Introduced and Invasive Species in Novel Rangeland Ecosystems: Friends or Foes?
نویسندگان
چکیده
Globally, new combinations of introduced and native plant and animal species have changed rangelands into novel ecosystems. Whereas many rangeland stakeholders (people who use or have an interest in rangelands) view intentional species introductions to improve forage and control erosion as beneficial, others focus on unintended costs, such as increased fire risk, loss of rangeland biodiversity, and threats to conservation efforts, specifically in nature reserves and parks. These conflicting views challenge all rangeland stakeholders, especially those making decisions on how best to manage novel ecosystems. To formulate a conceptual framework for decision making, we examined a wide range of novel ecosystems, created by intentional and unintentional introductions of nonnative species and land-use–facilitated spread of native ones. This framework simply divides decision making into two types: 1) straightforward–certain, and 2) complex–uncertain. We argue that management decisions to retain novel ecosystems are certain when goods and services provided by the system far outweigh the costs of restoration, for example in the case of intensively managed Cenchrus pastures. Decisions to return novel ecosystems to natural systems are also certain when the value of the system is low and restoration is easy and inexpensive as in the case of biocontrol of Opuntia infestations. In contrast, decisions whether to retain or restore novel ecosystems become complex and uncertain in cases where benefits are low and costs of control are high as, for example, in the case of stopping the expansion of Prosopis and Juniperus into semiarid rangelands. Decisions to retain or restore novel ecosystems are also complex and uncertain when, for example, nonnative Eucalyptus trees expand along natural streams, negatively affecting biodiversity, but also providing timber and honey. When decision making is complex and uncertain, we suggest that rangeland managers utilize cost–benefit analyses and hold stakeholder workshops to resolve conflicts.
منابع مشابه
Identification of Invasive Species Using Remote Sensing and Vegetation Indices, (Case Study: Vazroud Rangelands, Iran)
Biological invasions form a major threat to the provision of ecosystems productsand services and can affect ecosystems across a wide spectrum of bioclimatic conditions.Therefore, it is important to systematically monitor the spread of species over broad regions. Ithas long been recognized that remote sensing and geographical information system couldcontribute to this capacity. This paper aims t...
متن کاملاثر مدیریتهای مختلف چرایی بر تنوع و غنای گونهای در مراتع استپی ساوه
Livestock grazing is a common human-induced activity with direct and indirect effects even on the ecosystems of protected areas. The present study analyzed the effects of different grazing management methods on species diversity and richness in the steppe rangelands of Saveh, Iran. Data were collected from sixty 2×2 m plots within the areas of three, four-years protected range management projec...
متن کاملThe Structure of Plant Population of Forested Rangeland in Different Legal Definitions (Case Study: Sabzkouh Region, Chaharmahal & Bakhtiari Province, Iran)
There is less published research on ecosystems of forested rangeland in Iran. This research was conducted to investigate the forested rangeland area based on legal definition via comparison of indices species richness, diversity, and morphology of the trees and shrubs in Sabzkouh watershed, Chaharmahal Bakhtiari province, Iran. Quantitative characteristics of trees and shrubs were measured by 5...
متن کاملSoil seed bank size and composition under Pteridium aquilinum invasion in summer rangelands of Bandpay Babol, Mazandaran province
Pteridium aquilinum is known as an invasive species in different ecosystems of the world. The spread of this species is increasing in the north of Iran particularly outside of forest ecosystems. In this study, the amount and composition of soil seed banks in the dense pathes of Pteridium were investigated in summer rangelands of Bandpay in the south of Babol city in Mazandaran province, Iran...
متن کاملInvited Synthesis Paper: Principles and practices for managing rangeland invasive plants
Invasive plants reduce the capacity of ecosystems to provide goods and services required by society, alter ecological processes, and can displace desirable species. They can reduce wildlife habitat quality, riparian area integrity, rangeland economic value, and enterprise net returns. The invasion process is regulated by characteristics of the invading plant and the community being invaded. The...
متن کامل