Foxcroft L.C.,Conservation Services |
Foxcroft L.C.,Stellenbosch University |
Pickett S.T.A.,Cary Institute of Ecosystem Studies |
Cadenasso M.L.,University of California at Davis
Perspectives in Plant Ecology, Evolution and Systematics | Year: 2011
Numerous mechanisms driving alien plant invasions have been described in a rapidly growing body of literature. However these are frequently case specific, making generalizations across species and systems difficult. A number of conceptual approaches have been proposed to help synthesize the literature, stimulating healthy debate among scientists. We build on these syntheses, presenting an expanded framework that incorporates the processes contributing to invasions, and the context within which they must interact. We also provide a model template into which the framework we develop is incorporated, illustrating both with examples. Our general framework includes three contributing processes: these are (1) the characteristics of the introduced species, (2) system context, within which the invasion takes place, and (3) the features of the receiving habitat. System context refers to the influences arising outside of the receiving environment, both spatially and temporally. Each contributing process is comprised of specific mechanisms, drawn from literature on invasion ecology and other related fields. The framework invokes relevant mechanisms for a specific species or situation. Although, a number of frameworks already consider the characteristics of the invading species or those of the receiving habitat, they seldom include all possible characteristics of both. We propose that these approaches alone are inadequate to provide a comprehensive understanding of the invasion process, without explicitly examining the context within which the invasion takes place. The model template we present relates the contributing processes described for a particular invasion, to the change in habitat from one state to another. Each of the contributing processes defined in the framework modulates the degree to which the habitat is changed. We suggest that these additional tools and the explicit inclusion of all three contributing processes, provide for further synthesis and improved understanding of invasions by alien plants. © 2011 Perspectives in Plant Ecology, Evolution and Systematics.
Le Roux J.J.,Stellenbosch University |
Foxcroft L.C.,Stellenbosch University |
Herbst M.,Conservation Services |
Macfadyen S.,Stellenbosch University
Ecology and Evolution | Year: 2015
Hybridization between domestic and wild animals is a major concern for biodiversity conservation, and as habitats become increasingly fragmented, conserving biodiversity at all levels, including genetic, becomes increasingly important. Except for tropical forests and true deserts, African wildcats occur across the African continent; however, almost no work has been carried out to assess its genetic status and extent of hybridization with domestic cats. For example, in South Africa it has been argued that the long-term viability of maintaining pure wildcat populations lies in large protected areas only, isolated from human populations. Two of the largest protected areas in Africa, the Kgalagadi Transfrontier and Kruger National Parks, as well as the size of South Africa and range of landscape uses, provide a model situation to assess how habitat fragmentation and heterogeneity influences the genetic purity of African wildcats. Using population genetic and home range data, we examined the genetic purity of African wildcats and their suspected hybrids across South Africa, including areas within and outside of protected areas. Overall, we found African wildcat populations to be genetically relatively pure, but instances of hybridization and a significant relationship between the genetic distinctiveness (purity) of wildcats and human population pressure were evident. The genetically purest African wildcats were found in the Kgalagadi Transfrontier Park, while samples from around Kruger National Park showed cause for concern, especially combined with the substantial human population density along the park's boundary. While African wildcat populations in South Africa generally appear to be genetically pure, with low levels of hybridization, our genetic data do suggest that protected areas may play an important role in maintaining genetic purity by reducing the likelihood of contact with domestic cats. We suggest that approaches such as corridors between protected areas are unlikely to remain effective for wildcat conservation, as the proximity to human settlements around these areas is projected to increase the wild/domestic animal interface. Thus, large, isolated protected areas will become increasingly important for wildcat conservation and efforts need to be made to prevent introduction of domestic cats into these areas. © 2015 Published by John Wiley & Sons Ltd.
Foxcroft L.C.,Conservation Services |
Foxcroft L.C.,Stellenbosch University |
Jarosik V.,Charles University |
Jarosik V.,Academy of Sciences of the Czech Republic |
And 4 more authors.
Conservation Biology | Year: 2011
Human land uses surrounding protected areas provide propagules for colonization of these areas by non-native species, and corridors between protected-area networks and drainage systems of rivers provide pathways for long-distance dispersal of non-native species. Nevertheless, the influence of protected-area boundaries on colonization of protected areas by invasive non-native species is unknown. We drew on a spatially explicit data set of more than 27,000 non-native plant presence records for South Africa's Kruger National Park to examine the role of boundaries in preventing colonization of protected areas by non-native species. The number of records of non-native invasive plants declined rapidly beyond 1500 m inside the park; thus, we believe that the park boundary limited the spread of non-native plants. The number of non-native invasive plants inside the park was a function of the amount of water runoff, density of major roads, and the presence of natural vegetation outside the park. Of the types of human-induced disturbance, only the density of major roads outside the protected area significantly increased the number of non-native plant records. Our findings suggest that the probability of incursion of invasive plants into protected areas can be quantified reliably. ©2010 Society for Conservation Biology.
