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Global Changes and Sierra Nevada Forests of the Future: Managing in the Face of Uncertainty
... Strategies and their underlying approaches and tactics are designed to align with one or more of three key adaptation concepts, or "options": resistance, resilience, and transition (Table 1) [46,71]. We adopt the specific wording of Swanston et al. [46] to define resistance actions as those that "improve the defenses of an ecosystem against anticipated changes or directly defend the ecosystem against disturbance in order to maintain relatively unchanged conditions"; whereas "resilience actions accommodate some degree of change, but encourage a return to near-prior conditions after a disturbance, either naturally or through management"; and "transition actions intentionally anticipate and accommodate change to help ecosystems to adapt to changing and new conditions". ...
... Increasing habitat connectivity and ecosystem redundancy have the potential to facilitate recovery through revegetation and repopulation [71,174,175] and are preventative measures that can buffer against the effects of unacceptable fire. Proximity to source populations and corridors provide pathways for vegetation regeneration and wildlife repopulation [176][177][178]. ...
... The immediate aftermath of a disturbance provides a very practical window for realigning successional trajectories to expected future conditions instead of historical references [71]. Facing altered climate and fire regimes, some forest types and vegetation communities will be unlikely to recover from large-scale or high-severity wildfires [35]. ...
As the effects of climate change accumulate and intensify, resource managers juggle existing goals and new mandates to operationalize adaptation. Fire managers contend with the direct effects of climate change on resources in addition to climate-induced disruptions to fire regimes and subsequent ecosystem effects. In systems stressed by warming and drying, increased fire activity amplifies the pace of change and scale of severe disturbance events, heightening the urgency for management action. Fire managers are asked to integrate information on climate impacts with their professional expertise to determine how to achieve management objectives in a changing climate with altered fire regimes. This is a difficult task, and managers need support as they incorporate climate adaptation into planning and operations. We present a list of adaptation strategies and approaches specific to fire and climate based on co-produced knowledge from a science–management partnership and pilot-tested in a two-day workshop with natural resource managers and regional stakeholders. This “menu” is a flexible and useful tool for fire managers who need to connect the dots between fire ecology, climate science, adaptation intent, and management implementation. It was created and tested as part of an adaptation framework used widely across the United States and should be applicable and useful in many fire-prone forest ecosystems.
... Thus, existing experience and approaches for managing dynamic and unpredictable systems can be brought to bear on the new challenges of climate change-related uncertainty. For example, adopting a more agile, learning-based approach to management (i.e., adaptive management) has been recognized by the Forest Service as an important principle for addressing climate change (Millar et al. 2007;Joyce et al. 2008Joyce et al. , 2009). The 2012 Planning Rule (USFS 2012b) provides for an "adaptive planning cycle" that allows the Forest Service to "adapt to changing conditions and improve management based on new information." ...
... A rapidly changing climate, in particular, is compromising the idea among many managers that restoring forest conditions to those reflected by their HRV/NRV is an optimal, or even achievable, outcome (Millar et al. 2007, Millar 2014, Hanberry et al. 2015, Golladay et al. 2016, McKelvey et al. 2021. Although the concepts recognize and reflect dynamic and cyclic conditions, the general assumption has been that these variations typically revolve around a mean value (i.e., despite fluctuations, the value remains stable over the long term). ...
... In fact, evidence suggests this may already be occurring in some places, as forest systems are nearing or have surpassed ecological thresholds due to extreme conditions beyond what they likely have experienced in the past (e.g., Young et al. 2019, Hansen et al. 2020). Therefore, a growing number of scientists argue that exclusively relying on a selected set of historical conditions as benchmarks for forest restoration outcomes will be increasingly untenable (Millar et al. 2007, Alagona et al. 2012, Millar 2014, Dumroese et al. 2015, Jacobs et al. 2015, Millar and Stephenson 2015 of NRV for a suite of ecological characteristics as a basis for measuring "ecological integrity" (USFS 2012b, Safford and Stevens 2017). Continuing and accelerating climatic changes, however, are complicating the application of these concepts in restoration, and forest practitioners increasingly will need to anticipate and manage for conditions that exceed historical ranges of variability. ...
A rapidly changing climate, including rising temperatures, changing precipitation patterns, and more extreme storms, is having profound consequences for America’s national forests. Climate-related impacts on forest systems include larger and more severe disturbances (e.g., wildfires, drought, and insect outbreaks), shifts in tree species ranges and forest composition, and changes in forest dynamics and regeneration capacity.
Many of our national forests have been significantly modified by past management and land use, and forest managers are contending with ongoing threats from invasive species, disease outbreaks, and other challenges. With the added impacts on forest systems
from climate change, an enormous mismatch exists between the level of restoration work currently underway and the scale of the challenge. As a result, there is a need to substantially increase the pace, scale, and quality of restoration on our national forests,
and to ensure that this restoration is carried out in an ecologically appropriate and climate-smart manner.
Continuing and accelerating climatic changes, and their associated impacts, have significant implications for the effectiveness of traditional forest restoration efforts, including reliance on historical conditions as benchmarks for restoration outcomes. Drawing on a growing body of evidence, research, and experimentation, this science review and synthesis looks at how climate change is inspiring an important
evolution in approaches for national forest restoration and management. Over the past decade, the U.S. Forest Service has made considerable progress in understanding the effects of a changing climate on forest ecosystems and working to incorporate climate
considerations into its planning and management.
Nonetheless, varying perspectives on what climate change means for ecological restoration in practice and how to navigate potential trade-offs continue to pose challenges to integrating climate adaptation and mitigation in national forest planning and management. Addressing this challenge would benefit from a shared understanding among agency staff and stakeholders of what constitutes a forward-looking and climate-smart approach to national forest restoration. To this end, this report reviews and summarizes recent advances and ongoing evolution in how the concepts and
principles of climate adaptation and mitigation can help promote the development and application of climate-smart forest restoration.
... Multiple climate adaptation strategies have been suggested over the past 15 years, going back to Millar et al.'s (Millar, Stephenson, and Stephens 2007) "resistance, resilience, and response" adaptation strategies. These represent a spectrum of management objectives that are informed by the degree to which desired target conditions can be met. ...
... Response strategies would entail management investments to move current conditions into a less desirable state but one that is more achievable and will still yield valued ecosystem services. Since Millar et al. (2007), other adaptation frameworks have been proposed (Lynch et al. 2021), but they essentially reflect the same spectrum of outcomes that range from maintain and protect what is in good condition, implement adaptive strategies in areas that can achieve target conditions with high certainty, and direct sites that have a low potential of achieving desired target conditions into a different state that will be more resilient to future climate and disturbance (Schuurman et al. 2022). ...
... We categorized the range of management strategies to enhance the resilience and adaptive capacity to future climate conditions into four basic outcomes that represent a continuum of intended rates and degrees of change and novelty (sensu Millar et al. 2007). These four strategies are a function of where sites and watersheds fall in the bivariate space defined by current condition on the x-axis and the potential to achieve and maintain desired target conditions in the future on the y-axis ( Figure 4). ...
The forest restoration strategies defined in the Blueprint allow managers to tailor actions to be strategic, forward-looking, and responsive to projections of climate change impacts. The Blueprint can help managers determine where restoration treatments are likely to improve conditions over time, and conversely where they are not needed or where their impacts are less certain in the future. The Blueprint includes evaluations of 30 unique metrics, such as large tree density and probability of high severity fire, that describe conditions across five of the pillars of resilience: forest resilience, fire-adapted communities, fire dynamics, biodiversity conservation, and carbon sequestration.
The Blueprint uses a novel application of the Ecosystem Management Decision Support (EMDS) tool to evaluate spatial data layers against target conditions that are indicative of resilient landscapes. The Blueprint integrates assessments of both current conditions (2019) and future conditions (2020–2060) under climate change to reflect where management can likely make the most impact towards achieving functions on the landscape now and into the future. The model outputs spatial maps of condition scores ranging from -1 (out of target conditions) to +1 (within target conditions) for current and future conditions separately. These metric scores were then mapped onto a two-dimensional space, with current conditions on the x-axis and the potential to achieve target conditions in the future on the y-axis. Within that space, four restoration strategies were identified: Monitor, Protect, Adapt, and Transform.
... In this context, most adaptation models for ecosystem management advise for applying a portfolio of choices (Aplet and McKinley, 2017;Dudney et al., 2018;Royer-Tardif et al., 2021). Notably, the intensification and interaction of disturbances call for the development of forest management strategies that increase resistance (the ability to resist change; Millar et al., 2007) and resilience (the ability to both accommodate change and return to prior conditions; Millar et al., 2007) to multiple stressors, with a focus on finding opportunities to manage them as one global threat (Jactel et al., 2017;Scheller et al., 2018;Roberts et al., 2020). One such strategy is thinning, which is commonly used to control the density, structure and species composition of stands. ...
... In this context, most adaptation models for ecosystem management advise for applying a portfolio of choices (Aplet and McKinley, 2017;Dudney et al., 2018;Royer-Tardif et al., 2021). Notably, the intensification and interaction of disturbances call for the development of forest management strategies that increase resistance (the ability to resist change; Millar et al., 2007) and resilience (the ability to both accommodate change and return to prior conditions; Millar et al., 2007) to multiple stressors, with a focus on finding opportunities to manage them as one global threat (Jactel et al., 2017;Scheller et al., 2018;Roberts et al., 2020). One such strategy is thinning, which is commonly used to control the density, structure and species composition of stands. ...
... Aldea et al., 2017;Diaconu et al., 2017;Lechuga et al., 2017;Cardil et al., 2018;Dȃnescu et al., 2018;Ogaya et al., 2019;Steckel et al., 2020;van Mantgem et al., 2020) and that the magnitude of the effect might be partly explained by the species-specific sensitivity to local climate, in such way that higher climate sensitivity increases the potential to reduce drought susceptibility Table 1 Summary of the effect of thinning on tree responses to drought events or low soil water availability. The effect is reported as growth resistance (R T ; growth response during the event), growth resilience (R L ; ratio of the growth before and after the event), water use efficiency (WUE; evaluated through stable carbon isotope (δ13C) or sap flow), mortality (M) and general long-term effect (>20 years since thinning Resistance and resilience are used as described by Millar et al. (2007). Positive and negative effects are indicated by + and -, respectively; 0 indicates no effect; empty cells represent non-available data. ...
We reviewed recent literature to identify the positive and negative effects of thinning on both stand-and tree-level resistance and resilience to four stressors that are expected to increase in frequency and/or severity due to global change: (1) drought, (2) fire, (3) insects and pathogens, and (4) wind. There is strong evidence that thinning, particularly heavy thinning, reduces the impact of drought and also the risk and severity of fire when harvest slash is burned or removed. Thinning also increases the growth and vigor of residual trees, making them less susceptible to eruptive insects and pathogens, while targeted removal of host species, susceptible individuals and infected trees can slow the spread of outbreaks. However, the evidence that thinning has consistent positive effects is limited to a few insects and pathogens, and negative effects on root rot infection severity were also reported. At this point, our review reveals insufficient evidence from rigorous experiments to draw general conclusions. Although thinning initially increases the risk of windthrow, there is good evidence that thinning young stands reduces the long-term risk by promoting the development of structural roots and favouring the acclimation of trees to high wind loads. While our review suggests that thinning should not be promoted as a tool that will universally increase the resistance and resilience of forests, current evidence suggests that thinning could still be an effective tool to reduce forest vulnerability to several stressors, creating a window of opportunity to implement longer term adaptive management strategies such as assisted migration. We highlight knowledge gaps that should be targeted by future research to assess the potential contribution of thinning to adaptive forest management. One of these gaps is that studies from boreal and tropical regions are drastically underrepresented, with almost no studies conducted in Asia and the southern hemisphere. Empirical evidence from these regions is urgently needed to allow broader-scale conclusions.
... Globally, forests are subject to many drivers of anthropogenic change (McIntyre et al. 2015, Franklin et al. 2016, Balch et al. 2017) that may reduce their capacity to deliver expected levels of ecosystem services (Asner et al. 2015). Because these anthropogenic drivers interact in surprising ways and their future magnitude is also uncertain, the future of forests are highly uncertain (Millar et al. 2007, Lindner et al. 2014, Luce et al. 2016, Wang et al. 2016, Boulanger et al. 2018. Natural resource managers must account for uncertainty when making decisions (Nichols et al. 2011, Lindner et al. 2014) but climate change magnifies uncertainty and can be a barrier to management action (Polasky et al. 2011, Adams 2013, Scheller and Parajuli 2018. ...
... Model uncertainty can also be substantial (Petter et al. 2020). Forest disturbances contribute considerable uncertainty to our understanding of forest futures (Hicke et al. 2006, Millar et al. 2007, Littell et al. 2010, Scheller et al. 2011, Anderegg et al. 2015, Seidl et al. 2016, Bognounou et al. 2017, Coen et al. 2018, Stephens et al. 2018). On the contrary, negative feedbacks among disturbances, in combination with ecological memory, may reduce uncertainty. ...
... If an identified autochthonous provenance still proves to be inadequate in terms of adapting to climate change, forest management may nonetheless look at provenances of the same species from abroad or new exotic species [33,70]. However, as the data of this study indicates, forest managers may not need to look abroad for alternative species more resistant to drought stress. ...
... While the pressure of climate change continues to push the case for foreign provenances or exotic species [19,70], their introduction, particularly that of exotic species, may have negative ecological effects [33,74,75]. Forestry should, therefore, not ignore the autochthonous options available to adapt to the projected changes in climate. ...
