The Influences of Conventional and Low Density Thinning on Leaf Area, Growth, and Growing Space Relationships of Eastern White Pine (Pinus Strobus L.)

Despite the commercial importance and widespread management of eastern white pine {Pinus strobus L.) in the Northeast, surprisingly little is known about the effects of thinning on even-aged stand development. To address this, patterns of leaf area, bole form, volume growth, and growth efficiency - defined as volume increment per unit leaf area - were examined over a 17-year period within a thinning study in central Maine designed to compare the conventional B-line and low density thinning regimes. At the tree-level, many of the effects of thinning were as expected. Heavier, low density thinning resulted in significantly larger and deeper crowns with greater leaf area than equivalent trees in both the B-line and unthinned control treatments. These changes explained higher rates of diameter and volume growth. Thinning did not alter growth efficiency per se. but larger trees had slightly (but significantly) lower growth efficiency than smaller trees. Reconstruction of bole taper - quantified as Girard form class -showed that, surprisingly, B-line thinning produced more tapered butt-logs (first 5-meter) than low density thinning, resulting from a thinning-induced growth response at breast height but not at the top of the butt-log. At the stand-level, an annual record of leaf area index (LAI) attained by litterfall collection showed that leaf area in the control treatment was relatively constant or slightly declined over the study period. Thinning significantly reduced stand leaf area and thus gross volume growth, but the thinned treatments had nearly equal LAIs for the ten years following the initial thinning. This explained the similar gross volume growth rates and growth efficiencies of the thinning treatments. Following the re-entry harvest, B-line leaf area increased until the stands reached crown closure, while the low density treatment continued rates of crown expansion and LAI increase without reaching a peak. Due to greater LAI, B-line gross stand volume growth and growth efficiency were significantly higher during the latter growth period: low density stand growth efficiency was still no different from the control. Growth efficiency of the unthinned stands was found to be positively related to stand density. Results of this study have important implications to managers of eastern white pine. The contention that thinning below B-line stocking has deleterious effects on stand yield was in general not supported. On the contrary, only a minor loss of gross stand volume growth was found by thinning to a low density. In addition, low density trees were larger, faster growing, and had better stem form than comparable B-line trees. Therefore, low density thinning was found to be a viable alternative to conventional management

Vegetation type conversion in the US Southwest: frontline observations and management responses

Background Forest and nonforest ecosystems of the western United States are experiencing major transformations in response to land-use change, climate warming, and their interactive effects with wildland fire. Some ecosystems are transitioning to persistent alternative types, hereafter called &ldquo;vegetation type conversion&rdquo; (VTC). VTC is one of the most pressing management issues in the southwestern US, yet current strategies to intervene and address change often use trial-and-error approaches devised after the fact. To better understand how to manage VTC, we gathered managers, scientists, and practitioners from across the southwestern US to collect their experiences with VTC challenges, management responses, and outcomes. Results Participants in two workshops provided 11 descriptive case studies and 61 examples of VTC from their own field observations. These experiences demonstrate the extent and complexity of ecological reorganization across the region. High-severity fire was the predominant driver of VTC in semi-arid coniferous forests. By a large margin, these forests converted to shrubland, with fewer conversions to native or non-native herbaceous communities. Chaparral and sagebrush areas nearly always converted to non-native grasses through interactions among land use, climate, and fire. Management interventions in VTC areas most often attempted to reverse changes, although we found that these efforts cover only a small portion of high-severity burn areas undergoing VTC. Some areas incurred long (&gt;10 years) observational periods prior to initiating interventions. Efforts to facilitate VTC were rare, but could cover large spatial areas. Conclusions Our findings underscore that type conversion is a common outcome of high-severity wildland fire in the southwestern US. Ecosystem managers are frontline observers of these far-reaching and potentially persistent changes, making their experiences valuable in further developing intervention strategies and research agendas. As its drivers increase with climate change, VTC appears increasingly likely in many ecological contexts and may require management paradigms to transition as well. Approaches to VTC potentially include developing new models of desired conditions, the use of experimentation by managers, and broader implementation of adaptive management strategies. Continuing to support and develop science-manager partnerships and peer learning groups will help to shape our response to ongoing rapid ecological transformations. &nbsp;</p

Electrical consumption forecast using actual data of building end-use decomposition

