Functional Changes and Threats to Hyperseasonal Neotropical Savannas After Australian Acacia Invasion

2021 ◽  
Author(s):  
João Augusto Alves Meira-Neto ◽  
Pedro Manuel Villa ◽  
Nathália Silva ◽  
Maria Carolina Nunes Alves da Silva ◽  
Glaucia Tolentino ◽  
...  
Keyword(s):  
Global Change ◽  
Native Species ◽  
Vegetation Type ◽  
Species Turnover ◽  
Acacia Mangium ◽  
C4 Plants ◽  
C3 Plants ◽  
Change Scenario ◽  
Cam Plants ◽  
Functional Changes

Abstract The hyperseasonal savanna experiences regular flooding and drought stresses and is a neotropical vegetation type threatened by global change including Acacia spp. invasion. To deepen the understanding of hyperseasonal savannas after Acacia invasion in a climate change scenario, we aimed to answer if: i) the plants of the studied hyperseasonal savanna are separated into C3, C4 or CAM species; ii) Acacia invasion can change the hyperseasonal savanna functioning for C3, C4 and CAM plants; iii) how invasive Acacia uptake water compared to native species in this hyperseasonal savanna. We detected both C3 and C4 metabolic groups of plants but two C3 species are possibly CAM facultative. The functioning of C3 plants as a group was not affected by the Acacia invasion, but this result does not exclude a species turnover between C3 herbs and C3 trees. The C4 plants of invaded Mussununga lost their response of increasing water use efficiency to the increasing Leaf N%. Plants of hyperseasonal savannas depend on the same water source as the soil water from recent rains. There are differences in d18O among species because some grow mostly during the rainy season with the 18O-enriched water meanwhile the invader Acacia mangium grows throughout the year whenever it rains. According to our results, the threat to C4 plants is high and they can be excluded from Mussunungas and from hyperseasonal savannas. However, hyperseasonal savannas are threatened as a vegetation. Therefore, hyperseasonal savannas should be considered critically endangered because of global change, especially bacause Acacia invasions. Initiatives for conservation of hyperseasonal savannas could save these remarkable ecosystems.

Phosphoenolpyruvate Carboxykinase in C4 Plants: Its Role and Regulation

1997 ◽  
Vol 24 (4) ◽  
pp. 459 ◽  
Author(s):  
Robert P. Walker ◽  
Richard M. Acheson ◽  
László I. Técsi ◽  
Richard C. Leegood
Keyword(s):  
Molecular Mass ◽  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
C4 Plants ◽  
Panicum Maximum ◽  
C4 Plant ◽  
Cam Plants ◽  
Crude Extracts ◽  
High Concentrations ◽  
Regulatory Properties

Some of the recent findings which revise our view of the role and regulation of phosphoenolpyruvate carboxykinase (PEPCK) in C4 plants are discussed. Evidence is presented that PEPCK is present at appreciable activities in the bundle-sheath of some NADP-malic enzyme-type C4 plants, such as maize, but it was not detectable in NAD-malic enzyme-type C4 plants. PEPCK is rapidly inactivated in crude extracts of leaves of the C4 plant, Panicum maximum. This inactivation could be prevented by high concentrations of dithiothreitol or by the inclusion of ADP or ATP, suggesting the involvement of thiols at the active site. PEPCK is also subject to rapid proteolysis in crude extracts of a range of C4 plants, resulting in cleavage to a smaller (62 kDa) form. This can be reduced by extraction at high pH and by the inclusion of SDS, but it means that intact PEPCK has never been purified from a C4 plant. The molecular mass of PEPCK varies considerably in C4 plants, unlike C3 and CAM plants in which it is usually 74 kDa. PEPCK is phosphorylated during darkness (and reversed by light) in some C4 plants with PEPCK of a larger molecular mass, such as Panicum maximum (71 kDa), but it was not phosphorylated in the PEPCK-type C4 plant, Sporobolus pyramidalis (69 kDa). The known regulatory properties of PEPCK are discussed in relation to its role in C4 photosynthesis, in particular its sensitivity to regulation by adenylates and by Mn2+.

