Once a sideline in pine plantations, pine straw has become quite an industry. At almost $4 per bale, pine straw is now being harvested and sold by many landowners. In fact, pine straw theft is a big problem in South Carolina’s forests.
Pine straw, particularly from longleaf pines, is highly valued by landscapers. It is light, easy to transport and is relatively easy to apply. Homeowners find the red color of the undecayed needles attractive. While pine straw may be too acidic for some plants, it does provide many important benefits as a mulch as it reduces growth of weeds and moisture loss from the soil and improves soil texture. As mulch breaks down it releases nutrients required by trees for growth.
But all of these benefits are important to healthy pine forests too. Removing the layer of pine straw allows weed trees to establish more easily. These weeds compete with trees for nutrients and water. A bare soil surface loses more water to evaporation than a mulched surface, and trees in these conditions can be water-stressed.
Although trees remove as many nutrients from their leaves before they let them fall, some nutrients, like calcium and magnesium, are not mobile enough and remain in relatively high levels in the fallen foliage. Even nutrients like nitrogen, which is mobile, can be found in fallen leaves, though at much lower levels. However, with approximately one ton of mulch covering an acre of the forest floor, even the smaller levels of nitrogen and phosphorus add up. These nutrients may be important, particularly in forests with poor soils or where weed species are competing for scarce resources. The process of gathering pine straw can also damage trees and their roots, especially if machinery is used.
Harvesting pine straw is not always bad for the forest. The South Carolina Forestry Commission harvests pine straw from some of its forests. The key is to do it sustainably. Pine straw should never be harvested more than once a year, and it is probably better to only harvest every other year. This reduces the potential of damaging tree trunks and roots and allows some of the leaf litter to decay and keep the soil healthy. If you are harvesting pine straw from very poor soil, you may consider fertilizing your trees to put back the nutrients you are removing.
Some landowners may be tempted to keep dense stands of trees, thinking, incorrectly, that more trees equals more pine straw. Thinning will reduce the amount of pine straw for a year or two, but when the crowns spread out, straw production will resume at normal levels. Also, if you don’t thin your trees, insects like the Ips engraver beetles will.