(1) Background: Forestry will have to react to climate change because many tree species suffer. Mitigation can be realized either by planting non-native trees from regions with high climatic stress or by utilizing native tree provenances already adapted to stressful environments. Non-native trees have often generated problems in the past due to uncontrolled invasiveness. The use of native trees pre-adapted to the prospective climatic conditions is far less risky for the respective ecosystems. We offer a tool for selecting ecotypes of native trees as provenances for future forestry. (2) Methods: We propose the selection of tree species native to Middle Europe from a database of vegetation relevés of ± natural forest stands. By calculating the mean ecological indicator values of stands from their vegetation, cover sites can be elected that can provide seeds of provenances well adapted to future climatic conditions. (3) Results: By selecting the 10% partition of the most extreme stands of European tree species, seeds can be sampled and propagated for re-cultivating forests fit for future climate. (4) Conclusions: One can expect ecotypes of tree species that grow well on dry sites, since generations have faced evolutionary selection, for survival under stressful environments. This approach helps to avoid ecological risks of non-native trees.
... Site-scale or micro-refugia were identified as places where local landscape components buffer the vulnerability of organisms to climate change, such as areas receiving cold air drainage from ice caves (Noss, 2001) or locations with high groundwater availability (McLaughlin and Zavaleta, 2012). Millar et al. (2007) suggested that locally extreme soil types, which have served as refugia for native biodiversity from invasive species, might also reduce vulnerability to climate change. While in the first time period, refugia was conceptualized only as physiographic, in the second time period, the concept of genetic refugia also emerged (Mcleod et al., 2013). ...
... Conservation and management responses to climate change have been categorized according to their goals, as resistant versus resilient, transformative, accepting and/or directing (Lynch et al., 2021, Folke, 2006, Millar et al., 2007, Heller and Zavaleta, 2009, Peterson St-Laurent et al., 2021, adaptive versus transformative (Folke et al. 2010, Hagerman andPelai 2018), or promoting historical versus novel or wild vs. designed ecosystems (Prober et al., 2012, Kueffer, 2014. Broadly, these categorizations distinguish approaches that embrace novel or changing ecological processes and environments from those that attempt to restore historical or sustain current conditions. ...
Over the past three decades, climate change adaptation has become a central focus in conservation. To inform these efforts, the scientific community has provided a growing body of recommendations on biodiversity management with climate change. A previously published study reviewed the first wave of such recommendations in the peer-reviewed literature as they occurred between 1985 and 2007. Here we build on that work, reviewing the literature from the subsequent time period, 2007–2017. We report on the development of the field between the two time periods, and review in depth three highly ranked, climate change-specific conservation strategies from the more recent time period. Overall, recommended strategies for ecological management have remained remarkably consistent over the last three decades, and the field continues to draw mainly on conventional, long-standing conservation approaches. However, the actionability and specificity of recommendations have increased, and certain novel, climate change-specific strategies have become more prominent, pointing the way toward increasing options for practitioner response.
... Managing forests for adaptability and resiliency has been suggested as an approach that may allow forests and forest managers to buffer the uncertainty of future conditions (Millar et al., 2007;Spittlehouse and Stewart, 2003). Analysis of the outcomes of long-term silviculture studies in the Lake States region of the United States found multi-aged approaches, including irregular shelterwoods, may be the most effective at balancing mitigation and adaptation at the stand-level because they capture a wide range of historical disturbances and subsequent forest complexities Hupperts et al., 2020). ...
... History in the NHF and other forest types reveals periods of preferences for one extreme of silvicultural options or another (O'Hara, 2002;Smith, 1972) Such actions were restrictive then and would be even more detrimental today. Rather forestry practitioners need to consider all options, including novel tools and modification of existing silvicultural systems, guided by management approaches best suited to their specific objectives and forest conditions (Millar et al., 2007). In the context of changing future conditions, an overriding objective for selection and application of any given approach should be the maintenance of a wide range of structural and functional conditions at the stand and landscapelevel as a precautionary strategy for addressing the uncertainties associated with global change impacts Puettmann, 2011). ...
Northern hardwoods are an economically, ecologically, and culturally important forest type spanning the upper latitudes of the United States and the lower latitudes of Canada. The prevalence and value of these forests have driven silviculture research for over a century. During this time, silvicultural approaches have varied widely, searching for scenarios to meet traditional commodity-based and diversifying ecological forestry objectives. To better understand this forest type and the spectrum of appropriate silvicultural options, we analyzed regional inventory data from the United States and Canada and synthesized decades of scientific studies. Calculated overstory tree (stems ≥ 12.5 cm diameter at breast height) metrics show common structural conditions across mature northern hardwood forests and dominance of sugar maple (Acer saccharum). However, density and composition metrics for established reproduction (saplings 2.5 to 12 cm dbh) emphasize challenges for establishing and maintaining economically and ecologically valued trees species broadly and regionally. Our work underscores the variation in northern hardwoods within and across its distribution, driven by characteristics like disturbance regimes, land use history, and ownership patterns. We conclude maintaining this important forest type amid climate uncertainty and associated effects, like proliferation of exotic insects and diseases, requires recalibration of historically applied silvicultural systems and application of emerging tools.
... Indeed, climate change will reduce productivity, decrease growth rate, reduce seed and seedling survival, increase competition between mangrove species, and reduce diversity in the mangrove forest areas, resulting in a significant decrease in mangrove forest area and the final conversion to highly saline mud areas (Ward, Friess, Day, & MacKenzie, 2016). Overall, the main climatic factors that are implicated for forest degradation are higher wind speed, higher temperatures, frost, heavy rains, severe droughts and global temperature rise (IPCC, 2013;Janowiak, D'Amato, Swanston, Iverson, Thompson, Dijak, & Brandt, 2018;Millar, Stephenson, & Stephens, 2007;Millar, 2014;Nevins, D'Amato, & Foster, 2019;Puettmann, 2011;Savari et al., 2020;Velasco & Harder, 2014). ...
... Richards & Friess, 2016;Carugati et al., 2018;Millar et al., 2007, Mafi-Gholami et al., 2019Chen & Gong, 2020;Puettmann, 2011, IPCC, 2013: Yazdanpanah, Monfared, & Hochrainer-Stigler, 2013Velasco & Harder, 2014;Millar, 2014, Janowiak et al., 2018Nevins et al., 2019;Zhang et al., 2016;Duke et al., 1998;Elith et al., 2011;McLeod & Salm, 2006;Iverson, Prasad, & Matthews, 2008, Zhu et al., 2012, Iverson et al., 2017: Nevins et al., 2019Hungerford & Volk, 1990;Augustynczik et al., 2020;Azadi et al., 2013;Laužikas & Dailydaitė, 2015: Vilà-Cabrera et al., 2018Sözbilir, 2018; Martinez-Falero, 2017;Vicente-Molina et al., 2013;Valizadeh et al., 2020;Savari et al., 2021a;Bagheri et al., 2019;Aljahdali, Munawar, & Khan, 2021;Purnamasari, Kamal, & Wicaksono, 2021;Savari et al., 2021b;Valizadeh et al., 2021aValizadeh et al., ,2021bPakmehr, Yazdanpanah, & Baradaran, 2021;Savari et al., 2021b;Ghorbani, Eskandari-Damaneh, Cotton, Ghoochani, & Borji, 2021;Gabler et al., 2017;Osland et al., 2017;Rahimi-Feyzabad, Yazdanpanah, Burton, Forouzani, & Mohammadzadeh, 2020;Nooripoor & Sharifi, 2017;Savari, Damaneh, & Damaneh, 2022. ...
In Iran, mangroves are located in the south of the country, where they fulfill essential ecosystem functions, but some parts of them have been destroyed for various reasons in recent years so that it seems necessary to have a management plan consistent with the conservation of this ecosystem. But, it needs knowledge of the trend of and reasons for the degradation of these forests. So, the primary idea of this research was to discover the factors involved in the degradation of these forests and how to manage them. So, the research first used the remote sensing technique to determine the rate of their degradation over the last 20 years. Then, using the Delphi technique, 45 factors were identified for the degradation of these forests and they were classified into five categories including climatic and environmental, anthropogenic, socioeconomic, psychological, and policymaking and legal. Finally, the analytic hierarchy process (AHP) was used to rank these factors within two management paradigms of remediability and preventability so that the ecosystem can be soundly managed by classifying these factors. Overall, the results can provide policymakers with new insights into forest management and the policies presented here can contribute to the sustainability of this ecosystem.
... In a business-as-usual scenario in Brazil, future conservation of these species will eventually depend on policies of other countries (Guiana, Suriname, French Guiana). Therefore, present-day conservation strategies should focus on allocating resources to promote connectivity between PAs (Araújo et al., 2004;Millar, Stephenson & Stephens, 2007), primarily because of the temperature-reduced locomotory performance expected for them (Diele-Viegas et al., 2018). Ecological corridors are favored in a densely forested region such as the north of the Amazon River, and are the most logical plan. ...
... The eight thermoconformer lizards highlighted here represent present and future conservation concerns that should be carefully evaluated in extinction risk assessments. We propose mitigation strategies related to their specific response patterns to climate and landscape combined effects, complementing species representations in current PA networks and promoting connectivity between them (Araújo et al., 2004;Hannah et al., 2007;Millar, Stephenson & Stephens, 2007). Early response is the best cost-saving and cost-benefit strategy for anticipating climate change (Hannah et al., 2007). ...
The leading causes of the worldwide decline in biodiversity are global warming, allied with natural habitat loss and fragmentation. Here, we propose an analysis of the synergistic effects of these two factors in 63 species of Amazonian lizards. We predicted that the high-climatic suitability areas of species would be significantly impacted by different deforestation scenarios and the resultant landscape structure and considered that forest-dwelling species would be especially susceptible to deforestation scenarios. We also pointed out species threatened by both drivers and suggested critical areas for their future conservation. According to our results, most species will face future reductions in suitable areas for their occurrence according to five different patterns, two of which represent significant risks for 15 species. Some of these species already deal with severe habitat loss and fragmentation of their current distribution ranges, whereas others will suffer a considerable area reduction related to future range shifts. We emphasize the importance of protected areas (PAs), especially indigenous lands, and the need to plan combined strategies involving PAs' maintenance and possible implementation of ecological corridors. Finally, we highlight eight species of thermoconformer lizards that constitute present and future conservation concerns related to the combined effects of climate change and habitat loss and that should be carefully evaluated in extinction risk assessments.
... The world's forests are likely to see a continued and increased pressure from human use . At the same time, they are facing changing environmental conditions due to climate change in an unprecedented extent (Krankina et al., 1997;Dale et al., 2001;Millar et al., 2007;Lawler, 2009;Seidl et al., 2011). Precipitation and temperature patterns are changing and result in changes of forest species composition, health and structure (Millar et al., 2007;Lawler, 2009;Seidl et al., 2011). ...
... At the same time, they are facing changing environmental conditions due to climate change in an unprecedented extent (Krankina et al., 1997;Dale et al., 2001;Millar et al., 2007;Lawler, 2009;Seidl et al., 2011). Precipitation and temperature patterns are changing and result in changes of forest species composition, health and structure (Millar et al., 2007;Lawler, 2009;Seidl et al., 2011). Only recently, it was shown that the structural complexity of unmanaged forests strongly depends on precipitation , with the structural complexity of a forest stand being defined as all dimensional, architectural, and distributional patterns of plant individuals and their organs in a given forest space at a given point in time (McElhinny et al., 2005;Seidel et al., 2020). ...
Today, creating or maintaining forest structural complexity is a management paradigm in many countries due to the positive relationships between structural complexity and several forest functions and services. In this study, we tested whether the box-dimension (Db), a holistic and objective measure to describe the structural complexity of trees or forests, can be used to quantify the structural complexity of 14 European beech (Fagus sylvatica L.) dominated forest plots by means of mobile laser scanning (MLS). The goal of this study was to explore the potential of this approach for quantifying the effect of leaves (summer vs winter) and management (lately unmanaged vs managed) on forest structural complexity. The findings suggest that repeated measurements on the same site and at the same time yielded consistent results if the measuring scheme is standardized. The results also showed that standardized measurement protocols allowed quantifying differences in forest structural complexity due to season. The highest stand structural complexity was found in leaf-on condition during summer, with the complexity being significantly higher than in winter condition. Also, in case of our beech-dominated plots, managed forests were more complex in structure than formerly managed but now unmanaged forests. This study illustrates the potential of MLS for monitoring the changes in forest structural complexity and allows correcting stand structural information for seasonality.
... However, a high degree of uncertainty in the magnitude of change is caused by complex social dimensions and associated mitigation efforts as well as complex physical interactions and feedback loops [4][5][6]. Despite this uncertainty, for its long-term implications, current decision-making in forestry needs to account for climatic changes by the end of the century [7][8][9]. While measures to increase resistance to climate change are prevailing in research on adaptive forestry management, shifting the emphasis towards fostering resilience and the adaptive capacity of forest ecosystems is key when facing climate change [10][11][12]. ...
... Integrating stakeholders through participatory approaches is key for leverage of transformational change [89]. While the promotion of minor European natives comes with a lower risk potential compared to non-native tree species, where special care is paramount to avoid unforeseen ecological consequences [90], changes in tree species compositions with European natives will have implications for the shape of forest ecosystems nonetheless, also requiring careful observation [8]. Similarly, the socio-economic implications of shifting tree species composition need to be anticipated and addressed. ...
