Restoration Silviculture: An Ecophysiological Perspective - Lessons learned across 40 years

Involvement in forest restoration programs across North America for the past 40 years, dealing with nursery cultural practices, operational seedling quality programs and defining seedling performance on restoration sites has given me a unique perspective, which I have used to examine programs from both a research and operational perspective. Certain biological patterns and themes continually appeared across these programs and this paper discusses five of the most common themes.Learning To Think Like a Tree – It is important for practitioners to develop an understanding of the ecophysiological performance of tree species in a nursery or forest restoration program in order to understand how seedlings grow. This understanding leads to sound biologically based cultural decisions to improve seedling performance.Stress and the Cyclical Nature of Stress Resistance – Seedlings are exposed to stress when environmental conditions limit their performance. Plants develop physiological resistance attributes to mitigate stress and these attributes change throughout the seasonal cycle. Practitioners have developed hardening cultural practices that enhance seedling stress resistance, thereby improving seedling quality and site restoration success.Seedling Quality: Product versus Process – Seedling quality is an important component of successful restoration. Typically seedling quality is examined from a product perspective, thus defining functional integrity, operational grading or sometimes performance potential. An alternative approach monitors the process, with product quality the final output.Planting Stress and Seedling Establishment – Planting stress is prevalent in forest restoration. The act of planting can result in a seedling that does not have proper connections for water movement through the soil-plant-atmosphere continuum (SPAC). Seedling water stress, reduced growth performance and potentially death can occur if this SPAC connection is not restored.Seedling Death: Sometimes Simple and Sometimes Complicated – Seedling death can occur in restoration programs as a result of environmental extremes or incorrect management practices. Some problems can be easy to diagnose and correct practices can be implemented to rectify the problem. Other times, issues are complicated and it can be a challenge to define the potential factors causing seedling death

Somatic Embryogenesis for Conifer Seedling Production: The Biology of Scaling

Conifer somatic embryogenesis has long been recognized as an advanced vegetative propagation technology. Somatic embryogenesis provides a platform for capturing and long-term preservation of elite genotypes and developing commercial scale-up systems for mass production of plants. Although, significant success has been reported in improving conifer somatic embryogenic protocols, little has been presented to describe the complexity of integrating in vitro (laboratory) and ex-vitro (greenhouse) programs for developing a commercial production system capable of delivering tens of millions of conifer somatic seedlings. This integration requires both programs to run in concert and produce propagules capable of surviving and growing under greenhouse conditions at very early stages. It also requires the integration of seedling development events to ensure the production of quality seedlings that meet needs of the forest restoration program. This paper describes the importance of protocol optimization for scaling-up the in vitro and ex vitro programs. The ‘biology of scaling’ is discussed in view of plant cell, embryo, germinant and somatic seedling requirements throughout the program. Logistical issues related to protocol optimization and scale-up are addressed. Specific control points for monitoring and controlling the commercial process are presented. The importance of developing standard operating procedures, media batch records, and quality control systems are discussed. Ultimately, a fully integrated system capable of producing tens of millions of conifer somatic seedlings is presented

Direct Seeding in Reforestation – A Field Performance Review

Direct seeding has been considered a forest restoration option for centuries. Over the past half century, the use of this practice has declined in developed countries as forest regeneration programs have advanced with the production of quality seedlings that can successfully establish restoration sites. Direct seeding is being reconsidered as a restoration option as the potential size of the worldwide forest restoration program has grown because of massive deforestation in third-world nations and due to global climate change. This review examines direct seeding from a number of perspectives. First, merits of using this practice in restoration programs are defined. Major merits of this option are that it can be done quickly, over hard to reach and large disturbed areas, and at a relatively low cost. Second, current research findings from restoration programs are discussed. The major finding is that seedling establishment rates are low (i.e. typically around 20% of seeds planted) due to site conditions, seed predation and vegetation competition, and field performance (i.e. survival and growth) is lower than planted seedlings. Third, operational practices for the application in restoration programs are reviewed. To successfully conduct direct seeding programs practitioners need to consider seedbed receptivity, seed distribution and seeding rate. Fourth, potential new practices are presented. Some of these new practices attempt to create a more effective means to disperse seed across the site, minimize seed predation or create a more favorable microsite environment. This review provides a synthesis of what is known about direct seeding, thereby allowing practitioners to make a rational decision of whether to apply this practice towards their forest restoration program

