The impact of feral camels (Camelus dromedarius) on woody vegetation in arid Australia

2016 ◽  
Vol 38 (2) ◽  
pp. 181 ◽  
Author(s):  
Jayne Brim Box ◽  
Catherine E. M. Nano ◽  
Glenis McBurnie ◽  
Donald M. Waller ◽  
Kathy McConnell ◽  
...  
Keyword(s):  
Woody Species ◽  
Woody Vegetation ◽  
Plant Populations ◽  
Large Mammal ◽  
Canopy Volume ◽  
Adult Tree ◽  
Management Project ◽  
Acacia Aneura ◽  
The Impact

Data on the extent of feral camel damage on trees and shrubs in inland Australia are scarce, and there is currently no universally accepted theoretical framework for predicting the impact of a novel large mammal browser on arid vegetation. In other (mainly mesic) grassy systems, large mammal browsers can strongly suppress woody biomass across landscapes by limiting the transition of saplings to adulthood and by significantly thinning adult tree canopies. The recent Australian Feral Camel Management Project provided an opportunity to assess the impacts of camel browsing on woody vegetation in inland Australia. We examined browsing intensity and severity (stunting and canopy loss) in 22 species of woody plants in camel-affected regions across inland Australia prior to camel removal operations. The severity of plant damage increased with camel density as both trees and shrub growth were strongly suppressed where camel densities exceeded 0.25 km–2. In most tree and shrub species tested, camel browsing significantly stunted plants, suggesting that camel browsing has long-term impacts on plant populations. Browsing also reduced canopy volume in several species, including the structurally important Acacia aneura F.Muell. ex Benth. Thus, in this dryland ecosystem, camels can curtail the regeneration and growth of woody species enough to threaten ecosystem health. To avoid adverse impacts on woody plant populations, camel densities should be maintained at 0.25 camels km–2 or less over as much of inland Australia as possible.

scholarly journals The influence of the 1991/92 drought on the woody vegetation of the Kruger National Park

Koedoe ◽  
1995 ◽  
Vol 38 (2) ◽  
Author(s):  
A.J. Viljoen
Keyword(s):  
National Park ◽  
Woody Species ◽  
Aerial Photographs ◽  
Woody Vegetation ◽  
General Area ◽  
Variable Intensity ◽  
The North ◽  
Olifants River ◽  
Area North ◽  
The Impact

All observations and data related to the impact of the 1991/92 drought on the woody vegetation, excluding the riverine vegetation of major rivers, are summarised. This includes data from a visual estimate of damage from aerial photographs, surveys on selected sites, and general observations. Despite lower rainfall, the area north of the Olifants River (excluding the far-northern part) was less affected than the area south of it, suggesting that the woody vegetation in the north is more adapted to drought. A characteristic of the drought was the localised distribution pattern and variable intensity of damage to the same species in the same general area. Information on 31 species are presented briefly. Although a large number of woody species was to some extent damaged, when the woody vegetation is considered as a whole, the influence of the drought was not very severe.

scholarly journals An Assessment of Multiple Drivers Determining Woody Species Composition and Structure: A Case Study from the Kalahari, Botswana

Land ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 122 ◽  
Author(s):  
Meyer ◽  
Holloway ◽  
Christiansen ◽  
Miller ◽  
D’Odorico ◽  
...  
Keyword(s):  
Species Abundance ◽  
Woody Species ◽  
Environmental Variable ◽  
Woody Vegetation ◽  
Tobit Regression ◽  
Species Identity ◽  
Rainfall Gradient ◽  
Composition And Structure ◽  
Species Richness And Abundance ◽  
The Impact

Savannas are extremely important socio-economic landscapes, with pastoralist societies relying on these ecosystems to sustain their livelihoods and economy. Globally, there is an increase of woody vegetation in these ecosystems, degrading the potential of these multi-functional landscapes to sustain societies and wildlife. Several mechanisms have been invoked to explain the processes responsible for woody vegetation composition; however, these are often investigated separately at scales not best suited to land-managers, thereby impeding the evaluation of their relative importance. We ran six transects at 15 sites along the Kalahari transect, collecting data on species identity, diversity, and abundance. We used Poisson and Tobit regression models to investigate the relationship among woody vegetation, precipitation, grazing, borehole density, and fire. We identified 44 species across 78 transects, with the highest species richness and abundance occurring at Kuke (middle of the rainfall gradient). Precipitation was the most important environmental variable across all species and various morphological groups, while increased borehole density and livestock resulted in lower bipinnate species abundance, contradicting the consensus that these managed features increase the presence of such species. Rotating cattle between boreholes subsequently reduces the impact of trampling and grazing on the soil and maintains and/or reduces woody vegetation abundance.

