For many years there are terrible forest fires in the U.S. (for example); I was wondering about pro-active measures ( I'm sure there are many). One possibility is using a small army of robots that are designed to 'go anywhere' and act like 'artificial goats' eating any dry brush or grass. Of course another army of robots could ,using local water from a lake or streams, fill up with say 100 gallons each ( if designed for this) and spray water everywhere even without a fire emergency. This might sound silly but you have a lot of robotic derigibles carrying 1000 gallons of water or more slowly floating over a forest sprinkling water everywhere like a mild shower. So could certain 'robot armies' be used to fight the dry conditions in a forest?
This is counterproductive, both ecologically and economically, and is also well beyond the capabilities of current robots.
Forests have evolved to live with, and in many cases, to depend on forest fires. Aggressive fire prevention by the US Forest Service and other agencies throughout much of the 20th century resulted in unintended consequences. Many native species need fire to reproduce. For example, the pinecones of lodgepole pines remain sealed shut for years and only open when exposed to the high heat of a forest fire. Decades of active fire suppression led to the replacement of some of those native species by invasive ones.
Another unintended consequence was making large fires even larger. Some of the most intense fires happened in areas where small fires had been successfully suppressed for a number of years. The resultant buildup of dead wood, brush, and smaller trees gave fires a way to spread to the canopy level, something that didn't happen so often when small fires regularly burned away that lower level of fuel.
One of the biggest fire threats to people is those people who insist on living in forested areas and then let the trees grow right next to their houses. The simplest solution: Don't do that then! The Forest Service and others offer education to homeowners on how to make their homes more fire resistant, and in some cases, polices areas to ensure homeowners are following some minimum standard.
Another solution, one not yet adopted by the Forest Service, is an approach taken by the Federal Emergency Management Agency with regard those who live in the most flood-prone areas. After flooding one too many times, FEMA essentially forces homeowners to sell their houses at market value to FEMA. FEMA then promptly tears them down and marks the area as uninsurable. This might appear to be a waste of money, but in the long run it saves FEMA money, and potentially saves lives. Texas and some other states take even more drastic measures with coastal properties. A house is condemned once the coast line has eroded to the point that it is closer than some minimal distance of the house.
We can't build such robots, yet
The terrain where forests grow is not exactly suitable to robots. Much of the forested land in the contiguous US is mountainous. What isn't mountainous is dotted with bogs, swamps, and lakes. The weather is often rather nasty. An autonomous robot that could navigate and survive through such terrain is far in the future. Adding the ability to clean up terrain is even further in the future.
Aggressive fire suppression requires clearing out shrubs such as chaparral, which is rather tough stuff, dead and down trees that can be several meters in diameter, and small to medium sized non-canopy trees whose trunk can be up to a meter or so in diameter. This is not the job for little goat-sized robots. This is a job for an industrial-sized robot, and ED-209 won't cut it.
It has been suggested that proper management of large herds of goats, cattle, deer, or elephants on the land are effective in preventing desertification. So perhaps this could be used to mitigate conditions leading to excessive grass and forest fires. Maybe your idea would scale-up more effectively if the robots were set to manage large herds of animals that themselves do what herbivores do to control fuel, fertilize, and cultivate forest and grassland.
So perhaps 'robot goatherds' rather than 'robot goats' is what you need.
I really don't know if this would be a good idea or not but you may find this TED talk about using stock animals to combat desertification very interesting.
Fire’s role in dry land ecology (especially of the US West) is well understood. It's fire suppression that led to the disasters we have now. Fire fills an important niche in warmer ecosystems; It substitutes the role normally reserved for soil decomposers (Fungi/bacteria), but burning the woody debris and vegetation it frees up material and and soluable soil carbon thats essential to plant growth. – it sweeps away weeds that choke the forest floor, allowing successor trees to continue to proliferate. Giant sequoia breeds this way – eliminates competitive weeds/invasives – reintroduces nutrients (ash) back into the soil, with dry ecology; wood doesn't decompose at a fast rate; so fire converts wood/plants into ash which is water soluable. – produces ethylene gas (a natural plant growth booster) – heat/smoke of the fire heats up cones in conifer trees to open and release their seeds – triggers plants lying dormant in the soil