Seed dynamics of two fire-dependent Geranium species in the boreal forest of southeastern Sweden

Botany ◽  
2012 ◽  
Vol 90 (9) ◽  
pp. 794-805 ◽  
Author(s):  
Lotta Risberg ◽  
Anders Granström
Keyword(s):  
Seed Bank ◽  
Fire Suppression ◽  
Mineral Soil ◽  
Severe Drought ◽  
Humus Layer ◽  
Repeated Sampling ◽  
Viable Seeds ◽  
A Site ◽  
Ballistic Dispersal ◽  
Seed Dynamics

We analyzed critical life-history variables for two rare fire-dependent annual Geranium species in southern Sweden, which are today threatened because of effective fire suppression. At recently burned sites with abundant recruitment, seedlings occurred only where the humus layer had been completely removed by smoldering fire. Emergence depths ranged 1–6 cm in the mineral soil. Soil sampling at four sites revealed that in unburned soil Geranium seeds were located only in the mineral soil. Surprisingly, residual seeds were still present where fire had burned away the humus layer. An experiment showed that both species deposit seeds relatively evenly within a radius of 5–6 m, through ballistic dispersal. Repeated sampling in the field over a 2-year period after seed dispersal at one site indicated a low rate of seed depletion, corroborated by an indoor incubation of seeds. Our results show that successful management of these species depend on deep-burning prescribed fire, which can only result after severe drought. On the other hand, the seed bank is extremely long-lived, as viable seeds were present at a site last burned 200 years ago. This well-protected seed bank will likely buffer against both ill-timed fires and occasional failure in the recruiting seedling populations.

Soil acidity in 1970 and 1989 in a coniferous forest in southwest Finland

1998 ◽  
Vol 78 (3) ◽  
pp. 477-479 ◽  
Author(s):  
C. J. Westman ◽  
S. Jauhiainen
Keyword(s):  
Key Words ◽  
Soil Ph ◽  
Soil Acidity ◽  
Mineral Soil ◽  
Coniferous Forest ◽  
Soil Layers ◽  
Water Suspension ◽  
Ph Values ◽  
Humus Layer ◽  
Repeated Sampling

Forest soil pH in southwest Finland was measured with identical sampling and analysing methods in 1970 and 1989. The acidity of the organic humus layer increased significantly as pH values measured on water and on salt suspensions decreased between the two sampling dates. For the mineral soil layers, no unambiguous trend was found. pH values measured on salt suspension tended to be unchanged or lower, while pH on water suspension in some soil layers were even higher in 1989 than in 1970. Key words: pH, repeated sampling

scholarly journals Spatial and temporal dynamics of two cacti seed banks in a xerophytic shrubland in Mexico City

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Itzel Guzmán-Vázquez ◽  
Silvia Castillo-Argüero ◽  
Alma Orozco-Segovia ◽  
Margarita Collazo-Ortega
Keyword(s):  
Mexico City ◽  
Seed Bank ◽  
Temporal Dynamics ◽  
Seed Banks ◽  
Spatial And Temporal Dynamics ◽  
Seed Bank Dynamics ◽  
Viable Seeds ◽  
Seed Dynamics ◽  
Secondary Seed Dispersal ◽  
Inputs And Outputs

Background: Soil and aerial seed banks directly affect recruitment in plant populations. Soil banks result as the balance between seed inputs and outputs. Seed bank dynamics vary by species and environmental conditions. Few records on cacti seed banks are available. Questions: What types of seed banks do two cacti genera form in a lava-field reserve? Does seasonality influence the seed bank dynamics? Are inputs and outputs associated to the microenvironment? Studied species: Opuntia tomentosa, O. lassiacantha, Mammillaria haageana subsp. san-angelensis, M. magnimamma. Study site and dates: Xerophytic shrubland in the “Reserva Ecológica del Pedregal de San Ángel” in Mexico City. 2016 to 2018. Methods: We collected soil samples from four microenvironments during the rainy and the dry seasons, searched for seeds and tested their viability. We compared the number of inputs, outputs and viable seed by microenvironment and season. For M. magnimamma, each month we registered fruit maturation and searched for seeds remaining between tubercles. Results: Opuntia seed bank inputs occurred in all microenvironments and in both seasons. Rain favored inputs in hollows by secondary seed dispersal. We registered a large number of outputs caused by germination, granivory and loss of viability. Opuntia seed bank was developed in headland, plain and slope. No Mammillaria seed inputs were found, neither an aerial bank in M. magnimamma. Conclusion: Opuntia seed banks were restricted to microenvironments that provided “safe sites” which stored viable seeds. Mammillaria seed dynamics may hinders recruitment for their populations.

