The savanna tree Acacia polyacantha facilitates the establishment of riparian forests in Serengeti National Park, Tanzania

2009 ◽  
Vol 25 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Gregory J. Sharam ◽  
A. R. E. Sinclair ◽  
Roy Turkington ◽  
Aerin L. Jacob
Keyword(s):  
Tree Species ◽  
Natural Regeneration ◽  
National Park ◽  
Seedling Survival ◽  
Forest Tree ◽  
Riparian Forests ◽  
Forest Trees ◽  
Grass Cover ◽  
Serengeti National Park ◽  
Acacia Polyacantha

Abstract:Forests are being converted to grasslands and croplands across Africa and natural regeneration of forests is typically poor. In Serengeti National Park, Tanzania, the savanna tree species Acacia polyacantha established in riparian grasslands and forest trees subsequently established within these stands. We examined the conditions for establishment of: (1) A. polyacantha and (2) riparian (non-Acacia) forests. Fire was excluded from three grassland areas for 5 y allowing A. polyacantha to establish during 1999 when dry-season rainfall was high. The seedlings of forest tree species did not establish in grasslands, but were found in large A. polyacantha stands (> 0.3 ha) with reduced grass cover (< 10%), higher cover of herbs (> 80%) and thorny shrubs (> 90%). Seeding survival was high in large stands (0.87 y−1), but declined in artificial canopy gaps due to the ingrowth of grasses (0.21 y−1) and subsequent fires (0.07 y−1). Shrub removal also reduced seedling survival (0.46 y−1) due to browsing by antelope. We propose that: (1) A. polyacantha establishes in pulses perhaps as infrequently as twice per century, and (2) riparian forests in Serengeti have established via facilitation under larger stands where shade excludes grass, and therefore fires and thorny shrubs exclude browsers.

scholarly journals Fire suppression and seed dispersal play critical roles in the establishment of tropical forest tree species in southeastern Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tomohiro Fujita
Keyword(s):  
Seed Dispersal ◽  
Tree Species ◽  
Seedling Survival ◽  
Fire Suppression ◽  
Forest Tree ◽  
Tree Seedlings ◽  
Seedling Mortality ◽  
Forest Tree Species ◽  
Seed Deposition ◽  
Syzygium Guineense

AbstractThis study examined the mechanisms of facilitation and importance of seed dispersal during establishment of forest tree species in an Afrotropical woodland. Seedling survival of Syzygium guineense ssp. afromontanum was monitored for 2.5 years at four different microsites in savannah woodland in Malawi (southeastern Africa) under Ficus natalensis (a potential nurse plant), Brachystegia floribunda (a woodland tree), Uapaca kirkiana (a woodland tree), and at a treeless site. The number of naturally established forest tree seedlings in the woodland was also counted. Additionally, S. guineense ssp. afromontanum seed deposition was monitored at the four microsites. Insect damage (9% of the total cause of mortality) and trampling by ungulates (1%) had limited impact on seedling survival in this area. Fire (43%) was found to be the most important cause of seedling mortality and fire induced mortality was especially high under U. kirkiana (74%) and at treeless site (51%). The rate was comparatively low under F. natalensis (4%) and B. floribunda (23%), where fire is thought to be inhibited due to the lack of light-demanding C4 grasses. Consequently, seedling survival under F. natalensis and B. floribunda was higher compared with the other two microsites. The seedling survival rate was similar under F. natalensis (57%) and B. floribunda (59%). However, only a few S. guineense ssp. afromontanum seedlings naturally established under B. floribunda (25/285) whereas many seedlings established under F. natalensis (146/285). These findings indicate that the facilitative mechanism of fire suppression is not the only factor affecting establishment. The seed deposition investigation revealed that most of the seeds (85%) were deposited under F. natalensis. As such, these findings suggest that in addition to fire suppression, dispersal limitations also play a role in forest-savannah dynamics in this region, especially at the community level.

scholarly journals Factors Influencing the Natural Forest Regeneration at Khadimnagar National Park, Bangladesh

2021 ◽  
Vol 11 (1) ◽  
pp. 73-83
Author(s):  
MAHEDI HASAN LIMON ◽  
SAIDA HOSSAIN ARA ◽  
MOHAMMAD GOLAM KIBRIA
Keyword(s):  
Species Richness ◽  
Bulk Density ◽  
Total Variation ◽  
Soil Ph ◽  
Tree Species ◽  
Natural Regeneration ◽  
National Park ◽  
Canopy Openness ◽  
Site Factors ◽  
Tree Species Richness

