Growth of heath vegetation. II. The seasonal growth of a heath on ground-water Podzol at Wilson's Promontory, Victoria

1965 ◽  
Vol 13 (2) ◽  
pp. 281 ◽  
Author(s):  
RH Groves
Keyword(s):  
Soil Moisture ◽  
Ground Water ◽  
Shoot Growth ◽  
Late Summer ◽  
Dry Weight ◽  
Early Summer ◽  
Second Phase ◽  
Root Weight ◽  
Seasonal Growth ◽  
Third Phase

The seasonal growth of a heath on a ground-water podzol in southern Victoria is presented. Seasonal changes in the dry weight of standing vegetation, dry weight of surface roots, and soil moisture were followed. Three phases of growth are obvious. The first phase, shoot growth in late spring-early summer, may be the result of a redistribution of metabolites. During the second phase, a significant increase in the dry weight of tops may occur; this presumably leads to an increase in evapotranspiration and a decrease in soil moisture. Death of some roots then occurs, followed by abscission of older leaves and death of weaker plants. Any increase in the biomass of tops is thus cancelled in this heath ecosystem. With reduction in leaf area, evapotranspiration decreases and soil moisture increases. In this third phase in late summer, the root weight increases to approximately that of the previous winter. Thus the ecosystem maintains a fluctuating equilibrium in root-top biomass from year to year.

scholarly journals Increasing Cell Size and Reducing Medium Compression Enhance Lettuce Transplant Quality and Field Production

HortScience ◽  
1996 ◽  
Vol 31 (2) ◽  
pp. 184-189 ◽  
Author(s):  
Silvana Nicola ◽  
Daniel J. Cantliffe
Keyword(s):  
Cell Size ◽  
Sandy Soil ◽  
Shoot Growth ◽  
Weight Ratio ◽  
Dry Weight ◽  
Root Weight ◽  
Growth Ratio ◽  
Root Dry Weight ◽  
Total Dry Weight ◽  
Initial Root

`South Bay' lettuce (Lactuca sativa L.) seedlings were grown in a greenhouse during winter, spring, and fall to investigate the effect of cell size and medium compression on transplant quality and yield. Four Speedling planter flats (1.9-, 10.9-, 19.3-, 39.7-cm3 cells) and two medium compression levels [noncompressed and compressed (1.5 times in weight)] were tested. The two larger cell sizes and compression of the medium led to increased plant shoot growth. Conversely, root weight ratio [RWR = (final root dry weight ÷ final total dry weight + initial root dry weight ÷ initial total dry weight) ÷ 2] was highest with the smaller cells without medium compression. Lettuce transplants were field-grown on sand and muck soils. The larger cells delayed harvest by >2 weeks for plants grown on muck soil, but yield was unaffected. When grown on sandy soil, earliness was enhanced from plants grown in 19- and 40-cm3 cells, but head weights were not affected in the spring planting. In fall, heads were heavier for plants grown in 11-, 19-, or 40-cm3 cells compared with those from 2-cm3 cells. On sandy soil, harvest was delayed 13 days in spring and 16 days in fall for plants grown in the smallest cell size. Using the two smaller cell sizes saved medium and space in the greenhouse and increased the root growth ratio, but it led to reduced plant growth compared to using the bigger cells. Yield and earliness were more related to season and soil type than to transplant quality. On sandy soil, plants grown in 2- and 11-cm3 cells matured later, and yield was significantly decreased (8.6%) in fall by using plants from the 2-cm3 cells compared to the other sizes. From our results, compressing the medium in the cells was not justified because it is more costly and did not benefit yield in the field.

scholarly journals Soil CO<sub>2</sub> efflux of a larch forest in northern Japan

2010 ◽  
Vol 7 (11) ◽  
pp. 3447-3457 ◽  
Author(s):  
N. Liang ◽  
T. Hirano ◽  
Z.-M. Zheng ◽  
J. Tang ◽  
Y. Fujinuma
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Ecosystem Respiration ◽  
Late Summer ◽  
Early Summer ◽  
Larch Forest ◽  
Co2 Efflux ◽  
Soil Co2 ◽  
Soil C ◽  
Northern Japan