The Interface Between Economics and Nutrient Cycling in Amazon Land Development

2001 ◽  
Author(s):  
Carl F. Jordan
Keyword(s):  
Crop Production ◽  
Wood Fiber ◽  
Mineral Soil ◽  
Land Development ◽  
Low Fertility ◽  
Small Scale ◽  
Terra Firme ◽  
Humus Layer ◽  
Almost All ◽  
A Site

Most of the terra firme soils in the Amazon are highly weathered, highly leached, have low capacity for retaining nutrients against the continual leaching and weathering of the tropical climate, and are classified as Oxisols and Ultisols, soil types with extremely low fertility (see Cuevas, this volume). The naturally occurring forests of the region maintain a high production of wood and leaves through very efficient recycling of nutrients from decomposing litter to roots in a root-humus layer on top of the mineral soil or near its surface. The decomposing litter is important not only as a source of nutrients, but as a source of organic acids which prevent phosphorus fixation in the iron- and aluminium-rich soils of the Amazon. When forests on Amazonian terra firme soils are cut and burned, and the soils used for agriculture, litter, and humus are rapidly oxidized and destroyed. As a result, the potassium remaining from the original forest is quickly leached, the nitrogen is volatilized, and the phosphorus is immobilized in the mineral soil. This is one of the most important reasons that crop production can be carried out for only a few years under shifting cultivation. It is not just small scale agriculture that is limited by the low fertility of Amazonian soils. In the past, almost all types of development that destroy the nutrient conserving mechanisms of the forest have suffered financially. Two examples are given here to illustrate. In 1967, one of the largest conversions of tropical forest to pulp plantation began near the junction of the Jarí and Amazon rivers, in the state of Pará, Brazil (Time, 1976). The “Jarí” project was initiated and financed by Daniel K. Ludwig, one of the world’s richest men, and owner of numerous international corporations. Ludwig had anticipated a global shortage of wood fiber for pulp, and to meet this shortage, he and his advisors selected a site that they believed had high potential for pulp production (Time 1979, Kinkead 1981). By 1981, the total investment in the 12,000 km2 tract of land was approximately $1 billion (Kinkead 1981). Ludwig’s advisors recommended melina (Gmelina arborea) as the best species to plant.

Seed bank persistence and germination of chinee apple (Ziziphus mauritiana Lam.)

2016 ◽  
Vol 38 (1) ◽  
pp. 17 ◽  
Author(s):  
Faiz F. Bebawi ◽  
Shane D. Campbell ◽  
Robert J. Mayer
Keyword(s):  
Seed Bank ◽  
Ziziphus Mauritiana ◽  
Burial Depth ◽  
Temperature Regimes ◽  
Wide Range ◽  
Below Ground ◽  
Burial Duration ◽  
Viable Seeds ◽  
Tropical Woodlands ◽  
Seed Dynamics

Chinee apple (Ziziphus mauritiana Lam.) is a thorny tree that is invading tropical woodlands of northern Australia. The present study reports three experiments related to the seed dynamics of chinee apple. Experiment 1 and 2 investigated persistence of seed lots under different soil types (clay and river loam), levels of pasture cover (present or absent) and burial depths (0, 2.5, 10 and 20 cm). Experiment 3 determined the germination response of chinee apple seeds to a range of alternating day/night temperatures (11/6°C up to 52/40°C). In the longevity experiments (Expts 1 and 2), burial depth, soil type and burial duration significantly affected viability. Burial depth had the greatest influence, with surface located seeds generally persisting for longer than those buried below ground. Even so, no viable seeds remained after 18 and 24 months in the first and second experiment, respectively. In Expt 3 seeds of chinee apple germinated under a wide range of alternating day/night temperatures ranging from 16/12°C to 47 /36°C. Optimal germination (77%) occurred at 33/27°C and no seeds germinated at either of the lowest (11/6°C) or highest (52/40°C) temperature regimes tested. These findings indicated that chinee apple has the potential to expand its current distribution to cooler areas of Australia. Control practices need to be undertaken for at least two years to exhaust the seed bank.

