Effects of defoliation and competition on the post-fire response of Poa ligularis Ness. in semi-arid central Argentina

2011 ◽  
Vol 33 (1) ◽  
pp. 59 ◽  
Author(s):  
Daniel V. Peláez ◽  
Omar R. Elia ◽  
Francisco R. Blázquez
Keyword(s):  
Interspecific Competition ◽  
Growing Season ◽  
Belowground Biomass ◽  
Fire Response ◽  
Green Leaves ◽  
Central Argentina ◽  
Poa Ligularis ◽  
Growth Attributes ◽  
Different Levels ◽  
Semi Arid

The objectives of the study were to evaluate the effects of defoliation on tiller growth of Poa ligularis Ness. at two different intervals after fire as well as how recovery is affected by different levels of herbaceous interspecific competition during the subsequent growing season. Early post-fire defoliation (6 months after burning) reduced (P < 0.05) the height, number of green leaves and total green length of tillers on P. ligularis in comparison to Control plants. Late post-fire defoliation (12 months after burning) did not affect any of these growth attributes. Burnt plants of P. ligularis exposed to the no competition treatment (NC) had a higher number of green tillers per plant than plants exposed to the total competition treatment (TC). Moreover, the burnt plants exposed to the NC were significantly taller (P < 0.05) than plants exposed to TC. The highest (P < 0.05) above- and belowground biomass was recorded in those burnt P. ligularis plants growing in the NC treatment. Our results provide some evidence to show that early defoliation and interspecific competition after fire reduce the tiller growth and also the above- and belowground biomass of P. ligularis plants.

Agriculture expansion and deforestation in seasonally dry forests of north-west Argentina

2005 ◽  
Vol 32 (2) ◽  
pp. 140-148 ◽  
Author(s):  
H. RICARDO GRAU ◽  
N. IGNACIO GASPARRI ◽  
T. MITCHELL AIDE
Keyword(s):  
Global Trends ◽  
North West ◽  
Conservation Policies ◽  
Seasonally Dry ◽  
The North ◽  
Agriculture Expansion ◽  
Soybean Price ◽  
Different Levels ◽  
Semi Arid ◽  
Arid Chaco

In Argentina, deforestation due to agriculture expansion is threatening the Semi-arid Chaco, one of the largest forested biomes of South America. This study focuses on the north-west boundary of the Argentine Semi-arid Chaco, where soybean is the most important crop. Deforestation was estimated for areas with different levels of soil and rainfall limitation for agriculture between 1972 and 2001, with a finer analysis in three periods starting in 1984, which are characterized by differences in rainfall, soybean price, production cost, technology-driven yield and national gross domestic product. Between 1972 and 2001, 588 900 ha (c. 20% of the forests) were deforested. Deforestation has been accelerating, reaching >28 000 ha yr−1 after 1997. The initial deforestation was associated with black bean cultivation following an increase in rainfall during the 1970s. In the 1980s, high soybean prices stimulated further deforestation. Finally, the introduction of soybean transgenic cultivars in 1997 reduced plantation costs and stimulated a further increase in deforestation. The domestic economy had little association with deforestation. Although deforestation was more intense in the moister (rainfall >600 mm yr−1) areas, more than 300 000 ha have already been deforested in the drier areas, suggesting that climatic limitations are being overcome by technological and genetic improvement. Furthermore, more than 300 000 ha of forest occur in sectors without major soil and rainfall limitations. If global trends of technology, soybean markets and climate continue, and no active conservation policies are applied, vast areas of the Chaco will be deforested in the coming decades.

Competition and the response of three plant species to a salinity gradient

1991 ◽  
Vol 69 (11) ◽  
pp. 2497-2502 ◽  
Author(s):  
N. C. Kenkel ◽  
A. L. McIlraith ◽  
C. A. Burchill ◽  
G. Jones
Keyword(s):  
Salt Tolerance ◽  
Interspecific Competition ◽  
Poa Pratensis ◽  
Salinity Gradient ◽  
Belowground Biomass ◽  
Peak Performance ◽  
Total Biomass ◽  
Salinity Response ◽  
Hordeum Jubatum ◽  
Puccinellia Nuttalliana