Natural regeneration is an indicator of a healthy forest, hence, understanding the influence of site factors on natural regeneration is a significant concern for ecologists. This work aimed to assess the impact of site factors on natural tree regeneration at Khadimnagar National Park (KNP). Biotic factors (tree density, tree species richness, and basal area), physical factors (elevation, canopy openness), and soil properties (bulk density, moisture content, soil pH, organic matter, sand, silt, and clay) data were investigated from 71 sample plots to examine their effects on natural regeneration density and richness in KNP. Stepwise multiple linear regression analysis was done to predict both regeneration density and regeneration richness. The results showed that soil pH (p<0.001), canopy openness (p<0.001), tree species richness (p<0.01), and bulk density (p<0.01) had a significant effect on regeneration density, explaining 42% of the total variation. Regeneration richness was driven by four factors: tree species richness (p<0.01), soil pH (p<0.001), elevation (p<0.01), and canopy openness (p<0.01) with a model that explained 60% of the total variation. This study observed that soil pH, tree species richness, and canopy openness are the main controlling factors that influenced both the density and richness of regenerating species in KNP. Therefore, these findings have implications for natural resource management, especially in selecting suitable silvicultural systems in a tropical forest under protected area management where enhanced tree cover and conservation of biodiversity are needed.

scholarly journals Fate of forest tree biotechnology facing climate change

2021 ◽  
Vol 70 (1) ◽  
pp. 117-136
Author(s):  
M. R. Ahuja
Keyword(s):  
Climate Change ◽  
Somatic Embryogenesis ◽  
Loblolly Pine ◽  
Tree Species ◽  
Forest Tree ◽  
Future Climate Change ◽  
Forest Trees ◽  
Forest Tree Species ◽  
Tree Biotechnology

Abstract Woody plants have been cultured in vitro since the 1930s. After that time much progress has been made in the culture of tissues, organs, cells, and protoplasts in tree species. Tree biotechnology has been making strides in clonal propagation by organogenesis and somatic embryogenesis. These regeneration studies have paved the way for gene transfer in forest trees. Transgenics from a number of forest tree species carrying a variety of recombinant genes that code for herbicide tolerance, pest resistance, lignin modification, increased woody bio-mass, and flowering control have been produced by Agrobacterium-mediated and biolistic methods, and some of them are undergoing confined field trials. Although relatively stable transgenic clones have been produced by genetic transformation in trees using organogenesis or somatic embryogenesis, there were also unintended unstable genetic events. In order to overcome the problems of randomness of transgene integration and instability reported in Agrobacterium-mediated or biolistically transformed plants, site-specific transgene insertion strategies involving clustered regularly interspaced short palindromic repeats (CRISPR-Cas9) platform offer prospects for precise genome editing in plants. Nevertheless, it is important to monitor phenotypic and genetic stability of clonal material, not just under greenhouse conditions, but also under natural field conditions. Genetically modified poplars have been commercialized in China, and eucalypts and loblolly pine are expected to be released for commercial deployment in USA. Clonal forestry and transgenic forestry have to cope with rapid global climate changes in the future. Climate change is impacting species distributions and is a significant threat to biodiversity. Therefore, it is important to deploy Strategies that will assist the survival and evolution of forest tree species facing rapid climate change. Assisted migration (managed relocation) and biotechnological approaches offer prospects for adaptation of forest trees to climate change.

Occurrence of Polyembryony in Juniperus Polycarpos C. Koch.

2014 ◽  
Vol 37 (2) ◽  
pp. 161-164
Author(s):  
Pitambar Negi
Keyword(s):  
Seed Germination ◽  
Seed Dormancy ◽  
Tree Species ◽  
Natural Regeneration ◽  
Forest Tree ◽  
Rare Occurrence ◽  
Forest Tree Species ◽  
Single Seed ◽  
Germination Behaviour ◽  
Juniperus Polycarpos

The natural regeneration in Juniperus polycarpos is quite low due to seed dormancy. While studying the seed germination behaviour of Juniperus polycarpos, a twin seedling was found germinated from a single seed which has been reported. This is the first instance of occurrence of polyembryonic seedlings in Juniperus polycarpos which have been reported in this paper. The twin seedlings have been resulted due to the phenomenon of polyembryony which is of rare occurrence in this species, however, the production of twin seedlings has been reported earlier also in other forest tree species. The twin seedlings were found to be independent having separate taproots and cotyledons. The seedlings were later transplanted in a polybags filled with Soil: Sand: FYM (2:1:1 :) to observe the further growth of twin seedlings. After three months, it was noticed that both the twin seedlings shriveled and died where as normal seedlings continued to grow normally and produced all the essential features of a plant.

