Resprouting and mortality of juvenile eucalypts in an Australian savanna: impacts of fire season and annual sorghum

2010 ◽  
Vol 58 (8) ◽  
pp. 619 ◽  
Author(s):  
Patricia A. Werner ◽  
Donald C. Franklin
Keyword(s):  
Dry Season ◽  
Fire Season ◽  
Annual Grass ◽  
Fire Behaviour ◽  
Wet Season ◽  
Low Intensity ◽  
Canopy Tree ◽  
Carbohydrate Storage ◽  
Savanna Fires ◽  
Different Seasons

In northern Australian savannas, canopy tree species often have juvenile tree banks that are composed mainly of small individuals of indeterminate age that have resprouted repeatedly after fire. Little is known about their demography. We report the initial responses (mortality, topkill and resprouting type) of 3133 marked juvenile eucalypts to set fires of different seasons (early dry season, late dry season, wet season, unburnt) in a 32 400 m2 field experiment. Fire treatments were repeated in plots dominated by a native annual grass (sorghum) that becomes senescent before the early dry season and provides the main fuel of savanna fires, and in others with little or no sorghum, but instead other native grasses and forbs that remain green well into the dry season. Most juvenile eucalypts <150 cm high were topkilled but resprouted from underground tissues regardless of fire season or understorey (86–100% vs <5% in unburnt plots). Few saplings 200–500 cm high died or were topkilled, but impacts of fire were harsher in sorghum than in non-sorghum vegetation. The response of eucalypts 150–199 cm high was intermediate, suggesting a ‘tactical’ transition from suppressed persistence to growth toward maturity. Counter-intuitively, genet death of juvenile trees was >22% in the low-intensity early dry season fire in plots with little or no annual sorghum, compared with <2% in all other fire/understorey combinations. We suggest results are related to fire behaviour, seasonal carbohydrate storage dynamics and competition with ground-layer plants.

Effects of seasonal variation and locations on microbial load in sediment and water of a polluted ecosystem

2021 ◽  
Vol 36 (1) ◽  
pp. 93-105
Author(s):  
A.N. Okereke ◽  
J.C. Ike-Obasi
Keyword(s):  
Heterotrophic Bacteria ◽  
Standard Procedure ◽  
Dry Season ◽  
Microbial Load ◽  
Seasonal Effects ◽  
Wet Season ◽  
Different Seasons ◽  
Dry Seasons ◽  
Total Fungi ◽  
Hydrocarbon Utilizing Bacteria

Seasonal effects on microbial load of sediment and water at different locations along Bonny Estuary of Niger Delta was investigated for a period of 12 months. All analyses followed standard procedure. Results revealed that total fungi counts in sediment and water at different locations were not significantly different (p > 0.05) at both wet and dry seasons while hydrocarbon utilizing fungi showed significant differences (p < 0.05) at both seasons in both sediment and water samples. During the wet season, total faecal counts ranged from 5.0 to 10.0 x 105 CFU/g for sediment and 4.0 to 7.0x 105 CFU/g in water. In dry season, the concentration of hydrocarbon utilizing bacteria in the sediment ranged between 0.1 x 105 CFU/ml/g and 8.0 x 105 CFU/ml/g in wet season while in dry season, the concentration in water ranged between 0.1 x 105 CFU/ml/g and 6.0 x 105 CFU/ml/g at Abuloma. At Okwujagu, total heterotrophic bacteria counts in sediment ranged  from 0.1 to 8.0 x 105 CFU/g in dry season. This was higher than the range 0.1 to 6.8.0 x 105 CFU/ recorded in Abuloma, Okwujagu and Slaughter at dry season. The highest vibrio counts in water (11.0 x 105 CFU/ml) for wet and (10.0 x 105 CFU/ml) for dry seasons were recorded at Slaughter. In Oginiba, the feacal count recorded 3.0 x 105 CFU/ml in water during the wet season and 2.0 x 105 CFU/ml for dry season. Generally, there were significant differences (p < 0.05) in the bacterial concentrations in both sediment and water. This showed that different seasons favour the growth of certain microbial types.