Direct seeding of PinusSylvestris using microsite preparation and invigorated seed lots of different quality: 2-year results

1994 ◽  
Vol 24 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Hans Winsa ◽  
Urban Bergsten
Keyword(s):  
Seed Quality ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Direct Seeding ◽  
Growing Seasons ◽  
Humus Layer ◽  
Negative Effect ◽  
Mean Germination Time ◽  
Better Than

Direct seeding of Pinussylvestris L. is a regeneration method, with potential for development considering scarification, microsite preparation, seed invigoration, and seed quality. Three seed lots of different quality concerning seed weight, germination percent, and mean germination time were used on two sites in northern Sweden. Microsite preparation, 2 cm deep pyramidal indentations, of the mineral soil improved seedling emergence on the two sites by 48 and 62%, respectively, compared with seeding without preparation other than removal of the humus layer. Microsite preparation in combination with invigorated seed, i.e., seed incubated at 30% moisture content for 7 days at 15 °C, resulted in seedling emergence of about 85% for the highest and about 50% for the lowest seed quality at both sites. Noninvigorated seed, seeded without microsite preparation, reached about 55% for the highest and 22% at one and 43% at the other for the lowest seed quality. Without microsite preparation there was no, or a negative, effect of seed invigoration on seedling emergence. Seedling survival after the first winter improved significantly with better seed quality. Survival averaged 92 and 72% at the two sites, with frost heaving causing most mortality. Seedlings from invigorated and redried seed survived better than seedlings from untreated seed. Seedlings from the best seed quality had higher values in seedling height, about 35%, shoot length, about 60%, and needle length, about 30%, after two growing seasons than seedlings from lower seed qualities. Invigoration and microsite preparation had no effect on measured growth characteristics.

scholarly journals Effects of Brash Removal After Clear Felling on Soil and Soil-Solution Chemistry and Field-Layer Biomass in an Experimental Nitrogen Gradient

2001 ◽  
Vol 1 ◽  
pp. 457-466 ◽  
Author(s):  
E. Ring ◽  
L. Hogbom ◽  
H.A. Nohrstedt
Keyword(s):  
Soil Solution ◽  
Alternative Energy ◽  
Mineral Soil ◽  
Solution Chemistry ◽  
Soil Solution Chemistry ◽  
Inorganic N ◽  
Field Layer ◽  
Humus Layer ◽  
Irregular Pattern ◽  
N Dose

Biofuels, such as brash from forest fellings, have been proposed as an alternative energy source. Brash removal may affect the sustainability of forest production, e.g., through a change in the availability of cations and N in the soil. We report initial effects of brash removal on inorganic N content in humus and mineral soil, soil-solution chemistry, and field-layer biomass after clear felling an N-fertilisation experiment in central Sweden. The experiment comprised six different fertiliser levels, ranging from 0 to 600 kg N ha�1. Urea was given every 5th year during 1967 to 1982 to replicated plots, giving total doses of 0 to 2400 kg N ha�1. Clear felling took place in 1995, 13 years after the last fertilisation. The removal of brash decreased the NO3� content in the humus layer after clear felling. A decrease in the NO3� concentration of the soil solution was indicated during most of the study period as well. No effect of the previous N fertilisation was found in the humus layer, but in the mineral soil there was an increase in NO3� content for the highest N dose after clear felling (p = 0.06). The soil-solution chemistry and the field-layer biomass showed an irregular pattern with no consistent effects of brash removal or previous fertilisation.

Differential responses by sympatric macropodids to severe drought.

2004 ◽  
Vol 26 (2) ◽  
pp. 185
Author(s):  
PE Hornsby ◽  
EY Corlett
Keyword(s):  
South Australia ◽  
Severe Drought ◽  
The North ◽  
Flinders Ranges ◽  
Drought Conditions ◽  
Differential Responses ◽  
A Site ◽  
Significant Mortality

Responses to severe drought by two sympatric macropodids, the yellow-footed rock-wallaby (Petrogale xanthopus) and the euro (Macropus robustus erubescens) were examined at a site in the North Flinders Ranges of South Australia. The results indicate that the two species respond differentially to drought conditions. It was observed that small fluctuations occurred in the P. xanthopus population. In contrast, M. r. erubescens evidenced significant mortality, especially among larger animals.

scholarly journals 15N natural abundances in two podsol soils of two spruce forests differing in their atmospheric N deposition conditions