Opening Letter

"The best time to plant a tree is twenty years ago. The second best time is now." Chinese proverb There are five million hectares of new forests planted each year, according to Global Forest Resources Assessment (FAO 2015). How successful are we in planting these new forests? What are challenges that practitioners meet today in planting forests? What are challenges that forests established today will face in decades to come? There is a myriad of research results and a body of knowledge large enough to understand principles behind the field performance of planted forests. The environment is dynamic and inputs and outputs continually change, so there is a constant need for new research ranging from the global to microsite scale, and from the ecosystem and species to the population and genotype scale. The journal Reforesta offers a new site for publishing research results, presenting experiences, and bringing forward novel ideas and discussions on reforestation issues. Reforesta editors will strive to combine academic excellence with professional relevance and wish to appeal to both the professional and academic communities. There are a large number of scientific journals, many of which deal with forest ecosystems. So a reasonable question could be: Do we need yet another professional journal? We say yes, because of the following reasons. Reforesta will be a "niche" journal, focusing on research stemming from sourcing seed, to nursery cultural operations, to field planting (e.g., afforestation, reforestation and forest restoration). In addition, Reforesta will cover topics of forest genetics, tree breeding, and stand silviculture. We will encourage the submission of papers that provide interest and value to the international readership dealing with planted forests, such as: 1) novel ideas or approaches to reforestation challenges; 2) connections between plant ecophysiology and seedling field performance; 3) testing of new techniques and products in production of forest reproductive material, and at the planting site; and 4) reviews and discussions on timely and important topics. Establishment of the new journal can be compared to establishing a new forest. Initiation of the Reforesta journal will be supported by the editorial team (i.e. planning and site-species or site-provenance matching). The team will then select appropriate papers from the contributions of willing authors (i.e. selection of planting material, nursery operations, and culling). Then the stage is set: the web-site is operational; the journal is registered and applied for indexing (i.e. site preparation, monitoring and feedback). The inaugural issue is published (i.e. seedlings are planted) and the research community is notified (i.e. post-planting silviculture operations). The parallel between Reforesta and establishing a new forest will continue. The future success of Reforesta will be dependent on the interaction with its contributors and readership. The future size of the Reforesta audience will be dependent on its ability to secure its niche, and to provide services to the professional forestry community, while developing a symbiotic relationship with other forestry journals (i.e. competition and/or facilitation). Performance of Reforesta will be measured by monitoring readership and response levels (i.e. reforestation success) and its lifespan will be defined by its resilience and adaptation potential. Reforesta will follow the open access policy of non-profit journals, with no processing charges applied to any accepted articles and no fees for accessing articles published by Reforesta. This principle ensures that forest research is free and available to forestry professionals in support of a greater global exchange of knowledge. Like planted forests, Reforesta hopes to grow in an open environment with appropriate tending from the editorial team, thereby growing with needs of the professional forestry community. The Reforesta journal has one additional advantage. It is established solely on the enthusiasm of the editorial team. As long as there are enthusiasts recognizing the need for Reforesta, the journal will continue to flourish. The editorial team is here to set the scientific standards and ethical rules for the journal. However, the ultimate direction of Reforesta depends on authors and readership. We are delighted to launch this new journal, a product of a joint venture between enthusiasts ranging from undergraduate students to senior researchers and scientists. Reforesta has one underwriting sponsor - The Scientific and Professional Society Reforesta. We thank them for their support. Under the leadership of Vladan Ivetić, Editor-In-Chief, who initiated the idea for Reforesta, and Steven Grossnickle, Consultant-Editor who plays a supporting role; we have a worthy team. The inaugural issue of the Reforesta journal is in form of Thematic Proceedings resulting from the International Conference on Reforestation Challenges, which took place on 3-6 June 2015 in Belgrade, Serbia. We wish to thank participants who attended the Conference and especially thank the invited authors who contributed to this inaugural issue. We are also grateful to the technical team, made up of excellent young students and researchers. We will continue to develop and fine-tune content to enhance the quality, scope and diversity of Reforesta as the journal grows into an established member of the professional forestry community.&nbsp

Physiological variation among western redcedar (

• Variation in the ability of western redcedar (Thuja plicata Donn ex D. Don) populations to withstand water stress may exist because this species is found in coastal and interior biogeoclimatic subzones representing the full range of precipitation regimes in British Columbia, Canada. • Seven western redcedar populations from locations in British Columbia, representing a wide range of habitat types, were assessed for their gas exchange and water relations response to controlled drought. • Before drought, population variation occurred in stomatal conductance, net CO2 assimilation rate and intrinsic water use efficiency and the relative water content at turgor loss point. During drought, populations had different responses of net CO2 assimilation to decreasing predawn shoot water potential. After drought, populations differed in stomatal conductance and intrinsic water use efficiency, plus osmotic potential at turgor loss point, osmotic potential at saturation and apparent cuticular transpiration. Western redcedar populations from drier-inland habitats had a lower osmotic potential at turgor loss point, lower relative water content at turgor loss point and lower apparent cuticular transpiration in response to drought than populations from coastal origin with temperate maritime habitat. • Reduction of cuticular water loss and adjustments of cellular water relations in response to drought was found to occur among seven western redcedar populations originating along a precipitation gradient while; there were minimal population differences in the gas exchange response to drought