Effect of Adult Tree Density and Nearness to the Natural Forest on the Restoration of Degraded Deciduous Forests of Attappady, Western Ghats, Kerala

2016 ◽  
Vol 39 (4) ◽  
pp. 309-315
Author(s):  
Ajithakumari Anusree ◽  
Puthiya Karunakaran ◽  
Narayanaswamy Parthasarathy
Keyword(s):  
Western Ghats ◽  
Native Species ◽  
Species Turnover ◽  
Tree Density ◽  
Natural Forest ◽  
Deciduous Forests ◽  
Tropical Deciduous Forest ◽  
Restoration Success ◽  
Adult Trees ◽  
Adult Tree

Studied on the effect of adult tree density and the proximity to the natural forest on restoration success in one of the most exploited tropical deciduous forests, Attappady, Western Ghats. Random quadrats were laid and surveyed for trees and saplings in remnant tropical deciduous forest patches (hereafter called as fragmented forest and the sites being restored here after called as restoration patches) to determine floristic composition, species turnover among sites and the influence of adult tree density on sapling density. Forests composed of deciduous and evergreen trees with an average species richness of 28 and alpha diversity of 2.671 in a 0.2 ha plot. Similarity of restoration patches with natural forest increased as distance between them decreased and regeneration of native species were more efficient in sites with more number of adult trees. Local (adult tree density) and landscape level (isolation of patches) factors are both important in determining the restoration success of deciduous forests of Attappady.

scholarly journals GROWTH AND YIELD OF Shorea parvifolia PLANTED UNDER AKASIA PLANTS IN KAPUAS, CENTRAL KALIMANTAN

2016 ◽  
Vol 7 (3) ◽  
pp. S48-S49
Author(s):  
Wahyudi .
Keyword(s):  
Native Species ◽  
Research Result ◽  
Volume Growth ◽  
Acacia Mangium ◽  
Average Diameter ◽  
Growth And Yield ◽  
Central Kalimantan ◽  
Enrichment Planting ◽  
The Moment ◽  
Silvicultural System

Shorea parvifolia is the native species of Kalimantan and has a high commercial value. This research was aimed to analysis the growth and yield of meranti planted under Acacia mangium stands, as enrichment planting on the TPTI silvicultural system.  The research was conducted at Kapuas District, Central Kalimantan Province. Type of soil at the site is ultisol with 2 606 mm/year of precipitation average.  Initially, Acacia mangium planted with space namely 3 x 3 m at 1993. After two years, seedlings of Shorea parvifolia were planted among akasia plants with 1 111 tress/ha of density.  Thinning of akasia plants were conducted stage by stage, especially at the stunted plants or dead. The data were latest analyzed at 2014 or at the moment of 20 years old.  Research result showed that at the 1, 5, 10, 15, and 15 years old, life percentage of Shorea parvifolia are 94.8%, 78%, 66.4%, 57.5%, and 53% respectively. Average diameter of Shorea parvifolia at the same times are 1.27 cm, 6.13 cm, 12.8 cm, 19.86, and 27.46 cm respectively, and their average total height are 1.51 m, 5.27 m, 10.89 m, 17.18 m, and 24.41 m respectively. Volume growth of Shorea parvifolia at the same times namely 0.05 m3/ha , 3.97 m3/ha, 36.93 m3/ha, 145.44 m3/ha, and 303.62 m3/ha respectively.Key words: growth and yield, CAI, MAI, Shorea parvifolia.

scholarly journals The end of life on Earth is not the end of the world: converging to an estimate of life span of the biosphere?