Three grasses (Poa pratensis, Hordeum jubatum, and Puccinellia nuttalliana) were grown in monoculture and three-species mixture at each of eight salinity levels in a controlled environment chamber. In monoculture, all species grew best when no salts were added to the nutrient medium. When salts were added the species showed differing degrees of salt tolerance. Percent decreases in total biomass with increasing salinity and shifts in aboveground to belowground biomass ratios suggested increased salt tolerance in the order P. pratensis < H. jubatum < P. nuttalliana. In mixture, all species showed a significant change in salinity response when compared with their responses in monoculture. Interspecific competition resulted in P. pratensis being suppressed at all but the lowest salinities. Hordeum jubatum showed the least suppression at intermediate salinities, while P. nuttalliana was least suppressed at the highest salinities. These results indicate that interspecific competition results in a shift in the peak performance of more salt-tolerant species toward the high end of the salinity gradient. The species distributions in our experimental mixtures reflected those observed in the field, suggesting that competition plays an important role in structuring inland saline plant communities. Key words: halophyte, glycophyte, community, Hordeum jubatum, Puccinellia nuttalliana, Poa pratensis.

The effect of drainage height on plant-species composition on a semi-arid green roof system

2021 ◽  
Vol 67 (3-4) ◽  
pp. 149-155
Author(s):  
Har'el Agra ◽  
Hadar Shalom ◽  
Omar Bawab ◽  
Gyongyver J. Kadas ◽  
Leon Blaustein
Keyword(s):  
Species Composition ◽  
Plant Species ◽  
Plant Diversity ◽  
Urban Areas ◽  
Green Roof ◽  
Growing Season ◽  
Green Roofs ◽  
Plant Species Composition ◽  
Roof System ◽  
Semi Arid

Abstract Green roofs are expected to contribute to higher biodiversity in urban surroundings. Typically, green roofs have been designed with low plant diversity. However, plant diversity can be enhanced by controlling resource availability and creating distinct niches. Here we hypothesize that by using different drainage heights during the short plant-growing season in a semi-arid green roof system we can create distinct niches and plant communities. Our experiment took place at the University of Haifa, north Israel. We tested three different heights of drainage outlet: 10 cm under the surface of the substrate (Low), 1 cm under the surface of the substrate (Medium) and 3 cm above the surface of the substrate (High) on plant species-composition in green-roof gardens. Grasses cover was higher in High and Medium drainages while forbs cover was higher in Low drainage. Species richness was the highest in Low drainage while diversity indices showed the opposite trend. We conclude that by changing the height of the drainage we can create different niches and change species composition in a short time period of one growing season. This way we can create more diverse green roof communities and enhance biodiversity in urban areas, particularly in semi-arid regions.

Temporal-spatial changes in the belowground bud bank in interdune lowlands of an active sand dune ecosystem in northeastern China

2020 ◽  
Author(s):  
Jing Wu ◽  
Jianqiang Qian ◽  
Quanlai Zhou ◽  
Wanqin Yang ◽  
Zhimin Liu
Keyword(s):  
Arid Regions ◽  
Sand Dune ◽  
Growing Season ◽  
Bud Bank ◽  
Stem Base ◽  
Opposite Trend ◽  
Spatial Changes ◽  
Rhizome Bud ◽  
Semi Arid ◽  
Tiller Bud

Abstract Aims The belowground bud bank plays an important role in vegetation restoration of sand dune ecosystems in semi-arid regions. However, few studies have focused on the temporal-spatial changes of belowground bud banks in interdune lowlands. Methods The size and composition of belowground bud bank in five interdune lowlands with different sizes were investigated for one growing season to determine the temporal and spatial changes in belowground bud bank. Important Findings Total bud bank density was the highest in the medium-sized interdune lowland as was tiller bud density. The density of stem-base buds exhibited an opposite trend while rhizome bud density did not change with interdune lowland size. There was a significant seasonal change in the bud bank size. The total bud density peaked in August and was the lowest in October. A similar trend was found for rhizome bud density, whereas the density of stem-base buds showed an opposite trend, and tiller bud density did not change significantly during the growing season. We conclude that the belowground bud bank density is changed with interdune lowland size and season. These results contribute to the understanding of adaptive strategies of plants growing in active dune ecosystems and provide pointers for adopting effective measures to restore and conserve dune vegetation in semi-arid regions.