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>

scholarly journals Effects of Human Impact on Miombo Woodland in Northern Malawi

2010 ◽  
Vol 13 ◽  
pp. 22-34
Author(s):  
Tina Vanadis Bundschuh ◽  
Rüdiger Wittig ◽  
Karen Hahn
Keyword(s):  
Plant Diversity ◽  
Rural Population ◽  
Vegetation Type ◽  
Woody Species ◽  
Wild Plants ◽  
Wild Plant ◽  
Woody Vegetation ◽  
Miombo Woodland ◽  
Wild Plant Species ◽  
The Impact

Miombo woodland is found throughout the Zambezian regional centre of endemism where most of the rural population make use of its wild plant species. This article presents the results of a study on the composition of the woody vegetation and its anthropogenous alteration in northern Malawi with particular respect to the impact caused by the collection of wild plants. The main vegetation type in this area is miombo woodland which is composed of 80 woody species. The collection of wild plants does not show an effect on the plant diversity but effects are visible in the decreasing number of tall trees.

scholarly journals Woody vegetation change over more than 30 years in the interior duneveld of the Kalahari Gemsbok National Park

Bothalia ◽  
2020 ◽  
Vol 50 (Volume 50 No. 1) ◽  
Author(s):  
H. van der Merwe ◽  
N. van Rooyen ◽  
H. Bezuidenhout ◽  
J. du P. Bothma ◽  
M.W. van Rooyen
Keyword(s):  
National Park ◽  
Vegetation Change ◽  
Woody Species ◽  
Woody Vegetation ◽  
Bush Encroachment ◽  
Conservation Area ◽  
Grewia Flava ◽  
Carbon Dioxide Levels ◽  
Long Term Studies

Background and objectives: Long-term studies of woody plants in South Africa are scarce. This study, initiated in the late 1970s, therefore aids understanding of vegetation dynamics in the southern Kalahari by investigating woody vegetation change at and away from a watering point. Methods: At three sites, all woody individuals were counted by species in plots 0.5 or 1 ha in size. Seedlings were noted separately from the >0.2 m group of individuals. Results: Vachellia erioloba and shrub density decreased over time whereas dwarf shrub species’ numbers fluctuated markedly. Additionally, no increase in density of known bush encroaching species (e.g. Grewia flava, Rhigozum trichotomum and Senegalia mellifera) was found in this large conservation area. Discussion and conclusion: The changes in density of the woody species seem to point to the importance of particular rainfall patterns or sequences of events over different years that are responsible for these changes in the southern Kalahari, and the evident lack of bush encroachment in this conservation area supports the notion that bush encroachment in arid savannas is driven primarily by land-use practices and not by elevated carbon dioxide levels that are sometimes provided as cause for encroachment.

scholarly journals Browser impacts in Mapungubwe National Park, South Africa: Should we be worried?

Koedoe ◽  
2016 ◽  
Vol 58 (1) ◽  
Author(s):  
Corli Coetsee ◽  
Benjamin J. Wigley
Keyword(s):  
South Africa ◽  
Species Diversity ◽  
National Park ◽  
Woody Species ◽  
Woody Vegetation ◽  
Vegetation Types ◽  
Medium Term ◽  
Management Interventions ◽  
Rocky Outcrops ◽  
The Impact