Climate change is projected to trigger strong declines in the potential distribution of major
tree species in Europe. While minor natives have moved into the spotlight as alternatives, their ecology is often poorly understood. We use an ensemble species distribution modelling approach on a set of promising native tree species to gain insights into their distribution potential under different climate change scenarios. Moreover, we identify the urgency and potential of altered species distributions in favor of minor natives by comparing the niche dynamics of five major native tree species with the set of six minor natives in a case study. Our models project stark range contractions and range shifts among major tree species, strongly amplified under high emission scenarios. Abies
alba, Picea abies and Fagus sylvatica are affected the strongest. While also experiencing range shifts, the minor European natives Castanea sativa, Sorbus torminalis, and Ulmus laevis all considerably expand their range potential across climate change scenarios. Accompanied by Carpinus betulus, with a stable range size, they hold the potential to substantially contribute to sustainably adapting European forest to climate change.
... The resist-accept-direct (RAD) framework specifies three clear management approaches for managing in the context of change: resist change to maintain or restore historical or desirable ecological regimes, accept ecological regime change, or direct change to a new regime (Schuurman et al. 2020;Lynch et al. 2021; Thompson et al. 2021). The approaches described in the RAD framework and elsewhere (Millar et al. 2007;Glick et al. 2011;Fisichelli et al. 2016;Aplet and McKinley 2017) build upon resilience concepts (i.e., regime shifts or transformations), use clear and intuitive terminology, and help frame decision-making in the context of future trajectories. Because the RAD framework is relatively new and specific contexts of application can vary widely, limited guidance has been developed for how to decide which approach(es) to implement ). ...
As anthropogenic influences push ecosystems past tipping points and into new regimes, complex management decisions are complicated by rapid ecosystem changes that may be difficult to reverse. For managers who grapple with how to manage ecosystems under novel conditions and heightened uncertainty, advancing our understanding of regime shifts is paramount. As part of an ecological resilience assessment, researchers and managers have collaborated to identify alternate regimes and build an understanding of the thresholds and factors that govern regime shifts in the Upper Mississippi River System. To describe the management implications of our assessment, we integrate our findings with the recently developed resist-accept-direct (RAD) framework that explicitly acknowledges ecosystem regime change and outlines management approaches of resisting change, accepting change, or directing change. More specifically, we developed guidance for using knowledge of desirability of current conditions, distance to thresholds, and general resilience (that is, an ecosystem’s capacity to cope with uncertain disturbances) to navigate the RAD framework. We applied this guidance to outline strategies that resist, accept, or direct change in the context of management of aquatic vegetation, floodplain vegetation, and fish communities across nearly 2000 river kilometers. We provide a case study for how knowledge of ecological dynamics can aid in assessing which management approach(es) are likely to be most ecologically feasible in a changing world. Continued learning from management decisions will be critical to advance our understanding of how ecosystems respond and inform the management of ecosystems for desirable and resilient outcomes.
... The combination of warming temperatures and fire exclusion leaves forests in the modern era contending with a unique set of stressors with no historical analog (Millar et al. 2007). In previous periods in Earth's history where temperatures were warming, there was also increased fire activity across forested landscapes (Mohr et al. 2000, Briles et al. 2005. ...
Climate warming and altered disturbance regimes are changing forest composition and structure worldwide. Given that species often exhibit individualistic responses to change, making predictions about the cumulative effects of multiple stressors across environmental gradients is challenging, especially in diverse communities. For example, warming temperatures are predicted to drive species upslope, while fire exclusion promotes expansion of species at lower elevations where fire was historically frequent. We resampled 148 vegetation plots to assess 46‐years (1969 to 2015) of species and community‐level response to warming and fire exclusion in a topographically complex landscape in the Klamath Mountains, California (USA), a diverse region that served as a climate refugia throughout the Holocene. We compared cover and assessed change in the elevational distributions of 12 conifer species at different life stages (i.e., seedlings, saplings, canopy). We observed consistent but non‐significant shifts upward in elevation for eight species, and a significant shift upward for one species, all of which were far less than expectations based on recent warming. Six species declined in total cover and another five declined in at least one life stage, while the drought‐ and fire‐intolerant Abies concolor increased by 30.7%. The largest declines were at lower elevations in drought‐tolerant, early seral species (Pinus lambertiana and Pinus ponderosa) and at higher elevations for the shade‐tolerant Abies magnifica var. shastensis and the regionally rare Abies lasiocarpa. Regionally rare (Picea engelmannii) and endemic (Picea breweriana) species had reductions in early life stages, portending future declines. Multivariate analyses revealed a high degree of inertia with a minor but significant shift in composition and a slight decrease in species turnover along the elevation gradient driven by expansion of A. concolor. Our results indicate that most species are declining, especially at lower‐ and mid‐elevations where fire exclusion increased cover of shade‐tolerant species and reduced recruitment for fire‐adapted species. Collectively, declines in most species, insufficient upward movement to track warming, reductions in drought‐ and fire‐tolerant early seral species, and an increase in a single, shade‐tolerant species will leave these communities maladapted to projected climate scenarios and questions the potential for future climate refugia in this region.
... Increasing temperatures and more severe and frequent droughts as a consequence of global climate change have already had an impact on many biomes (Parmesan, 2006;Allen et al., 2010;Taccoen et al., 2019), raising concerns about the fate of trees and forests (Badeau et al., 1996;Millar et al., 2007;Petit et al., 2008;Lindner et al., 2010;Jump et al., 2017). There is great concern that the climate warming currently underway could outpace the response capacity of many tree populations (Jump et al., 2009). ...
The low-latitudinal range margins of many temperate and boreal tree species consist of scattered populations that persist locally in climate refugia. Recent studies have shown that such populations can be remarkably resilient, yet their past resilience does not imply that they are immune to threats from future climate change. The functioning of refugial tree populations therefore needs to be better understood if we are to anticipate their prospects correctly. We performed a detailed study of tree radial growth and vigour in a long-term climate refugial population of beech (Fagus sylvatica), comparing the observed trends with those of co-occurring pedunculate oak (Quercus robur). Annual growth rates (basal area increment, BAI) for both species were similar to those observed in range-core populations, but natural lifespan was half that in the mountains. The master chronologies spanning 1870 to 2015 revealed 22% (Fagus) and 20% (Quercus) increases in BAI until the 1980s and a smaller decrease (-6% for Fagus, -9% for Quercus) since then. Stable carbon isotope measurements (δ¹³C) revealed no effect of cambial age and an increase in water-use efficiency (iWUE) from 1870 to 2015 of about 50% for Fagus and 20% for Quercus. The trend continued until 2015 in Fagus, whereas Quercus reached its maximum in the 1980s. A detailed analysis of the relationship between climate and annual growth based on a 118-year meteorological record revealed a major role of water availability in the current and previous year. We used the observed climatic relationships to model future growth trends until 2100 for the IPCC scenarios RCP4.5 and RCP8.5. Most projections revealed no change in current growth rates, suggesting that this climate refugium will be able to provide suitable conditions for the persistence of Fagus and Quercus over the coming decades even under warmer and drier regional climate conditions. Overall, our study provides valuable insight into the precise climatic and biological mechanisms enhancing the persistence of refugial tree populations under ongoing climate change.
... Step 3, resolve, is used to develop adaptation options that promote sustainable resource management in a changing climate. This step encompasses several types of management strategies, characterized as "resistance, resilience, response, and realignment" (Millar et al. 2007 Vulnerability assessments for individual communities will likely provide better information on where and when water shortages may occur and can facilitate development of adaptation tactics customized to specific locations. However, because Sensitivity to climatic variability and change: Low summer flows will become lower. ...
The South-Central Oregon Adaptation Partnership (SCOAP) was developed to identify climate change issues relevant for resource management on federal lands in south-central Oregon (Deschutes National Forest, Fremont-Winema National Forest, Ochoco National Forest, Crooked River National Grassland, Crater Lake National Park). This science-management partnership assessed the vulnerability of natural resources to climate change and developed adaptation options that minimize negative impacts of climate change and facilitate transition of diverse ecosystems to a warmer climate. The vulnerability assessment focused on water resources and infrastructure, fisheries and aquatic organisms, vegetation, wildlife, recreation, and ecosystem services.
The vulnerability assessment shows that the effects of climate change on hydrology in south-central Oregon will be highly significant. Decreased snowpack and earlier snowmelt will shift the timing and magnitude of streamflow; peak flows will be higher, and summer low flows will be lower. Projected changes in climate and hydrology will have far-reaching effects on aquatic and terrestrial ecosystems, especially as frequency of extreme climate events (drought, low snowpack) and ecological disturbances (flooding, wildfire, insect outbreaks) increase.
Distribution and abundance of cold-water fish species are expected to decrease in response to higher water temperature, although effects will vary as a function of local habitat and competition with nonnative fish. Higher air temperature, through its influence on soil moisture, is expected to cause gradual changes in the distribution and abundance of plant species, with drought-tolerant species becoming more dominant. Increased frequency and extent of wildfire and insect outbreaks will be the primary facilitator of vegetation change, in some cases leading to altered structure and function of ecosystems (e.g., more forest area in younger age classes). Vegetation change will alter wildlife habitat, with both positive and negative effects depending on animal species and ecosystem. Animal species with a narrow range of preferred habitats (e.g., sagebrush, riparian, old forest) will be the most vulnerable to large-scale species shifts and more disturbance.
The effects of climate change on recreation activities are more difficult to project, although warmer temperatures are expected to create more opportunities for warm-weather activities (e.g., hiking, camping) and fewer opportunities for snow-based activities (e.g., skiing, snowmobiling). Recreationists modify their activities according to current conditions, but recreation management by federal agencies has generally not been so flexible. Of the ecosystem services considered in the assessment, timber supply and carbon sequestration may be affected by increasing frequency and extent of disturbances, and native pollinators may be affected by altered vegetation distribution and phenological mismatches between insects and plants.
Resource managers in the SCOAP developed adaptation options in response to the vulnerabilities of each resource, including high-level strategies and on-the-ground tactics. Many adaptation options are intended to increase the resilience of aquatic and terrestrial ecosystems, or to reduce the effects of existing stressors (e.g., removal of nonnative species). In terrestrial systems, a dominant theme of adaptation in south-central Oregon is to accelerate restoration and fuel treatments in dry forests to reduce the undesirable effects of extreme events and high-severity disturbances (wildfire, insects). In aquatic systems, a dominant theme is to restore the structure and function of streams to retain cold water for fish and other aquatic organisms. Many adaptation options can accomplish multiple outcomes; for example, fuel treatments in dry forests reduce fire intensity, which in turn reduces erosion that would degrade water quality and fish habitat. Many existing management practices are already “climate smart” or require minor adjustment to make them so. Long-term monitoring is needed to detect climate change effects on natural resources, and evaluate the effectiveness of adaptation options.
... Masting years are typically synchronized between individuals of a species, but not always between species, nor can be predicted more than a few months in advance (Pesendorfer et al. (2020)). Hence, it is a major constraint for forest managers planning the sand's regeneration phase, which requires several years of preparation (Millar et al. (2015)). 2015)), and can occur over short (under the canopy of mother tree) or long distances (dispersal by birds upto 16 km) (Van Der Putten (2012)). ...
Global environmental changes are affecting tree population demography with potentially significant impacts on forest biodiversity and wood industry. Forest regeneration processes include seed production, growth and survival of saplings to the recruitment sizes at which trees are considered in forest inventories. Changes in regeneration dynamics directly affect forest composition and structure and can jeopardize the sustainability of forest management. This is especially the case in mountain forests where environmental gradients are strong and where forests are often uneven-aged, i.e. combining trees of all ages in a single stand. Regeneration processes are difficult to monitor. Large data sets often give only fixed pictures of sapling densities with little information on demographic processes. In this thesis, we quantified the effects of different biotic and abiotic factors on regeneration dynamics of Picea abies (spruce), Abies alba (fir) and Fagus sylvatica (beech) in the French Alps and Jura mountains. We also predicted changes in tree recruitment fluxes in these forests, for potential climate change situations. We recorded sapling height increment and density of spruce, fir and beech in 152 plots across the French Alps and Jura mountains. We then analysed how biotic and abiotic factors known to affect regeneration, namely altitude, slope, aspect, light availability, soil characteristics, ungulate browsing, temperature, precipitation and evapotranspiration, affected sapling density and growth using non-linear mixed models. We showed that temperature has a positive non-linear effect on sapling height growth and water resource availability has a positive effect on sapling density. Terminal shoot browsing, which prevents sapling height growth, is especially frequent on fir. In a second analysis, we built a more comprehensive model of regeneration dynamics, representing explicitly the process of new seedling production, sapling growth, browsing and survival, and finally their recruitment into adult trees. We predicted parameters for these processes in combination, using Approximate Bayesian Computation (ABC), based on the field data collected earlier. The results imply that more frequent and intense heat and drought events could negatively influence sapling growth and survival of the three species, with probable reduction of forest renewal fluxes. An increase of ungulate populations leading to increased browsing could be especially detrimental to fir and possibly also to beech saplings. We also predicted the potential tree recruitment fluxes for different IPCC climate projection scenarios for the year 2100, and showed that a reduction in tree recruitments is highly likely. This study shows that the ABC method can be efficiently used to estimate regeneration dynamic processes, based on sapling density, height increment and browsing data. It highlights the vulnerability of future forest regeneration to water availability and ungulate presence, urging researchers and forest managers alike to anticipate future potential important changes in mountain forest dynamics.
... Climate change is considered a crucial challenge in the biosphere, which can both positively and negatively impact forest ecosystems [1,2]. However, such projections are accompanied by uncertainties regarding the future magnitude and possible consequences of rapid environmental changes in dynamic ecosystems [3,4]. Having profound knowledge of forest growth is crucial to understand tree-environment interactions [5]. ...
