Structure and phytomass production of a pioneer community

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Selected abstracts

93Z/00039 Feral pig. (Sus serofa) rooting in a monsoon forest-wetland transttion, northern Australia D. M. J. S. Bowman & L. McDonough, Wildlife Research, 18(6), 1991, pp 761-765. There was limited impact from pig rooting within the monsoon rainforest in either wet and dry seasons. The seasonally flooded swamp communities (Melaleuca forest and sedgeland) were prunarily exploited in the dry season, and dryland communities (eucalypt and Lophostemon forests) were exploited during the wet season. -from Authors

Restoration ecology Vegetative reproduction in Posidonia oceanica. I. Effects of rhizome length and transplanta93Z/00040

tion season in orthotropic shoots A. Meinesz, H. Molenaar, E. Bellone & F. Loques, Marine Ecology, 13(2), 1992, pp 163-174. Mortality was highest for transplants made in early summer, when temperatures exceeded 20"C, and lowest for those made in autumn. Although inital rhizome length had no discernible effect on subsequent mortality, it was positively related to the length of the necrosed portion one year later. The most successful transplants, made in autumn with 10-15cm long rhizomes, gave survival rates of 92-97%. -from Authors Vegetative reproduction in Posidonia oeeanica. II. Effects of depth changes on transplanted

93Z/00041

orthotropic shoots H. Mulenaar & A. Meinesz, Marine Ecology, 13(2), 1992, pp 175-185. Batches of transplants originating from 30m depth and replanted in shallower water (3, 14 and 20m) showed survival of 96-100% after 11 months, with ramification in 42% of the transplants and root formation in 44%. After the same time interval, batches originating from 3m depth and transplanted to deeper water showed lower survival (59% at 14m, 41% at 29m, and 3% at 36m) complete absence of ramification, and rooting in only one batch. Transplantation to water shallower than their origin was favourable for survival, growth and development while transplantation to deeper water led to progressively lower survival, growth and development of the shoots. Whatever the depth at which they were replanted horizontally, most transplants changed their growth mode from orthotropic to plagiotropic. -from Authors 93Z/00042 Gypsum and water manal[ement interactions for revegetation and productivity improvement of brackish marsh in Louisiana G. C. Sigua & W. H. Hudnall, Communications in Soil Science & Plant Analysis, 22(15-16), 1991, pp 1721-1739. At Hackberry, the overall growth and yield response of joint grass Paspalum vaginatum, marsh hay cordgrass Spartina patens, salt grass Distichlis spicata and American three square Scirpus americanus to gypsum addition (0 vs 7 Mg/ha) and water management (flooded versus nonflooded plots) were evaluated. Soil drying was detrimental to the overall growth and yield of all marsh vegetation. There was zero plant survival in the non-flooded plots except the marsh hay cordgrass with a survival rate of 32.8%. Plots receiving 7 Mg gypsum/ha had significantly higher dry matter production than the control. Gypsum application increased dry yield of joint grass (5.44-8.08 Mg/ha), marsh hay cordgrass (1.90-6.91 Mg/ha), salt grass (0.97-2.79 Mg/ha) and three square (1.55-2.84 Mg/ha) in flooded plots. -from Authors 93Z/00043 The influence of agriculture on the decline of west coast renosterveld, south-western Cape, South Africa C. McDowell & E. Moll, Journal of Environmental Management, 35(3), 1992, pp 173-192. West coast renosterveld, part of the floristically rich Fynbos Biom~ has survived on only 3% of its previous range oecause ot agricultural clearance in the SW Cape lowlands. Much of the present 'island' distribution is on hillocks and mountain slopes; these are unrepresentative of the previous range of renosterveld on the higher agrlcul-

tural potential flats. Red data species are prevalent on the small proportion of remnant renosterveld on the fiats. 'Agricultural threat' indices (likelihood of clearance for crops, are derived for each remnant using soil quality, gradient and rainfall measurements as parameters. Short-term prediction of capacity of sites to 'survive' agricultural pressures is 'tested' by empirical observation. 'Socioeconomic threat' indices relating to agricultural, urban or industrial expansion should, as an 'urgency' factor, supplement attributes traditionally rated for biota per se in ranking conservation priority of natural habitats. -from Authors 93Z/00044 Structure and phytomass production of a pioneer community M. Jochimsen & D. Janzen, in: Modern ecology: basic and applied aspects, ed G. Esser & D. Overdieck, (Elsevier), 1991, pp 39-60. Examined the nature of colonizing vegetation on colliery spoil in the Ruhr, with comments on phytomass, and on number of individuals and species. The degree of plant cover and humus accumulation are the most important factors for site improvement. Characteristic species are noted, eg Reseda lutea, MeIilotus spp., Silene vulgaris, Reseda

luteola, Echium vulgate, Poa compressa and Plantago Iaceolata, but the pioneer community is not always predictable. Therophytes were unimportant, and plant cover became established more rapidly than under natural circumstances, an important feature for restoration. -P.JJarvis 93Z/00045 The revegetation potential of selected Michigan native and naturalized plant species on fly ash deposits J. R. Wells, G. Brieger & R. D. Hunter, Michigan Botanist, 30(2), 1991, pp 49-58. Analyzed 25 native and naturalized species, mostly grasses, from the Great Lakes region for their growth potential on 100% fly ash from coal-fired electric generation plants. Fertilizer was added periodically to the watering cycle. Comparative growth response of the plants was based on germination, seedling survival, and biomassproduction. An index of species performance was b a s e d o n the above data. Species showm"g the best overall performance were Hordeum jubatum, Festuca arundinacea and Elymus canadensis. Among dicots tested, Atriplex patula and Lotus corniculatus grew best. -from Authors 93Z/00046 Value of mountain rye for suppression of annual bromegrasses on semiarid m i n e d lands M . R . Andersen, E. J. Depuit, R. H. Abemethy & L. H. Kleinman, Journal of Range Management, 45(4), 1992, pp 345-351. The value of Secale montanum for competitive suppression of downy brome Bromus tectorum and Japanese brome B. japonicus was investigated in a 3-yr study on reclaimed coal mined lands in SE Montana. Rye established rapidly and vigorou.sl~,, but did not persist appreciably (either through initially established plants or new seedlings) after the second year. However, mountain rye significantly reduced growth and reproduction of annual bromes during the first two growing seasons. Annual brome soil seedbanks were not sufficiently reduced in rye-seeded plots to prevent an eventual, third year recovery of brome productivity after a massive dieback of rye. Mountain rye therefore only proved effective for short term control of annual bromes. -from Authors 93Z/00047 Long-term soil and vegetation recovery in five semiarid Montana ghost towns P. A. Knapp, Professional Geographer, 43(4), 1991, pp 486-499. Recovery was strongly linked to the degree of the initial soil disturbance, vegetation type, and precipitation. -from Author