Virtual Environmental and Humanitarian Adviser Tool – (VEHA Tool) is a tool
to easily integrate environmental considerations in humanitarian response. Field Implementation guidances are useful for the design and execution of humanitarian activities in the field.

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VEHA - Field Implementation Guidance

Agricultural livelihoods
Recover livelihoods - Agroforestery
Forest pest prevention

Forest pest prevention


Environmental factors causing/contributing to the needs and affecting the humanitarian activity

A forest pest is any living organism that can cause harm to plants, trees or forests, or to forest products. Such organisms may be insects, spiders, mites, nematodes, fungi, bacteria, viruses, weeds (including woody weeds), mammals and other wildlife, and parasitic plants such as mistletoe.

Serious pest infestations can undermine years of management effort and greatly hamper the achievement of forest management objectives. Pests can adversely affect tree growth, vigor, and survival and reduce the yield and quality of wood and non-wood products. Damage caused by pests can degrade wildlife habitats, thereby reducing local biodiversity, and can also have major negative impacts on recreational, aesthetic, and socio-cultural values.

The presence of certain pests may result in the curtailment of reforestation programmes or require a change in the tree species used, and it may require the clear-felling of large areas of forest dominated by infested trees.

Gender, age, disability and HIV/AIDS implications

Indigenous people may have traditional knowledge about natural/organic pest prevention methods.


Environmental impact categories

Air pollution
Climate Change
Loss of biodiversity and ecosystems
Soil pollution
Water pollution

Summary of Impacts
Summary of potential environmental impacts

Invasive species disrupt forest ecosystems
Loss of biodiversity due to invasive species

Impact detail
Detailed potential environmental impact information

Native species have evolved to the local climate, hydrology, and geology conditions over a long period of time. These plants, animals, fungi, and insects define the basic structure and function of a local ecosystem.

Non-native species, on the other hand, are introduced on purpose or by accident and can disrupt ecosystems. Non-native or exotic species may not have natural predators at the sites where they are introduced, so they are prone to proliferate and outcompete healthy, native species, which can threaten the entire forest ecosystem.

Forest pests can be spread in many ways, including in forest operations. Increased travel, faster transportation, and greater volumes of international trade are increasing the risk that pests will spread to new areas, and local climatic change may be accentuating the potential of some pests to establish in new areas.


Summary of environmental activities

Apply Integrated Pest Management (IPM):

1. Maintaining the health of forests;

2. Managing native pest disturbances that threaten forests; and

3. Preventing the entry and spread of non-native species into new areas.

Detailed guidance for implementing suggested environmental activities

IPM can be defined as a combination of prevention, observation, and suppression measures that are ecologically and economically efficient and socially acceptable, in order to maintain pest populations at suitable levels. Prevention may include selecting species and varieties that are well suited to a particular site, as well as natural regeneration, planting, and thinning practices that reduce pest populations and favor sustainable control by natural enemies. Healthy trees and forests are less likely to be affected by pests, so maintaining the strength and vitality of trees is an important preventative measure. The selection and breeding of trees for pest resistance is another preventative tool that has grown in importance in recent decades.

Careful observation and monitoring of pest populations, for example through visual inspection or trapping systems, can indicate when and where control measures are needed. For pest suppression, it is preferable to use mechanical control, biological control involving the use of natural predators or controls and organic/biopesticides, and other sustainable methods rather than synthetic/chemical pesticides.

Biological control through the use of natural predators or controls is an essential component of IPM. Beneficial natural predators or controls may be promoted by suitable silvicultural practices – biological control by conservation, or by supplemental releases – biological control by augmentation.

The latter may also involve the use of biological pesticides, biopesticides, based on the natural microbial or fungal diseases of pests. A third approach commonly used in forestry, classical biological control, involves the control of non-native pests by importing natural predators or controls such as parasitoids, predators or fungal, bacterial or viral pathogens for pests, and arthropod herbivores and phytopathogens for weeds, from their regions of origin. This approach has been carried out successfully for well over a century. Nevertheless, introduced biological control agents can have undesirable side effects and it is important, therefore, to gather all possible information on biological control before introducing a natural predator or control of a pest to an area where it does not normally occur.

Lessons Learnt
Lessons from past experiences

Foundations for Farming, Zimbabwe, has reported success working with local farmers to revert to the natural control of crop pests and disease. They have provided evidence of wildlife habitats and local biodiversity recovering.

Activity Measurement
Environmental indicators/monitoring examples

# of forest pests reduced to sustainable levels through natural/organic/traditional sustainable methods

Activity Status
Main Focus
Focus of suggested activities

Prevention of environmental damage

Environmental enhancement

Resource implications (physical assets, time, effort)

Time to map and identify pests and natural predators and to identify historical trends and natural prevention methods

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