You can put down your rakes, America.

While President Trump is right that we need better forest management across the West, removing leaves won’t play a big part in it. And the federal government will.

That’s according to Wally Covington, an emeritus professor of forestry at Northern Arizona University and one of the West’s leading experts in forest restoration and fire management.

I spoke with Covington on Tuesday morning, as he paused during a drive to a research plot near the South Rim of the Grand Canyon. My specific interest was forest litter. The debris that accumulates on forest floors has gotten a bad name in recent years because if it’s allowed to build up, it helps cause more catastrophic wildfires.

But forest debris is also a key source of nutrients in forest soils. And it’s not the only key factor driving the increasingly catastrophic fires across the West.

Here’s how Covington answered questions about the topic he’s dedicated his life to since 1976.

Q: Is there any truth to the idea that if we remove the leaves from the forest floor, that will help prevent wildfires?

A: To be charitable, which is hard, immediately around the footprint of a house raking 100 feet, maybe 150 feet around the footprint of the house could be part of creating a defensible space. As part of a program of protecting individual houses or other kinds of buildings, raking can make sense.

To be uncharitable — I mean, no. Goodness gracious. You know, he (Trump) heard something somewhere and oversimplified it, as he often does, and came up with some simplistic idea of how to deal with a problem. But raking — there is no place in the world where raking is an important part of extensive forest management. It just doesn’t happen.

Q: Isn’t the decomposition of forest litter essential to the health of a forest?

A: In deciduous forests like the hardwood forest of the northern tier of states, decomposition is the main mechanism for recycling nutrients. As you move in to warmer and drier types of forest, decomposition is slower. So decomposition by itself can’t keep up with the amount of litter that’s cast off from the trees.

In those situations, it’s the synergy between periodic fire and decomposition that results in the recycling of the nutrients that sustains forests and understory vegetation or shrubs and grasslands and so on. That maintains our productivity, diversity and health.

Q: How much clearing of younger trees and brush do you do in a ponderosa pine forest, in a given acre or so? Do you cut everything under a certain diameter and pile it up and burn it?

A: We call this ecological restoration treatments. On the average acre, there were, before fire exclusion around the 1870s and 1880s, somewhere between 15 and 50 trees per acre. These were mostly large-diameter yellow bark trees that ranged in age from 100 years up to 700 years in age. And then after heavy livestock grazing and fire exclusion, those densities increased to between 400 and 1,500 trees per acre on average.

How do you clear those trees out? If there’s road access, you can harvest and sell, but that’s only a minority of the trees that are there. The majority of the trees, as you implied, they’re smaller diameter. There’s not much of a market for them right now. So those you either have to pile and burn or in cases where they’re near housing developments, you can haul them off and burn them off-site.

Q: Isn’t burning them on-site important to the soil health of these areas?

A: We’ve actually looked at that, and our restoration prescriptions would call for lopping and scattering the tree tops. It’s called broadcast burning. You know, most of the nutrients are in the tops of trees, the pine needles and the small twigs, so you lop and scatter that before the burning.

Now, when you burn that material, it releases not only carbon, but also nitrogen, potassium, calcium, magnesium. Some of that, especially the nitrogen and phosphorus, can go up in the air, in smoke. But a lot of it stays on site. We’ve measured it after burning. We’ve gotten some nitrogen levels in the soil after burning that are equivalent to fertilizing with 200 or 300 pounds of nitrogen per acre, which is a lot of nitrogen.

Q: The president dismissed climate change as a factor in the recent wildfires. What do you think?

A: There’s no doubt that climate change is in full force. I personally started writing about this back in the ’80s in my research. And we’ve been following the effects of climate change on some of our plots.

Climate change causes several problems. It extends the fire season. The temperatures are higher. The fuels are drier because of temperature and the extended fire season. And then when fires actually occur, we get much stronger winds.

The other thing I’d say is this is a global phenomenon. If it were just occurring in the western USA, you could say they’re just managing the forest poorly there. But we’ve had it occur in the Eastern forest. This is also occurring in Australia and it’s occurring in Europe and it’s occurring in South America. It’s occurring in Siberia. The fact that it’s occurring everywhere makes it highly unlikely that this is solely a consequence of forest management, as President Trump has said.

Q: How should the increasingly hot climate change how we manage forests?

A: Among forest ecologists and restoration ecologists, we’ve been talking about this for 30, 40 years now. There are a couple of fundamental approaches. One of them would be to restore the area and all the natural self-regulatory mechanisms. Then the ecosystems will be able to better deal with climate change. Many of us are concerned that the climate change is occurring so rapidly that the natural mechanisms may not be able to keep up with it.

That leads us to what we think of as a more engineering approach, where we try to anticipate what’s going to happen, what kind of vegetation is most likely to be self-sustaining on this site in 30 years time, and we managed toward that. That’s called facilitated migration. Right now, it’s about evenly divided among scientists about which approach to do. My personal thinking is we need to not put all our eggs in one basket, but let’s do a variety of approaches, monitor them, and see which ones work.

Q: The U.S. Forest Service manages most of the forests in the states that have been affected by burning. Are they doing enough?

A: They’re doing what they can with the money they have. Congress provided them about three years ago an additional $187 million to implement the national fire plan, the cohesive strategy that the Western governors put together. That has resulted in an acceleration of treatments. In my opinion, we need to be doing about 10 times that much.

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Contact: tsteller@tucson.com or 807-7789. On Twitter: @senyorreporter