Seedling Quality: History, Application, and Plant Attributes

Since the early 20th century, silviculturists have recognized the importance of planting seedlings with desirable attributes, and that these attributes are associated with successful seedling survival and growth after outplanting. Over the ensuing century, concepts on what is meant by a quality seedling have evolved to the point that these assessments now provide value to both the nursery practitioner growing seedlings and the forester planting seedlings. Various seedling quality assessment procedures that measure numerous morphological and physiological plant attributes have been designed and applied. This paper examines the historical development of the discipline of seedling quality, as well as where it is today. It also examines how seedling quality is employed in forest restoration programs and the attributes that are measured to define quality. The intent is to provide readers with an overall perspective on the field of seedling quality and the people who developed this discipline from an idea into an operational reality

Yellow-cedar and western redcedar ecophysiological response to fall, winter and early spring temperature conditions

Western redcedar (Thuja plicata Donn) and yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach) populations originating from an elevation zone where these two species naturally coexist were monitored to define their performance patterns in response to seasonal temperature conditions within the fall, winter and early spring field conditions of the Pacific Northwest coastal forest region. Western redcedar and yellow-cedar populations were measured for changes in growth rhythms, photosynthetic patterns and freezing tolerance. Net photosynthesis (Pn) for both species was directly related to minimum air temperature that occurred during the prior evening, though no population differences were detected within each species. Photosynthesis was greater in western redcedar, than yellow-cedar when minimum air temperature was above freezing. Freezing temperatures from ~0 to –5 °C caused a greater reduction in photosynthesis for western redcedar, though not a complete cessation of photosynthetic capability in either species. Freezing tolerance increased at a moderate rate in the fall as mean air temperature declined for both species when their shoot systems were still active, with freezing tolerance increasing at a rapid rate when shoot systems showed no mitotic activity. No shoot growth or mitotic activity was detected in shoot tips of both western redcedar and yellow-cedar when mean air temperature decreased to 4 °C for the previous week. No population differences, within each species, were detected in the development of fall freezing tolerance. Yellow-cedar obtained a slightly greater level of freezing tolerance when fall temperatures were < 4 °C. Both species had a loss of freezing tolerance as mean air temperature increased in late winter. Shoot growth resumed in both species in late winter when mean air temperature increased to 6 to 6.5 °C. The resumption of shoot growth resulted in a faster loss of freezing tolerance for western redcedar compared to yellow-cedar.Réponses écophysiologiques de Thuja plicata Donn et de Chamaecyparis nootkatensis (D. Don) Spach aux conditions thermiques automnales, hivernales et printanières. Des populations de Thuja plicata Donn et de Chamaecyparis nootkatensis (D. Don) Spach provenant d’une zone d’altitude où ces deux espèces coexistent ont été suivies pour définir leurs types de performances en réponse aux conditions thermiques saisonnières de l’automne, de l’hiver et du début du printemps dans la région forestière côtière du Nord Ouest Pacifique. Les populations de Thuja plicata et de Chamaecyparis nootkatensis ont été mesurées pour étudier les variations dans les rythmes de croissance, les types d’activité photosynthétique et la tolérance au gel. Pour les deux espèces, la photosynthèse nette (Pn) était directement liée au minimum de température du soir précédent, bien que des différences n’aient pas été mises en évidence entre populations dans chacune des espèces. La photosynthèse était plus élevée chez Thuja plicata que chez Chamaecyparis nootkatensis lorsque la température minimum était au-dessus de zéro degré. Les températures glaciales de –0 à –5 °C induisent la réduction la plus importante de la photosynthèse chez Thuja plicata, quoiqu’il n’y ait pas un complet arrêt de la capacité photosynthétique chez l’une ou l’autre des espèces. Pour les deux espèces, la tolérance au gel s’accroît en automne : modérément avec l’abaissement de la température moyenne de l’air quand leurs systèmes de pousse étaient encore actifs, rapidement lorsque leurs systèmes de pousses ne présentent plus d’activité mitotique. Aucune croissance des pousses ou activité mitotique n’a été notée chez Thuja plicata et Chamaecyparis nootkatensis lorsque la température moyenne de l’air baisse de 4 °C pendant le jour précédent. Aucune différence n’a été mise en évidence entre populations pour chacune des espèces, pour ce qui concerne le développement de la tolérance au gel. Thuja plicata a présenté un niveau de tolérance au gel légèrement plus grand quand en automne, les températures étaient < 4 °C. Les deux espèces avaient une perte de tolérance au gel avec l’accroissement de la température de l’air en fin d’hiver. La croissance des pousses a repris en fin d’hiver lorsque la température moyenne augmentait jusqu’à 6 à 6,5 °C. La reprise de la croissance des pousses a été le résultat d’une perte plus rapide de la tolérance au gel chez Thuja plicata par comparaison avec Chamaecyparis nootkatensis