The magnitude and duration of ongoing global warming affects tree growth, especially in semi-arid forest landscapes, which are typically dominated by a few adapted tree species. We investigated the effect of climatic control on the tree growth of Persian oak (Quercus brantii Lindl.), which is a dominant species in the Central Zagros Mountains of western Iran. A total of 48 stem discs was analyzed from trees at three sites, differing in local site and stand conditions (1,326 to 1,704 m a.s.l.), as well as the level and type of human impact (high human intervention for the silvopastoral site, moderate for the agroforestry site, and low for the forest site). We used principal component analysis (PCA) to investigate the common climatic signals of precipitation, air temperature, and drought (represented by SPEI 1 to 48 months) across the site chronologies. PC1 explains 83% of the total variance, indicating a dominant common growth response to regional climatic conditions that is independent of the local environmental conditions (i.e., forest stand density and land-use type). Growth–climate response analyses revealed that the radial growth of Q. brantii is positively affected by water availability during the growing season (r = 0.39, p < 0.01). Precipitation during April and May has played an ever-important role in oak growth in recent decades. Our study provides evidence that hydroclimatic conditions control tree-ring formation in this region, dominating the effects of topography and human impact. This finding highlights the great potential for combining historical oak samples and living trees from different forest stands in order to generate multi-centennial tree-ring-based hydroclimate reconstructions.
... Also, restoration policies must be flexible enough to be adjusted based on monitoring outcomes, including options such as additional planting, weeding, and thinning in response to the emerging stand trajectories Di Sacco et al. 2021). Such an adaptive management policy is a powerful approach for dealing with future uncertainty, including global climate change and associated change in disturbance regime (Millar et al. 2007;Seidl 2014;Tanner-McAllister et al. 2017). In closing, we highlight that in addition to experimental and observational approaches, simulation modeling can make an important contribution towards evidence-based and quantitative restoration ecology (O'Grady 2020). ...
Growing interest in ecosystem restoration has recently turned the focus on tree planting, one of the most widely used restoration tools globally. Here, we study the restoration potential of tree planting in a cool‐temperate forest in Shiretoko National Park, northern Japan. We used simulation modeling to investigate the long‐term success of tree planting in restoring biodiversity and the climate change mitigation function relative to intact natural forests. Specifically, we investigated 31 different restoration scenarios, consisting of five planting densities (1,000 to 10,000 trees ha−1) × six levels of planted tree species richness (one to six species) + one no‐planting scenario. We examined these scenarios at different distances from natural forests serving as a seed source (0 to 300 m) to quantify the potential for natural regeneration. In restoration areas in close proximity to a natural forest, species‐rich high density planting scenario performed best, reaching >50% of the reference values from intact natural forests within 33 years for both restoration goals. However, variation in restoration outcomes was small when >2,500 trees ha−1 of >4 species were planted, regardless of distance to seed source. In contrast, biodiversity restoration was considerably delayed in scenarios that planted species richness was low as well as in restoration areas that were far from a seed source yet relied solely on natural regeneration. We here demonstrate how forest landscape simulation can be used to identify viable restoration options for managers across multiple restoration goals as an important step to bridge the research‐implementation gap in forest restoration. This article is protected by copyright. All rights reserved.
... Different approaches have been proposed to help farmers make informed choices when adapting to changing climatic conditions. One of the most commonly used methods has been the use of projected models that explain the impacts of climate change [114] . Though widely used, the impacts of this approach have been limited due to certain constraints. ...
... However, by applying a systematic framework to climate change severity, we generate actionable information targeted to both policy makers and land managers for adaptation decisions. Emerging examples of "resistance-resilience" frameworks [32][33][34][35] aim to clarify strategies in response to measures of climate change severity where "resistance" is warranted where severity appears low, enhancing resilience is warranted for cases of moderate severity, and more intensive actions may be required to direct ecosystem conditions may be warranted where very high climate change severity is evident. Looking out to the upcoming decades, most types assessed here would benefit from resilience-based strategies, so restorative investments in the near term may limit needs for more extreme measures later in the century. ...
The IUCN Red List of Ecosystems (RLE) is a global standard for ecosystem risk assessment that integrates data and knowledge to document the relative risk status of ecosystem types as critically endangered (CR), endangered (EN), and vulnerable (VU). A series of indicators for each type gauge the probability of range wide “collapse”. Climate change vulnerability can factor into RLE assessments, especially as indicators of climate change severity under the criteria for environmental degradation over the recent and upcoming 50 years. We applied a new framework to assess climate change vulnerability—and, thus, severity of climate change degradation—to a cross-section of 33 upland ecosystem types in the United States to demonstrate this input to the RLE. The framework addressed climate exposure and ecosystem resilience. Measures of climate change exposure used climate projections for the mid-21st century compared against a 20th century baseline. Augmenting measures in use for RLE assessment, measures of resilience included several for adaptive capacity, including topoclimate variability, diversity with functional species groups, and vulnerability of any keystone species. All 33 types were listed as VU (n = 22), EN (n = 9), or CR (n = 2) and 51% scored at least one step higher (e.g., LC up to VU) from climate change severity.
... Different approaches have been proposed to help farmers make informed choices when adapting to changing climatic conditions. One of the most commonly used methods has been the use of projected models that explain the impacts of climate change [114] . Though widely used, the impacts of this approach have been limited due to certain constraints. ...
... Adaptive forest management is pivotal to sustain the provision of multiple ecosystem services and biodiversity (ESB) as well as forest multi-functionality in the face of climate change (Bolte et al. 2009;Keenan 2015;Millar et al. 2007;Spathelf et al. 2018). Adaptive management strategies include changing the tree species composition and promoting species and stand structural diversity to increase forest resilience to disturbances (Bolte et al. 2009;Messier et al. 2019;Pretzsch et al. 2017). ...
Climate-adaptive forest management aims to sustain the provision of multiple forest ecosystem services and biodiversity (ESB). However, it remains largely unknown how changes in adaptive silvicultural interventions affect trade-offs and synergies among ESB in the long term. We used a simulation-based sensitivity analysis to evaluate popular adaptive forest management interventions in representative Swiss low- to mid-elevation beech- and spruce-dominated forest stands. We predicted stand development across the twenty-first century using a novel empirical and temperature-sensitive single-tree forest stand simulator in a fully crossed experimental design to analyse the effects of (1) planting mixtures of Douglas-fir, oak and silver fir, (2) thinning intensity, and (3) harvesting intensity on timber production, carbon storage and biodiversity under three climate scenarios. Simulation results were evaluated in terms of multiple ESB provision, trade-offs and synergies, and individual effects of the adaptive interventions. Timber production increased on average by 45% in scenarios that included tree planting. Tree planting led to pronounced synergies among all ESBs towards the end of the twenty-first century. Increasing the thinning and harvesting intensity affected ESB provision negatively. Our simulations indicated a temperature-driven increase in growth in beech- (+ 12.5%) and spruce-dominated stands (+ 3.7%), but could not account for drought effects on forest dynamics. Our study demonstrates the advantages of multi-scenario sensitivity analysis that enables quantifying effect sizes and directions of management impacts. We showed that admixing new tree species is promising to enhance future ESB provision and synergies among them. These results support strategic decision making in forestry.
... The combination of warming temperatures and fire exclusion leaves forests in the modern era contending with a unique set of stressors with no historical analog (Millar et al. 2007). In previous periods in Earth's history where temperatures were warming, there was also increased fire activity across forested landscapes (Mohr et al. 2000, Briles et al. 2005. ...
Climate warming and altered disturbance regimes are changing forest composition and structure worldwide. Given that species often exhibit individualistic responses to change, making predictions about the cumulative effects of multiple stressors across environmental gradients is challenging, especially in diverse communities. For example, warming temperatures are predicted to drive species upslope, while fire exclusion promotes expansion of species at lower elevations where fire was historically frequent. We resampled 148 vegetation plots to assess 46-years (1969 to 2015) of species and community-level response to warming and fire exclusion in a topographically complex landscape in the Klamath Mountains, California (USA), a diverse region that served as a climate refugia throughout the Holocene. We compared cover and assessed change in the elevational distributions of 12 conifer species at different life stages (i.e., seedlings, saplings, canopy). We observed consistent but non-significant shifts upward in elevation for eight species, and a significant shift upward for one species, all of which were far less than expectations based on recent warming. Six species declined in total cover and another five declined in at least one life stage, while the drought-and fire-intolerant Abies concolor increased by 30.7%. The largest declines were at lower elevations in drought-tolerant, early seral species (Pinus lambertiana and Pinus ponderosa) and at higher elevations for the shade-tolerant Abies magnifica var. shastensis and the regionally rare Abies lasiocarpa. Regionally rare (Picea engelmannii) and endemic (Picea breweriana) species had reductions in early life stages, portending future declines. Multivariate analyses revealed a high degree of inertia with a minor but significant shift in composition and a slight decrease in species turnover along the elevation gradient driven by expansion of A. concolor. Our results indicate that most species are declining, especially at lower-and mid-elevations where fire exclusion increased cover of shade-tolerant species and reduced recruitment for fire-adapted species. Collectively, declines in most species, insufficient upward movement to track warming, reductions in drought-and fire-tolerant early seral species, and an increase in a single, shade-tolerant species will leave these communities maladapted to projected climate scenarios and questions the potential for future climate refugia in this region. Word count: 348
... Four main categories of adaptation and mitigation actions can be considered (Millar et al., 2007): ...
Numerous studies conducted during the past decade show that climate change is most likely
attributable to increased concentrations of anthropogenic greenhouse gases producing effects
on climatic patterns. Under this new and changing situation, forest management and policies
require new approaches that take into consideration the effects of climate change.
In recent years, governments, institutions, and NGOs in Lebanon are making huge efforts to carry
out reforestation programs throughout the country. Taking into account the future potentiality of
species currently used in reforestation by placing them under different climate change scenarios
is a useful tool to understand which species will thrive in future conditions.
For this purpose, almost seven thousand points of presence and twelve thousand points of
absence were identified in Lebanon. Ensemble projections for each species were obtained by
adding climatic variables for current conditions and running models with Biomod2 R-package
platform for future scenarios.
This study shows the Species Distribution Model for 2050. It takes into account twenty main
native species commonly used in Lebanese reforestation, and places them under A2 and B1
IPCC scenarios. In addition, vulnerability classification of Lebanese territory was conducted in
terms of species richness loss caused by climate change. This determines the critical areas to
be restored and/or protected in terms of species diversity.
Finally, general guidelines for future management and measures for adaptation and mitigation
to climate change are proposed for each species and case of potentiality status in the future. In
terms of potential species richness loss, specific actions are set for the considered critical areas.
The generated maps and raster files will help the forest manager in decision-making regarding
the priority areas for restoration or management and the potential species to be used considering
the future effects of climate change.
... Persistent climate related issues such as drought and fires, for example, will have significant impact on forest structure (Dale et al., 2001). Drought or fire-resistant plants will thrive while others will lose their regeneration ability, and requires local people to adjust their management practice (Millar et al., 2007). Increasing forest value for its ecosystem service function is yet another external intervention into the way forest is managed at local level. ...
Despite the growing interest in social forestry (SF), how much do we understand the social, economic and environmental outcomes and the conditions that enable SF to perform? In this article, we use a content analysis of literature on existing traditional SF practiced throughout Indonesia. It examines the outcomes of these systems and the conditions that enabled or hindered these outcomes to understand possible causal relations and changing dynamics between these conditions and SF performance. We discuss the gaps in how SF is assessed and understood in the literature to understand the important aspects of traditional SF that are not captured or that are lost when the diverse traditional systems are converted into other land uses. It aims to understand the potential trade-offs in the State's push for formalizing SF if these aspects continue to be ignored.
... In the case of forest ecosystems, various perturbations and drivers of change such as anthropogenic pressures (Foster et al., 2006;Kumar et al., 2021) and climate (Barlow et al., 2016;Midgley et al., 2002) may mark different thresholds guiding the fate of regime shift. The regime shift will impact the multifunctional role of forests which is threatened globally by a set of factors including climate (Hansen et al., 2001;Millar et al., 2007). These threats are expected to intensify in the coming decade (IPCC, 2007). ...
Forests across the latitudes are facing regime shift under the influence of changing climate where temperature and precipitation are recognized as prominent drivers. Regime shift of forests can be in the form of conversion of one forest type into another or the alteration of forests into degraded class such as “scrub”. The Indian Western Himalayan (IWH) region hosts valuable forests to support multiple ecosystem services which may be impacted under different thresholds of regime shift. We assessed the threshold of regime shift as transition of forests into scrub considering temperature and precipitation records of the recent decade (2000–2019). A logistic regression model was developed using the forest cover data of IWH as a dependent variable and climatic records (temperature and precipitation) obtained from ERA-5 data as independent variables. Probability values of two classes (forest and scrub) were computed and were used to define present resilience states. The majority of the forest of the IWH region may not withstand any significant rise in temperature or a reduced amount of precipitation as almost 88.68% of forests of the IWH are under the low to moderate resilience category. Forest resilience significantly decreases below 1500 mm of precipitation indicating its tipping point of regime shift into the scrub. Temperature below 6 °C is not favourable for forests whereas a temperature range of 10–20 °C was found as the conducive range for the existence of forests in the region. Such empirical study would support the formulation of management plans and policies for sustainable forest resources and to assess the impacts of climate change.
... The use of prescribed fire, however, requires careful consideration of treatment effects on wildlife species and communities. In particular, the uncertainty of management outcomes given potentially novel ecological conditions and processes with the interaction of climate change and human disturbance elevate the need for quantifying ecological responses (Millar et al. 2007;Seastedt et al. 2008;McKelvey et al. 2021). ...
