition limitation. In ingrowth cores enriched by fertilizers, especially in the cores enriched with P fertilizer, the FRBD and FRLD were significantly higher than that in the control cores. Significantly higher specific root length of fine roots of ash, hence the decrease of fine roots diameter were also found with the P treated patches. The responses of fine roots of larch to patchy nutrients treatment were weak in comparison to that of ash.4. The survey of the spatial distribution pattern of nutrients fine roots of ash tree in soil in a 15-yr-old monoculture ash stand employing geostatistical method demonstrated that strong auto-correlation in the spatial distribution of soil pH, nitrogen, phosphorous and potassium, and obvious spatial pattern. (1) The autocorrelation scale for soil pH, total P, total K, total N, available P, available K, and available N were between 2.274.46 m,0.726-0.973 m,1.02-1.05 m, 0.90-1.18m, 0.90-1.2m, 0.95-2.86m and 1.41-4.25 m, re...