Competitive interactions between four foliose lichen species with and without nutrient enrichment

Competition between four foliose lichen species, common on slate rock surfaces in South Gwynedd, Wales, UK, was studied in experimental plots with and without nutrient enrichment by bird droppings. Fragments of the four lichens were glued to pieces of slate on horizontal boards in monoculture and in two-, three- and four-species mixtures in a factorial experimental design. In monoculture, nutrient enrichment increased thallus area of Parmelia conspersa (Ehrh. ex. Ach.) Ach., decreased thallus areas of Parmelia saxatilis (L.) Ach. and Parmelia glabratula ssp. fuliginosa (Fr. ex. Duby) Laundon, and did not affect thallus area of Phaeophyscia orbicularis (Necker) Moberg compared with untreated thalli. In the mixtures, P. conspersa and Ph. orbicularis were equally effective competitors in plots with and without nutrient enrichment. Addition of bird droppings, however, altered the ability of P. saxatilis and P. glabratula ssp. fuliginosa, to compete with the other species, the competitive ability of both species being reduced in some mixtures but increased in others. The results suggest that nutrient enrichment may alter the competitive balance between the four lichen species and this may be a factor determining their relative abundance on rock surfaces in South Gwynedd.

Characterization of engineered biochar for soil management

Pyrolysis is an energy conversion technology which by heating organic materials in the absence of oxygen, produces liquid, gaseous, and solid fuel products. Biochar, the solid product, can also be used as a soil amendment and, simultaneously, enables us to sequester carbon in the soil. By controlling the pyrolysis process, it is possible to engineer biochar suitable for the remediation of specific soil management problems. This research uses a characterization method more suited to producing biochar for soil amendment purposes than the existing biochar fuel characterization standards. This is the first research to use wastewater irrigated willow as a pyrolysis feedstock. The extensive characterization of biochar produced over a range of temperatures (410-810°C) yielded data on key properties relevant to soil under management: low surface area (1.4 to 5.4 m2/g), low bulk density (0.15-0.18 g/cm3), high pH values (7.8-9.4) and high water-holding capacity (1.8 to 4.3 cm3/g). Extraction experiments demonstrated low bioavailability of char nutrients (N, P, K, Ca, and Mg). This research also studied this artificial nitrogen cycle of pyrolysis: nitrogen accumulated in the wood from the wastewater and high levels of nitrogen remained in the biochar in a stable form not directly available to plants. Copyright © 2013 American Institute of Chemical Engineers Environ Prog.