Effects of growth rate, size, and light availability on tree survival across life stages: a demographic analysis accounting for missing values and small sample sizes.

The data set supporting the results of this article is available in the Dryad repository, http://dx.doi.org/10.5061/dryad.6f4qs. Moustakas, A. and Evans, M. R. (2015) Effects of growth rate, size, and light availability on tree survival across life stages: a demographic analysis accounting for missing values.Plant survival is a key factor in forest dynamics and survival probabilities often vary across life stages. Studies specifically aimed at assessing tree survival are unusual and so data initially designed for other purposes often need to be used; such data are more likely to contain errors than data collected for this specific purpose

Forest landscape ecology and global change: an introduction

Forest landscape ecology examines broad-scale patterns and processes and their interactions in forested systems and informs the management of these ecosystems. Beyond being among the richest and the most complex terrestrial systems, forest landscapes serve society by providing an array of products and services and, if managed properly, can do so sustainably. In this chapter, we provide an overview of the field of forest landscape ecology, including major historical and present topics of research, approaches, scales, and applications, particularly those concerning edges, fragmentation, connectivity, disturbance, and biodiversity. In addition, we discuss causes of change in forest landscapes, particularly land-use and management changes, and the expected structural and functional consequences that may result from these drivers. This chapter is intended to set the context and provide an overview for the remainder of the book and poses a broad set of questions related to forest landscape ecology and global change that need answers

Effects of multiaged silvicultural systems on reserve tree growth 19 years after establishment across multiple species in the Acadian forest in Maine, USA

This study investigated the growth response of mature, isolated reserve trees (n = 528) in two multiaged silvicultural systems in the Acadian Forest Ecosystem Research Project (AFERP). The absolute and percent increase in basal area increment (BAI; cm2 yr-1) was assessed for the five predominant reserve tree species in AFERP: Acer rubrum, Picea rubens, Pinus strobus, Thuja occidentalis, and Tsuga canadensis. Absolute growth was significantly greater in the large-gap treatment (23.7 ± 1.1; mean ± SE) than in the small-gap treatment (16.3 ± 0.9). The percent growth increase was greater in the small-gap treatment (187.6% ± 15.8) than the large-gap treatment (143.4% ± 19.3) and both treatments had greater percent increases than the unharvested control (9.6% ± 5.2). Species differed in their response to treatment. Pinus strobus had the greatest absolute increase (large-gap: 52.5), while Tsuga canadensis (large-gap: 270% ± 71.6) and Acer rubrum (small-gap: 262% ± 42.4) had the greatest percent increases. Growth responses typically diminished with increasing tree size and pre-treatment growth rate; however, reserve trees showed greater growth responses than their paired analogues in the control across all initial tree sizes and prior growth rates. The results suggest these silivicultural systems accelerate the development of large trees.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Growth Dominance In A Long-Term Red Pine Thinning Experiment

Forest stand development is driven by individual tree growth, which is a function of resource acquisition and resource-use efficiency. Although larger trees may have a greater opportunity to acquire resources, physiological constraints of larger trees may restrict their ability to convert resources into growth. One approach to understanding the consequences of resource acquisition and utilization on stand growth is to examine growth dominance, defined as positive when larger trees in the stand display proportionally greater growth than smaller trees, and negative when smaller trees have proportionally greater growth than larger trees. Binkley (2004; 2006) developed a method for quantifying stand-level growth dominance and proposed a hypothesis for how dominance progresses through stand development. We applied this approach to long-term red pine silvicultural experiments to characterize how stand age, thinning treatments (thinned from above, below, or both) and stocking levels (residual basal area) influence stand-level growth dominance through time. In stands thinned from below or from both above and below, dominance was not significantly different from zero at any age or stocking level. Growth dominance in stands thinned from above, by contrast, trended from negative at low stocking levels to positive at high stocking levels and was positive in young stands but not significantly different from zero in older stands. Growth dominance in un-thinned stands was consistently positive and increased with age, supporting Binkley’s hypothesis. These results suggest that growth dominance provides a useful tool for assessing the efficacy of thinning treatments designed to reduce competition between trees and promote even growth across a population