News Article | December 9, 2015
A two-year conservation project studying the island's lizard populations led to the discovery of the Cuban brown anole, a species once rumored to inhabit the North Atlantic island, but was never verified until now. "The Cuban brown anole most likely reached Bermuda by human transport," said Stroud, a Ph.D. student. "These lizards hitch rides between ports as unintended stowaways amongst cargo, usually in nursery plants and building materials. Although further research is needed to confirm it, this route of introduction seems likely." The introduction of the Cuban anole could pose difficulties for the endangered Bermuda skink, the island's only native lizard species. Also known as a rock lizard, the skink is listed as critically endangered in the International Union for Conservation of Nature's (IUCN's) Red List, the world's authority on the conservation status of plant and animal species. According to the researchers, Cuban brown anoles excel at thriving outside of their native geographical area. The lizards can live in a variety of natural and human-made habitats, and feed on a variety of prey, potentially putting them at an advantage to other lizard species who might not be as tolerant. "We have discovered that the Cuban brown anole does not yet overlap its distribution with the Bermuda skink," Stroud said. "Therefore, the potential effects of the non-native brown anole on the native Bermuda skink are currently unknown. This topic forms part of our ongoing research interests in Bermuda" After surveying all of Bermuda, Stroud found populations of the Cuban lizard at all life stages indicating they are thriving in the central part of the island. He also found the established Jamaican anole continues to be found all over the island, but the Antiguan anole has significantly expanded into areas where the Barbadian lizards live. The discovery was made alongside former FIU master's student Sean Giery and Bermuda's Department of Conservation Services. Originating in Cuba and the Bahamas, the Cuban brown anole is one of the most widespread lizards outside of its native area with large populations found from Florida to Texas, California, Hawaii, Costa Rica, Singapore and Taiwan. Cuban brown anoles can be found in urban environments including downtown Miami and natural environments such as the Everglades. Anoles are very diverse group of lizards and about 372 species are currently known to exist. Stroud recently traveled to Costa Rica where he conducted the first-ever study of the Cuban brown anole's ecology and distribution in the Central American country. He is devoting his doctoral research to studying the evolution, interactions and community patterns of Anolis lizards in the tropics.
Daemane M.E.,Conservation Services |
Cilliers S.S.,North West University South Africa |
Bezuidenhout H.,Conservation Services
Koedoe | Year: 2012
The objective of the proposed Highveld National Park (HNP) is to conserve a considerable area of the poorly conserved Rocky Highveld Grassland and Dry Sandy Highveld Grassveld of the western Grassland Biome in South Africa. The park has not yet been proclaimed, but is currently under the management of the North West Parks and Tourism Board. The main aim of this study was to classify and describe the vegetation in the Spitskop area in the HNP. The areas affected by soil degradation were on the midslopes, footslopes, valley bottomland and the floodplains around the Spitskop hill. The concentrated grazing around the Spitskop area was also influenced by the existing dam in the floodplains. Floristic and soil degradation data were collected and used to classify and describe the plant communities of the Spitskop area. Vegetation sampling was performed by means of the Braun-Blanquet method and a total of twenty plots were sampled. A numerical classification technique (TWINSPAN) was applied to the floristic data to derive a first approximation of the main plant communities. Further refinement was achieved by Braun-Blanquet procedures. The final results of the classification procedure were presented in the form of a phytosociological table, with three major communities and three subcommunities being described. Canonical correspondence analysis was used to determine the direct correlation between plant communities and soil degradation types. Soil compaction and sheet erosion were found to be the most significant variables determining plant community composition. Rill and gully erosion were shown to be of lesser significance in explaining the variation in plant communities. © 2012. The Authors.