Photothermal zoning of castor (Ricinus communis L.) growing season in the semi-arid Mediterranean area

2019 ◽  
Vol 142 ◽  
pp. 111837 ◽  
Author(s):  
Cristina Patanè ◽  
Salvatore Luciano Cosentino ◽  
Sebastiano Andrea Corinzia ◽  
Giorgio Testa ◽  
Orazio Sortino ◽  
...  
Keyword(s):  
Ricinus Communis ◽  
Growing Season ◽  
Mediterranean Area ◽  
Ricinus Communis L ◽  
Semi Arid

Study on the effects of different levels of grazing and exclosure on vegetation and soil properties in semi-arid rangelands of Iran

2020 ◽  
Vol 40 (6) ◽  
pp. 425-431 ◽  
Author(s):  
Jamal Bakhshi ◽  
Seyed Akbar Javadi ◽  
Ali Tavili ◽  
Hossein Arzani
Keyword(s):  
Soil Properties ◽  
Arid Rangelands ◽  
Different Levels ◽  
Semi Arid

Seasonal shift in the climate responses of Pinus sibirica, Pinus sylvestris, and Larix sibirica trees from semi-arid, north-central Mongolia

2011 ◽  
Vol 41 (6) ◽  
pp. 1242-1255 ◽  
Author(s):  
Louis De Grandpré ◽  
Jacques C. Tardif ◽  
Amy Hessl ◽  
Neil Pederson ◽  
France Conciatori ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Tree Ring ◽  
Growing Season ◽  
Larix Sibirica ◽  
Pinus Sibirica ◽  
North Central ◽  
Central Mongolia ◽  
False Rings ◽  
Seasonal Shift ◽  
Semi Arid

In light of a significant increase in the warming trend observed in recent decades in semi-arid Mongolia, tree-ring attributes and anomalies were analysed to detect potential changes in the growth–climate relationship. In a moisture-limited environment, an increase in temperature could cause a shift in the seasonal response of trees to climate. Chronologies were developed for the dominant tree species (Larix sibirica Ledeb., Pinus sibirica Du Tour, and Pinus sylvestris L.) from north-central Mongolia. In addition to annual ring width, both earlywood and latewood width were measured, and tree-ring anomalies such as false rings and light rings were systematically identified. Earlywood width was mainly associated with precipitation in the year prior to ring formation and early growing season conditions. Temperature was associated with current year growth and mainly influenced latewood development. False rings were good indicators of early summer droughts, whereas light rings were mainly associated with a cold end of summer. A seasonal shift in the significance of monthly climate variables was observed in recent decades. This displacement presumably resulted from changes in the timing and duration of the growing season. Tree growth starts earlier in spring and is now affected by late summer to early autumn climate conditions.

Molecular and physiological bacterial diversity of a semi-arid soil contaminated with different levels of formulated atrazine

2006 ◽  
Vol 34 (2-3) ◽  
pp. 93-102 ◽  
Author(s):  
M. Ros ◽  
M. Goberna ◽  
J.L. Moreno ◽  
T. Hernandez ◽  
C. García ◽  
...  
Keyword(s):  
Bacterial Diversity ◽  
Arid Soil ◽  
Different Levels ◽  
Semi Arid

Trap Strip and Field Border Modification for Management of the Wheat Stem Sawfly (Hymenoptera: Cephidae)

2001 ◽  
Vol 36 (1) ◽  
pp. 34-45 ◽  
Author(s):  
Wendell L. Morrill ◽  
David K. Weaver ◽  
Gregory D. Johnson
Keyword(s):  
Winter Wheat ◽  
Production System ◽  
Wheat Cultivar ◽  
Growing Season ◽  
Border Effect ◽  
Wheat Stem Sawfly ◽  
New Crops ◽  
Wheat Stubble ◽  
Summer Fallow ◽  
Semi Arid

The alternate-year summer fallow wheat production system predominates in the semi-arid prairie regions of Montana. These farms consist of the current crop and idle fields in which the previous year's crop was located. Larvae of the wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), overwinter in post-harvest wheat stubble. Adults appear and disperse to new crops during the following growing season. Adults begin oviposition as soon as suitable hosts are encountered; therefore, larval infestations usually are concentrated along field borders. We tested several types of trap strips as intercepts to reduce dispersion of adult sawflies into fields. The most successful system was a fall-planted winter wheat trap that protected spring-planted wheat. These trap strips utilized the “border effect” as well as the higher attractiveness of the earlier maturing winter wheat. In another trial, losses were reduced by planting a semi-resistant solid-stemmed wheat cultivar within the border of a comparatively higher yielding hollow-stemmed cultivar.

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