Background
Low-severity prescribed fire is an important tool to manage fire-maintained forests across North America. In dry conifer forests of the western USA, prescribed fire is often used to reduce fuel loads in forests characterized historically by mixed- and low-severity fire regimes. Understanding the ecological effects of prescribed fire treatments is important for predicting the impacts of these management actions on wildlife communities. Few studies, however, have estimated small landbird responses to forest treatments at spatial scales relevant to their ecology or have examined potential differences in treatment effects applied within historically mixed- vs. low-severity fire regimes. Therefore, we evaluated prescribed fire treatment effects and relationships with burn severity for avian communities in dry conifer forests dominated by ponderosa pine ( Pinus ponderosa ) located on seven national forests in the interior western USA. We surveyed birds for 1–4 years and 1–3 years before and after prescribed fire treatments at mixed- and low-severity fire regime locations, respectively, following a before-after, control-impact study design — 8 paired control-treatment units in mixed-severity locations (16 total study units with 320 survey points) and 4 paired control-treatment units in low-severity locations (10 total study units with 278 survey points). Using a Bayesian hierarchical multi-species occupancy model, we investigated responses to prescribed fire treatments by a community of 95 bird species.
Results
We found statistically supported treatment effects and/or burn severity relationships for 33 species primarily in mixed-severity locations. The data supported positive treatment effects at mixed-severity locations for 9 species (American robin [ Turdus migratorius ], western bluebird [Sialia mexicana], hairy woodpecker [ Dryobates villosus ], black-backed woodpecker [ Picoides arcticus ], American three-toed woodpecker [ Picoides dorsalis ], house wren [ Troglodytes aedon ], dusky flycatcher [ Empidonax oberholseri ], western wood-pewee [ Contopus sordidulus ], gray flycatcher [ Empidonax wrightii ]), whose occupancy was more likely after treatment at the most severely burned units, and a negative effect for one species (ruby-crowned kinglet [ Corthylio calendula ]), whose occupancy was less likely after treatment at the most severely burned units. At low-severity locations, only two species exhibited treatment effects, both negative (red-faced warbler [ Cardellina rubrifrons ] and lark sparrow [ Chondestes grammacus ]). We also found supported occupancy relationships with burn severity post-treatment (i.e., regardless of species distribution before treatment) for 29 species, most of which were consistent with their life histories (e.g., patterns of positive relationships for cavity-nesting, bark insectivores and negative relationships for open-nesting, foliage insectivores). Stronger responses to prescribed fire treatments at mixed-severity locations were unexpected because prescribed fire applications were more similar to historical wildfires characteristic of low-severity fire regimes.
Conclusions
Bird populations in historically low-severity locations may be relatively unresponsive to prescribed fire because fire there is typically more frequent and regular. By comparison, fire events in forests characterized by a mixed-severity regime are less common, potentially eliciting more responses to an infrequent opportunity, even by species that are strongly associated with recently burned forests by wildfire. Our results suggest that fire management activities intended to reduce fuels and lower the risk of high-severity wildfire can also be effective in creating habitat for some fire specialists at least in the short term.
... The accuracy of species distribution models (SDMs) is essential for sound conservation decision making. By predicting the presence of a species through time and space, biologists and managers can use SDMs to forecast biological invasions, identify critical habitats, prioritize the locations of reserves, appropriately translocate endangered species (Guisan et al. 2013), and inform large-scale land management practices (Thomas et al. 2 2006, Millar et al. 2007. While SDMs are a ubiquitous tool, they require several assumptions that may not be realistic, decreasing prediction accuracy and therefore model transferability (Guisan and Thuiller 2005, Pearman et al. 2008, Elith and Leathwick 2009. ...
Species distribution models (SDMs) provide insights into species' ecology and distributions and are frequently used to guide conservation priorities. However, many uses of SDMs require model transferability, which refers to the degree to which a model built in one place or time can successfully predict distributions in a different place or time. If a species' model has high spatial transferability, the relationship between abundance and predictor variables should be consistent across a geographical distribution. We used Breeding Bird Surveys, climate and remote sensing data, and a novel method for quantifying model transferability to test whether SDMs can be transferred across the geographic ranges of 129 species of North American birds. We also assessed whether species' traits are correlated with model transferability. We expected that prediction accuracy between modeled regions should decrease with 1) geographical distance, 2) degree of extrapolation and 3) the distance from the core of a species' range. Our results suggest that very few species have a high model transferability index (MTI). Species with large distributions, with distributions located in areas with low topographic relief, and with short lifespans are more likely to exhibit low transferability. Transferability between modeled regions also decreased with geographical distance and degree of extrapolation. We expect that low transferability in SDMs potentially resulted from both ecological non‐stationarity (i.e. biological differences within a species across its range) and over‐extrapolation. Accounting for non‐stationarity and extrapolation should substantially increase the prediction success of species distribution models, therefore enhancing the success of conservation efforts.
... Forests are seen as large carbon reservoirs, and precise evaluation of their CO 2 sequestration rate is required for their management and adequate forest protection (Millar et al. 2007). Clear-cut harvesting is one of the essential types of forest management but is considered to be a significant source of CO 2 going into the atmosphere (Houghton 2003). ...
Clear-cut harvesting is one of the important types of forest management but is considered to be a large CO 2 source to the atmosphere. Understanding how this form of logging affects a site's CO 2 balance is critical for determining appropriate management scenarios, yet we have little understanding of how wood harvesting affects the ecosystem CO 2 balance. An experimental clear-cutting and plantation establishment study has been conducted in a cool-temperate mixed forest in northern Japan to obtain a complete series of pre-and post-harvest data on the net ecosystem CO 2 exchange (NEE) between the ecosystem and the atmosphere until a disturbed ecosystem once more become a net CO 2 sink in the annual budget and recapture all the emitted CO 2 after the harvest. A mixed forest, which had been a weak CO 2 sink, was disturbed by clear-cutting and was replaced with a hybrid larch (Larix gmelinii × L. kaempferi) plantation. The ecosystem turned to be a large CO 2 source just after the harvesting in 2003, and the cumulative net CO 2 emission reached up to 15.4 MgC ha-1 at 7 years after the harvesting, then the ecosystem turned to be a CO 2 retrieve mode (CO 2 sink in the annual budget). This ecosystem recaptured all CO 2 emission 18 years after the harvesting in 2020, if off-site carbon storage in forest products is not considered. This implies one harvesting operation cause large invisible and long-lasting effect on the forest ecosystem CO 2 balance.
... Diversification of forest composition is a key strategy to adapt to the challenges of climate change in temperate forests (e.g. increased susceptibility to herbivores; Bauhus et al., 2017;DeLucia et al., 2012;Millar et al., 2007). As in many diversity experiments, the right combination of tree species is on a par with the best performing monocultures or even exceeds their productivity (Forrester & Bauhus 2016) and increases diversity across species groups (Penone et al. 2019). ...
It is generally assumed that trees growing in mixed forests are less susceptible to insect herbivore damage than trees in monocultures. However, to date, there are almost as many studies confirming as rejecting this assumption. Possible underlying drivers, such as tree species composition and herbivore diet breadth, are the subject of current research. For example, specialised herbivores are expected to lead to more damage in monocultures, where they find higher food resource concentration than in mixtures (associational resistance). In contrast, generalist herbivores are expected to lead to more damage in mixtures, due to food resource complementarity (associational susceptibility). However, more research is needed to fully disentangle the drivers of such associational effects. Another phenomenon of plant–herbivore interaction, where deeper understanding of underlying mechanisms is needed, is the enemy release effect for non-native plants (i.e. less herbivory on non-native plants). My thesis contributes to our understanding of these processes by revealing possible explanations for tree diversity and tree origin effects on herbivory. Chapter 1 summarises current knowledge on tree diversity effects on herbivores and enemy release for non-native trees.
Chapter 2 investigates how enemy release is affected by surrounding tree diversity (i. e. tree diversity that is present in the plot). To date, experimental evidence of how tree origin interacts with surrounding tree diversity is sparse. By taking advantage of a transatlantic experiment (IDENT) with congeneric pairs of North-American and European trees, I teased apart tree species identity from native vs. exotic tree origin. Arthropod sampling and leaf damage assessment was conducted on 1971 trees in 364 plots. I analysed whether enemy release is independent of tree species identity and surrounding tree diversity. The systematic comparison of enemy release in this transatlantic experiment showed that there was lower herbivore abundance on non-native trees independent of tree species identity. This result was only partly confirmed for leaf damage, where only for non-native Betula less leaf damage was observed. The effect of tree origin on herbivore abundance was also independent of surrounding tree diversity, and thus can be expected in novel communities and mixed forests, not just in pure stands. These results highlight that enemy release is a general phenomenon for non-native trees, regardless of tree diversity and species identity.
Chapter 3 reports how tree diversity effects on insect herbivory change over time. Plant diversity effects on herbivory have been studied on trees, but it remains unclear whether these effects need time to establish with tree growth. Arthropod abundance and leaf damage were reported for four consecutive years in a young tree diversity experiment (IDENT-Freiburg) in Germany. Herbivore abundance fluctuated between years with a positive tree diversity – herbivory relationship in one year (associational susceptibility). There was a consistently positive diversity – leaf damage relationship throughout the years of study. The positive relationship between predator abundance and tree diversity was also consistent over years. This study highlights that when addressing biodiversity effects on arthropods, yearly changes of this relationship need to be considered.
Chapter 4 reports how tree diversity affects a specific insect pest: the bark beetle Pityogenes chalcographus. Until now, there have been few studies on tree diversity effects on bark beetles. In this study, bark beetle boreholes were recorded on six coniferous tree species in the tree diversity experiment IDENT-Freiburg after a severe drought to test how infestation risk and density are affected by tree diversity. Infestation risk was expected to decrease with species richness and to be lower for the exotic tree species in each congeneric pair (spruce, larch and pine). Infestation probability decreased for the main hosts (European spruce Picea abies and European larch Larix decidua) with increasing tree species richness. However, for less preferred hosts (pine), the probability of infestation increased with increasing species richness. The results show that tree diversity may reduce the risk of bark beetle infestation only for preferred hosts, but not for the tree community as a whole.
The findings of chapters 2, 3, and 4 are synthesised in chapter 5, and implications and new perspectives for the future study of tree diversity effects on herbivores are discussed. Taken together, this thesis shows that associational susceptibility, which is often found in young tree diversity experiments might vanish or turn into associational resistance over time as forests mature. The main host species in mixed stands may benefit from associational resistance against the outbreak species Pityogenes chalcographus and less preferred tree species may suffer from associational susceptibility in mixtures. Overall, this thesis highlights the importance of considering tree species origin and composition, herbivore diet breadth and changes over years when analysing tree diversity and tree origin effects on herbivores.
... These factors can be considered in the context of forest management treatments that are commonly used within regions and actions that purposefully focus on adapting forests to the potential negative impacts of climate change (e.g. insect outbreaks, drought, etc.) [1][2][3]. Current research suggests multi-aged forest management systems, such as irregular shelterwood and selection systems, may enhance C stocks and accumulation in naturally regenerated forests when compared to silvicultural practices that remove most of the standing biomass during single entries with little or no focus on tree regeneration (e.g. commercial clearcutting) [4][5][6]. ...
... Terrestrial ecosystems are facing challenges brought about by global climate change (IPCC, 2007;Millar et al., 2007), with prolonged droughts expected to have drastic effects on various terrestrial ecosystems (Konings and Gentine, 2017). Wet forests, where plants are adapted to relatively high water availability (Sperry et al., 2002), are expected to be particularly at risk (Meir and Woodward, 2010). ...
Forest tree species in wet and dry habitats are generally considered functionally divergent in leaf and stem functional traits such as leaf area, leaf mass per area, wood density and tree height. Yet, these traits have limited utility for characterizing plant water transport adaptations and strategies. We tested the hypothesis that wet and dry forest trees are functionally divergent in their water conducting apparatus. To assess trait differences and adaptations, we sampled branch wood from nine same-genus species-pairs, each species-pair occurring respectively in the wet (>1500 mm annual rainfall) and dry forest (<800 mm annual rainfall) in tropical Queensland, Australia. From branch wood sections, we measured anatomical traits involved in water conduction (stem vessel dimensions, fractions and their spatial distributions, theoretical water conductivities), storage (parenchyma), and providing hydraulic safety functions (fibres fractions, vulnerability index). Relative to wet forest species, we found on overall that dry forest trees had trait combinations showing adaptations to aridity such as more storage tissue and greater vessel connectivity which may provide alternative pathways for water transport should vessel embolism occur. Habitat is an environmental filter that influences trait behavior across related species. However, depending on the genera, species in both dry and wet forest habitats also exhibit various tradeoffs in trait values, highlighting the existence of diverse hydraulic strategies within wet forest and dry forest trees.
... Prichard et al. (2021), through an extensive literature review, show the strengths and limitations of fuel reduction treatments and argue that increasing the pace and scale of management is essential to reducing the potential negative effects of large-scale wildfires. However, uncertainty in the timing and location of these events poses a challenge to land managers and decision makers when planning treatments across large landscapes (Millar et al., 2007). For example, Stevens et al. (2016) found that the desired reduction in fire extent could be attained through treating only ∼30% of their study watershed, and they show that the type and configuration of treatments had significant effects on fire size, severity, and smoke production. ...