This study explores the impact of browsers on vegetation types within the Mapungubwe National Park and specifically whether rocky outcrops or ridges in the park serve as refugia from browsers, particularly elephants. We sampled 80 transects at 20 sites and recorded 1740 plants comprising 65 species. We found that a high proportion (> 80%) of the woody vegetation sampled indicated browser utilisation. Although certain woody species (e.g. Albizia harveyi, Boscia albitrunca, Lannea schweinfurthii) appeared to be preferred by browsers, browsing levels were relatively high among all woody species. High levels of browsing by herbivores other than elephants suggest that they have a significant impact on the park’s vegetation. We did not find that rocky ridges acted as refugia to browsers, but instead found that vegetation in rocky ridges was more severely impacted by browsers than vegetation in flat areas, despite vegetation being more accessible in flat areas. If elephant numbers continue to increase at the current rate (e.g. elephant numbers doubled between 2007 and 2010), we predict that some of the heavily utilised species will become locally rare over time.Conservation implications: High levels of browsing by both elephant and smaller herbivores contribute to significant impacts on vegetation away from rivers in Mapungubwe National Park. Without management interventions that address both types of impact, structural and species diversity are bound to decrease over the short to medium term.

scholarly journals Long term effects of fire frequency and season on the woody vegetation dynamics of the Sclerocarya birrea/Acacia nigrescens savanna of the Kruger National Park

Koedoe ◽  
2000 ◽  
Vol 43 (1) ◽  
Author(s):  
B.W. Enslin ◽  
A.L.F. Potgieter ◽  
H.C. Biggs ◽  
R. Biggs
Keyword(s):  
National Park ◽  
Structural Changes ◽  
Environmental Parameters ◽  
Woody Species ◽  
Fire Frequency ◽  
Kruger National Park ◽  
Woody Vegetation ◽  
Long Term Effects ◽  
Season Of Burn

A lack of knowledge together with vacillating fire management approaches in the Kruger National Park until the mid 1950s, gave rise to a long term fire research experiment aimed at shedding light on savanna responses to various combinations of fire fre- quencies and seasons. This trial was laid out in 1954 in four of the six major vegetation zones of the park. With the future of the experiment now being reconsidered, full scale vegetation surveys have been conducted on all the plots and compared to the surveys done in 1954. This paper examines the woody vegetation responses to fourteen fire treatments in the Knobthorn/Marula savanna. Parameters of interest were woody species composition responses, together with tree & shrub density and structural changes. The results indicate that no significant changes in woody species had occurred for the peri- od 1954 vs 1998, while density decreased on biennial and increased on triennial treatments. The proportion of single stemmed plants increased over the period. Season of burn has a marked effect on structure, with April and August burns giving rise to the largest basal areas but the lowest heights. Environmental parameters such as climate, varying herbivory and differing soils, and their respective interactions on vegetation morphology, together with fire behaviour, further influenced results.

scholarly journals Vegetation Dynamics in the Northern Zones of Niger: Case of the Rural Commune of Tanout (Zinder) and Aderbissinat (Agadez)

2021 ◽  
Vol 2 (1) ◽  
pp. 30-36
Author(s):  
Abdoul Kader Soumaila Sina ◽  
Nouhou Ali ◽  
Amadou Garba ◽  
Bernard Minoungou
Keyword(s):  
Land Use ◽  
Vegetation Dynamics ◽  
Methodological Approach ◽  
Woody Species ◽  
Woody Vegetation ◽  
Landsat Images ◽  
Floristic Inventory ◽  
Northern Zone ◽  
The Impact ◽  
Land Use Maps

The present study conducted in the northern zone of Niger aims to show the impact of land use dynamics on woody vegetation. The methodological approach consisted in making in addition to the floristic surveys, the analysis of land use maps (LANDSAT images of the years 1975 and 2018). The floristic inventory allowed the identification of twenty-seven (27) woody species of which eleven (11) in Tanout and sixteen (16) in Aderbissinat. The most important families remain the Fabaceae-Mimosoideae which represent 37.5% at Aderbissinat and 45.45% at Tanout. The biological types remain dominated by microphanerophytes which dominate (86.67%), while for the phytogeographic types it is the Sudano-Zambezian and Sudanian species that dominate, with proportions respectively equal to 31.25%. There is a regression of woody vegetation at the level of these communes with a slight loss in Aderbissinat (60588,034 ha) and an accentuated degradation of vegetation in Tanout (781797,738 ha).

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

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