Role of Forest Tree Species in the Carbon Storage of the Kaptai National Park, Bangladesh

2021 ◽  
Vol 50 (2) ◽  
pp. 365-371
Author(s):  
Mohammed Mukhlesur Rahman ◽  
Syed Hafizur Rahman ◽  
Mohammed Al Amin
Keyword(s):  
Carbon Storage ◽  
Tree Species ◽  
National Park ◽  
Carbon Stock ◽  
Tectona Grandis ◽  
Forest Tree ◽  
Carbon Stocks ◽  
Acacia Auriculiformis ◽  
Gmelina Arborea

The study was conducted to estimate the biomass and carbon stock in the dominant tree species of the Kaptai National Park of Bangladesh. A total of 77 tracks and 308 plots were selected and all trees in each plot were measured to estimate the biomass following allometric equations. There were planted stand of Acacia auriculiformis, Dipterocarpus turbinatus, Gmelina arborea, Lagerstroemia speciosa, Swietenia macrophylla and Tectona grandis. Biomass and carbon stocks of these corresponding tree species were 35.03, 73.86, 23.52, 30.16, 44.49, and 42.67 mg/ha. The highest carbon stock per tree was in D. turbinatus (372.19 kg C/tree), followed by S. macrophylla (226.49 kg C/tree), T. grandis (215.06 kg C/tree), A. auriculiformis (176.56 kg C/tree), L. speciosa (151.19 kg C/tree) and G. arborea (118.54 kg C/tree), respectively. The findings of the study will be helpful for the estimation of carbon stocks in the forests of Bangladesh. Bangladesh J. Bot. 50(2): 365-371, 2021 (June)

scholarly journals Genetische Struktur von Waldbäumen im Alpenraum als Folge (post)glazialer Populationsgeschichte | Genetic structures of forest tree species in the range of the European Alps as a result of (post-)glacial population history

2010 ◽  
Vol 161 (6) ◽  
pp. 207-215 ◽  
Author(s):  
Felix Gugerli ◽  
Christoph Sperisen
Keyword(s):  
Tree Species ◽  
Forest Tree ◽  
Population History ◽  
Mountain Range ◽  
European Alps ◽  
Forest Trees ◽  
The Balkans ◽  
Forest Tree Species ◽  
The Alps ◽  
Genetic Structures

Fossil records (pollen, macroremains) and genetic structures based on molecular markers provide complementary data sets for elucidating the (post-)glacial histories of extant plant populations. Based on comparative studies using both data sources, this article focuses on the effects of postglacial recolonization on the genetic structures in common, widespread forest tree species in the Alpine range. We recall that at least at the continental level, the three large southern European peninsulas, Iberia, Italy and the Balkans, but also the Carpathians represented important refugial areas for many European tree species during the last glacial maximum. However, these refugia had a minimal impact on the recolonization of the Alpine range. In contrast, recent studies demonstrate that refugial areas in the proximity of the Alps, e.g. at their eastern and western ends, harbored prominent source populations of current occurrences of the dominant forest trees in the Alpine range. Furthermore, there is strong evidence that several species were able to maintain populations north of the Alps, such as in the Bohemian Massif. We advocate that the Alps did not necessarily represent a barrier to northward migration, since terrain for advancement from various refugia was available along the margins of this mountain range. Such migration patterns allowed diverged genetic lineages to meet, leading to increased genetic diversity in respective contact zones. This overview underlines how paleoecological and molecular genetic studies may complement each other to develop a more comprehensive vision of the postglacial history of forest trees in the Alpine range.

scholarly journals Fire Suppression as Well as Seed Dispersal Play Critical Role in the Establishment of Forest Tree Species in Tropical Woodland

2021 ◽  
Author(s):  
Tomohiro Fujita
Keyword(s):  
Seed Dispersal ◽  
Tree Species ◽  
Seedling Survival ◽  
Fire Suppression ◽  
Critical Role ◽  
Forest Tree ◽  
Forest Tree Species ◽  
Natural Establishment ◽  
Tropical Woodland ◽  
Syzygium Guineense