Trade-offs between xylem water and carbohydrate storage among 24 coexisting subtropical understory shrub species spanning a spectrum of isohydry

2020 ◽  
Author(s):  
Peipei Jiang ◽  
Frederick C Meinzer ◽  
Xiaoli Fu ◽  
Liang Kou ◽  
Xiaoqin Dai ◽  
...  
Keyword(s):  
Photosynthetic Performance ◽  
Dry Season ◽  
Adaptation Strategies ◽  
Wet Season ◽  
Drought Adaptation ◽  
Drought Avoidance ◽  
Carbohydrate Storage ◽  
Trade Offs ◽  
Volume Curve ◽  
Hydraulic Capacitance

Abstract Hydraulic capacitance and carbohydrate storage are two drought adaptation strategies of woody angiosperms. However, we currently lack information on their associations and how they are associated with species’ degree of isohydry. We measured total stem xylem nonstructural carbohydrate (NSC) concentration in the dry and wet seasons, xylem hydraulic capacitance, native leaf water potentials, pressure–volume curve parameters and photosynthetic performance in 24 woody understory species differing in their degree of isohydry. We found a trade-off between xylem water and carbohydrate storage both in storage capacitance and along a spectrum of isohydry. Species with higher hydraulic capacitance had lower native NSC storage. The less isohydric species tended to show greater NSC depletion in the dry season and have more drought-tolerant leaves. In contrast, the more isohydric species had higher hydraulic capacitance, which may enhance their drought avoidance capacity. In these species, leaf flushing in the wet season and higher photosynthetic rates in the dry season resulted in accumulation rather than depletion of NSC in the dry season. Our results provide new insights into the mechanisms through which xylem storage functions determine co-occurring species’ drought adaptation strategies and improve our capacity to predict community assembly processes under drought.

scholarly journals Root carbohydrate storage in young saplings of an Amazonian tidal várzea forest before the onset of the wet season

1994 ◽  
Vol 8 (2) ◽  
pp. 129-139 ◽  
Author(s):  
Fabio Rubio Scarano ◽  
José Henrique Cattânio ◽  
Robert M.M. Crawford
Keyword(s):  
Tree Species ◽  
Dry Season ◽  
Carbohydrate Content ◽  
Adaptive Mechanism ◽  
Wet Season ◽  
Glucose Content ◽  
Palm Trees ◽  
Carbohydrate Storage ◽  
Flood Regime ◽  
Root Starch

Root starch and glucose content were measured for young saplings of 18 Amazonian tidal várzea tree species during a dry season. The pattern of carbohydrate storage depended on the type of plant involved and soil topography which is directly linked to flood regime. Most plants showed high root carbohydrate content at this point in the dry season, however, several typically flood-tolerant species (particularly palm trees) presented a low root carbohydrate content, suggesting a strategy of acquiring reserves during the wet season to survive the dry season, when depletion occurs. Plant survival in these flood-prone forests seems to be the result of more than only one adaptive mechanism.

scholarly journals Study on Purification Effect of Artificial Wetland on Micro-polluted River

2019 ◽  
Vol 136 ◽  
pp. 06023
Author(s):  
Zhao Changheng ◽  
Cha Fengjuan ◽  
Le Yongzhi ◽  
Zhou Guangsheng ◽  
Qian Liping
Keyword(s):  
Water Quality ◽  
Removal Rate ◽  
Dry Season ◽  
Wet Season ◽  
Artificial Wetland ◽  
Artificial Wetlands ◽  
Polluted River ◽  
Different Seasons ◽  
Artificial Surface ◽  
Surface Wetland

The research on the purification effect of artificial wetland on micro-polluted river and the detection of aquatic plants showed that TP, TN, NH3-N and COD in river were significantly lower than those in untreated river, indicating that the artificial wetland has a good purification effect on these water quality indicators; Testing from different wetland types, it can be seen that the effect of removing TP, TN, NH3-N and other factors in the subsurface wetland is the best, and the artificial surface wetland is second, while the effect of removing COD factor it is close to that of artificial surface wetland. As for the effect of removing pollution factors in artificial wetlands in different seasons, it can be drawn frow the test that the removal rate of TP and TN in artificial wetlands in different seasons can be obtained: wet season > normal season > dry season; and the removal rate of NH3-N and COD is normal season > dry season > wet season. In addition to the TN factor, the water quality during the dry season and normal season is significantly better than that during the wet season. Based on the analysis of the total amount of heavy metals absorbed by three kinds of aquatic plants, it can be concluded that different plant has different effect of removing TN and TP.

Does season affect fire behaviour in the Cerrado?