Abstract. We had continuously measured soil CO2 efflux (Rs) in a larch forest in northern Japan at hourly intervals for the snow-free period in 2003 with an automated chamber system and partitioned Rs into heterotrophic respiration (Rh) and autotrophic respiration (Rr) by using the trench method. In addition, we applied the soil CO2 concentration gradients method to continuously measure soil CO2 profiles under snowpack in the snowy period and to partition Rs into topsoil (Oa and A horizons) CO2 efflux (Ft) with a depth of 0.13 m and sub-soil (C horizon) CO2 efflux (Fc). We found that soil CO2 effluxes were strongly affected by the seasonal variation of soil temperature but weakly correlated with soil moisture, probably because the volumetric soil moisture (30–40% at 95% confidence interval) was within a plateau region for root and microbial activities. The soil CO2 effluxes changed seasonally in parallel with soil temperature in topsoil with the peak in late summer. On the other hand, the contribution of Rr to Rs was the largest at about 50% in early summer, when canopy photosynthesis and plant growth were more active. The temperature sensitivity (Q10) of Rr peaked in June. Under snowpack, Rs was stable until mid-March and then gradually increased with snow melting. Rs summed up to 79 gC m−2 during the snowy season for 4 months. The annual Rs was determined at 934 gC m−2 y−1 in 2003, which accounted for 63% of ecosystem respiration. The annual contributions of Rh and Rs to Rs were 57% and 43%, respectively. Based on the gradient approach, Rs was partitioned vertically into litter (Oi and Oe horizons) with a depth of 0.01–0.02 m, topsoil and sub-soil respirations with proportions of 6, 72 and 22%, respectively, on an annual basis. The vertical distribution of CO2 efflux was consistent with those of soil carbon and root biomass.

Pruning Northern Red Oak Nursery Seedlings: Effects on Root Regeneration and Early Growth

1975 ◽  
Vol 5 (3) ◽  
pp. 381-386 ◽  
Author(s):  
M. M. Larson
Keyword(s):  
Seedling Growth ◽  
Shoot Growth ◽  
Late Summer ◽  
Early Growth ◽  
Red Oak ◽  
Root Pruning ◽  
Root Weight ◽  
Northern Red Oak ◽  
Root Regeneration ◽  
Early Fall

Northern red oak seedlings were top-pruned in the seedbed each month from August until the next March. In late March, all trees were lifted, planted in the greenhouse, and harvested 30 days later. Any top-pruning treatment that directly or indirectly removed the leaves in late summer or early fall markedly reduced root regeneration and initial shoot growth after planting in March. Removal of all the visible buds at any date resulted in increased numbers of new shoots after planting, while pruning stems at the groundline reduced new shoot growth.In additional studies, shoots and roots of trees lifted in March were pruned to various levels before planting. Results indicated that root pruning influenced seedling growth much more than shoot pruning. The amount of new shoot growth was significantly correlated with root weight of seedlings when planted, whether differences in root weight were natural or obtained by pruning. The effects of shoot pruning and root pruning on seedling growth were largely independent of each other.

Seasonal growth of field layer plants in two stands of Mallee vegetation

1968 ◽  
Vol 16 (3) ◽  
pp. 615 ◽  
Author(s):  
PG Holland
Keyword(s):  
Shoot Growth ◽  
Early Summer ◽  
Late Spring ◽  
Present Climate ◽  
Seasonal Growth ◽  
Growth Rhythm ◽  
Perennial Plants ◽  
Field Layer ◽  
Growth Studies

Changes in the aerial biomass of annual and perennial plants in the field layers of two stands in the mallee vegetation were followed from spring 1964 until spring 1966, and it is shown that these plants reach their maximum aerial biomass in the late spring and early summer respectively at, or before, the time when the shrubs and mallee eucalypts begin their new season's shoot growth. Studies of some Australian grasses and shrubs reveal that their shoot growth rhythms are "out of phase with the present climate", but the results reported here suggest that the various plants in mallee vegetation may conform to more than one growth rhythm.

scholarly journals Effect of Wind and Soil Moisture on the Growth of `Bluecrop' (Vaccinium corymbosum L.)