Small mammal controls on the climate-driven range shift of woody plant species

Climate change is resulting in shifts in species' ranges as species inhabit new climatically suitable areas. A key factor affecting range-shifts is the interaction with predators. Small mammals, being primary seed predators and dispersers in forest ecosystems, may play a major role in determining which plant species will successfully expand and the rate at which range-shifts will occur. Plants dispersing seeds beyond the species' current range limits will encounter seed predators to which these seeds are novel; however, empirical studies of seed predator-novel seed interactions are lacking. The aims of our study were to: 1) quantify seed selection by small mammals presented with 'novel' seeds; 2) quantify the post-selection fate of 'novel' seeds; and 3) identify seed traits that affect seed selection and post-selection seed fate. We designed a field experiment exposing small mammal communities to novel seeds produced by plants expected to shift their ranges in response to climate change. We matched novel seeds with reference 'familiar' seeds and studied key steps defining interactions between small mammals and novel seeds. We found that the probability of selection of a novel seed varied among species and was, at times, higher than the selection probability of familiar seeds. Key traits that affected seed selection and the distance a seed was dispersed for caching were shell hardness and seed mass. We also found that 33% of dispersed seeds were cached in optimal germination sites (e.g. within fallen logs and buried under the leaf litter mat). Through seed emergence trials we found that emergence was higher for larger seeds, suggesting that the role of small mammals may be modulated by emergence rates. Our results suggest that the interaction between small mammals and novel seeds may have cascading effects on climate-induced plant range shifts and community composition

Decadal dead wood biomass dynamics of coterminous US forests

Due to global change, temperate forests are expected to face growing threats to forest health (e.g. insects/disease) and increasing probabilities of severe disturbances (e.g. wildfires), which may result in amplified tree mortality against a backdrop of a changing climate and associated ecosystem/atmospheric feedbacks (i.e. increased rates of dead wood decay/combustion). Despite these expectations, we lack a fundamental understanding of current forest biomass trends among live and dead components across large spatial and temporal domains. The goal of this study was to examine changes in forest biomass components (downed dead wood (DDW), standing dead trees (SDs), and live trees) across coterminous US forests using a nation-wide, multi-decade (∼2006–2010 to ∼2015–2019) repeated forest inventory at the scale of regional ecosystems. It was found that the total biomass stocks of DDW, standing dead, and live trees all increased (18.3%, 14.7%, and 3.9%, respectively) with biomass accumulation in large live trees coupled with increases in the biomass of smaller sized down dead wood illustrating the influence of stand development across US forests at the scale of individual forest ecosystems (i.e. self-thinning). Coupled with this observation, tremendous positive skew of biomass change across all biomass components and size classes demonstrates the ability of severe but episodic disturbance events to produce substantial biomass inputs to SD and DDW pools with legacy effects exceeding the period of this study. Overall, against a backdrop of expected future global change and growing interest in the maintenance of the terrestrial forest carbon pool, the incorporation of dead wood-focused analytics such as decay-related functional traits, microbial/fungal community assessments, or dead/live biomass relationships into broader forest carbon/biomass monitoring efforts is essential

Assessing the role of natural disturbance and forest management on dead wood dynamics in mixed-species stands of central Maine, USA

Dead wood pools are strongly influenced by natural disturbance events, stand development processes, and forest management activities. However, the relative importance of these influences can vary over time. In this study, we evaluate the role of these factors on dead wood biomass pools across several forest management alternatives after 60 years of treatment on the Penobscot Experimental Forest in central Maine, USA. After accounting for variation in site quality, we found significant differences in observed downed coarse woody material (CWM; â Ľ 7.6 cm small-end diameter) and standing dead wood biomass among selection, shelterwood, and commercial clearcut treatments. Overall, total dead wood biomass was positively correlated with live tree biomass and was negatively correlated with the average wood density of non-harvest mortality. We also developed an index of cumulative harvest severity, which can be used to evaluate forest attributes when multiple harvests have occurred within the same stand over time. Findings of this study highlight the dynamic roles of forest management, stand development, and site quality in influencing dead wood biomass pools at the stand level, and underscore the potential for various outcomes from the same forest management treatment applied at different times in contrasting stands.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author