2017 ◽  
Vol 26 (5) ◽  
pp. 427 ◽  
Author(s):  
Mariana Ninno Rissi ◽  
M. Jaime Baeza ◽  
Elizabeth Gorgone-Barbosa ◽  
Talita Zupo ◽  
Alessandra Fidelis
Keyword(s):  
Dry Season ◽  
Flame Height ◽  
Fuel Load ◽  
Fire Season ◽  
Fire Intensity ◽  
Fire Behaviour ◽  
Dead Biomass ◽  
Management Plans ◽  
Fire Exclusion ◽  
Fuel Moisture Content

Fire has played an important role in the plant dynamics and diversity of the Cerrado for millions of years. We evaluated fire behaviour in different fire seasons in areas of an open savanna, providing information for fire management plans. It has been hypothesised that early fires (May – end of the rainy season) will be less intense than those conducted in the middle and end of the dry season (July and October) owing to the amount of dead biomass accumulated. Therefore, we compared fire behaviour in early, mid- and late dry season, evaluating the main fire and environmental variables. Fire intensity was mainly influenced by the combination of dead fuel percentage and fuel load. Even though this combination was the best model to explain fire intensity variability, fire parameters (including fire intensity) did not differ between fire seasons. Flame height was best explained by dead fuel percentage + fuel moisture content, dead fuel percentage + fuel load and also by dead fuel percentage. Our study showed that, in areas with fire exclusion for 2 years, fire season did not influence fire parameters and fire behaviour and the main factors influencing fire intensity were the proportion of dead biomass and total fuel load.

Water quality assessment of the river Buriganga, Bangladesh

2018 ◽  
Vol 4 (1) ◽  
pp. 47-54 ◽  
Author(s):  
K Fatema ◽  
M Begum ◽  
M Al Zahid ◽  
ME Hossain
Keyword(s):  
Water Quality ◽  
Water Quality Assessment ◽  
Quality Parameters ◽  
Dry Season ◽  
River Ecosystem ◽  
Wet Season ◽  
Different Seasons ◽  
Water Quality Status ◽  
Quality Status

The present investigation was conducted to assess the water quality status of the river Buriganga. Water samples were collected from three selected stations in wet (June-August) and dry (November-January) seasons during the years 2017 and 2018. Temperature and Dissolved Oxygen (DO) of water varied from 22.80 to 31.40 °C and 0.22 to 2.74 mg/L, respectively. Electrical conductivity of water varied from 180 to 598 μS/cm while pH ranged from 7.61 to 8.97. This study showed that temperature, DO and Fe were higher in wet season than in the dry season, whereas pH, conductivity and phosphate were higher in dry season than in the wet season. But manganese did not vary in different seasons. It is found that the differences of water quality parameters were significant in seasons (p<0.05) except for Fe and insignificant for stations (p>0.05) except for DO. The results reveal that there were significant differences between sampling seasons (wet and dry) (p<0.05) except for temperature and manganese. A significant correlation (p<0.01) was also found among temperature and other parameters viz. DO, conductivity, pH, phosphate. According to the result obtained in the present study, it may be said that the water quality of the river Buriganga is not acceptable to declare the river-ecosystem as a sound one ecologically.J. Biodivers. Conserv. Bioresour. Manag. 2018, 4(1): 47-54

scholarly journals Seasonal variation of suspended sediment and its relationship with turbidity in Cam - Nam Trieu estuary, Hai Phong (Vietnam)

2021 ◽  
Vol 21 (3) ◽  
pp. 271-282
Author(s):  
Minh Hai Nguyen ◽  
Sylvain Ouillon ◽  
Duy Vinh Vu
Keyword(s):  
Seasonal Variation ◽  
Suspended Sediment ◽  
River Flow ◽  
Suspended Particle ◽  
Strong Dependence ◽  
Dry Season ◽  
Wet Season ◽  
Different Seasons ◽  
Spm Concentration ◽  
Suspended Particle Matter

We analyzed the seasonal variation of suspended sediment and its relationship with Turbidity in Cam - Nam Trieu estuary based on data measured during three different seasons: Early wet season (May 2015), wet season (September 2015) and dry season (January 2016). The results highlighted the seasonal variation of suspended particle matter (SPM) concentrations with river flow. The average SPM concentration was highest during the dry season, with 62.95 mg/L. They were not significantly different between the early wet and wet seasons, with 59.65 mg/L and 50.94 mg/L, respectively. This study also demonstrated a strong dependence between SPM and Turbidity in the study area. The coefficients of determination varied from 0.867 to 0.971 (linear relationship), and from 0.95 to 0.991 (proportional relationship). Therefore, turbidity can be used to estimate SPM concentration. However, this relationship changed markedly with the seasons, and hence when determining SPM concentration, seasonal factors must be considered.

scholarly journals On the reproductive ecology of Premna latifolia L. and Premna tomentosa Willd. (Lamiaceae)