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 648c-648
Author(s):  
W. Alan Erb ◽  
Mark Pyeatt
Keyword(s):  
Soil Moisture ◽  
Leaf Area ◽  
Weight Ratio ◽  
Dry Weight ◽  
Root Weight ◽  
Total Leaf Area ◽  
Root Weight Ratio ◽  
Leaf Weight Ratio ◽  
Canopy Volume ◽  
Temperature Experiment

This study was conducted in the greenhouse by running two experiments at different temperature regimes (22°C day and 13°C night and 33°C day and 22°C night). One-year-old tissue culture propagated plants were irrigated at three different soil moisture tension levels (5, 15, and 30 cnbars) and either exposed to moving or still air. The moving air treatment was created by two 51-cm-diameter fans running at either low (5.6 mph) or medium (8.2 mph) speed. Each experiment included, forty-eight plants arranged in a randomized complete block design. Each block consisted of a greenhouse bench containing two fans, a plastic dividing wall and two plant replications for each treatment. Canopy volume measurements were taken at the beginning, middle and end of each experiment to estimate growth rate. At the end of each experiment, total leaf area and leaf, stem and root dry weight data were collected. In the moderate temperature experiment, the still air treated plants had the highest canopy volume and leaf weight ratio while the moving air treated plants had the highest stem weight ratio. The only difference for the moisture treatments was the 5-cnbar treatment had the highest canopy volume. In the high temperature experiment, the still air treated plants had the highest canopy volume, total leaf area, leaf dry weight, shoot/root ratio, leaf weight ratio and leaf area duration while the moving air treated plants had the highest root weight ratio. The 5-cnbar treatment had the highest canopy volume and biomass accumulations. The 30-cnbar treatment had the highest root weight ratio.

Seasonal growth patterns of ovulate strobili of Pinus resinosa in central Wisconsin

1969 ◽  
Vol 47 (6) ◽  
pp. 839-848 ◽  
Author(s):  
D. I. Dickmann ◽  
T. T. Kozlowski
Keyword(s):  
Pinus Resinosa ◽  
Dry Weight ◽  
Growth Patterns ◽  
First Year ◽  
Second Phase ◽  
Seasonal Growth ◽  
Final Size ◽  
Diameter Increment ◽  
Diurnal Fluctuations ◽  
Second Year

Seasonal growth patterns and water balance of first- and second-year strobili and seeds of Pinus resinosa Ait. were studied. Strobili emerged from the bud in late May or early June and grew slowly during the first season, reaching approximately 1/40 the weight of mature strobili. After a rapid period of hydration which lasted until mid-June, the weight of water in first-year strobili remained stable, but percentage of moisture decreased, primarily because of increasing dry weight. Strobili resumed growth in mid-April of the second year and grew slowly until June. Then, at about the time that fertilization of ovules occurred, dry weight increment of strobili increased greatly until a final weight of 6 to 8 g was reached early in August. However, strobili reached final size in mid-July. After mid-June, both the weight of water and percentage of moisture of second-year strobili decreased greatly, reflecting characteristic dehydration of cones during maturation. Seeds increased rapidly in dry weight after fertilization, but decreased sharply in percentage of moisture and weight of water.Continuous monitoring of strobilus diameters with dendrographs showed that, during the first year, strobili expanded slowly and showed diurnal fluctuations in diameter during periods of water stress. Second-year strobili showed three growth phases: an initial phase characterized by net diameter increment; a second phase in which no large net diameter increment took place although diurnal fluctuations regularly occurred; and a third, dehydration, phase during which time strobilus diameters decreased, accompanied by diurnal contraction and partial reexpansion.

Response of SO2-fumigated Pinus resinosa seedlings to postfuniigation temperature

1981 ◽  
Vol 59 (4) ◽  
pp. 470-475 ◽  
Author(s):  
R. J. Norby ◽  
T. T. Kozlowski
Keyword(s):  
Growth Rate ◽  
Growth Inhibition ◽  
Significant Interaction ◽  
Shoot Growth ◽  
Pinus Resinosa ◽  
Dry Weight ◽  
Red Pine ◽  
Root Weight ◽  
Temperature Regimes

Effects of postfumigation temperature on SO2-fumigated seedlings of red pine (Pinus resinosa Ait.) were studied. Seedlings were fumigated with either 0.2 ppm SO2 for 91 h or with 0.5 ppm SO2 for 30 h. Seedling injury was much greater at the higher SO2 concentration. At the lower SO2 concentration, only root weight of fumigated seedlings was affected, and it was about 20% less than that of unfumigated controls after 6 weeks at 12, 22, or 32 °C; there was no interaction between SO2 treatment and postfumigation temperature on growth rate. Postfumigation growth was reduced more by the higher concentration of SO2. Significant interaction between SO2 and postfumigation temperature occurred, with growth of roots, primary needles, and secondary needles being reduced most at 12 °C. At higher postfumigation temperatures, SO2-fumigated seedlings recovered (partially) and initiated secondary needles, thereby providing a new source of photosynthate and further reducing growth inhibition. But at 12 °C, shoot growth was slow and injured needle tissue was not replaced; hence the dry weight of roots of plants fumigated at the higher SO2 concentration was <30% of that of controls after 6 weeks. Interpretation of effects of fumigation temperature on SO2 toxicity should also consider influences of postfumigation temperature regimes.

