Comparing the Long-Term Impacts of Different Anthropogenic Disturbance Regimes on California Sage Scrub Recovery

2013 ◽  
Vol 66 (3) ◽  
pp. 468-479 ◽  
Author(s):  
Kyra Engelberg ◽  
Paul Laris ◽  
Brian Nagy ◽  
Scott Eckardt
Keyword(s):  
Anthropogenic Disturbance ◽  
Disturbance Regimes ◽  
Sage Scrub

scholarly journals Distribution and ecological segregation on regional and microgeographic scales of the diploidCentaurea asperaL., the tetraploidC. seridisL., and their triploid hybrids (Compositae)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5209 ◽  
Author(s):  
Alfonso Garmendia ◽  
Hugo Merle ◽  
Pablo Ruiz ◽  
Maria Ferriol
Keyword(s):  
Anthropogenic Disturbance ◽  
Large Scale ◽  
Latitudinal Gradient ◽  
Soil Parameters ◽  
Fine Scale ◽  
Contact Zones ◽  
Ecological Requirements ◽  
Adaptive Processes ◽  
Sympatric Cytotypes

Although polyploidy is considered a ubiquitous process in plants, the establishment of new polyploid species may be hindered by ecological competition with parental diploid taxa. In such cases, the adaptive processes that result in the ecological divergence of diploids and polyploids can lead to their co-existence. In contrast, non-adaptive processes can lead to the co-existence of diploids and polyploids or to differentiated distributions, particularly when the minority cytotype disadvantage effect comes into play. Although large-scale studies of cytotype distributions have been widely conducted, the segregation of sympatric cytotypes on fine scales has been poorly studied. We analysed the spatial distribution and ecological requirements of the tetraploidCentaurea seridisand the diploidCentaurea asperain east Spain on a large scale, and also microspatially in contact zones where both species hybridise and give rise to sterile triploid hybrids. On the fine scale, the position of eachCentaureaindividual was recorded along with soil parameters, accompanying species cover and plant richness. On the east Spanish coast, a slight latitudinal gradient was found. TetraploidC. seridisindividuals were located northerly and diploidC. asperaindividuals southerly. Tetraploids were found only in the habitats with strong anthropogenic disturbance. In disturbed locations with well-developed semi-fixed or fixed dunes, diploids and tetraploids could co-exist and hybridise. However, on a fine scale, although taxa were spatially segregated in contact zones, they were not ecologically differentiated. This finding suggests the existence of non-adaptive processes that have led to their co-existence. Triploid hybrids were closer to diploid allogamous mothers (C. aspera) than to tetraploid autogamous fathers (C. seridis). This may result in a better ability to compete for space in the tetraploid minor cytotype, which might facilitate its long-term persistence.

Causes and Consequences of Broad-Scale Changes in the Distribution of Migratory Caribou (Rangifer tarandus) of Southern Hudson Bay

ARCTIC ◽  
2015 ◽  
Vol 68 (4) ◽  
pp. 472 ◽  
Author(s):  
Erica J. Newton ◽  
Kenneth F. Abraham ◽  
James A. Schaefer ◽  
Bruce A. Pond ◽  
Glen S. Brown ◽  
...  
Keyword(s):  
Body Size ◽  
Anthropogenic Disturbance ◽  
Rangifer Tarandus ◽  
The Body ◽  
Dietary Quality ◽  
Hudson Bay ◽  
Substantial Change ◽  
Term Data ◽  
Broad Scale

Understanding the factors driving changes in species distributions is fundamental to conservation, but for wide-ranging species this is often complicated by the need for broad-scale observations across space and time. In the last three decades, the location of summer concentrations of migratory caribou (Rangifer tarandus) in southern Hudson Bay (SHB), Canada, has shifted south and east as much as 500 km. We used long-term data (1987 – 2011) to test two hypotheses that could explain the distribution shift: forage depletion and anthropogenic disturbance. Over time and space, we compared the body size of live-captured adult female caribou, dietary quality from fecal nitrogen in July, the location of VHF- and GPS-collared female caribou in July, distribution of all-terrain vehicle (ATV) tracks and caribou tracks in August, and the proximity of collared caribou to sections of the coast with higher ATV activity in spring and summer. The forage depletion hypothesis was supported by greater body size and dietary quality in caribou of the eastern portion of SHB than in western SHB animals in 2009 – 11. The anthropogenic disturbance hypothesis was supported by the negative correlation of the distributions of ATV tracks and caribou tracks on the coast in 2010 and the fact that caribou avoided areas with ATV activity by 10 – 14 km. In 1987, collared caribou were observed largely along the coast in western SHB in mid-July, while in 2009 – 11, they were inland in western SHB and along the coast in eastern SHB. While these locations demonstrate a substantial change in summer distri­bution over three decades, we were unable to differentiate between forage depletion and anthropogenic disturbance as a single causal factor of the distribution shift.

