LIVE FENCES: This common silvopastoral system simply is a row of trees that follow property or pasture boundaries to which barbed wire is affixed. Farmers select species for two principal traits: 1) the ability to sprout and 2) the ability to grow quickly. Farmers build live fences by cutting straight branches from living trees, usually a little over 1 m in length. These “live posts” are then “planted” along the fence line and barbed wire is affixed to the post. Relatively quickly the live post sprouts roots and branches growing into a new tree. The spacing of these trees averages one every 3 m, or 30 per 100 m when all posts are comprised of live posts.  Farmers may also use pre-exisiting trees to delineate property and pasture boundaries, and then fill in the remaining space with either live or dead posts. Farmers prefer live fences because they are more economical and last longer than typical fences. Farmers frequently prune live fences to prevent tree competition with grass, and to reduce the probability of tree fall during a storm, destroying the fence. The conservation value of live fences lies in their ability to connect forest patches in fragmented landscapes and depends on tree diversity, density and the distance between the fence to the nearest patch amongst other factors. Photos: Live fences play important roles as corridors for biodiversity (top); some live fences are made by simply attaching barbed wire to pre-exisitng trees before the forest is cleared for pasture.

RIPARIAN FORESTS: As with live fences, riparian forests are linear elements in the landscape, the similarity however ends there. Live fences are comprised of a single row of trees, typically of the same species, and follow property or human made boundaries. Riparian forests, are classified by their proximity to streams or rivers and more closely resemble natural forests. They can be between a couple to over a hundred meters wide, and unlike live fences where the species are selected by farmers, trees found in riparian forests originate from natural regeneration, with species richness and composition  resembling that natural forests. Other features that distinguish riparian forests from other silvopastoral systems are the structural diversity of the forest. Because the similarities between riparian forests and native forests are high, they are the silvopastoral system with the greatest conservation value following forest fragments. In addition, they can play important roles in maintaining landscape connectivity. Unfortunately they are rapidly disappearing and lose their conservation value when cattle are permitted to enter to drink or graze.  Management practices that exclude cattle from these zones (see photos on the left) are amongst the most promising for conservation. Photos: a riparian zone (top), the same zone, but viewed from the pasture side where the farms has fenced off access to the stream (bottom).

TREES DISPERSED IN PASTURES: In addition to live fences, trees dispersed in pastures are the most common, and most traditional silvopastoral system found in our Honduras and Nicaragua field sites. Guevara refers to these as “los arboles que la selva dejo atras” or the trees that the forest left behind. Unlike live fences which are planted by farmers, trees retained in pastures are either relicts from when the forest was originally cleared for pasture, or less commonly, natural regeneration that is permitted by the farmer. This means that the majority of trees in pastures are natives, though the diversity is much lower than in natural forests.  Few farmers actively plant trees in their pastures without additional incentives such as payment for ecosystem services. The density of trees in pastures varies from zero, to approximately 30 or more per hectare. Few farmers permit greater than 25% canopy cover in their pastures fearing that greater tree cover will diminish the amount of pasture produced. The conservation value of a pasture increased with percent canopy cover, the diversity of trees found in that pasture, the number of strata or size classes of trees, and the distance of that pasture to the nearest forest fragment. In addition, selecting trees that are important sources of food for wildlife increases the conservation value of these systems. The photos on the left represent a pasture with low tree density (top) and high tree density (bottom).

FOREST FRAGMENTS: There are at least two reasons to include forest fragments as silvopastoral systems. (1) In pasture dominated landscapes, forest fragments are critical to conservation. (2) In both field sites, cattle are actively permitted to enter these forests to graze thus justifying the definition of integrating trees and livestock. We differentiate between forest fragments and pastures with high density by management techniques used in each. In forest fragments, the farmer does not actively promote the growth, or presence of grasses in the understory, but rather allows natural regeneration to occur. In Matiguas, Nicaragua forest fragments make-up approximately 10% of the landscape. Only fifteen of the forest patches in this landscape are greater than 10 ha in size, and only two are greater than 80 ha. Forest fragments are characterized by having relatively high tree species richness, dominated by native tree species, multiple horizontal strata and limited human management (extraction of fuelwood, timber, or non-timber goods). Some of the more important factors that increase the conservation value of forest fragments include the size of the fragment, the distance to the nearest adjacent fragments, and their size and finally the distance to the nearest road or path. Photos: One of the largest forest fragments in Matiguas (top) and a pasture with a forest fragment on top of the hill on the left, and trees dispersed in pastures on the hill on the right.