Spatial analysis of anthropogenic disturbance regimes and roadside shrubs in a fragmented agricultural landscape

Natural hydrological fluctuations within river floodplains generate habitat diversity through variable connections between habitat patches and the main river channel. Human modification of floodplains can alter the magnitude and frequency of large floods and associated sediment movement by interrupting these floodplain connections. The lower Wolastoq | Saint John River and its associated floodplain wetlands are experiencing anthropogenic disturbances arising from climate change, increased urbanization in the watershed, changing upstream agricultural landscape practices, and, most notably, major road and dam construction. By comparing digitized aerial images, we identified key periods of change in wetland extent throughout an ecologically significant component of the floodplain, the Grand Lake Meadows and Portobello Creek wetland complex, with significant erosion evident in coves and backwater areas across the landscape following dam construction and significant accretion around the Jemseg River following highway construction. Connectivity and hydrological regime also influenced other habitat components, namely nutrients and metals retention, as well as the composition of the local macrophyte community. These findings address two key aspects of floodplain management: (1) understanding how hydrological alteration has historically influenced floodplain wetlands can inform us of how the ecosystem may respond under future conditions, such as climate change, and (2) the mechanisms by which habitat diversity and disturbance regimes filter biological communities, with the potential for patches to host a rich biodiversity continuously supporting critical ecosystem functions.

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Humanizing savanna models: integrating natural factors and anthropogenic disturbance regimes to determine tree–grass dynamics in savannas

Journal of Land Use Science ◽

10.1080/1747423x.2011.597444 ◽

2012 ◽

Vol 7 (4) ◽

pp. 459-482 ◽

Cited By ~ 7

Author(s):

Paul Laris ◽

Fadiala Dembele

Keyword(s):

Anthropogenic Disturbance ◽

Disturbance Regimes ◽

Natural Factors

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Collateral benefit: unconscious conservation of threatened plant species

Australian Journal of Botany ◽

10.1071/bt06104 ◽

2007 ◽

Vol 55 (3) ◽

pp. 221 ◽

Cited By ~ 10

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.

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