Active forest management is applied in many parts of the western United States to reduce wildfire severity, mitigate vulnerability to drought and bark beetle mortality, and more recently, to increase snow retention and late-season streamflow. A rapidly warming climate accelerates the need for these restorative treatments, but the treatment priority among forest patches varies considerably. We simulated four treatment scenarios across the 3,450 km2 Wenatchee River basin in eastern Washington, United States. We used a decision support tool (DST) to assess trade-offs and synergies within and among treatments on wildfire risk and smoke emissions, water yield and snow retention, biomass production, and economic return. Treatment scenarios emphasized prescribed burning (BurnOnly), biomass production (MaxBiomass), gap-based thinning to optimize water yield (IdealWater), and a principle-based restoration scenario (RA1). Fire hazard, smoke emissions, and biomass production metrics were evaluated across scenarios using the Forest Vegetation Simulator, and water yields were modeled using the Distributed Hydrology Soil Vegetation Model. Simulations were summarized to both patch- (101–102 ha) and subwatershed- (103–104 ha) scales, and treatment effects were evaluated against an untreated baseline landscape. We used logic models to rank effect sizes by scenario across metrics along a continuum between −1 (no or weak effect) to +1 (large effect). All treatments produced benefits across one or more ecosystem services and led to synergistic benefits to water yield and wildfire hazard reduction. Tradeoffs among resource benefits were clear in wilderness where reliance on prescribed burning without mechanical treatment increased costs and eliminated the potential for biomass recovery. The BurnOnly scenario improved fire risk metrics and streamflow, but effect sizes were lower compared to other treatments. IdealWater showed the strongest benefits overall, demonstrating the ability to capture multiple resource benefits through spatially explicit thinning. Our study provides a framework for integrating strategic and tactical models that evaluate tradeoffs and synergies gained through varied management approaches. We demonstrate the utility of decision support modeling to enhance management synergies across large landscapes.
... °C (IPCC 2014). The cascading effects of climate change will have deleterious impacts on ecosystems, affecting an array of different trophic levels and species interactions (Parmesan and Yohe 2003;Millar et al. 2007;Bonan 2008). One of the best-documented responses of this crisis is habitat shifts (Thomas et al. 2004a, b;Thuiller et al. 2005;Visser and Both, 2005), as changing climatic conditions shift species' climatic niches along time and space (Bellard et al. 2012;Thomas et al. 2004a, b). ...
Climate change can be expected to alter ecosystems and influence the spatial distribution of species. Understanding the effects of climate change on species distribution can help develop effective conservation protocols to tackle further biodiversity loss. Striped hyena (Hyaena hyaena) global populations appear to follow an overall decreasing trend as the species faces numerous threats. Hyena presence location data was collected, and we utilized a Maxent species distribution model to predict current and future distribution patterns in Nepal. We used two distinct representative concentration pathway (RCP) values (RCP 4.5 and RCP 8.5) to determine potential impacts on hyena distribution. We found that hyena current suitable habitat in Nepal extends over 22,000 km2 and is projected to significantly decrease in both (RCP 4.5 and RCP 8.5) scenarios. In terms of habitat reduction, we further showed that RCP 8.5 was more adverse than RCP 4.5. We found that the Chure hills and the Terai regions hold the largest extent of hyena habitat in Nepal. Hyena habitat reduction was comparatively lower within the protected areas. Future projections, however, portend severe consequences for the species’ survival as suitable habitat areas will be drastically reduced in the next 50 years. Further research on hyena microhabitat suitability under anthropogenic and topographic variables will be useful for future conservation policies.
... Strategies for enhancing the core attributes of adaptive capacity in restoration practice, governance, and the target ecosystem (ecology). Ideas adapted from Folke et al. (2002), Millar et al. (2007), Cost (2015), Parker and Simpson (2020), Chaudhury and Colla (2021), Trisos et al. (2021). ...
In the face of rapid environmental change, restoration will need to emphasize innovative approaches that support the long‐term resilience of social and ecological systems. To this end, we highlight the critical, but often overlooked, role of adaptive capacity, which enables restoration practice, governance, and target ecosystems to adapt to directional environmental change. We identify three core attributes of adaptive capacity: 1) diversity, 2) connectivity, and 3) flexibility. For each attribute, we describe key strategies, including enhancing mechanisms of ecological memory, facilitating the generation of beneficial novelty, and developing governance structures that are flexible and anticipatory. These core attributes can also lead to maladaptive outcomes; careful consideration of a social‐ecological system's resilience and vulnerabilities to environmental change will likely be critical to avoid unwanted outcomes. Ultimately, implementing strategies that increase adaptive capacity can bolster restoration efficacy as it seeks to confront the global challenge of rapid environmental change. This article is protected by copyright. All rights reserved.
... This multiyear mortality event was unprecedented in magnitude and geographic extent (Stephens et al., 2018), resulting in significant mortality of ecologically important large pine trees (Fettig et al., 2019;Stephenson et al., 2019), adversely impacting federally protected wildlife species (Kordosky et al., 2021), destabilizing forest carbon stores and reallocating forest carbon debt (Earles et al., 2014;Goodwin et al., 2020), and creating fuel conditions conducive to more extreme fire behavior Stephens et al., 2018). Projected declines in winter snowpack along with increased drought frequency and intensity (Marshall et al., 2019;Ullrich et al., 2018) highlight the need to develop forest management strategies to mitigate the effects of extreme drought on forest mortality and ecosystem services (Millar et al., 2007;Stephens et al., 2020). ...
An estimated 128 M trees died during the 2012–2016 California drought, largely in the southern Sierra Nevada Range. Prescribed burning and mechanical thinning are widely used to reduce fuels and restore ecosystem properties, but it is unclear if these treatments improve tree growth and vigor during extreme drought. This study examined tree growth responses after thinning, prescribed burning, and extreme drought at the Teakettle Experimental Forest, a historically frequent fire mixed-conifer forest in the southern Sierra Nevada of California, USA. Mechanical thinning (no thin, understory thin, and overstory thin) and prescribed burning (unburned, fall burning) were implemented in 2000–2001. Using annual growth data from increment cores, over 10,000 mapped and measured trees, and lidar-derived metrics of solar radiation and topographic wetness, we had two primary questions. First, what were the growth responses to thinning and prescribed burning treatments, and did these responses persist during the 2012–2016 drought? Second, what tree-level attributes and environmental conditions influenced growth responses to treatments and drought?
Thinning increased residual tree growth and that response persisted through extreme drought 10–15 years after treatments. Growth responses were higher in overstory versus understory thinning, with differences between thinning types more pronounced during drought. Species-specific growth responses were strongest with overstory thinning, with sugar pine (Pinus lambertiana) and incense-cedar (Calocedrus decurrens) having higher growth responses compared to white fir (Abies concolor) and Jeffery pine (Pinus jeffreyi). For individual trees, factors associated with higher growth responses were declining pretreatment growth trend, smaller tree size, and post-treatment low neighborhood basal area. Growth responses were initially not influenced by topography, but topographic wetness became important during extreme drought. Mechanical thinning resulted in durable increases in residual tree growth rates during extreme drought over a decade after thinning occurred, indicating treatment longevity in mitigating drought stress. In contrast, tree growth did not improve after prescribed burning, likely due to fire effects that reduced surface fuels, but had little effect on reducing tree density. Thinning treatments promoted durable growth responses, but focusing on stand-level metrics may ignore important tree-level attributes such as localized competition and topography associated with higher water availability. Mechanical thinning was effective at improving growth in trees that had been experiencing declining growth trends, but was less effective in improving growth responses in large old trees of higher ecological importance.
The purpose of this document is to help individuals and organizations effectively engage in the forest planning process to ensure that newly revised national forest plans adequately address climate considerations and concerns. And while there are many components and outcomes of national forest plans, our particular focus is on how these plans can help increase the quality, pace, and scale of ecologically appropriate and climate- smart forest restoration
Climate change is altering the distribution of woody plants by influencing demographic processes and modifying disturbance regimes. Trailing-edge forests may be particularly vulnerable to these effects because they exist at warm, dry margins of tree distributions. To better understand recent climate-driven changes in trailing-edge forests, we used Landsat time series and 1558 field reference plots to develop annual land cover maps from 1985 to 2020 in two large, biodiverse landscapes in central Arizona, USA. We then combined annual land cover maps with tree ring records and spatial data describing interannual climate, terrain, bark beetle (Curculionidae: Scolytinae) activity, wildfire, and harvest to quantify drivers of forest change. Throughout the two landscapes, forest extent declined by 0.3 % and 0.8 % from 1985 to 2020. However, considerable variation occurred within the study period, with abrupt (ca. 1–2 years) declines in forest extent followed by gradual (ca. 10 years) recovery on each landscape. Pinyon-juniper (Pinus edulis, Pinus monophylla, and/or Juniperus spp.) cover increased from 1985 to ca. 2000 but declined after 2000, a period of extreme drought and regional tree die-off. In contrast, pine-oak (Pinus ponderosa and Quercus spp.) cover increased from 2000 to 2020, primarily due to declines in ponderosa pine and mixed conifer cover over the same period. Wildfire was a key driver of transitions from forest to non-forest cover in our study area, with the occurrence of multiple compounded drought years playing an important role in unburned areas. By driving transitions to alternative forest types or non-forest cover, disturbance and drought will increasingly shape forest dynamics and ecosystem transformations throughout the southwestern US.
The term 'adaptation' is commonplace in conservation research and practice, but often without a reflection on the assumptions, expectations, or frames of reference used to define goals and actions. Communities of practice (e.g. conservation researchers, protected areas managers) have different interpretations of climate change impacts on biodiversity and different ways of defining, operationalizing and implementing adaptation. Their cognitive and motivational expectations for the future are associated with different paths to reach such desired futures. To understand how adaptation is framed in conservation, we undertook a systematic review with a thematic synthesis of the definitions of the term as used in the academic conservation literature. From a sample of 150 articles, only 36 provided a definition of adaptation. We critically appraised the explicit definitions to identify emergent themes that represent particular adaptation approaches. Themes were then grouped, and each group was assigned to a scholarly tradition, onto-epistemological approach and theoretical perspective. Based on theoretical perspectives on social change, we propose a framework (including individual cognitive basis, social interactions, and openness to alternatives) to analyse how change is framed in the definitions and how the framings influence adaptation options. The grouped themes represent passive, active, or indirect adaptation approaches. We used these themes to generate a conceptual model to guide conservation researchers and practitioners engaged in climate adaptation research, policy and management to aid reflection and understanding of the options available to design adaptation agendas and allow negotiation of diverse interests, views and expectations about the future. ARTICLE HISTORY
Ecosystems are dynamic systems with complex responses to environmental variation. In response to pervasive stressors of changing climate and disturbance regimes, many ecosystems are realigning rapidly across spatial scales, in many cases moving outside of their observed historical range of variation into alternative ecological states. In some cases, these new states are transitory and represent successional stages that may ultimately revert to the pre-disturbance condition; in other cases, alternative states are persistent and potentially self-reinforcing, especially under conditions of altered climate, disturbance regimes, and influences of non-native species. These reorganized states may appear novel, but reorganization is a characteristic ecosystem response to environmental variation that has been expressed and documented throughout the paleoecological record. Resilience, the ability of an ecosystem to recover or adapt following disturbance, is an emergent property that results from the expression of multiple mechanisms operating across levels of organism, population, and community. We outline a unifying framework of ecological resilience based on ecological mechanisms that lead to outcomes of persistence, recovery, and reorganization. Persistence is the ability of individuals to tolerate exposure to environmental stress, disturbance, or competitive interactions. As a direct expression of life history evolution and adaptation to environmental variation and stress, persistence is manifested most directly in survivorship and continued growth and reproduction of established individuals. When persistence has been overcome (e.g., following mortality from stress, disturbance, or both), populations must recover by reproduction. Recovery requires the establishment of new individuals from seed or other propagules following dispersal from the parent plant. When recovery fails to re-establish the pre-disturbance community, the ecosystem will assemble into a new state. Reorganization occurs along a gradient of magnitude, from changes in the relative dominance of species present in a community, to individual species replacements within an essentially intact community, to complete species turnover and shift to dominance by plants of different functional types, e.g. transition from forest to shrub or grass dominance. When this latter outcome is persistent and involves reinforcing mechanisms, the resulting state represents a vegetation type conversion (VTC), which in this framework represents an end member of reorganization processes. We explore reorganization in greater detail as this phase is increasingly observed but the least understood of the resilience responses. This resilience framework provides a direct and actionable basis for ecosystem management in a rapidly changing world, by targeting specific components of ecological response and managing for sustainable change.
Fires in Amazon rainforest, Hurricane Dorian in Bahamas, and wildfires in California are among some of the recent events related to the climate change. The rising sea levels, higher temperatures, and extreme precipitation are some of the causation of climate change. The communities around the world are coping with these changes now. In this regard, an untypical effort from all sectors of community is needed to address critical problems of adapting to climate change and feeding 7.7 billion people.
The Internet of Things for Sustainable Community Development addresses the key inter-related environmental, climate change, energy, water, health, mining, agroeconomic, and cybersecurity challenges that limit the development of sustainable and resilient society. The aim of this book is to present an integrated depiction of how the Internet of Things “IoT” can stimulate the sustainable community development. The expertise across multiple domains including engineering and technology, ecosystems and natural resource management, environmental toxicology, human health, agriculture, mining, and urban underground infrastructure monitoring is introduced to examine important environmental challenges that can be solved with applications of recent advancements in Internet of Things.