2019 ◽  
Vol 19 (1) ◽  
pp. 25-42 ◽  
Author(s):  
Fernando de Sousa Mello ◽  
Amâncio César Santos Friaça
Keyword(s):  
Partial Pressure ◽  
Life Span ◽  
Quantitative Agreement ◽  
C4 Plants ◽  
C3 Plants ◽  
Ocean Mass ◽  
The Future ◽  
Geophysical Processes ◽  
Red Giant ◽  
Life On Earth

AbstractEnvironmental conditions have changed in the past of our planet but were not hostile enough to extinguish life. In the future, an aged Earth and a more luminous Sun may lead to harsh or even uninhabitable conditions for life. In order to estimate the life span of the biosphere we built a minimal model of the co-evolution of the geosphere, atmosphere and biosphere of our planet, taking into account temperature boundaries, CO2 partial pressure lower limits for C3 and C4 plants, and the presence of enough surface water. Our results indicate that the end of the biosphere will happen long before the Sun becomes a red giant, as the biosphere faces increasingly more difficult conditions in the future until its collapse due to high temperatures. The lower limit for CO2 partial pressure for C3 plants will be reached in 170(+ 320, − 110) Myr, followed by the C4 plants limit in 840(+ 270, − 100) Myr. The mean surface temperature will reach 373 K in 1.63(+ 0.14, − 0.05) Gyr, a point that would mark the extinction of the biosphere. Water loss due to internal geophysical processes will not be dramatic, implying almost no variation in the surface ocean mass and ocean depth for the next 1.5 billion years. Our predictions show qualitative convergence and some quantitative agreement with results found in the literature, but there is considerable scattering in the scale of hundreds of millions of years for all the criteria devised. Even considering these uncertainties, the end of the biosphere will hardly happen sooner than 1.5 Gyr.

Distinctive diel growth cycles in leaves and cladodes of CAM plants: differences from C3 plants and putative interactions with substrate availability, turgor and cytoplasmic pH

2005 ◽  
Vol 32 (5) ◽  
pp. 421 ◽  
Author(s):  
Liezel M. Gouws ◽  
C. Barry Osmond ◽  
Ulrich Schurr ◽  
Achim Walter
Keyword(s):  
Malic Acid ◽  
Growth Dynamics ◽  
Maximum Growth ◽  
Co2 Assimilation ◽  
Growth Patterns ◽  
Phase Iii ◽  
C3 Plants ◽  
Cytoplasmic Ph ◽  
Cam Plants ◽  
Cell Turgor

Distinct diel rhythms of leaf and cladode expansion growth were obtained in crassulacean acid metabolism (CAM) plants under water-limited conditions, with maxima at mid-day during phase III of CO2 assimilation. This pattern coincided with the availability of CO2 for photosynthesis and growth during the decarboxylation of malic acid, with maximum cell turgor due to the nocturnally accumulated malic acid, and with the period of low cytoplasmic pH associated with malic acid movement from vacuole to cytosol. Maximum growth rates were generally only 20% of those in C3 plants and were reached at a different time of the day compared with C3 plants. The results suggest that malic acid, as a source of carbohydrates, and a determinant of turgor and cytoplasmic pH, plays a major role in the control of diel growth dynamics in CAM plants under desert conditions. The observed plasticity in phasing of growth rhythms under situations of differing water availability suggests that a complex network of factors controls the diel growth patterns in CAM plants and needs to be investigated further.

Elevated Atmosphere Partial Pressure of CO2 and Plant Growth. III. Interactions Between Triticum aestivum (C3) and Echinochloa frumentacea (C4) During Growth in Mixed Culture Under Different CO2, N Nutrition and Irradiance Treatments, With Emphasis on Below-Ground Responses Estimated Using the δ13C Value of Root Biomass

1991 ◽  
Vol 18 (2) ◽  
pp. 137 ◽  
Author(s):  
SC Wong ◽  
CB Osmond
Keyword(s):  
Triticum Aestivum ◽  
Mixed Culture ◽  
Elevated Co2 ◽  
Root Biomass ◽  
Shoot Growth ◽  
Mixed Cultures ◽  
C4 Plants ◽  
C3 Plants ◽  
Δ13c Value ◽  
Echinochloa Frumentacea

Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species, were grown in pots in monoculture and mixed culture (2 C3 : 1 C4 and 1 C3:2 C4) at two ambient partial pressures of CO2 (320 and 640 μbar), two photosynthetic photon flux densities (PPFDs) (daily maximum 2000 and 500 �mol m-2 s-1) and two levels of nitrogen nutrition (12 mM and 2 mM NO3-). Growth of shoots of both components in mixed culture was measured by physical separation, and the proportions of root biomass due to each component were calculated from δ13C value of total root biomass. In air (320 μbar CO2) at high PPFD and with high root zone-N, the shoot biomass of C3 and C4 components at the first harvest (28 days) was in proportion to the sowing ratio. However, by the second harvest (36 days) the C4 component predominated in both mixtures. Under the same conditions, but with low PPFD, C3 plants predominated at the first harvest but C4 plants had over- taken them by the time of the second harvest. Elevated atmospheric CO2 (640 μbar) stimulated shoot growth of Triticum in 15 of 16 treatment combinations and the stimulation was greatest in plants provided with low NO3-. Root growth of the C3 plants was generally stimulated by elevated CO2, but was only occasionally sensitive to the presence of C4 plants in mixed culture. However, growth of the C4 plants was often sensitive to the presence of C3 plants in mixed culture. In mixed cultures, elevated CO2 plants stimulated growth of C4 plants at high PPFD, high-N and in all low-N treatments but this was insufficient to offset a marked decline in shoot growth with increasing proportion of C3 plants in mixed cultures. The unexpected stimulation of growth of C4 plants by elevated CO2 was correlated with more negative δ13C values of C4 root biomass, suggesting a partial failure of the CO2 concentrating mechanism of C4 photosynthesis in Echinochloa under low-N. These experiments show that for these species nitrogen was more important than light or elevated pCO2 in determining the extent of competitive interactions in mixed culture.

scholarly journals Discordant Temporal Turnovers of Sediment Bacterial and Eukaryotic Communities in Response to Dredging: Nonresilience and Functional Changes

2016 ◽  
Vol 83 (1) ◽  
Author(s):  
Na Zhang ◽  
Xian Xiao ◽  
Meng Pei ◽  
Xiang Liu ◽  
Yuting Liang
Keyword(s):  
Time Course ◽  
Species Turnover ◽  
Macrobenthic Community ◽  
Ecosystem Functions ◽  
Rrna Gene ◽  
Functional Changes ◽  
Macrobenthic Communities ◽  
Temporal Turnover ◽  
The Stability ◽  
Ecosystem Multifunctionality

ABSTRACT To study the stability and succession of sediment microbial and macrobenthic communities in response to anthropogenic disturbance, a time-series sampling was conducted before, during, and 1 year after dredging in the Guan River in Changzhou, China, which was performed with cutter suction dredgers from 10 April to 20 May 2014. The microbial communities were analyzed by sequencing bacterial 16S rRNA and eukaryotic 18S rRNA gene amplicons with Illumina MiSeq, and the macrobenthic community was identified using a morphological approach simultaneously. The results indicated that dredging disturbance significantly altered the composition and structures of sediment communities. The succession rates of communities were estimated by comparing the slopes of time-decay relationships. The temporal turnover of microeukaryotes (w = 0.3251, P < 0.001 [where w is a measure of the rate of log(species turnover) across log(time)]) was the highest, followed by that of bacteria (w = 0.2450, P < 0.001), and then macrobenthos (w = 0.1273, P < 0.001). During dredging, the alpha diversities of both bacterial and microeukaryotic communities were more resistant, but their beta diversities were less resistant than that of macrobenthos. After recovery for 1 year, all three sediment communities were not resilient and had reached an alternative state. The alterations in sediment community structure and stability resulted in functional changes in nitrogen and carbon cycling in sediments. Sediment pH, dissolved oxygen, redox potential, and temperature were the most important factors influencing the stability of sediment communities and ecosystem multifunctionality. This study suggests that discordant temporal turnovers and nonresilience of sediment communities under dredging resulted in functional changes, which are important for predicting sediment ecosystem functions under anthropogenic disturbances. IMPORTANCE Understanding the temporal turnover and stability of biotic communities is crucial for predicting the responses of sediment ecosystems to dredging disturbance. Most studies to date focused on the bacterial or macrobenthic community, only at two discontinuous time points, before and after dredging, and hence, it was difficult to analyze the community succession. This study first compared the stabilities and temporal changes of sediment bacterial, microeukaryotic, and macrobenthic communities at a continuous time course. The results showed that discordant responses of the three communities are mainly related to their different biological inherent attributes, and sensitivities to sediment geochemical variables change with dredging, resulting in changes in sediment ecosystem multifunctionality.

