Abstract. Rates of growth of seedlings of E. globulus, E.regnans and E. nitens were related to phosphorus supply in two soils but concentrations of total nitrogen and total phosphorus in most plant tissues did not vary significantly among soil or phosphorus treatments. Differences in concentrations of nitrogen and phosphorus and in the composition of the pool of free amino-acids among leaves at different stages of development were far greater than differences between treatments. The most significant of these differences were several-fold greater concentrations of arginine in the oldest leaves and these are most likely due to protein degradation and/or in situ synthesis since arginine is not generally phloem mobile. The concentration of reduced nitrogen in xylem sap was inversely related to growth and glutamine was by far the dominant nitrogenous solute. We suggest that specific nitrogenous solutes may be useful indices of the nitrogen status of eucalypt tissues for insect herbivores.

In view of the problems of limited energy of the nodes and threat to routing security in wireless sensor networks, Energy-efficient Secure Routing Protocol (ESRP), an energy-efficient secure routing protocol for wireless sensor networks, is proposed. According to the structured topology of hexagonal mesh, hops at different directions are calculated on the optimal route for transmitting data packets in ESRP. With the help of characters of hops, the nodes can rapidly find a route among multiple optimal routes by the policy of the twice probability routing selection. Data breach is prevented by data encryption and data security is realized by one-way hash key chain and symmetric key authentication. Analysis and simulation results show that ESRP has better performance on security and saving energy.

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Due to the node failures incurred by intrusion threat, a wireless sensor networks will initiate topology re-generation, which is based on correct availability evaluation of current intrusion-tolerant topology. The paper proposes an availability evaluation model based on semi-Markov process (SMP) to estimate topology availability of the intrusion-tolerant topology concerning the effects from intrusion behaviors. In view of some limitations of node computation ability and storage ability, this model reduces the complexities resulting from modeling the different intrusion threats and is set up on the uniform intruding results to simplify the model design. Using the DTMC model embedded in SMP topology availability is computed and finally we analyze the sensitivity to parameters in the model.