Long-term Ecological Consequences of Anthropogenic Disturbance on Saginaw Bay Coastal Wet Meadow Vegetation

2005 ◽  
Vol 31 ◽  
pp. 147-159 ◽  
Author(s):  
Kurt E. Stanley ◽  
Peter G. Murphy ◽  
Harold H. Prince ◽  
Thomas M. Burton
Keyword(s):  
Anthropogenic Disturbance ◽  
Ecological Consequences ◽  
Wet Meadow ◽  
Saginaw Bay

Collateral benefit: unconscious conservation of threatened plant species

2007 ◽  
Vol 55 (3) ◽  
pp. 221 ◽  
Author(s):  
J. B. Kirkpatrick
Keyword(s):  
Plant Species ◽  
Anthropogenic Disturbance ◽  
Temporal Heterogeneity ◽  
Disturbance Regimes ◽  
Threatened Plant ◽  
Disturbed Land ◽  
Threatened Plant Species ◽  
Threatening Processes ◽  
Native Pastures ◽  
Introduced Trees

In Europe, the conservation of rare or threatened plant species (ROTS) largely involves the manipulation of anthropogenic disturbance regimes rather than the mitigation of human-induced threatening processes, as has been the case in Australia. In Tasmania, there are many ROTS, especially those of the depleted and stock-grazed grasslands and grassy woodlands, which survive because, unconscious of the needs of ROTS, people have disturbed land in ways that suit their life-cycle requirements. Such species are found in quarries, in borrow pits, in scrapes, on roadsides, on track edges, on old roads, under introduced trees, in heavily grazed native pastures, in regenerating clearfell coupes and on mown ground. They are disturbance-dependent species, usually with poor competitive abilities. Many cannot survive stock-grazing. Unconscious conservation of these species needs to become conscious, in the European manner. Spatial heterogeneity in disturbance regimes is important for maintaining this set of species, whereas temporal heterogeneity is likely to lead to their doom.

Holocene climate–fire–vegetation interactions at a subalpine watershed in southeastern British Columbia, Canada

2014 ◽  
Vol 81 (2) ◽  
pp. 228-239 ◽  
Author(s):  
Colin J. Courtney Mustaphi ◽  
Michael F.J. Pisaric
Keyword(s):  
British Columbia ◽  
Fire Regime ◽  
Environmental Gradients ◽  
Forest Biomass ◽  
Fire Frequency ◽  
Ecosystem Responses ◽  
Disturbance Regimes ◽  
Subalpine Lake ◽  
Fuel Accumulation

AbstractVegetation assemblages and associated disturbance regimes are spatially heterogeneous in mountain ecosystems throughout the world due to the complex terrain and strong environmental gradients. Given this complexity, numerous sites describing postglacial vegetation and fire histories are needed to adequately understand forest development and ecosystem responses to varying climate and disturbance regimes. To gain insight into long-term historical climate–fire–vegetation interactions in southeastern British Columbia, Canada, sedimentological and paleoecological analyses were performed on a sediment core recovered from a small subalpine lake. The pollen assemblages, stomata, and macroremains indicate that from 9500 to 7500 cal yr BP, Pinus-dominated forests occurred within the catchment and Alnus was also present. Climate was an important control of fire and fire frequency was highest at this time, peaking at 8 fires 1000 yr− 1, yet charcoal accumulation rates were low, indicative of low terrestrial biomass abundance. From 7500 to 4600 cal yr BP, Pinus decreased as Picea, Abies and Larix increased and fire frequencies decreased to 3–6 fires 1000 yr− 1. Since 7500 cal yr BP the fire regime varied at a millennial scale, driven by forest biomass abundance and fuel accumulation changes. Local scale (bottom-up) controls of fire increased in relative importance since at least 6000 cal yr BP.

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