PYGMY CONIFERS IN NEW MEXICO: WHERE IS ENCROACHMENT?

摘要

Encroachment is the growth of plant populations by either in-filling of low-density stands or appearance in a new habitat and plant association. Pygmy conifer (juniper and pinon) populations grew in the late little-ice-age period. Past population growth accelerates encroachment today. Long-distance dispersal by birds and other vertebrates increases the likelihood of encroachment within several miles of mature pygmy conifer stands. The central New Mexico Mountains and northern plateau, mesas, and rangelands are likely to be encroached by pygmy conifers when junipers and pinons are found on-site, or nearby. Forest restoration treatments, which reduce PIPO stands to scattered individuals or tree clumps, and fail to take into account increased seed rainfrom adjacent pygmy conifer stands, are likely to need frequent maintenance and may not reach long-term objectives. Pygmy conifer management zones are an alternative to individual site treatments to slow encroachment into valuable land-uses.