Effects of Severe Defoliation on the Long-Term Resistance to Insect Attack and on Leaf Chemistry in Six Woody Species of the Southern African Savanna

1991 ◽  
Vol 137 (1) ◽  
pp. 50-63 ◽  
Author(s):  
John P. Bryant ◽  
Ignas Heitkonig ◽  
Peggy Kuropat ◽  
Norman Owen-Smith
Keyword(s):  
Woody Species ◽  
Leaf Chemistry ◽  
African Savanna ◽  
Insect Attack

scholarly journals The National Tree Seed Centre Celebrates 40 Years

2007 ◽  
Vol 83 (5) ◽  
pp. 719-722
Author(s):  
J D Simpson ◽  
B S.P. Wang
Keyword(s):  
Seed Storage ◽  
Ex Situ ◽  
Future Research ◽  
Gene Conservation ◽  
Forest Land ◽  
Seed Physiology ◽  
Technology Research Group ◽  
Insect Attack ◽  
Tree Seed

The National Tree Seed Centre has been providing seed of known origin and quality for research for 40 years. Seed is also stored for long-term gene conservation purposes to provide a source of germplasm for future research and restoration. This is particularly important for species facing such threats as insect attack, disease, climate change, or conversion of forest land to non-forest uses. The Centre's inventory focuses on native tree and shrub species, striving to store samples from throughout their ranges. Over 26 000 seed samples have been sent to researchers in 65 countries, 70% of these samples being distributed within Canada. Seed research has always been a component of the Seed Centre's program. One notable accomplishment is the development of the Petawawa Germination Box. The Seed Centre participates in and contributes to activities of the Association of Official Seed Analysts, the International Seed Testing Association, and the IUFRO Seed Physiology and Technology Research Group. Key words: collection, dormancy, ex situ gene conservation, germination, research, seed, storage

scholarly journals Slow-release fertilizers and possibilities of their utilizing in nursery

2004 ◽  
Vol 52 (2) ◽  
pp. 155-164
Author(s):  
Petr Salaš
Keyword(s):  
Slow Release ◽  
Ornamental Plants ◽  
Woody Species ◽  
Soil Surface ◽  
Berberis Thunbergii ◽  
Slow Release Fertilizers ◽  
Picea Omorika ◽  
One Year ◽  
Two Stages

Reserve, slow-release fertilizers (SRF) enable to simplify the whole system of plant nutrition and fertilisation. Tabletted fertilizers of the Silvamix series represent a prospective product of Czech provenience. At our university, these fertilizers have been tested and used since the year 1991. Ornamental woody species grown in containers were investigated in two stages. Experiments with ornamental plants were established using one-year-old cuttings and seedlings of the following deciduous and evergreen woody species:Cotoneaster dammeri Skogholm,Berberis thunbergii,Potentilla fruticosa Snowflake,Ligustrum vulgare AtrovirensandPicea omorika. After planting into containers, fertilizers in the dose of 1 tablet (i.e. 10 g) per litre of substrate were applied either to roots level or on the soil surface in the container. Silvamix in the dose of 5 g.l-1was used as the tested fertilizer in the second stage. It was applied during the planting in the form of tablets and/or a powder. Control plants were fertilized in the course of growing season using a common agricultural fertilizer Cererit Z. The annual plants increments were measured. These experiments demonstrated a long-term optimum effect of this product on woody species and an equal quality and efficiency of its tabletted and powdered forms.

scholarly journals Effects of root exudates of woody species on the soil anti-erodibility in the rhizosphere in a karst region, China

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3029 ◽  
Author(s):  
Zhen Hong Wang ◽  
Hong Fang ◽  
Mouhui Chen
Keyword(s):  
Organic Matter ◽  
Root Exudates ◽  
Woody Species ◽  
Interspecific Variation ◽  
Root Density ◽  
Gas Chromatography Mass Spectrometry ◽  
Karst Region ◽  
Soil Stability ◽  
Interspecific Differences