Mating of Helicoverpa armigera (Lepidoptera: Noctuidae) moths and their host plant origins as larvae within Australian cotton farming systems

2012 ◽  
Vol 103 (2) ◽  
pp. 171-181 ◽  
Author(s):  
G.H. Baker ◽  
C.R. Tann
Keyword(s):  
Host Plant ◽  
Helicoverpa Armigera ◽  
Stable Carbon Isotopes ◽  
Production Systems ◽  
Farming Systems ◽  
C4 Plants ◽  
C3 Plants ◽  
Bt Cotton ◽  
Cotton Production ◽  
Helicoverpa Armígera

AbstractTransgenic (Bt) cotton dominates Australian cotton production systems. It is grown to control feeding damage by lepidopteran pests such as Helicoverpa armigera. The possibility that these moths might become resistant to Bt remains a threat. Consequently, refuge crops (with no Bt) must be grown with Bt cotton to produce large numbers of Bt-susceptible moths to reduce the risk of resistance developing. A key assumption of the refuge strategy, that moths from different host plant origins mate at random, remains untested. During the period of the study reported here, refuge crops included pigeon pea, conventional cotton (C3 plants), sorghum or maize (C4 plants). To identify the relative contributions made by these (and perhaps other) C3 and C4 plants to populations of H. armigera in cotton landscapes, we measured stable carbon isotopes (δ13C) within individual moths captured in the field. Overall, 53% of the moths were of C4 origin. In addition, we demonstrated, by comparing the stable isotope signatures of mating pairs of moths, that mating is indeed random amongst moths of different plant origins (i.e. C3 and C4). Stable nitrogen isotope signatures (δ15N) were recorded to further discriminate amongst host plant origins (e.g. legumes from non-legumes), but such measurements proved generally unsuitable. Since 2010, maize and sorghum are no longer used as dedicated refuges in Australia. However, these plants remain very common crops in cotton production regions, so their roles as ‘unstructured’ refuges seem likely to be significant.

Habitat use by the jacky lizard Amphibolurus muricatus in a highly degraded urban area

2011 ◽  
Vol 61 (2) ◽  
pp. 185-197 ◽  
Author(s):  
Shelley Burgin ◽  
Danny Wotherspoon ◽  
Dennis John Hitchen ◽  
Peter Ridgeway
Keyword(s):  
Urban Areas ◽  
Native Species ◽  
Vegetation Type ◽  
Urban Expansion ◽  
Native Vegetation ◽  
Invasive Weeds ◽  
Vegetation Types ◽  
Ecological Community ◽  
Amphibolurus Muricatus ◽  
Exotic Vegetation

AbstractOver time native vegetation remnants in urban areas are typically eroded in size and number due to pressures from urban expansion and consolidation. Such remnants, frequently neglected and invaded by weeds, may constitute the last remaining habitat for some species' populations in urban areas. In the restoration of remnants for biodiversity, weed removal is often a high priority but there is a dearth of information on the role that exotic vegetation plays as habitat for fauna such as small reptiles. We investigated the vegetation type preference of urban remnants at the edge of a Sydney golf course by Amphibolurus muricatus, the native jacky lizard. The three vegetation types present were Eastern Suburbs Banksia Scrub (an Endangered Ecological Community) with sparse groundcover, dense stands of the introduced Eragrostis curvula African love grass, and open fairways of lawn: three structurally different habitats. Captured jacky lizards were spooled and their movements traced by following the thread left as they moved through their home range. Jacky lizards preferred areas that afford them most cover. While they foraged throughout the stands of love grass, they tended to avoid the edge of native vegetation remnants. They also basked on the lawn close to the vegetation where they had recently foraged, or traversed it to enter natural vegetation or grass. We concluded that introduced love grass offered additional habitat because of the relatively dense vegetation cover, and that areas should not be managed with the assumption that invasive weeds are detrimental to native species without appropriate assessment.

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