2011 ◽  
Vol 51 (No. 9) ◽  
pp. 416-422 ◽  
Author(s):  
S.P. Sah
Keyword(s):  
Mineral Soil ◽  
Vertical Gradient ◽  
N Deposition ◽  
Climatic Conditions ◽  
Organic Layer ◽  
Atmospheric N Deposition ◽  
Spruce Forests ◽  
Humus Layer ◽  
N Enrichment ◽  
Deposition Conditions

This study aims to investigate the changes in isotope ratios in foliage and soils of the two spruce forests [Picea abies (L.) Karst.] differing greatly in their atmospheric N deposition and climatic conditions. As expected, both N concentrations and <sup>15</sup>N values in both needles and litter were found to be significantly higher in the Solling stand (N-saturated) compared to the Hyytial&auml; stand (N-poor). For the N-limited site (Hyytial&auml; plot), a typical vertical gradient of the soil <sup>15</sup>N-enrichment (both in organic and mineral soil) was observed. The N-saturated site (Solling) differs from the N-limited site (Hyytial&auml;) with respect to the <sup>15</sup>N abundance trend in organic layer. In the upper organic layer up to O-f horizon, i.e. mor layer (0&ndash;3.5 cm depth) of Solling plot, there is almost a trend of slight soil <sup>15</sup>N-depletion with increasing depth, and then there is a <sup>15</sup>N-enrichment from O-h horizon (humus layer) of organic layer to mineral soil horizons. This is explained by the presence of prominent NO<sub>3</sub><sup>&ndash;</sup> leaching at this plot

scholarly journals Predicting rut depth induced by an 8-wheeled forwarder in fine-grained boreal forest soils

2020 ◽  
Vol 77 (2) ◽  
Author(s):  
Jori Uusitalo ◽  
Jari Ala-Ilomäki ◽  
Harri Lindeman ◽  
Jenny Toivio ◽  
Matti Siren
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Bulk Density ◽  
Soil Moisture Content ◽  
Mineral Soil ◽  
Coarse Grained ◽  
Forest Operations ◽  
Fine Grained ◽  
Humus Layer ◽  
Cumulative Mass

Abstract Key message Rut depth in fine-grained boreal soils induced by an 8-wheeled forwarder is best predicted with soil moisture content, cumulative mass of machine passes, bulk density and thickness of the humus layer. Context Forest machines are today very heavy and will cause serious damage to soil and prevent future growth if forest operations are carried out at the wrong time of the year. Forest operations performed during the wettest season should therefore be directed at coarse-grained soils that are not as prone to soil damage. Aims The study aimed at investigating the significance of the most important soil characteristics on rutting and developing models that can be utilized in predicting rutting prior to forest operations. Methods A set of wheeling tests on two fine-grained mineral soil stands in Southern Finland were performed. The wheeling experiments were conducted in three different periods of autumn in order to get the largest possible variation in moisture content. The test drives were carried out with an 8-wheeled forwarder. Results Soil moisture content is the most important factor affecting rut depth. Rut depth of an 8-wheeled forwarder in fine-grained boreal soil is best predicted with soil moisture content, cumulative mass of machine passes, bulk density and thickness of the humus layer. Conclusion The results emphasize the importance of moisture content on the risk of rutting in fine-grained mineral soils, especially with high moisture content values when soil saturation reaches 80%. The results indicate that it is of high importance that soil type and soil wetness can be predicted prior to forest operations.

Viable seed populations by soil depth and potential site recolonization after disturbance

1977 ◽  
Vol 55 (18) ◽  
pp. 2408-2412 ◽  
Author(s):  
Janice M. Moore ◽  
Ross W. Wein
Keyword(s):  
Soil Depth ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Organic Soil ◽  
Viable Seed ◽  
Soil Layers ◽  
Forest Experiment Station ◽  
Viable Seeds ◽  
Study Sites ◽  
Germination Experiment

Seedling emergence from organic and mineral soil layers was measured for nine study sites at the Acadia Forest Experiment Station near Fredericton, New Brunswick. The number of viable seeds showed a decrease from deciduous-dominated forest, to conifer-dominated forest, to organic soil study sites. Viable seed number varied from 3400/m2 for a deciduous-dominated forest study site to zero for a bog study site. Most seeds germinated from the upper organic soil layers of all study sites and were predominantly Rubus strigosus Michx. After the germination experiment, ungerminated seeds, which showed no viability by the tetrazolium test, were separated from the soil. These seeds were almost entirely Betula spp. and seed numbers were as high as 4200–9400/m2 for a deciduous-dominated forest. The applicability of the results to differing types of postdisturbance revegetation is discussed.

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