scholarly journals The temporally varying roles of rainfall, snowmelt and soil moisture for debris flow initiation in a snow dominated system: the compound trigger concept

2017 ◽  
Author(s):  
Karin Mostbauer ◽  
Roland Kaitna ◽  
David Prenner ◽  
Markus Hrachowitz
Keyword(s):  
Soil Moisture ◽  
Debris Flow ◽  
High Intensity ◽  
Debris Flows ◽  
Late Summer ◽  
Early Summer ◽  
Temporal Separation ◽  
Antecedent Soil Moisture ◽  
Trigger Mechanisms ◽  
Debris Flow Initiation

Abstract. Debris flows represent a severe hazard in mountain regions. Though significant effort has been made to predict such events, the trigger conditions as well as the hydrologic disposition of a watershed at the time of debris flow occurrence are not well understood. Traditional intensity-duration threshold techniques to establish trigger conditions generally do not account for distinct influences of rainfall, snowmelt, and antecedent moisture. To improve our knowledge on the connection between debris flow initiation and the hydrologic system and to overcome the above limitations, this study explores the use of a semi-distributed conceptual rainfall-runoff model, linking different system variables such as soil moisture, snowmelt, or runoff with documented debris flow events in the inner Pitztal watershed, western Austria. The model was run on a daily basis between 1953 and 2012. Analyzing a range of modelled system state and flux variables at days on which debris flows occurred, three distinct dominant trigger mechanisms could be clearly identified. While the results suggest that for 68 % (17 out of 25) of the observed debris flow events during the study period high-intensity rainfall was the dominant trigger, snowmelt was identified as dominant trigger for 24 % (6 out of 25) of the observed debris flow events. In addition, 8 % (2 out of 25) of the debris flow events could be attributed to the combined effects of low-intensity, long-lasting rainfall and transient storage of this water, causing elevated antecedent soil moisture conditions. The results also suggest a relatively clear temporal separation between the distinct trigger mechanisms, with high-intensity rainfall as trigger being limited to mid- and late summer. The dominant trigger in late spring/early summer is snowmelt. Based on the discrimination between different modelled system states and fluxes and more specifically, their temporally varying importance relative to each other, rather than their absolute values, this exploratory study demonstrates that already the use of a relatively simple hydrological model can prove useful to gain some more insight into the importance of distinct debris flow trigger mechanisms in a compound trigger concept, highlighting in particular the relevance of snowmelt contributions and the switch between mechanisms in early- to mid-summer in snow dominated systems.

scholarly journals POTASIUM AND MICRO FERTILIZERS APPLICATION FOR IMPROVING CASSAVA PRODUCTION HARVESTING AT 7 AND 10 MONTH AFTER PLANTING

2020 ◽  
Vol 19 (2) ◽  
pp. 63
Author(s):  
Kukuh Setiawan
Keyword(s):  
Shoot Growth ◽  
Block Design ◽  
Dry Weight ◽  
Root Weight ◽  
Root Number ◽  
Randomized Block Design ◽  
Cassava Production ◽  
Leaf Dry Weight

