Root Architechture Of Pinus Thunbergii In Sandy Coast Protective Forest

Pinus thunbergii forest is the important component of coastal protective forest system in Shandong province, it is the mainly protective tree species which can not be replacemented by other tree species. Environment varies greatly at different gradient in sandy coast, so does the crown architecture of P. thunbergii forest during a long time adaption, but whether the root architecture of P. thunbergii forest have the same adaption mechanism with the crown architecture which is still unknown to us.To study the root architecture characteristics of P. thunbergii at different environment, we conducted field surveys under the P. thunbergii forest in Lingshan Bay National Forest Park from May, 2009 to October, 2010. Two belt transects, i. e 0-50m and 400-450m at the vertical direction of the coastline were selected, named as transectâ… andâ… respectively. In each belt transect, 1 sample(20m×50m) was set up to survey the root length, root diameter, root numbers and root biomass. Othermore, the soil physi-chemical properties of different transect were surveyed, too. One-way ANOVA was used to test their differences, Person Correlation was used to analysed the relationship between the root architecture and the soil physi-chemical properties. Finally, imitating models were carried out to simulate the root length, root numbers and root biomass for different soil depth in the two transect.Our objective was to reveal the root architecture adaption mechanism to the environment and its biomass distribution in the different soil depth in the two transect. The findings will play important roles in managing costal protective forest which can provide a rationable guidance for managing coastal protective forest reasonably in the future.The results showed that as the followings.1. Soil physi-chemical propertiesSoil bulk density of different soil depth in transectâ… w as higher than that of transectâ… , which in the two transects increased with the soil depth increasing except for that in the 20-40cm soil depth of the transectâ… , all the soil bulk density in 20-40,40-60 and 60-80cm soil depth had significant differences(p<0.05)between transectâ… a nd transectâ… . The soil water content in the two transects increased with the soil depth increasing, but decreased a little in 80-100cm soil depth, futhermore, which in the 20-100cm soil depth in transectâ… was significantly higher than that of transectâ… . The soil temperature at two transect decreased with the soil depth increasing, which in the 0-80cm soil depth at transectâ… was significantly higher than that of transectâ… . The soil nutrients in two transect decreased with the soil depth increasing, which in transectâ… was a little higher than that at transectâ… , but there was no significant differences between the two transects.2. Root architecture of P. thunbergiiRoot architecture of P. thunbergii in different transect shows much more plasticity. Wind was an important factor for root regime asymmetrical between the windward and leeward of transectâ… . The windward root numbers, root length, root volume, root surface area and root biomass of P.thunbergii i was as 1.59, 2.25, 2.43, 3.21and3.00 times as which of the leeward in transectâ… . The wind in transectâ… was merely 0.98ms^-1, which can not enough affect its root architecture regime of P. thunbergii, so the symmetrical root architecture was dominant there.The root distribution of P. thunbergii in different soil depth is different between transectâ… and transectâ… . Root numbers,root length, root diameter, root surface area, root volume and root biomass of P.thunbergii in transectâ… decreased with soil depth increasing. But, they were the biggest in 20-40cm at transectâ… , while decreased with soil depth increasing under 40cm soil depth, too. There were closed relationships between the root distribution pattern and soil physi-chemical properties. Soil bulk density and water content may the main limiting factors for the root downgrowthing into deeper soil. There were positive relationships between the root growth and soil physi-chemical properties, such as soil temperature, organic matter, alkali-hydrolyzable nitrogen, available phosphorus and available potassium content, which leaded to horizontal root regime in the top soil, while that of transectâ… were affected by the competing for the water and nutrient from the herb roots.3. The topological index and the fractal dimensionThe root branching pattern of two transect all comply with herringbone topological structure. The topological index and the fractal dimension size are transectâ… windward > transectâ… w indward > transectâ… leeward > transectâ… l eeward. 4. The Leonardo da Vinci for root diameterThe root cross-sectional area before and after the root branching of P. thunbergii in the two transect all followed the Leonardo da Vinci d²_defore= a∑ⁿ_i=1d²_i which can provide with certain references for forecasting root biomass and modeling related models In the future.5. Simulation models for root numbers, root length and root biomass with soil depthRoot numbers in transectâ… w indward, root length in transectâ… windward and leeward varied with the soil depth increased all complyed with Logarithm Fit Model, y=a+blnx. Root biomass in transectâ… w indward varied with the soil depth increased all complyed with Logistic Model, y=a/(1+be^-cx). Root numbers and biomass in transectâ… leeward varied with the soil depth increased all complyed with Exponential Fit Model, y=aebx. Root numbers and biomass in transectâ… w indward and leeward varied with the soil depth increased all complyed withVapor Pressure Model, y=e^a+b/x+clnx. Root length in transectâ… windward and leeward varied with the soil depth increased all complyed with Hoerl Model Model, y=ab^xx^c.