News Article | November 1, 2016
Today, the American Tree Farm System (ATFS) announced the 2016 National Outstanding Tree Farmer of the Year award, will go to the Defrees family of northeast Oregon. Father and son duo, Lyle and Dean Defrees, along with their family, Sharon Defrees, Dallas Hall, Riley Hall, Nathan Defrees, Jess Defrees, Tyler Defrees and Max Patashnik, have been protecting their forested land, the wildlife habitat it provides, and the water supply that runs through it, for more than 100 years. “We’re truly honored to be chosen as the National Outstanding Tree Farmers of the Year,” said Lyle Defrees. “Our family has had a passion for our land and conservation for generations. Most everything we do is to protect our land from fire so it can continue to provide for us, the wildlife in our region, and our fellow Oregonians. We joined ATFS in 1980 because we wanted to be a part of a community of other forest owners that share our interest, where we could learn from them, as well as share our own experiences and help others.” The Defrees Tree Farm is located in northeast Oregon, a region of the state prone to intense wildfires that have consumed both forest and homes, and affected the watersheds that supply the communities of the state with their drinking water. The Defrees experienced ones of these wildfires firsthand when the Huckleberry Forest Fire of 1986 burned 500 acres of their 2,000-acre Tree Farm. Devastated by the effects, the Defrees committed to protecting their forest and all that it provides from future loss. They spent the initial years after the fire replanting the acres lost, running into challenges that added to their workload – seedlings were hard to come by and a bark beetle infestation took over sections of their forest. Yet the Defrees persevered, using the ATFS network to seek out advice, connect with experts, and gain more knowledge on forest management. They spent decades building and maintaining defensible fire lanes, thinning their forest to reduce the fuel load that can feed wildfires, and keeping their creek and stream banks well planted to curtail erosion and preserve water quality. With the high costs of this forest management, they would not have been able to do this work without the support of cost-share dollars from National Resources Conservation Services (NRCS), a program of the U.S. Department of Agriculture (USDA). All of the Defrees work has resulted in a tremendous impact on the ground – a fire resilient forest, needed wildlife habitat, healthy creeks and waterways and more. In addition, the Defrees, as part of ATFS, have been active in their community, mentoring other landowners on the importance of forest management to get ahead of wildfire. They have participated in state advocacy, presented at ATFS events and hosted groups on their land. “The Defrees family showcases the impact family forest owners can have, when they are able to overcome barriers,” said Tom Martin, President and CEO of the American Forest Foundation, the forest conservation organization that houses the ATFS program. “We have found through our work in the West that landowners want to do the right thing to protect our natural resources, but need help with expertise and cost. Through ATFS and our placed-based work, we are helping landowners overcome these barriers, so we can have more landowners like the Defrees keeping our forests healthy and providing Americans with the clean water, clean air, wood supplies they count on.” Each year, ATFS, which this year celebrates its 75th anniversary, recognizes four Regional Outstanding Tree Farmers out of the 74,000 Tree Farmers nationwide. This year’s regional awardees include Bobby Watkins of Mississippi; Jug Kann of Wisconsin; and the Eve-Cowles family, of Massachusetts, in addition to the Defrees family. Awardees have been selected for their dedication and work over the years to protect and provide sustainable wood supplies, wildlife habitat and clean water on their Tree Farms, as well their efforts to promote forest stewardship in the community. The AFF governance and the ATFS community select a National awardee from among the Regional awardees. “The Defrees family lives a land ethic that predates the 75 year legacy of the American Tree Farm System,” said Scott Hayes, Chair of the Oregon Tree Farm System. “For over a century they have practiced sustainable forest and cattle management. Their storybook tale is about pioneering the West, with a foundation built on family and land. They truly are National Outstanding Tree Farmers of the Year.” The Defrees family will be honored along with the Regional Outstanding Tree Farmers of the Year on December 6, at a reception on Capitol Hill in Washington, D.C. to celebrate the 75th Anniversary of the program. This year’s Outstanding Tree Farmer of the Year award is made possible thanks in part to the generous support of Weyerhaeuser.
Jennings E.,Dundalk Institute of Technology |
Allott N.,Trinity College Dublin |
Lenihan D.,Kerry County Council |
Quirke B.,Conservation Services |
And 2 more authors.