2018 ◽  
Vol 10 (1) ◽  
pp. 11105
Author(s):  
B. Dileepu Kumar ◽  
D. Sandhya Deepika ◽  
A.J Solomon Raju
Keyword(s):  
Reproductive Ecology ◽  
Soil Nutrient ◽  
Dry Season ◽  
Flowering Period ◽  
Wet Season ◽  
Different Seasons

Premna latifolia and Premna tomentosa shed their foliage during winter but produce foliage at different periods to avoid competition for nutrients, P. latifolia during the dry season while P. tomentosa during the wet season.  Flowering also occurs at different seasons, P. latifolia during the wet season and P. tomentosa during the dry season.  The flowering period of P. latifolia is comparatively longer than P. tomentosa; however, both of them display profuse flowering for 2–3 weeks only.  The flowers are of gullet type, weakly bilabiate, and the stamens and stigma are situated near the upper corolla lip and are dichogamous, herkogamous and facultatively xenogamous in both species.  In P. latifolia, the pollinators are wasps and butterflies while in P. tomentosa, in addition to wasps and butterflies, the bees and flies are also pollinators.  Camponotus ants rob the nectar of P. latifolia by removing the entire corolla together with stamens and sometimes also with the style and stigma.  Both the species display ornithochory, anthropochory and anemochory. The seeds germinate during wet season in both the species irrespective of their time of dispersal but their continued growth depends on the soil nutrient and moisture environment.  

scholarly journals Seasonal assessment of existing mud crab (Scylla sp.) fattening practice in Bangladesh

2015 ◽  
Vol 2 (1) ◽  
pp. 135-141 ◽  
Author(s):  
Zannatul Ferdoushi
Keyword(s):  
Market Price ◽  
Stocking Density ◽  
Dry Season ◽  
Production Performance ◽  
Mud Crab ◽  
Wet Season ◽  
Alternative Employment ◽  
Different Seasons ◽  
Rain Fall ◽  
Lower Production

The present study was conducted in the southwest part of Bangladesh from 2008 to 2009 in order to assess of mud crab fattening practice and its production performance between two different seasons. Generally two crab fattening seasons are observed in Bangladesh, one is the dry or peak season (October to May) and another one is lean season or wet season (June to September). Significant variation in stocking density was observed between two seasons during the study period. Comparatively higher stocking density and higher production was found in dry season in comparison to wet season. The reasons behind higher production and production rate were; the availability of the crabs and high market price for the crabs during dry season. On the other hand, rain fall, occurrence of diseases and natural disaster might be the cause of lower production of crab during wet season. Crab farming and fishery could play a sustainable alternative employment opportunity for the development of coastal people. So government should take some necessary steps for the development of this fishery.Res. Agric., Livest. Fish.2(1): 135-141, April 2015

scholarly journals Causes of the decline of the Gouldian Finch Erythrura gouldiae

1996 ◽  
Vol 6 (1) ◽  
pp. 49-61 ◽  
Author(s):  
Sonia C. Tidemann
Keyword(s):  
Clutch Size ◽  
Nest Site ◽  
Northern Territory ◽  
Dry Season ◽  
Northern Australia ◽  
Wet Season ◽  
Breeding Sites ◽  
Low Intensity ◽  
Tree Hollows ◽  
Gouldian Finch

SummaryPopulations of Gouldian Finch Erythrura gouldiae, an estrildid endemic to northern Australia, declined markedly during the last two or three decades. A survey revealed the species in two areas of Northern Territory, with an estimated 2,000 individuals, including juveniles. Recaptures were low either because of mortality or dispersal. Gouldian Finches eat predominantly Sorghum spp. seeds, but consume other seeds before Sorghum ripens. Other finches declined as cattle increased. Gouldian Finches breed in tree hollows of predominantly two species of eucalypts that grow on rocky slopes. They require water within about 4 km of the nest site. There was no shortage of nesting hollows at the known breeding sites. Fires in the early to mid-dry season allow birds access to seed without damaging trees, but later fires can destroy trees with nest hollows and remove shade. Average clutch-size is 5.2. About 72% of eggs laid, and 63% of nests, fledged young. Pairs lay up to three clutches in a season (February-August), the length of which may depend on rainfall during the preceding wet season. Air-sac mite (Sternostoma tracheacolum), found in 62% of Gouldian Finches sampled, may be preventing the species recovering to former numbers. New colonies of Gouldian Finches should be identified, populations monitored, and habitat managed by effecting patchy burns by low-intensity fires early in the dry season.

Sign in / Sign up

Export Citation Format

Share Document