Abstract This study examined the mechanisms of facilitation and importance of seed dispersal during establishment of forest tree species in a tropical woodland. Seedling survival of Syzygium guineense ssp. afromontanum seedling (forest tree species) was monitored for 2.5 years in four different microsites in savannah-woodland in Malawi under Ficus natalensis (a potential nurse plant), Brachystegia floribunda (a woodland tree), and Uapaca kirkiana (a woodland tree), and in a treeless site. S. guineense ssp. afromontanum seed deposition was also monitored in the four sites, and the natural establishment of forest tree species was observed to confirm the importance of seed dispersal. Protection from fire was found to be the most important facilitation mechanism in this area, with a total fire-induced mortality rate of 43%. However, the rate was comparatively low under F. natalensis, where fire is thought to be inhibited due to the lack of light-demanding C4 grasses. B. floribunda also offered protection from fire, and seedling survival did not differ between these two microsites. However, only a few individual forest tree species naturally established under B. floribunda, indicating that the facilitative mechanism of fire suppression is not the only factor affecting establishment in this tropical woodland. A higher rate of seed dispersal was also observed under F. natalensis compared with the other three microsites, suggesting that dispersal processes are also critical for the establishment of forest tree species in woodland in this region.

scholarly journals Natural regeneration potential of Madhupur National Park, Bangladesh

2020 ◽  
Vol 49 (4) ◽  
pp. 989-996
Author(s):  
Md Rayhanur Rahman ◽  
MK Hossain ◽  
Md Akhter Hossain ◽  
Mohammad Emran Hasan
Keyword(s):  
Tree Species ◽  
Natural Regeneration ◽  
National Park ◽  
Alien Invasive Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Height Range ◽  
Shorea Robusta ◽  
Extensive Collection ◽  
Litsea Glutinosa

Natural regeneration is an essential tool to evaluate the overall health of a forest ecosystem. Natural regeneration of the tree species in Madhupur National Park showed 47 regenerating tree species among which Shorea robusta has maximum density (18,046 seedlings per ha) followed by Aporosa sp., whereas minimum density (19 seedling per ha) was recorded for Cassia nodosa, Litsea glutinosa, Grewia asiatica and Syzygium cumini, respectively. Relative density, relative frequency and relative abundance were estimated to assess the Importance Value Index (IVI) of the seedlings of different tree species. IVI of S. robusta was highest (66.25 out of 300) followed by Mallotus philippensis (27.33). G. asiatica, Derris robusta, and L. glutinosa showed the lowest IVI (0.93) among the regenerating tree species. Distribution of seedlings into different height classes showed that maximum number (31.4%) of seedlings in the height range of 50 - <100 cm. Among the recorded seedlings, Protium serratum showed maximum (11%) recruitment success. Alien invasive species, pineapple and banana based participatory agroforestry, frequent occurrence of fire, extensive collection of fuelwood and litter are the potential threats to the natural regeneration of Madhupur National Park.

Frugivory and the fate of dispersed and non-dispersed seeds of six African tree species

1996 ◽  
Vol 12 (4) ◽  
pp. 491-504 ◽  
Author(s):  
Colin A. Chapman ◽  
Lauren J. Chapman
Keyword(s):  
Tree Species ◽  
National Park ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Kibale National Park ◽  
Lower Probability ◽  
Foraging Activity ◽  
Seedling Density ◽  
Trade Off ◽  
The Relationship

ABSTRACTThe relationship between seedling recruitment (under and away from parent trees) and the behaviour of seed dispersers and predators, was explored in a three-year study in Kibale National Park, Uganda. On the basis of 1261 hours of observation, the foraging activity of the diurnal frugivores which fed on fruit from six tree species was quantified. The fate of dispersed and non-dispersed seeds and seedlings was examined experimentally. The findings suggest that a trade-off exists between factors that promote seedling growth in areas with high seedling density and factors that promote dispersal by frugivores. For example, dispersal ofMimusops bagshaweiincreases both seed and seedling survival; seeds placed away from adult conspecifics had a 8% lower probability of disappearing than seeds placed under adults and seedlings away from adults had a 30% greater probability of surviving than seedlings grown under adults. In contrast, forUvariopsis congensis, dispersed seeds had a 56% greater probability of disappearing than seeds directly under a parent tree, while the survival of dispersed and non-dispersed seedlings was similar. Non-dispersed seed and seedling disappearance were correlated with the percentage of the fruit crop removed from focal trees, suggesting that the ability to survive under an adult maybe related to other aspects of the tree's life history.

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