Open Access
Forests may need centuries to recover their original productivity after continuous intensive management: an example from Douglas-fir stands
(Elsevier, 2012) Blanco Vaca, Juan Antonio; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
How long would it take for forests to recover their original productivity following continuous intensive management if they are left untouched? This issue was explored using the model FORECAST, calibrated and validated for coastal Douglas-fir stands on Vancouver Island (western Canada). Three types of forest management (production of timber, pulp, and biomass) were simulated, being different in utilization level and rotation length (stem-only and 75-year rotation for timber production, whole-tree and 30-year rotation for pulp/fibre, and whole-tree and 15-year rotations for biomass production). Management was simulated for 150 years, followed by several cycles of natural growth without management ending with a stand-replacing windstorm with a return time of 200 years. Productivity-related ecological variables in previously managed stands were compared to natural forests. Stands developed after management for timber would quickly reach values similar to non-managed forests for tree and understory total biomass, stored carbon, available nitrogen and soil organic matter (SOM). However, intensive management regimes designed for fibre and biomass production would cause a decrease in SOM and nutrient availability, increasing understory biomass. As a consequence, stands recovering from intensive management would need at least two stand-replacing events (400 years) to reach a productivity status similar to non-managed stands. Stands developed after management for biomass would take much longer, up to 600 or 800 years to recover similar values of SOM and understory biomass, respectively. Current fertilization prescriptions will likely be not enough to stop a quick drop in forest productivity associated with intensive management. Intensifying forests management to achieve short-term objectives could produce a reduction of stand productivity that would influence tree growth for very long time (up to several centuries), if such management is continuously implemented at the same stand. Some of these effects could be reduced if one rotation of intensive management (for pulp or bioenergy) is followed by a rotation of management for timber, or leaving the forest without management for an equivalent time.
Open Access
Highlighting complex long-term succession pathways in mixed forests of the Paciﬁc Northwest: a Markov chain modelling approach
(MDPI, 2021) Blanco Vaca, Juan Antonio; Lo, Yueh-Hsin; Kimmins, J.P. (Hamish); Weber, Adrian; Ciencias; Zientziak
Forest succession is an ecological phenomenon that can span centuries. Although the concept of succession was originally formulated as a deterministic sequence of different plant communities by F. Clements more than a century ago, nowadays it is recognized that stochastic events and disturbances play a pivotal role in forest succession. In spite of that, forest maps and management plans around the world are developed and focused on a unique “climax” community, likely due to the difﬁculty of quantifying alternative succession pathways. In this research, we explored the possibility of developing a Markov Chain model to study multiple pathway succession scenarios in mixed forests of western red cedar, hemlock and Paciﬁc silver ﬁr on northern Vancouver Island (western Canada). We created a transition matrix using the probabilities of change between alternative ecological stages as well as red cedar regeneration. Each ecological state was deﬁned by the dominant tree species and ages. Our results indicate that, compared to the traditional Clementsian, deterministic one-pathway succession model, which is unable to replicate current stand distribution of these forests in the region, a three-pathway stochastic succession model, calibrated by a panel of experts, can mimic the observed landscape distribution among different stand types before commercial logging started in the region. We conclude that, while knowing the difﬁculty of parameterizing this type of models, their use is needed to recognize that for a given site, there may be multiple “climax” communities and hence forest management should account for them.
Open Access
Fire in the woods or fire in the boiler: implementing rural district heating to reduce wildfire risks in the forest-urban interface
(Elsevier, 2015) Blanco Vaca, Juan Antonio; Dubois, David; Littlejohn, Dale; Flanders, David N.; Robinson, Peter; Moshofsky, Molly; Welham, Clive; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Many rural communities in British Columbia (western Canada) are at risk from wildfire. This risk will increase over time as a result of climate change because of higher average temperatures, longer growing seasons, and more intense droughts. On the other hand, these communities are also faced with rising fuel costs and a growing demand for heat as suburban population increases. The fact these communities are surrounded by forests presents an opportunity to combine community wildfire risk abatement with bioenergy development. Additional co-benefits include: 1) reduced community energy expenditures; 2) the creation of local jobs; 3) climate change mitigation; and 3) increased community energy security. Here, we present results from three pilot rural communities (Burns Lake, Invermere, and Sicamous, British Columbia) designed to evaluate the feasibility of wildfire risk abatement in conjunction with bioenergy production. Maps were created showing each community’s forest-urban interface area with quantified estimates of its sustainable woody biomass resource potential under different management scenarios while monitoring ecosystem and soil health. The results and experience gained through this work has been synthesized in a calculator tool to help other communities make their own screening-level assessments. This calculator is a freely available on-line tool: FIRST Heat.
Open Access
Soil organic matter: a sustainability indicator for wildfire control and bioenergy production in the urban/forest interface.
(The Soil Science Society of America, Inc., 2014) Blanco Vaca, Juan Antonio; Dubois, David; Littlejohn, Dale; Flanders, David N.; Robinson, Peter; Moshofsky, Molly; Welham, Clive; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Many rural communities in British Columbia (western Canada) are increasingly at risk from wildfire as temperatures rise and droughts become more frequent. In addition, these communities are also faced with rising fuel costs, and a growing demand for heat as their populations increase. The fact these communities are surrounded by forests presents an opportunity to combine community wildfire risk abatement with bioenergy development. Here we show how the ecological model FORECAST was linked with GIS and economic models to create a freely available on-line tool (FIRST Heat) to help other communities make their own screening-level ecological assessments of combining wildfire risk control with district heating systems. The tool incorporates an ecological sustainability index based on the relative change in soil organic matter (SOM) after 50 years of management compared to initial levels. Two thresholds were defined: 10% SOM lost as “warning” level, and 20% SOM lost as “critical” level. The tool was able to adequately capture the influences of ecological zone, stand age, site quality, and intensity of forest management on SOM losses. Stands in the sub-boreal and arid interior were significantly more exposed to SOM losses than in other ecological zones, as well as soils in old-growth forests. Stands in poor sites were significantly more sensitive to forest management than young and fertile sites. All things considered, our results show the suitability of incorporating ecological models and SOM thresholds in user-friendly decision-support tools to successfully transfer scientific knowledge on forest soils to local stakeholders and decision makers.

Blanco Vaca, Juan Antonio

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