IntroductionRhizospheres, the most active interfaces between plants and soils, play a central role in the long-term maintenance of the biosphere. The anti-erodibility of soils (AES) regulated by the root exudates is crucial to the soil stability in the rhizospheres. However, scientists still debate (1) the key organic matter of the root exudates affecting the AES and (2) the interspecific variation of these root exudates.MethodsWe used an incubation of soils to test the effects of the root exudates from eight woody plant species on the change in soil aggregation and identified the organic matter in these root exudates with gas chromatography-mass spectrometry (GC-MS) and biochemical methods. Furthermore, the relationships between the organic matter in the exudates and the AES in the rhizospheres of 34 additional tree species were analyzed.ResultsThe water-stable aggregates of the soils incubated with the root exudates increased by 15%–50% on average compared with control samples. The interspecific differences were significant. The root exudates included hundreds of specific organic matter types; hydrocarbon, total sugar, total amino acids, and phenolic compounds were crucial to the AES. These organic matter types could explain approximately 20–75% of the variation in the total effect of the root exudates on the AES, which was quantified based on the aggregate status, degree of aggregation, dispersion ratio, and dispersion coefficient.DiscussionThe effects of the root exudates on the AES and the interspecific variation are as important as that of root density, litters, and vegetation covers. Many studies explored the effects of root density, litters, vegetation covers, and vegetation types on the AES, but little attention has been paid to the effects of the root exudates on the AES. Different plants secrete different relative contents of organic matter resulting in the variation of the effect of the root exudates on the AES. Our study quantified the causal relationships between the root exudates and the AES using modeling experiments in laboratory and field observations and indicated the interspecific variation of the AES and organic matter of the root exudates.ConclusionsMore organic compounds of the exudates related to the AES were recognized in this study. These results enhance the understanding of the soil stability at a slope and can be applied to ecosystem restoration.

scholarly journals Water availability, bedrock, disturbance by herbivores, and climate determine plant diversity in South-African savanna

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Martin Hejda ◽  
Jan Čuda ◽  
Klára Pyšková ◽  
Guin Zambatis ◽  
Llewellyn C. Foxcroft ◽  
...  
Keyword(s):  
Species Richness ◽  
South African ◽  
Plant Diversity ◽  
Water Availability ◽  
Large Scale ◽  
Woody Species ◽  
Plant Species Richness ◽  
African Savanna ◽  
Shrub Species ◽  
Large Herbivores

AbstractTo identify factors that drive plant species richness in South-African savanna and explore their relative importance, we sampled plant communities across habitats differing in water availability, disturbance, and bedrock, using the Kruger National Park as a model system. We made plant inventories in 60 plots of 50 × 50 m, located in three distinct habitats: (i) at perennial rivers, (ii) at seasonal rivers with water available only during the rainy season, and (iii) on crests, at least ~ 5 km away from any water source. We predicted that large herbivores would utilise seasonal rivers’ habitats less intensely than those along perennial rivers where water is available throughout the year, including dry periods. Plots on granite harboured more herbaceous and shrub species than plots on basalt. The dry crests were poorer in herb species than both seasonal and perennial rivers. Seasonal rivers harboured the highest numbers of shrub species, in accordance with the prediction of the highest species richness at relatively low levels of disturbance and low stress from the lack of water. The crests, exposed to relatively low pressure from grazing but stressed by the lack of water, are important from the conservation perspective because they harbour typical, sometimes rare savanna species, and so are seasonal rivers whose shrub richness is stimulated and maintained by the combination of moderate disturbance imposed by herbivores and position in the middle of the water availability gradient. To capture the complexity of determinants of species richness in KNP, we complemented the analysis of the above local factors by exploring large-scale factors related to climate, vegetation productivity, the character of dominant vegetation, and landscape features. The strongest factor was temperature; areas with the highest temperatures reveal lower species richness. Our results also suggest that Colophospermum mopane, a dominant woody species in the north of KNP is not the ultimate cause of the lower plant diversity in this part of the park.

