bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodiversity and multiple disturbances: boreal forest ground beetle (Coleoptera: Carabidae) responses to wildfire, harvesting, and herbicide
Authors: Cobb T.P. , Langor D.W. , Spence J.R. 
Published: November 2007

Rising societal demands for forest resources along with existing natural disturbance regimes suggest that sustainable forest management will increasingly depend on better understanding the cumulative effects of natural and anthropogenic disturbances. In North America, for example, there is increasing economic pressure to salvage log burned forests, although the ecological consequences of combining fire and harvesting on the same sites are unclear. We examined the short-term (2 year) responses of boreal forest ground beetles (Coleoptera: Carabidae) to the individual and combined effects of wildfire, harvesting, and herbicide. Ground beetle responses to wildfire and forestry-related disturbances differed strongly and suggested that, although some species may appear to benefit from disturbance combinations (e.g., Sericoda quadripunctata (DeGeer)), these effects are detrimental to others (e.g., Sericoda bembidioides Kirby). Species compositional variability was significantly reduced by disturbance combinations suggesting that multiple disturbances may lead to a simplification of this entire assemblage. In addition, ground beetle responses were correlated with changes in several key habitat parameters such as amount of woody debris, exposed ground, and plant species richness suggesting avenues for future study. Overall, however, our results suggest that efforts to avoid compounding disturbances on any site should be considered when developing current and future forest management guidelines.
Overstory tree mortality resulting from reintroducing fire to long-unburned longleaf pine forests: the importance of duff moisture
Authors: Varner J. Morgan , Hiers J. Kevin , Ottmar Roger D. , Gordon Doria R. , Putz Francis E. , Wade Dale D. 
Published: November 2007

In forests historically maintained by frequent fire, reintroducing fire after decades of exclusion often causes widespread overstory mortality. To better understand this phenomenon, we subjected 16 fire-excluded (ca. 40 years since fire) 10 ha longleaf pine ( Pinus palustris Mill.) stands to one of four replicated burning treatments based on volumetric duff moisture content (VDMC): wet (115% VDMC); moist (85% VDMC); dry (55% VDMC); and a no-burn control. During the first 2 years postfire, overstory pines in the dry burns suffered the greatest mortality (mean 20.5%); pine mortality in the wet and moist treatments did not differ from the control treatment. Duff reduction was greatest in the dry burns (mean 46.5%), with minimal reduction in the moist and wet burns (14.5% and 5%, respectively). Nested logistic regression using trees from all treatments revealed that the best predictors of individual pine mortality were duff consumption and crown scorch (P < 0.001; R2 = 0.34). Crown scorch was significant only in dry burns, whereas duff consumption was significant across all treatments. Duff consumption was related to moisture content in lower duff (Oa; R2 = 0.78, P < 0.001). Restoring fire to long-unburned forests will require development of burn prescriptions that include the effects of duff consumption, an often overlooked fire effect.
Chlorophyll fluorescence response of red spruce and balsam fir to a watershed calcium fertilization experiment in New Hampshire
Authors: Boyce Richard L. 
Published: November 2007

Decreases in soil exchangeable calcium (Ca) due to acid deposition have been linked with declines of forest species in the northeastern United States, particularly red spruce (Picea rubens Sarg.). In 2005, chlorophyll fluorescence measurements were taken on red spruce and balsam fir (Abies balsamea (L.) Mill.) trees growing on two watersheds at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire. One watershed had been fertilized with CaSiO3 in 1999 to replace the soil Ca losses of the past 50 years, and the other was a reference watershed. In March, there were no differences in any chlorophyll fluorescence parameter between sites or species. In August, however, dark-adapted ratios of variable fluorescence to maximum fluorescence (Fv/Fm) were significantly greater (p = 0.05) in the Ca-treated watershed for both spruce and fir, and spruce values were significantly greater than fir. No differences were found in the light-adapted fluorescence parameters. These results suggest that both spruce and fir respond to increases in Ca availability, even though fir does not exhibit the decline symptoms seen in spruce. It is unclear what physiological effect is responsible for the observed differences in Fv/Fm. The Fv/Fm values appear to respond to differences in Ca availability in forest tree species; thus, the ratio has the potential to be used in these two watersheds at HBEF to determine if other forest species are also responding to Ca additions.
Forest sampling combining fixed- and variable-radius sample plots
Authors: Packard Kevin C. , Radtke Philip J. 
Published: November 2007

We examine the statistical properties of a forest sampling strategy that combines methods of fixed- and variable-radius plot sampling. Circular fixed-radius plots are established at the same locations as variable-radius plots to take advantage of their known efficiencies for unbiasedly estimating stem density and basal area, respectively. The design eliminates the need for measuring stem diameters, except to check borderline trees on variable-radius plots. Separate controls on allowable error for stem density and basal area estimates are possible. An unbiased estimator of volume (Vol) is derived that uses an existing volume equation having the form Vol = a + bd2h, where d is tree diameter at breast height, h is tree height, and a and b are model parameters. Calculation of volume requires only the measurement of heights for those trees tallied on the variable-radius plots. Properties of the estimator are demonstrated for a mixed-species hardwood forest in the southern Appalachian Mountains of North Carolina, USA.
Optimized harvest planning under alternative foliage-protection scenarios to reduce volume losses to spruce budworm
Authors: Hennigar Chris R. , MacLean David A. , Porter Kevin B. , Quiring Dan T. 
Published: November 2007

