Best Animal for Preventing Underbrush?

I'm considering the idea of purchasing a piece of land that has a lot of weedy secondary forest. I want to rent the land to cattle farmers, but I also want to preserve and improve the forest over time. I know most others locally would purchase this land and just slash and burn it. Maybe they would first harvest a couple trees here and there that have decent timber, and sell them to the local carpenter.

What I'm thinking is to save all the trees that are past a certain height, and only clear the undergrowth (3m height or less) using machetes. I want to completely get rid of the undergrowth, and replace it with pasture grass. I've seen a few examples locally of timber/pasture agroforests where people planted timber trees into pasture or vice/versa.. The results actually work pretty well. The timber trees help nutrient cycling, and provide shade for livestock, so these sorts of properties are sought after when people are looking to rent cattle pasture.

I can have people clear all the undergrowth in a short amount of time, but it will always try to regrow. So, what animal or animals are best to keep the undergrowth from resprouting. I was thinking pigs, but I'm not sure if they would also harm the larger trees I'm trying to maintain. There are some tropical sheep breeds that could help, but I doubt they'd eat everything. Normally goats would work, but no one raises goats anywhere near here, so I'm thinking that maybe it's just not the right climate.

How long would I need to maintain the animals in the undergrowth before I could successfully broadcast pasture seeds?

I don't have forest pigs so I could be wrong here but...my pigs are unlikely to help me eradicate underbrush. We do have a tree line with caragana spreading wildly and they don't bother it all aside from an occasional crushing as they walk. They aren't interested in eating woody things as far as I can tell. Maybe without other food options they would, or they might just break out. Hard to say.

Your success in getting pasture forage to grow will be heavily dependant on getting down to bare dirt as the seeds have MUCH better germination rates if they're raked into the soil.  Also, while preserving the trees is noble, if you want good pasture you still have to consider the canopy's effect.  I would selectively thin the tree aiming for at minimum 6m on center spacing (I'm assuming here your trees are some mix of conifer and/or deciduous hardwoods and not jungle type.  

To effectively clear that land goats or hair sheep can help but they won't consume anything woody.  So if the undergrowth is fairly mature you probably will have to hack it back, either manually with hand held tools (whether a machete or something with a small engine like a chainsaw or weed trimmer), or rent a piece of equipment like a mini-excavator or hire a forestry mulcher.  Once hacked back the caprines (goats/sheep) will be effective at keeping the regrowth at bay while you work on clearing excess trees, and prepping the ground for pasture seeds.

Re-reading, and to more directly answer your questions, it's less a matter of time that the sheep or goats are on the land and more a matter of the effort you put into prepping the ground.  Since you can only work on so much at a time, the animals will be used to keep the underbrush from re-growing in the areas you haven't yet been able to get to, and maintaining the areas you have completed until the cattle are ready to move in.  

The lack of local goats is probably more a factor of local convention than goats per se not being suitable to the environment.  People raise goats from the hottest parts of Africa to the northern reaches of the USA.  So there is likely a breed that would work for your application, but it may just not be feasible because nobody around you has them.  

I don't think pigs are much of a threat to large, established trees, but they certainly would be to saplings and immature trees.  How effective they'd be at clearing depends heavily on the breed.  A type that loves to root through soil for tasty tidbits would be the kind you'd want, rather than a grazer like kunekune.  

Andrew Mayflower wrote:Re-reading, and to more directly answer your questions, it's less a matter of time that the sheep or goats are on the land and more a matter of the effort you put into prepping the ground.  Since you can only work on so much at a time, the animals will be used to keep the underbrush from re-growing in the areas you haven't yet been able to get to, and maintaining the areas you have completed until the cattle are ready to move in.  

The lack of local goats is probably more a factor of local convention than goats per se not being suitable to the environment.  People raise goats from the hottest parts of Africa to the northern reaches of the USA.  So there is likely a breed that would work for your application, but it may just not be feasible because nobody around you has them.  

I don't think pigs are much of a threat to large, established trees, but they certainly would be to saplings and immature trees.  How effective they'd be at clearing depends heavily on the breed.  A type that loves to root through soil for tasty tidbits would be the kind you'd want, rather than a grazer like kunekune.  

So you'd argue that goats are the better option? I like hairsheep here, but I'm sure goats would be better. Pigs aren't really recommended then for my purpose? How do these animals get along together in terms of parasites?

You mentioned a couple climates for goats, but I haven't heard of many goats that are successful in humid tropical jungle type environments. My area is a little cooler than low jungle, because we're at 950m elevation. That means the typical high temperature is 80F instead of 90F. The closest government run weather station measures 1750mm of avg. annual rainfall, but that's further out in the valley. We're in the foothills of a huge cloudforest mountain range, so I'm sure we easily get over 2000mm of avg annual rainfall. Our house location is basically an observatory of how the orographic effect works. We're on the ridge of a steep foothill, so it's just us and the sky and the mountains. You can literally witness how storms form and get stuck, unable to cross over the mountain range.

The interesting thing though, is that there is a "dry" season, when It's significantly less wet, and sunnier. The rainy season is kind of a drag. Lots of grey days, and torrential Noah's ark type rain events that happen at least a couple times per month. We've had nights where the pounding rain just does not let up. During some storms it rains so hard and so long that it actually feels stressful. This is what I feel would limit the success of goats here, but I could be wrong. I have heard of Nigerian Dwarf Goats, which suggests they might be adaptable to a more jungle climate...unless there are significantly drier parts of Nigeria. I can't recall hearing of examples of rainforest goats. Even if there were, I'd be surpirsed if they were available in Peru. Most of the agricultural development is done on the coast in this country, so I'd be more likely to find goats better suited to dry environments. Eastern Peru is basically it's own country, which lacks a lot of basic services and commodities. There is one research station nearby that's run by the regional government. They've developed F1 hybrids of Dorper and Pelibuey sheep. I don't recall if they have goats. They mostly work with cattle, and have stuff like Brangus. Most cattle are pretty successful in our neighborhood, so I don't know if that's any indication to you that goats would be successful.

Based on our 6 years experience only, pigs will mess with baby trees, pull them about, uproot them, eat them if the leaf is interesting... but not guaranteed.  Sheep and goats will probably eat young growth but not bother with older stuff or woody stuff, although there is a good chance that they will debark young trees.  I think a lot depends on your time frame.  We have used pigs and sheep living together to clear areas, but you may still need to clear things by hand where the critters are not at all interested.

Lots of good comments here.

Effective silvo-pasture likely needs the canopy opened to allow adequate light to the soil.

Goats will be affective at clearing leafy/thin brash, but they won’t kill the root systems.

Pigs may kill root systems, but only if they are penned into the area for long enough, and in sufficient numbers, to till the soil.

With this in mind I’d probably plan around a combination of both, with movable electric fencing so you can manage the degree of impact they are having.