Influence of soil changes on natural regeneration in abandoned oil and gas fiels of Northern Patagonia (Argentina)

FUCHS, JULIO; GAINZA, MARIA ANDREA; FRAUNHOFFER NICOLÁS A.; ZULETA, GUSTAVO A.

Zaragoza. España.

Conferencia; 17th Annual International Conference of society for Ecological Restauration; 2005

Society for Ecological Restoration International

&amp;amp;lt;!-- /* Font Definitions */ @font-face {font-family:Bookman-Light; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} @font-face {font-family:Bookman-Demi; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:595.3pt 841.9pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&amp;amp;gt; Oil and gas exploitation constitutes a widespread and highly severe disturbance in arid shrub steppes of Patagonia. Natural regeneration of abandoned locations takes at least 45-60 years to reach 75% similarity in vegetation and burrowing wildlife composition and diversity with control areas. In order to reveal how changes in soil properties influence ecosystem rehabilitation, we investigated temporal trends in pH, electrical conductivity, gravel content and organic matter content in soil cores of 13 abandoned locations representing a 35 years chronosequence. We used a paired sample design, in which each oil/gas abandoned location was compared to a nearby reference site (control). Differences in the values of each of the four variables between the abandoned location and the control site were calculated for two habitat types: open (bare soil) and vegetation (mounds) patches. Temporal changes in these differences were examined by linear regression analysis with post-disturbance time as the independent variable. Our results indicate that only gravel content varied significantly with post-disturbance time in both habitat types: r= - 0.70 (p< 0.001) and r= -0.58 (p< 0.001) for open and vegetation patches, respectively. These results suggest that, in general, plant establishment is not primarily related to changes in soil properties; however, the considerable decrease in gravel content might play a role in the development of microsites suitable for germination, at least of some species. Keywords: Temporal soil changes, oil fields, Patagonia, soil physical properties, restoration.