[APWG] [RWG] Ecosystem Restoration Collapse

[Wayne Tyson]

APWG:

Ecosystems are a reflection of the complex factors that make up habitats, and some of these factors are going to be different and change with time. Things like species composition are unlikely to quickly be the same under change, and many known and unknown factors are involved. As Imlay has pointed out, nothing is ever exactly the same, so the goal of "restoration" can't sensibly be to "return" and ecosystem to what it was or may have been in the past. The "restored" ecosystem may be different in the sense of conventional measurements, but if it is self-sufficient it will still be an ecosystem. The species composition will be a reconciliation of a number of forces, such as climate and the organisms themselves, in varying amounts and ratios that change with changing circumstances. Perhaps Imlay will elaborate on his earlier post. 

Fire, grazing, and other disturbances all have different effects depending upon uncountable and perhaps unknown or unknowable variables. 

As a practical matter, diversity tends to "wobble" a bit, and that's one of its advantages. Under one set of circumstances, types, species, and genes will "move" toward center-stage, as it were, and in another recede. DeLeo is quite right in her observation that the availability of propagules is an important factor, and introduction of seeds, spores, and other elements necessary for the development of an historic ecosystem component may need to be artificial--part of a restoration program. When natural sources and/or dispersal agents are missing, the restoration program should consider whether or not that piece of the puzzle should be left out or compensated for by acting as a temporary vector. 

Rodents and other fauna often play a seemingly contrary role in restoration programs, but I have learned to look more deeply into their role (Rodents, for example, are important in the soil-building process.) in the ecosystem recovery process, which may take more time that that arbitrarily "determined" by us. I have resorted to various tricks to "restore" structure, for example (e.g., perching and nesting poles and boxes, brush piles, etc.), which can have an indirect effect on faunal activity and its effects on the developing ecosystem. If a site is so isolated by development as to banish access and habitat for some top-predators like coyotes, for example, raptors and other predator species might be employed to limit the amplitude of boom/bust cycles. 

WT
  ----- Original Message ----- 
  From: DeLeo, Claire 
  To: apwg at lists.plantconservation.org 
  Sent: Monday, February 27, 2012 2:28 PM
  Subject: Re: [APWG] [RWG] Ecosystem Restoration Collapse


  We have done some fairly extensive grassland restoration of old ag fields in our agency. Some of these restoration projects go back 15 years. One thing we struggle with is managing our grassland restorations for disturbances that grasslands are evolved with, such as fire and grazing. We don't have the ability to manage some of our restored grasslands in this way because of prescribed fire restrictions or expense of fencing to allow grazing. When we can't manage this way, we see the weeds returning. We have to resort to mowing, but it doesn't really mimic natural grassland disturbances.

   

  The other thing we struggle with is diversity in our restorations. We are pretty good at getting cool season grasses to establish, but warm season grasses and forbs are much harder in our semi-arid climate. We aren't seeing these species come in on their own, probably because the seed source is not there in the surrounding areas (too much development).

   

  I have seen collapse of our grassland restorations when prairie dogs move in too soon after restoration has been initiated. I'd like to hear from others what the optimum time is for a grassland restoration to be able to support prairie dogs? We have been saying at least 10 years, but we really don't know. 

   

  Thanks, Claire

   

  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  Claire DeLeo

  Plant Ecologist

  Boulder County Parks and Open Space

  5201 St. Vrain Road

  Longmont, CO 80503

  303-678-6205



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