Impact of long-term experimental water level drawdown on vegetation and carbon gas dynamics of boreal mire ecosystems

2020 ◽  
Author(s):  
Eeva-Stiina Tuittila ◽  
Aino Korrensalo ◽  
Anna Laine ◽  
Nicola Kokkonen ◽  
Lauri Mehtätalo ◽  
...  
Keyword(s):  
Water Level ◽  
Gas Dynamics ◽  
Experimental Studies ◽  
Net Ecosystem Exchange ◽  
Woody Species ◽  
Long Term Results ◽  
Moss Species ◽  
Poor Fen ◽  
The Impact

<p>Recent paleoecological studies have demonstrated an ongoing drying trend in temperate and boreal peatlands in Europe and in Canada. This drying is likely to alter vegetation and carbon gas exchange with atmosphere. However, to revel the expected change in carbon gas dynamics associated with decrease in water level experimental studies and long-term monitoring are needed. In here we present results from long term experiment in Finland where the impact of water level drawdown (WLD) of ~10 cm on three different peatland sites, two fens and a bog, has been studied since year 2000.</p><p> </p><p>Response to WLD differed between the three ecosystem types. In the nutrient rich fen WLD initiated rapid directional succession from sedge dominated system to the dominance of woody species. In the poor fen changes were less drastic: Initially WLD benefitted dwarf scrubs already present at the site, later they were overtaken by pines.  Sedges as a group hold their position but Carex species were replaced by Eriophorum. Similarly to sedges, in the moss layer proportions of different Sphagnum moss species changed. Bog vegetation was more stable than fen vegetation.</p><p> </p><p>In all the ecosystems methane emissions decreased directly after WLD. In contrast, the response of CO2 dynamics was more complex. While long term net ecosystem exchange decreased to lower level than in controls in all studied ecosystems, the response of photosynthesis and respiration differed between the three ecosystems and between short term and long term. Results show how the response of peatlands to climate change is diverse and emphasize the need to understand what factors regulate the stability and resilience of peatland functioning.</p>

Exploring seed longevity of UK native trees: implications for ex situ conservation

2020 ◽  
Vol 30 (2) ◽  
pp. 101-111
Author(s):  
Rachael M. Davies ◽  
Alice R. Hudson ◽  
John B. Dickie ◽  
Charlotte Cook ◽  
Tom O'Hara ◽  
...  
Keyword(s):  
Seed Bank ◽  
Ageing Time ◽  
Seed Storage ◽  
Woody Species ◽  
Ex Situ ◽  
Accelerated Ageing ◽  
Actual Performance ◽  
Long Term Storage ◽  
Multiple Samples

AbstractUK trees require increased conservation efforts due to sparse and fragmented populations. Ex situ conservation, including seed banking, can be used to better manage these issues. We conducted accelerated ageing tests on seeds of 22 UK native woody species, in order to assess their likely longevity and optimize their conservation in a seed bank. Germination at four ageing time points was determined to construct survival curves, and it was concluded that multiple samples within a species showed comparable responses for most species tested, except for Fraxinus excelsior. Of all species studied, one could be classified as very short-lived, four as short-lived and 17 as medium, with none exceeding the medium category. The most important finding of this manuscript is that although some taxonomic trends were observed, the results indicate the need for caution when making broad conclusions on potential seed storage life at a species, genus or family level. Longevity predictions were compared to actual performance of older collections held in long-term storage at the Millennium Seed Bank, Kew. Although most collections remain high in viability in storage after more than 20 years, for short-lived species at least, there is some indication that accelerated ageing predicts longevity in seed bank conditions. For species with reduced potential longevity, such as Fagus sylvatica and Ulmus glabra, additional storage options are recommended for long-term gene banking.

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