ABSTRACTThe harvest of cassava usually conducted by farmers in Lampung province is around 7 months after planting (MAP).  Moreover, either farmers or industry cassava rarely fertilized by using potassium (KCl) and also micro fertilizers to improve the cassava production.  This condition could decrease the production both root weight and strach content.  Consequently, the objective of this study was to evaluate the cassava production applied by potassium and micro fertilizers harvested at 7 and 10 MAP.  Treatments were arranged by factorial (2x2) in completely randomized block design with three reps used as block.  First factor were First factor was two levels of KCl, 200 and 300 kg KCl/ha.  Second factor was two levels of micro nutrient, 0 and 20 kg zincmicro nutrient/ha.  The result showed that there was no variation of root number and root weight due to application of potassium and micro fertilizers.  This means that root number and root weight were not significantly different applied by potassium and micro fertilizers.  In addition, application of potassium and micro fertilizers could significantly influence shoot growth as stem dry weight and leaf dry weight at 10 MAP.Keywords: harvest, leaf dry weight, micro fetilizer, potassium, production, stem dry weight ABSTRAKCara panen ubikayu yang biasa dilakukan di tingkat petani adalah sekitar tanaman umur 7 bulan setelah tanam (BST).  Selain itu, petani maupun pihak industri sangat jarang melakukan pemupukan kalium (KCl) maupun unsur mikro untuk perbaikan produksi ubikayu.  Hal ini akan menyebabkan penurunan produksi baik dari bobot ubi maupun kadar pati.  Oleh karena itu, tujuan penelitian ini adalah untuk mengevaluasi produksi ubikayu akibat aplikasi pemupukan kalium (KCl) dan mikro pada umur panen 7 dan 10 BST.  Perlakuan disusun secara faktorial (2x2) dalam rancangan kelompok teracak lengkap (RKTL) dengan tiga ulangan sebagai kelompok.  Faktor pertama adalah aplikasi dua dosis pupuk KCL, 200 dan 300 kg KCl/ha.  Faktor kedua adalah aplikasi dua dosis pupuk mikro, 0 dan 20 kg Zincmikro/ha.  Hasil menunjukkan bahwa tidak ada variasi pada variabel jumlah ubi dan bobot ubi akibat pemupukan kalium dan mikro.  Hal ini menggambarkan bahwa aplikasi pupuk kalium dan mikro menghasilkan jumlah ubi dan bobot ubi yang tidak berbeda.  Selanjutnya, aplikasi pupuk kalium dan mikro memberikan pengaruh pada variabel pertumbuhan tajuk seperti bobot kering batang dan daun pada umur 10 BST.Kata kunci: bobot kering batang, bobot kering daun, kalium, mikro, panen, produksi

scholarly journals Seasonal fluctuations of the rusty carbon sink in thawing permafrost peatlands

2021 ◽  
Author(s):  
Monique Patzner ◽  
Nora Kainz ◽  
Erik Lundin ◽  
Maximilian Barczok ◽  
Chelsea Smith ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Organic Carbon ◽  
Active Layer ◽  
Carbon Sink ◽  
Carbon Mineralization ◽  
Ghg Emissions ◽  
Late Summer ◽  
Early Summer ◽  
Summer Season ◽  
Redox Conditions

In permafrost peatlands, up to 20% of total organic carbon (OC) is bound to reactive iron (Fe) minerals in the active layer overlying intact permafrost, potentially protecting OC from microbial degradation and transformation into greenhouse gases (GHG) such as CO2 and CH4. During the summer, shifts in runoff and soil moisture influence redox conditions and therefore the balance of Fe oxidation and reduction. Whether this “rusty carbon sink” is stable or continuously dissolved by Fe(III) reduction and reformed by Fe(II) oxidation during redox shifts remains unknown. We exposed ferrihydrite (FH)-coated sand in the active layer along a permafrost thaw gradient in Stordalen mire (Abisko, Sweden) over the summer (June to September) to capture changes in redox conditions and quantify formation and dissolution of reactive Fe(III) (oxyhydr)oxides and associated OC. We found that Fe(III) minerals formed under the constantly oxic conditions in palsa soils overlying intact permafrost over the full summer season. In contrast, in fully-thawed fen areas, conditions were continuously anoxic and by late summer 50.4% of the original Fe(III) (oxyhydr)oxides were lost via dissolution while 44.7% and 4.9% of the Fe remained as Fe(III) and Fe(II) on the sand, respectively. Periodic redox shifts (from 0 mV to +300 mV) were observed over the summer season in the partially-thawed bog due to changes in active layer depth, runoff and soil moisture. This resulted in dissolution and loss of 47.5% of initial Fe(III) (oxyhydr)oxides and release of associated OC in early summer when conditions are wetter and more reduced, and new formation of Fe(III) minerals (34.7% gain in comparison to initial Fe) in the late summer under more dry and oxic conditions which again sequestered Fe-bound organic carbon. Our data suggests that the so-called rusty carbon sink is seasonally dynamic in partially-thawed permafrost peatlands, thus likely either promoting or suppressing carbon mineralization and leading to seasonal changes in GHG emissions.

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