Challenges and constrains of conservation and management of even-aged and uneven-aged Nothofagus forests at Southern Patagonia: Adaptation strategies in the current socio-political framework.

MARTÍNEZ PASTUR, GUILLERMO J.; BARRERA, MARCELO DANIEL; CELLINI, JUAN MANUEL; LENCINAS, MARIA VANESSA; PERI, PABLO L.

Valdivia

Workshop; XI Uneven-aged Workshop: Challenges for increasing adaptability.; 2018

IUFRO

Abstract:Native forests tends to uneven-aged structures ontime, increasing their ecosystem services (ES) andbiodiversity values. However, traditional silviculturepromote the even-aged structures, increasing thetimber quality values and decreasing the operationalcosts. These silviculture proposals make feasible theforest industry at large scale, generating simplifiedforest structures, and open a great debate about theirsustainability compared to multifunctional landscapes.The challenge for the new silvicultural proposals is todevelop alternatives that maintain the ecologicalfunctionalities of the uneven-aged forests into thesemanaged landscapes. Two research strategies areindispensables to this task: (i) BACI approach (before-after-control-impact), and (ii) long-term monitoring.Both strategies were included in the PEBANPAnetwork (Biodiversity and Ecological Long-Term Plotsin Southern Patagonia), and the outputs from the last25 years are discussed here. Shelterwood cuts andclearcuts, as well as thinning cuts, were proposed astools to homogenize the native forest structure,generating significant impacts over biodiversity and ESvalues. Some variables presented a negative trend (e.g.biodiversity and supporting ES), while others werepositives (provisioning ES). Variable retentionapproach was proposed as an alternative to decreasethe impacts of these traditional silviculture, leading touneven-aged stands by patches, decreasing theimpacts both, at stand and landscape level. Thisproposal allowed to decrease the impacts in all thestudied variables in the first 20 years of themanagement cycle. Also, their implementation wasfeasible to implement for large scale timberoperations, decreasing the harvesting costs, andmaintaining the yield compared to the first cut of theshelterwood cuts. The advantages of the variableretention approach can be explained in the promotionof the uneven-aged structure in-situ, leading toheterogeneous landscapes combining differentmanagement objectives in each managed stand.Knowledge gaps and silviculture challenges will bealso presented and discussed.