The calculation of electricity consumption forecast a few days ahead is a complex issue and studies about this matter are continually being performed. Advances in this field enable obtaining consumption forecasts increasingly accurate. These consumption forecasts aim to improve the knowledge of the facilities, the planning and control of consumption and the measurement and verification of energy saving measures, among others. In this study the authors present several advances related to consumption forecast using end-use (EU) approach. In the disaggregation of the total consumption process, the correlation between energy and external variables, such as mean temperature, degree days or daylight, is studied. Additionally, an extrapolation method to obtain a total consumption forecast from forecasted EUs consumption that cover approximately 60% of total consumption is developed. With this procedure, total consumption forecasts with high accuracy can be obtained. The higher accuracy in each end-use, the better results are obtained in the total consumption forecast. For this reason, the study is focused in the end-uses disaggregation and its forecast calculation. The entire methodology is illustrated and contrasted using the consumption of the Universitat Politècnica de València (UPV).This research work has been possible with the support of the Universitat Politecnica de Valencia through grant CE19990032.Escrivá Escrivá, G.; Roldán Blay, C.; Álvarez Bel, CM. (2014). Electrical consumption forecast using actual data of building end-use decomposition. Energy and Buildings. 82:73-81. https://doi.org/10.1016/j.enbuild.2014.07.024S73818

B4: Bedrock Geology of Mt. Washington, Presidential Range, NH

Guidebook for field trips in Western Maine and Northern New Hampshire: New England Intercollegiate Geological Conference, p. 177-196

Sampling Bias Overestimates Climate Change Impacts on Forest Growth in the Southwestern United States

Climate−tree growth relationships recorded in annual growth rings have recently been the basis for projecting climate change impacts on forests. However, most trees and sample sites represented in the International Tree-Ring Data Bank (ITRDB) were chosen to maximize climate signal and are characterized by marginal growing conditions not representative of the larger forest ecosystem. We evaluate the magnitude of this potential bias using a spatially unbiased tree-ring network collected by the USFS Forest Inventory and Analysis (FIA) program. We show that U.S. Southwest ITRDB samples overestimate regional forest climate sensitivity by 41–59%, because ITRDB trees were sampled at warmer and drier locations, both at the macro- and micro-site scale, and are systematically older compared to the FIA collection. Although there are uncertainties associated with our statistical approach, projection based on representative FIA samples suggests 29% less of a climate change-induced growth decrease compared to projection based on climate-sensitive ITRDB samples

Upgrade of an artificial neural network prediction method for electrical consumption forecasting using an hourly temperature curve model

This paper presents the upgrading of a method for predicting short-term building energy consumption that was previously developed by the authors (EUs method). The upgrade uses a time temperature curve (TTC) forecast model. The EUs method involves the use of artificial neural networks (ANNs) for predicting each independent process end-uses (EUs). End-uses consume energy with a specific behaviour in function of certain external variables. The EUs method obtains the total consumption by the addition of the forecasted end-uses. The inputs required for this method are the parameters that may affect consumption, such as temperature, type of day, etc. Historical data of the total consumption and the consumption of each end-use are also required. A model for prediction of the time temperature curve has been developed for the new forecast method (TEUs method). The temperature at each moment of the day is obtained using the prediction of the maximum and minimum daytime temperature. This provides various benefits when selecting the training days and in the training and forecasting phases, thus improving the relationship between expected consumption and temperatures. The method has been tested and validated with the consumption forecast of the Universitat Politècnica de València for an entire year.This research work has been possible with the support of the Universitat Politecnica de Valencia (Spain) with grant #CE 19990032.Roldán Blay, C.; Escrivá-Escrivá, G.; Álvarez Bel, CM.; Roldán Porta, C.; Rodriguez-Garcia, J. (2013). Upgrade of an artificial neural network prediction method for electrical consumption forecasting using an hourly temperature curve model. Energy and Buildings. 60:38-46. https://doi.org/10.1016/j.enbuild.2012.12.009S38466

A fire deficit persists across diverse North American forests despite recent increases in area burned.

Rapid increases in wildfire area burned across North American forests pose novel challenges for managers and society. Increasing area burned raises questions about whether, and to what degree, contemporary fire regimes (1984-2022) are still departed from historical fire regimes (pre-1880). We use the North American tree-ring fire-scar network (NAFSN), a multi-century record comprising &gt;1800 fire-scar sites spanning diverse forest types, and contemporary fire perimeters to ask whether there is a contemporary fire surplus or fire deficit, and whether recent fire years are unprecedented relative to historical fire regimes. Our results indicate, despite increasing area burned in recent decades, that a widespread fire deficit persists across a range of forest types and recent years with exceptionally high area burned are not unprecedented when considering the multi-century perspective offered by fire-scarred trees. For example, record contemporary fire years such as 2020 burned 6% of NAFSN sites-the historical average-well below the historical maximum of 29% sites that burned in 1748. Although contemporary fire extent is not unprecedented across many North American forests, there is abundant evidence that unprecedented contemporary fire severity is driving forest loss in many ecosystems and adversely impacting human lives, infrastructure, and water supplies