In these domains, the sensing data is generated by a wide range of sensors, from point-based direct in situ measurements to airborne and remote sensing for global coverage through satellites. In each domain, the sensing requirements change considerably, stretching from plant level water status to field level soil moisture, and regional level cloud hydrometer to global scale climate crises and greenhouse gases. The integration of huge volumes of data being generated across these spatial–temporal scales is a major challenge. Moreover, the transmission and processing of this data in decision support systems to address sustainability challenges requires cross-disciplinary endeavors with expertise in sensing, wireless communications, systems science, and modeling, in addition to the specific domain knowledge. The Internet of Things has strong potential to foster the creation of these cross-disciplinary next-generation sensing and communication systems using IoT. These IoT systems for data gathering, wireless communications, processing, and presentation of sensing data are vital to get insights into the biological, physical, and chemical processes in the environment, and forecasting the prospective advancement of ecosystems sustainability. Such forecasts are also required to support policy and regulation decisions.
The Internet of Things for Sustainable Community Development presents a portfolio of cutting-edge, interdisciplinary research developments and challenges in IoT sensing, communications, and systems. It provides a well-founded coverage of these technologies with rigorous focus on scientific concepts, evolution, and applications to sustainability. The comprehensive contents are arranged systemically to provide the scientific foundations of Internet of Things for sustainable community development. The book covers research and innovation ecosystem of the Internet of Things for sustainability in the following major areas that are explored in this book. These areas highlight converging activities that enable the main cohesive objective of sustainable community development.
• Climate Change
• Sustainable Energy Systems
• Sustainable Water
• Human Health
• Sustainable Mining
• Decision Agriculture
• Storm and Wastewater
• Sustainable Forestry
Each of these areas emphasizes core IoT research challenges and solutions while leveraging their shared traits, interdependencies, and expertise to converge on applications of IoT to sustainability challenges. These sections of our community do not exist in segregation. The energy and water are fully intertwisted because the water is used to produce energy, and the energy is needed to drain, remedy, and transport water, which underscores the connection between the water-dependent crop growers and city dwellers. Moreover, the human health is impacted by water availability and quality, energy availability, cultivation, mining, and waste management, inter alia, impacting patients, diseases spread, and outbreak. Furthermore, forestry and watershed are impacted by water availability, energy supply, climate crisis, and biodiversity.
In that regard, the book emphasizes IoT paradigm’s sensing, wireless communications, monitoring, actuation, and real-time decision capabilities for sustainability “things”. Thus, proper focus is also given to systems, standards, and tools that have tremendous potential to achieve United Nations Sustainable Development Goals. It provides a comprehensive reference to all these aspects in an easy language that is understandable by a wide audience. It also includes advanced treatment of sustainability IoT technology applications and provides in-depth coverage of research developments and open research challenges.
While intended primarily for sustainable engineering and technology professionals, researchers, and students, this book is also beneficial to policy makers, city planners and managers, technicians, and industry professionals. The research in Internet of Things for sustainability has a vital role to play in shaping the future of our community as they must create a research and education ecosystem promoting impactful solutions-oriented science to help citizenry, government, industry, and other stakeholders work collaboratively to make informed, socially responsible, science-based decisions. The socio-technical analysis presented in this monograph together with application of the latest innovations in IoT sensing, systems, and wireless communications technologies allows for a deeper understanding and management of these complex interconnected human-socio-environmental challenges.
Along with the increase in the frequency of disastrous wildfires and bushfires around the world during the recent decades, scholarly research efforts have also intensified in this domain. This work investigates divisions and trends of the domain of wildfire/bushfire research. Results show that this research domain has been growing exponentially. It is estimated that the field, as of 2021, it has grown to larger than 13,000 research items, with an excess of 1,200 new articles appearing every year. It also exhibits distinct characteristics of a multidisciplinary research domain. Analyses of the underlying studies reveal that the field is made up of five major divisions. These divisions embody research activities around (i) forest ecology and climate, (ii) fire detection and mapping technologies, (iii) community risk mitigation and planning, (iv) soil and water ecology, and (v) atmospheric science. Research into the sub-topics of reciprocal effects between climate change and fire activities, fire risk modelling/mapping (including burned area modelling), wildfire impact on organic matter, biomass burning, and human health impacts currently constitute trending areas of this field. Amongst these, the climate cluster showed an explosion of activities in 2020 while the human health cluster is identified as the most recent emerging topic of this domain. On the other hand, dimensions of wildfire research related to human behaviour—particularly issues of emergency training, risk perception and wildfire hazard education—seem to be notably underdeveloped in this field, making this one of its most apparent knowledge gaps. A scoping review of all reviews and meta-analysis of this field demonstrates that this sub-topic is also virtually non-existent on the research synthesis front. This meta-synthesis further reveals how a western, deductive view excludes socioecological and traditional knowledge of fire.
This chapter describes the impact of some nonbiotic factors on forest health in Europe during the past decades. Storms, floods, and fires, as well as anthropogenic factors, were taken into consideration as primary disturbances predisposing trees to biotic damage. Data and information on the main harmful factors in a few countries obtained since 1950 are presented. These damage agents negatively influence forest health, reducing the survival of trees, and lead to biomass losses. The consequences of abiotic stress for the tree in the final balance are reduced photosynthesis efficiency, weakened plant immunity, increased susceptibility to infections, reduced tolerance to fungi, and increased opportunities for polycyclic diseases. The impact of these abiotic environmental elements is further discussed in relation to climate change.
Variations in temperature and rainfall patterns due to climate change will lead to alterations in the potential habitat of species. This change will affect the interactions between species, being more evident in vulnerable species with fragmented habitat. This study aims to test the importance of abiotic and biotic factors determining the niche of threatened species in mountainous conifer forests. We used as study case the endangered Abies pinsapo in Southern Spain to understand its co-occurrence patterns in relation to the distribution and habitat suitability of key competing species. We estimated the intensity of interactions in relation to environmental gradients and development stage by single and joint species distribution models using a Bayesian approach in combination with niche overlap metric methods. Average temperature of the coldest month and precipitation were key variables shaping the current distribution of A. pinsapo. The ensemble potential distribution of the species showed very high overlap with the distribution of A. pinsapo. The joint species distribution model showed a potential negative interaction between A. pinsapo and the adults of Q. faginea and P. halepensis and positively with Juniperus species. A. pinsapo populations located at the low elevation distribution area are the most vulnerable, ultimately triggering a shift towards higher altitudes in a context of climate change. This abiotic stress will be exacerbated by competition dynamics of competing species from lower altitudes. This likely shift is shared by other mountain conifer species, with a success in survival limited by the availability of suitable area at higher altitudes.
The real‐world application of climate change adaptation practices in terrestrial wildlife conservation has been slowed by a lack of practical guidance for wildlife managers. Although there is a rapidly growing body of literature on the topic of climate change adaptation and wildlife management, the literature is weighted towards a narrow range of adaptation actions and administrative or policy recommendations that are typically beyond the decision space and influence of wildlife professionals. We developed a menu of tiered adaptation actions for terrestrial wildlife management to translate broad concepts into actionable approaches to help managers respond to climate change risks and meet desired management goals. The menu includes actions related to managing wildlife populations as well as managing wildlife habitat. We designed this resource to be used with the Adaptation Workbook, a structured decision‐support tool for climate adaptation. We describe real‐world examples in which managers have used the Wildlife Adaptation Menu to integrate climate adaptation considerations into wildlife management and conservation projects. Our examples illustrate how a comprehensive and structured menu of adaptation approaches can help managers brainstorm specific actions and more easily and clearly communicate the intent of their climate adaptation efforts. We present a structured, comprehensive menu of climate change adaptation strategies and approaches for managers of terrestrial wildlife. This menu can help managers define specific actions to implement and communicate the intent of their actions.
Tree mortality rates have been increasing globally with mountainous regions experiencing higher temperatures and impacts from the expansion and intensification of pests and invasion by non-native agents. Western North American high-elevation forests exemplify these trends, and they often include one or more species of five-needle white pines (High-5 hereafter). These species share many characteristics critical to defining the structure and function of many subalpine forests. The main threats to High-5 populations include the non-native pathogen Cronartium ribicola, which causes the disease white pine blister rust, climate-driven drought stress, episodic and high mortality from mountain pine beetle (Dendroctonus ponderosae), and wildfires of increasing frequency, size, and intensity. The six High-5 species occurring in western North America (whitebark pine, Pinus albicaulis; limber pine, P. flexilis; southwestern white pine, P. strobiformis; Rocky Mountain bristlecone pine, P. aristata; Great Basin bristlecone pine, P. longaeva; and foxtail pine, P. balfouriana) differ in their health status and threat level. The convergence of threats impacting the rapidly declining species could portend future declines in the species and populations currently less impacted by recent disturbances. Differences in the innate adaptive capacities of the species affect their population trajectories under these novel combinations of stressors. We evaluate the status and outlook for each species and address the following questions: (1) Is the environment changing too fast and the intensity of stressors too great for the species to adapt and recover? (2) Do the species have the heritable traits necessary to sustain fitness under C. ribicola and climatic stresses? (3) Are other mortality factors increasing to the degree that they reduce the populations further and delay or preclude adaptation and population recovery? (4) Can the species escape the stressors through migration? Insights related to these questions provide guidance for forest management to facilitate adaptation and increase the resilience of these species into the future.
The adaptive capacity of forests and foresters to overcome the adverse effects of climate change remains highly uncertain despite intense research efforts. While foresters are often invited “not to put all their eggs in one basket,” adaptation strategies to climate change mostly depend on silvicultural diversification. To explore how socioeconomic adaptive tools can complement these technical evolutions in forestry, we designed an interdisciplinary and participatory simulation of forest management combining a role-playing game, ecological models of forest evolution, and a severe climate change scenario. Participants from French natural parks and forest organizations responded positively to its multiple applications. Here, we investigate the technical and timber-focused framing of climate change by forest managers. We also analyze participants’ negotiations when attempting to change the simulation rules of forest management. Drawing on this experience, we highlight how establishing a payment system for ecosystem services can reduce financial imbalance driven by climate change.
An extensive ground survey of the white pine species in Sequoia and Kings Canyon National Parks was performed on foot from 1995-1999. The white pine distribution, including sugar pine (Pinus lambertiana), whitebark pine (Pinus albicaulis), foxtail pine (Pinus balfouriana), limber pine (Pinus flexilis), and western white pine Pinus monitcola) was modeled using existing (1995) data in the form of vegetation type maps and an aerially stratified random sampling scheme was devised for the installation and evaluation of 151 permanent monitoring plots. Three additional plots were installed in areas of particular interest. Observed white pine distribution was mapped in selected areas in conjunction with the plot establishment. Within each plot, an average of 48 white pines greater than one meter tall were measured and mapped for long-term monitoring, and evaluated for white pine blister rust (Cronartium ribicola) infection. Data from these plots provides a rough estimate of the incidence and severity of effect of blister rust upon the populations of these species within the park boundaries. The average incidence of rust infection was 6.6% for all plots in the random sampling scheme; rust was found only in plots containing sugar pine (21.1% average incidence) and western white pine (2.7% average incidence). Incidence and severity of rust were related to associated Ribes species, elevation, and topographic position. Rust was found to be more often associated with Ribes nevadense and Ribes roezlii than other Ribes species, rarely found above 8800 feet in elevation, and most often found in valley bottoms. In certain areas, sugar pines and western white pines have been significantly affected by bole infections in smaller trees, which often results in mortality. The populations of foxtail, whitebark, and limber pines within these parks appear to remain virtually unaffected by blister rust.
Alternative fire hazard reduction techniques are needed for managing fuel profiles in forest ecosystems located within the so-called wildland-urban interface. The present study includes experimental fuel manipulations initiated along the Rocky Mountain National Park interface with residential areas in Colorado, USA. Three thinning/slash disposal treatments were applied on two lodgepole pine (Pinus contorta) stands: thinning with whole-tree removal; thinning with stem removal - lopping and scattering; and thinning with stem removal - hand piling and burning. Results indicate that treatments reduced surface fire behavior parameters, bringing them down and closer to Limits of direct attack methods. Crown fire potential was decreased not only because of canopy removal, but also as a result of potential reduction in heat generated by surface fuels. Projected fire behavior for the thinning-without-slash-removal scenario indicates the possibility of serious control problems with major fire runs and crown fires given an outbreak.
Owens Valley, California, was markedly different during the Wisconsin glacial stage from what it is today. Alpine glaciers bounded the Sierra Nevada, and pluvial Owens Lake reached highstands and overflowed its natural basin. We analyzed three layers from two packrat middens, dated to ca 23,000-14,500 yr BP, obtained from Haystack Mountain (1155 m) only 10 m above and < 100 m from the highstand strandline of pluvial Owens Lake. During this period vegetation near Owens Lake reflects the influence of the Tioga glacial advance and retreat on lake levels, and microclimatic effects on shoreline vegetation. Between ca 23,000 and 17,500 yr BP a Utah juniper (Juniperus osteosperma) and single-needle pinyon pine (Pinus monophyllla) woodland existed at the site. In the layers dated to ca 17,500 and 16,000 yr BP, macrofossils document the presence of Rocky Mountain juniper (Juniperus scopulorum), a species that no longer occurs in California. It is suggested that meltwater from the retreating glacial ice inundated the Owens River Lake chain causing pluvial Owens Lake to reach its highstand. This caused an increase in effective moisture, due to high groundwater, allowing the mesophytic Rocky Mountain juniper to exist at the site.
