Short-term changes in soil properties after prescribed fire and mulching with fern in Mediterranean forests

Prescribed fire,although having low intensity and being able to reduce the risk of wildfire may modify soil properties in the short term,with possible increases in runoffand erosion risk.Soil mulching with vegetation residues is one of the most common post-fire management strategies.Residues of fern,which is abundant on the Mediterranean forest floor,may be used to replace straw for mulching fireaffected areas.However,the effects of prescribed fires are not completely understood,and there is no data regarding the use of fern to protect soil after fire in the literature.To fill this gap,selected soil chemical parameters were analyzed,on a comparative basis,in three Mediterranean forests(pine,oak and chestnut)in Calabria(Southern Italy).These parameters were measured immediately and one year after fire in unburned,burned and not treated,and burned and mulched soils.Changes in soil chemical properties among the different treatments were significant,and the effects of the prescribed fire and mulching were dependent on the time elapsed from their application and forest species.In general,mulching was not effective in limiting the changes in the monitored soil properties compared to the pre-fire values.Each forest species showed different temporal trends in changes of soil properties.

Dynamics and Relationships of Ca,Mg,Fe in Litter,Soil Fauna and Soil in Pinus koraiensis-Broadleaf Mixed Forest

The Liangshui Natural Reserve in Heilongjiang Province of China was selected as the study area. The authors collected the samples of forest litter （Tilia amurensis, Fraxinus mandshurica, Pinus koraiensis, Acer mono, Betula costata, and mixed litter）, soil in humus horizon （0--5cm） and soil horizon （5-20cm）, and soil macrofauna （Oligochaeta, Geophiloporpha and Juliformia） from 2001 to 2002. The role of soil macrofauna in the material cycle was analyzed through comparing the macro-element contents among various parts of the subsystems and using enrichment index （El）. The results indicate that dynamic changes of various litters are very complicated. The contents of Fe in each kind of litter increase firstly, and then decrease in the study period. The changes of macro-element contents are greater in the broad-leaf litter than in the coniferous litter, and the mixed litter is in the middle level, but the differences among them are not significant. The contents of Mg and Fe in humus are higher than those in soil, but the contents of Ca in soil are higher than that in humus. The dynamic changes of macro-element contents in soil and soil fauna are not consistent with those in litter. The diplopod presented obvious enrichment of Ca and Mg （E1〉1）, but it does not significantly enrich Fe. Earthworm has a stronger enrichment ability of Fe than diplopod and scolopendra, but E1〈1. Soil fauna can make great influences on the material cycle of the subsystems.

A Cubic H3-Nonconforming Finite Element

The lowest degree of polynomial for a finite element to solve a 2^th-order elliptic equation is k.The Morley element is such a finite element,of polynomial degree 2,for solving a fourth-order biharmonic equation.We design a cubic H3-nonconforming macro-element on two-dimensional triangular grids,solving a sixth-order tri-harmonic equation.We also write down explicitly the 12 basis functions on each macro-element.A convergence theory is established and verified by numerical tests.

Physico-Chemical Properties of Compost Based Waste-Recycling of Grape Fruit as Nursery Growing Medium

The present study reports the physico-chemical properties of four compost based squeezed grape fruit wastes (SGFW) consisting of 60% SGFW + 40% chicken manure (including sawdust) (CMS) (v/v), 80% SGFW + 20% bean hay (BH) (v/v), 80% SGFW + 20% chicken manure (including wheat hay) (CMH) (v/v) and 100% SGFW. Results showed that 100% SGFW compost had a suitable pH and EC with 7.82 and 1.68 dSm-1, respectively. Also, 80% SGFW + 20% BH compost was very rich in organic matter similar to coco peat, but 80%SGFW + 20% CMH compost had the lowest C/N ratio (5.2). The N, P and K concentrations in SGFW composts were higher than the coco peat or vermiculite. The soluble cations (Ca2+, Mg2+, K+) and anions (CO23, HCO-3 ) in 60% SGFW+ 40% CMS compost were the highest among substrates. The concentrations of trace elements and heavy metals in SGFW composts were far lower than the range of phytotoxicity. On the other hand, total phenols in SGFW composts were higher than coco peat.

A nonlinear dynamic macro-element for demand assessment of bridge substructures subjected to ship collision

For the dynamic demand assessment of bridge structures under ship impact loading,it may be prudent to adopt analytical models which permit rapid analysis with reasonable accuracy.Herein,a nonlinear dynamic macro-element is proposed and implemented to quantify the demand of bridge substructures subjected to ship collisions.In the proposed nonlinear macro-element,a combination of an elastic-plastic spring and a dashpot in parallel is employed to describe the mechanical behavior of ship-bows with strain rate effects.Based on the analytical model using the proposed macro-element,a typical substructure under 5000 deadweight tonnage(DWT) ship collision is discussed.Our analyses indicate that the responses of the structure using the nonlinear macro-element agree with the results from the high resolution model,but the efficiency and feasibility of the proposed method increase significantly in practical applications.Furthermore,comparisons between some current design codes(AASHTO,JTGD60-2004,and TB10002.1-2005) and the developed dynamic analysis method suggest that these design codes may be improved,at least to consider the effect of dynamic amplification on structural demand.

Water extractable plant nutrients in soils amended with cow manure co-composted with maple tree residues

Studies on the availability of plant nutrients in soils treated with manure co-composted feed-stocks are very rare.The present investigation aimed at studying the nutrient release pattern from three soils amended with maple tree leaves co-composted with cow manure.Soils were mixed with the compost at the rate of 20 t/hm^(2) and incubated at room temperature.Prior to incubation,plants residue samples were analyzed for total elemental concentrations(NO_(3),NH_(4),P,K,Ca,Mg,Na,Zn,Mn,Fe,Cu,Ni and Cd).Water extractability of nutrients from soils was affected by the type of soil and ratio of composted manure applied.Extractable NH_(4),P,K,Ca and Mg concentrations varied in the descending order of sandy clay,sandy loam and silt loam except NO_(3).The concentrations of P,K,Ca and Mg in the amended soils increased with the ratio of manure co-composted with leaf litter while those of NO_(3),NH_(4) and trace elements decreased.The residual nutrients in soil varied directly with their contents in the compost amendments.Co-composting improved the availability of nutrients in soils and this should be an ideal approach to managing the enormous waste generated from the livestock sector for restoring soil fertility.