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8.02.04 - Ecology of alien invasives



Biological invasions in forests: trade, ecology and management

Prague, Czech Republic; 20-24 September 2021
Units involved: 7.03.07, 7.03.12, 8.02.04

Topics covered by the conference:

  • Invasions of non-native insects, tree pathogens, plants and other organisms in forest ecosystems
  • The role of trade and travel as pathways for invasions
  • Ecology and impact of non-native species in forests
  • Management of invasions / Biosecurity


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Jose Shibu, United States


Daizy Batish, India

About Unit

Mission: to bring international focus to invasion by alien species; seek cooperation in tackling the menace; share and encourage an interaction between scientists, policy makers, regional governments and institutions for developing effective strategies in line with CBD for checking homogenization of biota at the cost of economic growth.

Rationale: Invasive Alien Species (IAS) pose a major threat to the ecology and economy in the invaded regions, especially forest ecosystems. They cause a major change in vegetation at global level and threaten biodiversity. Though this phenomenon has been occurring since long, yet the problem of invasion has gained momentum in the last 2 decades because of global economic growth. The magnitude of impact varies depending on the geographical features of the area, population density and type of landscape.

The ecological impacts of IAS on forest ecosystems have attracted the attention of researchers, managers and policy makers the world over. As per the reports of World Conservation Union (WCU), the Convention on Biological Diversity (CBD), and the Global Invasive Species Programme (GISP), IAS proliferate and spread in new environments and are detrimental to human and national interests. The real challenge before man is to control their spread for meeting the objectives of the CBD and save the local, national and global ecology from destruction. For such reasons, the problem of IAS has been addressed under Article 8(h) of the CBD. This being a priority area demanding urgent policy decisions and alert of all societies, CBD focused year 2009 on the theme of IAS to celebrate International Biodiversity Day.

The Working Party is of the opinion that foresters, ecologists and biologists have a responsibility of devising means of managing the menace of invasion with seriousness and strong commitment it deserves. 

The Working Party realises that the area invaded by alien plants attracts alien dependent fauna. The later could serve as an initial carrier of plant propagule, but primary invaders by and large are the plants. Thus the invasion by Plants, the producers, is obviously a basic issue, since all other forms of biota are dependent on them. Therefore, invasion by alien plants in forest ecosystems is the area of primary focus of the group.

State of Knowledge

Alien species that invade an area and outgrow the native biota and increase their own territory, often lead to negative economic, environmental, and social impacts. Even native species, by their exponential spread, can behave like invasives. On the other hand, not all non-native species are invasive but may have the potential to turn so. Invasions and Introductions of exotic plants in non-native areas are not new. However, as the human population explodes and trade becomes increasingly globalized, the trans-boundary movement of species from their place of origin to alien areas has escalated and is expected to continue further in the coming decades.

The threat of invasive alien Plants to biodiversity is second only to habitat loss and even more than pollution. They affect native ecosystems by altering hydrology, fire regimes, and nutrient cycling apart from competing with native plants, reducing species richness, changing structure and composition of native communities and altering natural vegetation development. This impacts on flora, dependent fauna, soil, microbial component thus the ecosystem integrity and ecology.
The ecological impacts of invasive alien species (IAS) of plants, on forest ecosystems have attracted the attention of researchers, managers, and policy makers the world over. The real challenge before man is to control their spread for meeting the objectives of the Convention on Biodiversity and save the local, national and global ecology from destruction. Perhaps for such a reason, IAS has been addressed under Article 8(h) of the CBD.

The dimensions and nature of the issue is such that no individual or a nation can combat the threat alone. Since alien species do not recognize political boundaries, we will have to involve neighbouring countries and also gain from the rich experiences of international community. The world at large will have to join hands to tackle the problem collectively.

Accomplished Ecologists/Scientists, Forest Officers and Wildlife Wardens need to join hands and discuss the issue with a view to finding some workable solutions and make recommendations for effective implementation at local, regional and global levels. The problem of invasion and consequential biodiversity loss seems to more acute in forested ecosystem. Therefore, Working Party unanimously resolved to address the issue with utmost urgency. It was honestly admitted by all that the science of biological invasions being relatively new (although the threat is very serious), we unfortunately have inadequate knowledge about complete list of IAS in forest ecosystems around the world, their geographical distribution, their rate of spread, area occupied  by different IAS, new potential invaders or the candidate species having potential  for invasion, genetic adaptability of alien species in their new environment, their value and risk assessment from IAS or potential invasive aliens, their mechanism of overpowering natives and the means of their management. It was also strongly realized that unless current status of Invasive Alien Species is known, no effective management practice / tool could be successful.  

Hot Topics:

  • Database of invasive species for each Biosphere reserve, with an in-place monitoring programme;
  • List of worst alien species that have invaded the natural ecosystems, particularly in the rich and fast depleting biodiversity areas, their distribution, rates of invasion, and their population dynamics;
  • Ecosystems / habitats vulnerable to plant invasion or already invaded by alien plants;
  • Identifying potential Invasive Alien Plant Species;
  • Preparing protocols for early detection and risk assessment of alien invasives;
  • Path and mechanism of invasion including succession;  
  • Economic implications of Biological Invasion;
  • Ecological and Environmental Impact of invasion and spread with special reference to biodiversity and soil;
  • Value addition and sustainable utilization of bio-resources for weed and pest management
  • Policy &  legislative mechanisms for management/eradication/ mitigation;
  • Selection of at least 25 most noxious invasive species from different regions and consolidation of all available information including their biology, itemizing at the same time the knowledge gaps;
  • Identification of  a cross–sectoral group to assess the situation in the form of case-studies on these species, and also to deal with the prediction, prevention and control;
  • Identification of  a nodal local agencies to coordinate all the above efforts, to develop a national policy
  • Launch of a relatively long-term coordinated research programme involving 5-6 regional centres to cover major geographical areas.