The Most Popular Smartphone Apps for Weight Loss: A Quality Assessment

Background: Advancements in mobile phone technology have led to the development of smartphones with the capability to run apps. The availability of a plethora of health- and fitness-related smartphone apps has the potential, both on a clinical and public health level, to facilitate healthy behavior change and weight management. However, current top-rated apps in this area have not been extensively evaluated in terms of scientific quality and behavioral theory evidence base. Objective: The purpose of this study was to evaluate the quality of the most popular dietary weight-loss smartphone apps on the commercial market using comprehensive quality assessment criteria, and to quantify the behavior change techniques (BCTs) incorporated. Methods: The top 200-rated Health & Fitness category apps from the free and paid sections of Google Play and iTunes App Store in Australia (n=800) were screened in August 2014. To be included in further analysis, an app had to focus on weight management, include a facility to record diet intake (self-monitoring), and be in English. One researcher downloaded and used the eligible apps thoroughly for 5 days and assessed the apps against quality assessment criteria which included the following domains: accountability, scientific coverage and content accuracy of information relevant to weight management, technology-enhanced features, usability, and incorporation of BCTs. For inter-rater reliability purposes, a second assessor provided ratings on 30% of the apps. The accuracy of app energy intake calculations was further investigated by comparison with results from a 3-day weighed food record (WFR). Results: Across the eligible apps reviewed (n=28), only 1 app (4%) received full marks for accountability. Overall, apps included an average of 5.1 (SD 2.3) out of 14 technology-enhanced features, and received a mean score of 13.5 (SD 3.7) out of 20 for usability. The majority of apps provided estimated energy requirements (24/28, 86%) and used a food database to calculate energy intake (21/28, 75%). When compared against the WFR, the mean absolute energy difference of apps which featured energy intake calculations (23/28, 82%) was 127 kJ (95% CI -45 to 299). An average of 6.3 (SD 3.7) of 26 BCTs were included. Conclusions: Overall, the most popular commercial apps for weight management are suboptimal in quality, given the inadequate scientific coverage and accuracy of weight-related information, and the relative absence of BCTs across the apps reviewed. With the limited regulatory oversight around the quality of these types of apps, this evaluation provides clinicians and consumers an informed view of the highest-quality apps in the current popular app pool appropriate for recommendation and uptake. Further research is necessary to assess the effectiveness of apps for weight management

Seed Release in Lodgepole Pine Forests After Mountain Pine Beetle Outbreak

Serotinous lodgepole pine (Pinus contorta var. latifolia) usually regenerates after fire or harvesting provided conditions that are warm enough to open the cones. There are concerns that large-scale stand mortality due to mountain pine beetle (MPB) outbreak could greatly reduce natural regeneration of lodgepole pine because the closed cones are held in place in the tree canopy without any seed release. We selected 15 stands (five gray-attacked, five red-attacked, and five green) in the Sub-Boreal Spruce biogeoclimatic zone of British Columbia to determine loss of canopy seed via breakage of twig-bearing cones and cone opening (i.e., loss of serotiny) throughout the 2008 growing season. We also quantified seed loss of fallen cones via predation and cone opening. Red-attacked stands lost an estimated 175 000 seed-bearing canopy cones ha-1 yr -1 due to crown friction resulting in twig breakage, representing an over three-fold increase compared to green stands. This result was considered ecologically important since it equated to over 25 % of canopy cones lost to the forest floor. Red- and gray-attacked stands also had 15 % of canopy seed lost due to cone weathering resulting in cone opening. Additional seed losses occurred in the gray-attacked stands due to additional cone opening (58 % yr-1) on the forest floor and predation (12 000 fallen seed-bearing cones ha-1 yr-1). MPB-killed stands released some canopy seed through breakage of twig-bearing cones, partial loss of serotiny, and forest floor cone opening. The implications are: i) seed supply is gradually lost in the first years after attack; ii) if adequate levels of regeneration are to occur, either anthropogenic or fire disturbances must happen shortly after tree mortality. We conclude that lodgepole pine is poorly-adapted to disturbances such as MPB because seed is slowly released onto an unfavorable seed bed

Suckering response of aspen to traffic-induced-root wounding and the barrier-effect of log storage