Ecological restoration is the process of reestablishing the structure and func- tion of native ecosystems and developing mutually beneficial human-wildland interactions that are compatible with the evolutionary history of those systems. Restoration is based on an ecosystem's reference conditions (or natural range of variability); the difference between reference conditions and contemporary conditions is used to assess the need for restorative treatments and to evaluate their success. Since ecosystems are highly complex and dynamic, it is not possible to describe comprehensively all possible attributes of ref- erence conditions. Instead, ecosystem characteristics with essential roles in the evolutionary environment are chosen for detailed study. Key characteristics of structure, function, and disturbance—especially fire regimes in ponderosa pine ecosystems—are quantified as far as possible through dendroecological and paleoecological studies, historical evidence, and comparison to undisrupted sites. Ecological restoration treatments are designed to reverse recent, human-caused ecological degradation. Testing of restoration treatments at four sites in northern Arizona, USA, has shown promise, but the diverse context of management goals and constraints for Southwestern forest ecosystems means that appropriate applica- tions of restoration techniques will probably differ in various settings.
Tree-ring records spanning the past seven centuries from the central and southern Rocky Mountains were studied using wavelet analysis to examine multidecadal (>30-70 yr) patterns of drought variation. Fifteen tree-ring series were grouped into five regional composite chronologies based on shared low-frequency behavior. Strong multidecadal phasing of moisture variation was present in all regions during the late 16th century megadrought. Oscillatory modes in the 30-70 yr domain persisted until the mid-19th century in two regions, and wet-dry cycles were apparently synchronous at some sites until the 1950s drought. The 16th/17th century pattern of severe multidecadal drought followed by decades of wet conditions resembles the 1950s drought and post-1976 wet period. The 16th century megadrought, which may have resulted from coupling of a decadal (similar to20-30 yr) Pacific cool phase with a multidecadal warm phase in the North Atlantic, marked a substantial reorganization of climate in the Rocky Mountain region.
Forest insects and pathogens are the most pervasive and important agents of disturbance in North American forests, affecting an area almost 50 times larger than fire and with an economic impact nearly five times as great. The same attributes that result in an insect herbivore being termed a "pest" predispose it to disruption by climate change, particularly global warming. Although many pest species have co-evolved relationships with forest hosts that may or may not be harmful over the long term, the effects on these relationships may have disastrous consequences. We consider both the data and models necessary to evaluate the impacts of climate change, as well as the assessments that have been made to date. The results indicate that all aspects of insect outbreak behavior will intensify as the climate warms. This reinforces the need for more detailed monitoring and evaluations as climatic events unfold. Luckily, we are well placed to make rapid progress, using software tools, databases, and the models that are already available.
Improved understanding of tree growth responses to climate is needed to model and predict forest ecosystem responses to current and future climatic variability. We used dendroecological methods to study the effects of climatic variability on radial growth of a subalpine conifer, mountain hemlock (Tsuga mertensiana). Tree-ring chronologies were developed for 31 sites, spanning the latitudinal and elevational ranges of mountain hemlock in the Pacific Northwest. Factor analysis was used to identify common patterns of inter- annual growth variability among the chronologies, and correlation and regression analyses were used to identify climatic factors associated with that variability. Factor analysis identified three common growth patterns, representing groups of sites with different climate-growth relationships. At high-elevation and midrange sites in Wash- ington and northern Oregon, growth was negatively correlated with spring snowpack depth, and positively correlated with growth-year summer temperature and the winter Pacific Decadal Oscillation index (PDO). In southern Oregon, growth was negatively correlated with spring snowpack depth and previous summer temperature, and positively correlated with previous summer precipitation. At the low-elevation sites, growth was mostly insen- sitive to annual climatic variability but displayed sensitivity to decadal variability in the PDO opposite to that found at high-elevation sites. Mountain hemlock growth appears to be limited by late snowmelt, short growing sea- sons, and cool summer temperatures throughout much of its range in the Pacific Northwest. Earlier snowmelt, higher summer temperatures, and lower summer precipitation in southern Oregon produce conditions under which growth is limited by summer temperature and/or soil water availability. Increasing atmospheric CO2 concentrations could produce warmer temperatures and reduced snowpack depths in the next century. Such changes would likely increase mountain hemlock growth and productivity throughout much of its range in Washington and northern Oregon. Increased summer drought stress and reduced productivity would be likely, how- ever, in mountain hemlock forests of southern Oregon and near the species lower elevation
Climate in the North Pacific and North American sectors has experienced interdecadal shifts during the twentieth century. A network of recently developed tree-ring chronologies for Southern and Baja California extends the instrumental record and reveals decadal-scale variability back to 1661. The Pacific decadal oscillation (PDO) is closely matched by the dominant mode of tree-ring variability that provides a preliminary view of multiannual climate fluctuations spanning the past four centuries. The reconstructed PDO index features a prominent bidecadal oscillation, whose amplitude weakened in the late l700s to mid-1800s. A comparison with proxy records of ENSO suggests that the greatest decadal-scale oscillations in Pacific climate between 1706 and 1977 occurred around 1750, 1905, and 1947.
Evidence gleaned from the instrumental record of climate data identifies a robust, recurring pattern of ocean–atmosphere climate variability centered over the midlatitude North Pacific basin. Over the past century, the amplitude of this climate pattern has varied irregularly at interannual-to-interdecadal timescales. There is evidence of reversals in the prevailing polarity of the oscillation occurring around 1925, 1947, and 1977; the last two reversals correspond to dramatic shifts in salmon production regimes in the North Pacific Ocean. This climate pattern also affects coastal sea and continental surface air temperatures, as well as streamflow in major west coast river systems, from Alaska to California.
Ecological responses to climatic variability in the Southwest include regionally synchronized fires, insect outbreaks, and pulses in tree demography (births and deaths). Multicentury, tree-ring reconstructions of drought, disturbance history, and tree demography reveal climatic effects across scales, from annual to decadal, and from local (�102 km2) to mesoscale (104–106 km2). Climate–disturbance relations are more variable and complex than previously assumed. During the past three centuries, mesoscale outbreaks of the western spruce budworm (Choristoneura occidentalis) were associated with wet, not dry episodes, contrary to conventional wisdom. Regional fires occur during extreme droughts but, in some ecosystems, antecedent wet conditions play a secondary role by regulating accumulation of fuels. Interdecadal changes in fire–climate associations parallel other evidence for shifts in the frequency or amplitude of the Southern Oscillation (SO) during the past three centuries. High interannual, fire–climate correlations (r � 0.7 to 0.9) during specific decades (i.e., circa 1740–80 and 1830– 60) reflect periods of high amplitude in the SO and rapid switching from extreme wet to dry years in the Southwest, thereby entraining fire occurrence across the region. Weak correlations from 1780 to 1830 correspond with a decrease in SO frequency or amplitude inferred from independent tree-ring width, ice core, and coral isotope reconstructions.
The main objective of this project was to reconstruct past fire history in different giant sequoia groves distributed along a north·south transect from Yosemite National Park southward to Mountain Home State Forest. We planned to develop millennia-length fire-scar chronologies
for different sequoia mixed-conifer groves and to compare the fire histories (fire frequency, size, intensity, and season) within and among these groves. Earlier fire-scar studies in the Redwood Mountain Grove by Kilgore and Taylor (1979) demonstrated that pre-settlement (pre·1875) surface fires were relatively frequent with two to three year mean fire intervals within watersheds of about 800 to 1000 ha., and five to nine year mean fire intervals in smaller sites of 3 to 16 ha. These fire-scar chronologies, based upon specimens from pines, fir, and incense cedar, were used to estimate fire frequency variations within two watersheds back to about A.D. 1700, although a few samples had scars extending back into the late 1400s. Our goal has been to spatially expand and temporally extend the knowledge base of fire history to other sequoia mixed-conifer groves in the Sierra Nevada by sampling ancient fire-scarred sequoias.
Natural scientists are being encouraged by environmental and developmental agencies to define and operationalize the concept of sustainability in a “scientific” manner. Such an approach is fraught with dangers because values, opinions, and social influences are an inextricable part of science, especially applied science. Natural scientists’ attempts to define sustainability, particularly to decide what should be sustained, cannot therefore be value-neutral. They simply end up shifting value judgments to different levels by choosing either a single obvious objective, an arbitrary range of objectives, or an arbitrary method of aggregating different preferences. This lack of self-reflectiveness on the part of scientists has important consequences for the direction of research and its political implications. Natural scientists should heed lessons from earlier cases of scientists’ involvement in policy and redefine the terms of reference before shouldering their social burden. The dilemma of pursuing objective science in a value-loaded and socially charged discourse can be resolved by properly understanding the role of analysis and by pursuing a socially grounded pluralistic approach to problem definition and research methodology.
Question: What are the shape, abundance, size, and structural characteristics of sapling patches in an old-growth Pinus jeffreyi-mixed conifer forest with a relatively intact disturbance regime? Location: Sierra San Pedro Martir, Baja California, Mexico. Methods: Regeneration was quantified by sampling sapling patches on seven 1200 m permanently marked line transects. For all patches intersected, tree size, species, age, and patch canopy cover were recorded. Patch structural characteristics were statistically compared to data from unbiased forest inventory plots. The minimum regeneration patch was defined as three saplings in a 49-m2 area. Results: We sampled 54 sapling regeneration patches. Patch size varied from 6.6 to 674.8 m2. A small portion of the forest was in patches (patch fraction = 3.8%, patch abundance = 8.5 per ha). The majority of the patches were small; 64.8% were less than the mean patch area of 100.1 m2. Patches were shaped as a rhombus. For all forest characteristics, mean values inside patches were significantly different than those from the unbiased forest inventory plots. Conclusions: These forests have a fine-grained pattern of regeneration patches. Our largest patch size of 674.8 m2 is the smallest reported in Pinus jeffreyi, P. ponderosa, and mixed conifer forests; other studies have probably had more difficulty delineating regeneration patches because of forest ingrowth from fire exclusion. Frequent fire, irregular seed crops, and seed dispersal by small mammals and birds could create this regeneration patch regime. High variation in nutrient availability after fire could also contribute to increased stand patchiness. Nomenclature: Hickman (1993) for vascular plants; Kays & Wilson (2002) for mammals. Abbreviation: Pj-mc = Pinus jeffreyi-mixed conifer; SSPM = Sierra San Pedro Martir.
Compares the simulations of three biogeography models (BIOME2, Dynamic Global Phytogeography Model (DOLY), and Mapped Atmosphere-Plant Soil System (MAPSS)) and the biogeochemistry models (BIOME-BGC (BioGeochemistry Cycles), CENTURY, and Terrestrial Ecosystem Model (TEM)) for the coterminous United States under contemporary conditions of atmospheric CO2 and climate. Also compares the simulations of these models under doubled CO2 and a range of climate scenarios. -from Authors
The basin and range topography creates a situation where montane vegetation is discontinuous and separated into habitat islands of various sizes. Packrat Neotoma midden coverage is heavily skewed toward the late Wisconsinan and Late Holocene. The full glacial flora of the basin was impoverished and the shift from a Late Wisconsinan to modern vegetation occurred at different sites. Inferred midden vegetation assemblages from the Great Basin-Mojave Desert reflect a full glacial climate with temperatures 7-8°C below modern levels and a mean annual precipitation greater by 30-40% over today's values. -S.J.Yates
We reconstructed a 3500-yr history of fluctuations in treeline elevation and tree abundance in the southern Sierra Nevada. Treeline elevation was higher than at present throughout most of the last 3500 yr. Declines in the abundance of live trees and treeline elevation occurred twice during the last 1000 yr: from 950 to 550 yr BP and from 450 to 50 yr BP. The earlier decline coincided with a period of warm temperatures (relative to present) in which at least two severe, multidecadal droughts occurred. This decline was apparently triggered by an increase in the rate of adult mortality in treeline forests. The more recent decline occurred during a period of low temperatures lasting for up to 400 yr and was apparently caused by a sustained failure of regeneration in combination with an increased rate of adult mortality. The apparent past importance of precipitation in controlling the position and structure of the treeline ecotone suggests that climatic controls over treeline may be more complex than previously thought. In the Sierra Nevada, responses of high-elevation forests to future warming may depend strongly on water supply.
The presettlement state of a giant sequoia-mixed conifer forest community in the Redwood Creek watershed, Kings Canyon National Park, is reconstructed using in backward projection in time of plant aggregations. The most conspicuous change in the forest community from the presettlement condition (@?1890) was a general increase in the area of aggregations dominated by polesize trees and mature trees, and a corresponding decrease in the area of aggregations dominated by sapling- and seedling-size trees. Aggregations dominated by white fir had both the greatest decline in area for sapling and seedling aggregations and the greatest increase in area for large mature, mature, and pole aggregations of any species in the watershed. The area of aggregations dominated by shrubs also declined, with manzanita aggregations showing the largest loss in area for any shrub species. Hardwoods were also a far more important part of the presettlement forest community than they are today.
Significant climate anomalies have characterized the last 1000 yr in the Sierra Nevada, California, USA. Two warm, dry periods of 150- and 200-yr duration occurred during AD 900-1350, which were followed by anomalously cold climates, known as the Little Ice Age, that lasted from AD 1400 to 1900. Climate in the last century has been significantly warmer. Regional biotic and physical response to these climatic periods occurred. Climate variability presents challenges when interpreting historical variability, including the need to accommodate climate effects when comparing current ecosystems to historical conditions, especially if comparisons are done to evaluate causes (e.g., human impacts) of differences, or to develop models for restoration of current ecosystems. Many historical studies focus on "presettlement" periods, which usually fall within the Little Ice Age. Thus, it should be assumed that ecosystems inferred for these historical periods responded to different climates than those at present, and management implications should be adjusted accordingly. The warmer centuries before the Little Ice Age may be a more appropriate analogue to the present, although no historic period is likely to be better as a model than an understanding of what conditions would be at present without intervention. Understanding the climate context of historical reconstruction studies, and adjusting implications to the present, should strengthen the value of historical variability research to management.