Marine and Freshwater Research | Year: 2013
Excess phosphorus (P) loading is a major cause of deterioration in surface water quality. In Ireland, regulation has focussed on control of P losses from agriculture and wastewater treatment plants (WWTPs): the two main sources of excess P. Hindcast modelling for Lough Leane, south-west Ireland, indicated that, while the only municipal (point) source contributed up to 41% of the annual TP loading until the mid 1980s, over 90% of the TP load was from diffuse sources following upgrading of the WWTP. Field data from 2000-2006 confirmed that most of the TP load came from agriculture, with 73% being exported between September and February, generally the wettest months in the region. However, the WWTP contributed up to 60% of daily loads during summer. Short lake residence times (two to four months) between October and February indicated that external loadings during these months were unlikely to make a significant contribution to summer phytoplankton growth in the lake. In contrast, the potential effects of point sources during low flows were maximised by longer residence times between April and September. The results highlight the importance to aquatic pollution impacts of, and therefore the need for regulatory responses to respect, seasonal variations in loading and residence time. © 2013 CSIRO.
Freitag S.,Scientific Services |
Biggs H.,Conservation Services |
Breen C.,University of KwaZulu - Natal
Ecology and Society | Year: 2014
Natural resource management is embedded within social-ecological environments and requires decisions to be taken within this broad context, including those that pertain to protected areas. This realization has led to South African National Parks adopting a strategic adaptive management approach to decision making. Through narrative, we show why and how this practice has progressively spread and evolved both within the organization and beyond, over the past two decades. A number of catalytic events and synergies enabled a change from reactive tactical management approaches to more inclusive forward-looking approaches able to embrace system complexity and associated uncertainty and change. We show how this long period of innovation has lead to an increased appreciation for the heterogeneous social-ecological system, and for the importance of constructing relationships and colearning, such that organizational transformation has enabled more legitimate and effective operation within an expanding and diversifying constituency. © 2014 by the author(s).
Grant R.C.C.,Scientific Services Kruger National Park |
Peel M.J.S.,Animal Production Institute |
Bezuidenhout H.,Conservation Services
Koedoe | Year: 2011
African savannas are characterised by temporal and spatial fluxes that are linked to fluxes in herbivore populations and vegetation structure and composition. We need to be concerned about these fluxes only when management actions cause the system to shift towards a less desired state. Large herbivores are a key attribute of African savannas and are important for tourism and biodiversity. Large protected areas such as the Kruger National Park (KNP) manage for high biodiversity as the desired state, whilst private protected areas, such as those adjacent to the KNP, generally manage for high income. Biodiversity, sustainability and economic indicators are thus required to flag thresholds of potential concern (TPCs) that may result in a particular set of objectives not being achieved. In large conservation areas such as the KNP, vegetation changes that result from herbivore impact, or lack thereof, affect biodiversity and TPCs are used to indicate unacceptable change leading to a possible loss of biodiversity; in private protected areas the loss of large herbivores is seen as an important indicator of economic loss. Therefore, the first-level indicators aim to evaluate the forage available to sustain grazers without deleteriously affecting the vegetation composition, structure and basal cover. Various approaches to monitoring for these indicators were considered and the importance of the selection of sites that are representative of the intensity of herbivore use is emphasised. The most crucial step in the adaptive management process is the feedback of information to inform management decisions and enable learning. Feedback loops tend to be more efficient where the organisation's vision is focused on, for example, economic gain, than in larger protected areas, such as the KNP, where the vision to conserve biodiversity is broader and more complex. Conservation implications: In rangeland, optimising herbivore numbers to achieve the management objectives without causing unacceptable or irreversible change in the vegetation is challenging. This manuscript explores different avenues to evaluate herbivore impact and the outcomes of management approaches that may affect vegetation. © 2011.
PubMed | Cape Research Center and Conservation Services
Type: | Journal: Journal of environmental management | Year: 2017
To aid prescribed burn decision making in TableMountain National Park, in South Africa a priority ranking system was tested. Historically a wildfire suppression strategy was adopted due to wildfires threatening urban areas close to the park, with few prescribed burns conducted. A large percentage of vegetation across the park exceeded the ecological threshold of 15 years. We held a multidisciplinary workshop, to prioritize areas for prescribed burning. Fire Management Blocks were mapped and assessed using the following seven categories: (1) ecological, (2) management, (3) tourism, (4) infrastructure, (5) invasive alien vegetation, (6) wildland-urban interface and (7) heritage. A priority ranking system was used to score each block. The oldest or most threatened vegetation types were not necessarily the top priority blocks. Selected blocks were burnt and burning fewer large blocks proved more effective economically, ecologically and practically due to the limited burning days permitted. The prioritization process was efficient as it could be updated annually following prescribed burns and wildfire incidents. Integration of prescribed burn planning and wildfire suppression strategies resulted in a reduction in operational costs. We recommend protected areas make use of a priority ranking system developed with expert knowledge and stakeholder engagement to determine objective prescribed burn plans.