In a growth chamber, we tested how the seasonal timing of placing a physical barrier (simulating a possible effect of log storage) and inflicting root damage impacted aspen (Populus tremuloides Michx.) root systems and their suckering capability. Roots from 4-year-old saplings were used, and one half of these root systems had the above-ground portion cut in the winter (dormant) while the other half was cut during the growing season in the summer. Damage was inflicted to the roots by driving a large farm tractor over them, and a covering treatment was applied using a polystyrene board to prevent suckers from emerging from the soil. Soil temperatures for the winter-cut root systems were kept at 5 8C over the growing season, using a water bath, while for the summer-cut root systems soil temperatures were maintained at 17 8C over the growing season. In the winter-cut root systems, both log storage and root wounding caused a 40% reduction in living root mass and carbohydrate reserves, as well as reducing sucker numbers and their growth performance. In the summer-cut root systems log storage and root wounding reduced living root mass by approximately 35% as well as sucker growth, but had less of an impact on the number of suckers produced

Spatially explicit modeling of PAR transmission and growth of Picea glauca and Abies balsamea in the boreal forests of Alberta and Quebec

To investigate the feasibility of a spatially explicit, radiation-based regeneration model for the boreal forest, we tested the predictions of a three-dimensional simulator of photosynthetically active radiation transmission (%PAR), MIXLIGHT, and the growth response of understory Abies balsamea (L.) Mill. (balsam fir) and Picea glauca (Moench) Voss (white spruce) to %PAR in two large (>1 ha) mixed-species forest sites, one in eastern Canada at Lac Duparquet, Quebec, and one in western Canada at Calling Lake, Alberta. Overstory tree locations and dimensions were obtained from aerial photographs or ground measurements and allometric relationships. Seasonal %PAR calculated by MIXLIGHT for the Calling Lake site was very similar to seasonal %PAR measured by quantum sensors (n = 5, %PAR range = 15%-33%, r = 0.93). Daily measurements of %PAR were also predicted well by simulations at both sites (n = 34-36, %PAR range = 1%-45%, r ≥ 0.76). Functional relationships, designed to saturate at the maximum height growth potential of these sites, were developed to predict sapling height growth from simulated seasonal %PAR and initial height (R 2 ≥ 0.74). These results demonstrate the potential of the MIXLIGHT simulator for estimating PAR at microsites within heterogeneous forests and for modeling understory tree growth

Aspen regeneration on log decking areas as influenced by season and duration of log storage

This study assessed aspen regeneration on decking areas as affected by season of log deck building and duration of log storage; as well as root wounding, soil com- paction, and slash depth. On former decking areas that were built after a summer harvest, aspen regeneration was 50% lower and root death 35% greater compared to former decking areas of a fall harvest. Duration of log storage after a fall harvest had little effect on aspen regeneration; short (1.5–3 months) or long (11 months) storage resulted in similar regeneration. Slash load was greatly increased on decking areas while root wounding and soil bulk density were only slightly increased compared to controls. For best management practices, log storage after summer harvest should be avoided especially when logs are kept over the growing period when suckering occurs. Additionally, removing the inter- woven mat of slash covering decking areas and limiting machine traffic to frozen soil will ensure vigorous suckering

Regeneration of aspen following partial and strip understory protection harvest in boreal mixedwood forests

Trembling aspen regeneration was studied in 2 types of partial harvest systems designed to harvest mature aspen but pro- tect immature spruce and encourage natural aspen regeneration. Two partial harvest systems, where the residual aspen was either left in strips or was dispersed uniformly, were compared to traditional clearcuts. After the first and second year since harvest, aspen sucker density and growth was similar between the 2 partial harvests, but was much lower than in the clearcuts. However, in the partial cuts the regeneration density was very much dependent on the location relative to residual trees. The density of regeneration was inversely related to the basal area of residual aspen; however, sucker height was inversely related to the basal area of the residual spruce. Although there were adequate numbers of suckers after partial harvest, their viability and contribution to the long-term productivity of these mixedwood stands is not clear

N-transfer through aspen litter and feather moss layers after fertilization with ammonium nitrate and urea