The influence of land-use activities and regional drought on historical fire regimes of Buryatia, Siberia

Every year, millions of hectares burn across Siberia, driven by a combination of warming temperatures, regional drought and human-caused ignitions. Dendrochronology provides a long-term context to evaluate recent trends in fire activity and interpret the relative influence of humans and climate drivers on fire regimes. We developed a 400 year record of fire-scarred trees from 17 sites in pine-dominated forests located southeast of Lake Baikal. Site-level mean fire return intervals (MFIs) ranged from 4 to 27 years for all fires and 8 to 35 years for widespread fires within sites. Sites with the lowest MFI values were located within 1 km of agricultural fields in grassland valleys, suggesting that agricultural burning influenced MFIs at nearby sites. Fire frequency varied over the record, with significantly high values around 1790, from 1865 to 1880, 1948 to 1955 and 1995 to 2005. The increased fire activity corresponded with migration waves to the region and major socio-economic change connected with the establishment and breakdown of the Soviet Union. At broader scales, superposed epoch analysis showed that synchronous fire years were associated with regional drought and precipitation deficits. Wet conditions for 2&ndash;3 years prior to the event year were also significant, suggesting that increased moisture promoted growth of understory fine fuels to support more extensive fires across the study area. Although fire frequencies increased during the 20th century, fire&ndash;climate relationships weakened, suggesting increased human-caused ignitions may override regional climate drivers. Our dataset presents a continuous record of frequent surface fires over the past 400 years, providing a valuable opportunity to compare dendrochronology-based reconstructions with satellite and documentary records. &nbsp;</p

Indigenous fire management and cross-scale fire-climate relationships in the Southwest United States from 1500 to 1900 CE

Prior research suggests that Indigenous fire management buffers climate influences on wildfires, but it is unclear whether these benefits accrue across geographic scales. We use a network of 4824 fire-scarred trees in Southwest United States dry forests to analyze up to 400 years of fire-climate relationships at local, landscape, and regional scales for traditional territories of three different Indigenous cultures. Comparison of fire-year and prior climate conditions for periods of intensive cultural use and less-intensive use indicates that Indigenous fire management weakened fire-climate relationships at local and landscape scales. This effect did not scale up across the entire region because land use was spatially and temporally heterogeneous at that scale. Restoring or emulating Indigenous fire practices could buffer climate impacts at local scales but would need to be repeatedly implemented at broad scales for broader regional benefits. &nbsp;</p

The North American tree-ring fire-scar network

Fire regimes in North American forests are diverse and modern fire records are often too short to capture important patterns, trends, feedbacks, and drivers of variability. Tree-ring fire scars provide valuable perspectives on fire regimes, including centuries-long records of fire year, season, frequency, severity, and size. Here, we introduce the newly compiled North American tree-ring fire-scar network (NAFSN), which contains 2562 sites, >37,000 fire-scarred trees, and covers large parts of North America. We investigate the NAFSN in terms of geography, sample depth, vegetation, topography, climate, and human land use. Fire scars are found in most ecoregions, from boreal forests in northern Alaska and Canada to subtropical forests in southern Florida and Mexico. The network includes 91 tree species, but is dominated by gymnosperms in the genus Pinus. Fire scars are found from sea level to >4000-m elevation and across a range of topographic settings that vary by ecoregion. Multiple regions are densely sampled (e.g., >1000 fire-scarred trees), enabling new spatial analyses such as reconstructions of area burned. To demonstrate the potential of the network, we compared the climate space of the NAFSN to those of modern fires and forests; the NAFSN spans a climate space largely representative of the forested areas in North America, with notable gaps in warmer tropical climates. Modern fires are burning in similar climate spaces as historical fires, but disproportionately in warmer regions compared to the historical record, possibly related to under-sampling of warm subtropical forests or supporting observations of changing fire regimes. The historical influence of Indigenous and non-Indigenous human land use on fire regimes varies in space and time. A 20th century fire deficit associated with human activities is evident in many regions, yet fire regimes characterized by frequent surface fires are still active in some areas (e.g., Mexico and the southeastern United States). These analyses provide a foundation and framework for future studies using the hundreds of thousands of annually- to sub-annually-resolved tree-ring records of fire spanning centuries, which will further advance our understanding of the interactions among fire, climate, topography, vegetation, and humans across North America