When fertilizer is broadcast in boreal forest stands, the applied nutrients must pass through a thick layer of either feather moss or leaf litter which covers the forest floor. In a growth chamber experiment we tested the transfer of N through living feather moss or aspen litter when fertilized with urea ((NH2)2CO) or NH4NO3 at a rate of 100 kg ha−1 and under different watering regimes. When these organic substrates were frequently watered to excess they allowed the highest transfer of nutrients through, although 72% of the applied fertilizer was captured in the substrates. In a field experiment we also fertilized moss and aspen litter with urea ((NH2)2CO) or NH4NO3 at a more operationally relevant rate of 330 kg ha−1. We captured the NO3− or NH4+ by ion exchange resin at the substrate–mineral soil interface. In contrast to the growth chamber experiment, this fertilizer rate killed the moss and there was no detectable increase in nutrient levels in the aspen litter or feather moss layers. Instead, the urea was more likely transferred into the mineral soil; mineral soil of the urea treatment had 1.6 times as much extractable N compared to the NH4NO3 treatment. This difference between the growth chamber and field studies was attributed to observed fertilizer- damage to the living moss and possibly damage to the litter microflora due to the higher rate of fertilization in the field. In addition, the early and substantial rainfall after fertilization in the field experiment produced conditions for rapid leaching of N through the organic layers into the mineral soil. In the field, only 8% of the urea-N that was applied was captured by the ion exchange resin, while 34% was captured in for the NH4NO3 fertilization. Thus, the conditions for rapid leaching in the field moved much of the N in the form of urea through the organic layers and into the mineral soil before it was hydrolyzed

Carbon isotope discrimination and water stress in trembling aspen following variable retention harvesting

Variable retention harvesting (VRH) has been proposed as a silvicultural practice to maintain biodiversity and ecosystem integrity. No previous study has examined tree carbon isotope discrimination to provide insights into water stress that could lead to dieback and mortality of trees following VRH. We measured and compared the carbon isotope ratios (δ13C) in stem wood of trembling aspen (Populus tremuloides Michx.) before and after VRH. Eight trees were sampled from isolated residual, edge and control (interior of unharvested stand) positions from each of seven plots in three regions (Calling Lake and Drayton Valley, Alberta and Lac Duparquet, Qu

Do position and species identity of neighbours matter in 8–15-year-old post harvest mesic stands in the boreal mixedwood?

Neighbourhood competition indices (NCI), where position and species identity of neighbours are known, have been used to investigate growth and competitive interactions among adult trees. In this study, we used NCI in 8–15-year-old stands following clear-cutting in a boreal mixedwood forest of eastern Canada to improve our understanding of early successional forest dynamics. Trees of increasing diameter from the center (≥1 cm) to the edge (≥5 cm) were mapped in twenty-five circular 450m2 plots. Target trees (DBH≥1 cm) were sampled in plot center to determine their annual radial stem growth. For each species, we compared a set of growth models using either a spatially explicit NCI or a non-spatial competition index. Both types of indices estimated a species-specific competition coefficient for each pair of competitor–target species. NCI were selected as the best competition model for all target species although differences in variance explained relative to the non-spatial index were small. This likely indicates that competition occurs at the local level but that the high density and the relative uniformity of these young stands creates similar neighbourhoods for most trees in a given stand. The effective neighbourhood radius for competitors varied among species and was smaller for shade tolerant species. Intraspecific neighbours were the strongest competitors for most species. Aspen (Populus tremuloides) was a weak competitor for all species as opposed to balsam fir (Abies balsamea) which was a strong competitor in all cases. These results are in contradiction with some widely used forest policies in North America (e.g. free-to-grow standards) that consider broadleaf species, such as aspen, as the strongest competitors. For these early successional forests, the decision regarding the use of spatial or non-spatial competition indices should rest on the intended use. For even-age management, spatial indices might not justify their use in highdensity stands but they are needed for the simulation of novel harvest techniques creating complex stand structure

Inconsistent Growth Response to Fertilization and Thinning of Lodgepole Pine in the Rocky Mountain Foothills Is Linked to Site Index

Fertilization of conifers often results in highly variable growth responses across sites which are difficult to predict. The goal of this study was to predict the growth response of lodgepole pine (Pinus contorta var. latifolia) crop trees to thinning and fertilization using basic site and foliar characteristics. Fifteen harvest-origin stands along the foothills of the Rocky Mountains of Alberta were subjected to six treatments including two levels of thinning (thinning to 2500 stems per hectare and a control) and three types of fertilization (nitrogen-only fertilization, complete fertilization including nitrogen with added P, K, S, Mg, and B, and no fertilization). After three growing seasons, the growth response and foliar status of the crop trees were examined and this response was related to site and foliar characteristics. There was a small and highly variable additive response to fertilization and thinning; diameter growth of crop trees increased relative to the controls an average of 0.3 cm with thinning, 0.3 cm with either N-only or complete fertilization and 0.6 cm when thinned and fertilized. The increase in diameter growth with thinning and nitrogen-only fertilization was positively related to site index but not to any other site factors or pretreatment foliar variables such as nutrient concentrations, ratios, or thresholds