Spruce budworm ( Choristoneura fumiferana Clem.) severely defoliates balsam fir ( Abies balsamea (L.) Mill.) and spruce ( Picea spp.) in large periodic outbreaks and represents one of Canada’s most damaging and widespread forest insects. We present a modeling framework that integrates stand-level spruce budworm volume impacts used in the Spruce Budworm Decision Support System (SBWDSS) into an industrial-scale timber supply model for the 209 000 ha Black Brook District in northwestern New Brunswick, Canada. This approach uses linear optimization of harvest scheduling, salvage, and insecticide application to minimize volume reduction. One hundred and ninety-five scenarios were simulated, including normal and severe spruce budworm outbreaks, beginning in 2002, with combinations of varying insecticide efficacy, timing, and spatial extent of protection. After simulated severe defoliation from 2007 to 2016, maximum harvest reductions of 35% were predicted for a normal outbreak for the 2012–2016 period, and 46% for a severe outbreak for the 2017–2021 period; these impacts were reduced to 25% and 34% using re-optimized harvest scheduling and salvage. Results suggest that combined optimized salvage and harvest rescheduling could reduce future harvest reductions by up to 12%. Spatial optimization of protected areas gave similar results to those obtained using protection priority assignments based on marginal stand-level volume reduction in the SBWDSS.
Differential impacts of the southern pine beetle, Dendroctonus frontalis, on Pinus palustris and Pinus taeda
Authors: Friedenberg Nicholas A. , Whited Brenda M. , Slone Daniel H. , Martinson Sharon J. , Ayres Matthew P. 
Published: November 2007

Patterns of host use by herbivore pests can have serious consequences for natural and managed ecosystems but are often poorly understood. Here, we provide the first quantification of large differential impacts of the southern pine beetle, Dendroctonus frontalis Zimmermann, on loblolly pine, Pinus taeda L., and longleaf pine, Pinus palustris P. Mill., and evaluate putative mechanisms for the disparity. Spatially extensive survey data from recent epidemics indicate that, per square kilometre, stands of loblolly versus longleaf pine in four forests (380–1273 km2) sustained 3–18 times more local infestations and 3–116 times more tree mortality. Differences were not attributable to size or age structure of pine stands. Using pheromone-baited traps, we found no differences in the abundance of dispersing D. frontalis or its predator Thanasimus dubius Fabricius between loblolly and longleaf stands. Trapping triggered numerous attacks on trees, but the pine species did not differ in the probability of attack initiation or in the surface area of bark attacked by growing aggregations. We found no evidence for postaggregation mechanisms of discrimination or differential success on the two hosts, suggesting that early colonizers discriminate between host species before a pheromone plume is present.
Partial cutting as an analogue to stem exclusion and dieback in trembling aspen (Populus tremuloides) dominated boreal mixedwoods: implications for deadwood dynamicsThis article is one of a selection of papers published in the Special Forum IUFRO 1.05 Uneven-Aged Silvicultural Research Group Conference on Natural Disturbance-Based Silviculture: Managing for Complexity.
Authors: Harvey B. D. , Brais S. 
Published: November 2007

In the winter of 1998–1999, two partial harvesting treatments that removed 33% (1/3) and 61% (2/3) of stand basal area were applied to even-aged trembling aspen ( Populus tremuloides Michx.) stands and compared with unharvested control stands. Stands in the 1/3 treatment were low thinned, while stands in the 2/3 removal were crown thinned. Coarse woody debris dynamics were assessed during the following 6 years by means of permanent sampling plots and downed wood inventories. Between 1999 and 2004, tree mortality was, respectively, 18%, 17%, and 32% in control stands and 1/3 and 2/3 harvesting treatments. Although total snag density was similar between controls and partial cutting treatments, total snag basal area was significantly higher in controls in 2004. Between 1999 and 2004, net change in aspen snag density was positive for controls and negative for both partial cutting treatments. Partial cutting also exacerbated mortality of small-diameter white birch ( Betula papyrifera Marsh.). Downed wood volume increased by 35 m3·ha–1 in controls and by 25 m3·ha–1 in the 2/3 harvesting treatment, while it decreased by 7 m3·ha–1 in the 1/3 harvesting treatment. Coarse woody debris goals can be established in silviculture prescriptions; type, timing, and intensity of partial cutting are crucial to the outcome.
Natural canopy gap disturbances and their role in maintaining mixed-species forests of central Quebec, CanadaThis article is one of a selection of papers published in the Special Forum IUFRO 1.05 Uneven-Aged Silvicultural Research Group Conference on Natural Disturbance-Based Silviculture: Managing for Complexity.
Authors: Kneeshaw Daniel D. , Prévost Marcel 
Published: November 2007

Until recently, natural dynamics of mixedwood stands have been largely ignored, resulting in the transformation of many North American mixedwoods into conifer- or hardwood-dominated stand types. The goal of this study was to examine canopy gap dynamics in balsam fir ( Abies balsamea (L.) Mill.) – yellow birch ( Betula alleghaniensis Britt.) mixedwoods to better understand possible mechanisms for species coexistence. Gap proportion in 12 study stands varied between 9% and 30% of the total stand area, while gap size varied from 20 to 2100 m2. Balsam fir mortality was the primary cause of gap formation. Balsam fir and mountain maple ( Acer spicatum Lamb.) dominated the tree and shrub regeneration layers, respectively. Shrub competition slows the natural filling of gaps by tree species. Our results indicate that yellow birch is most abundant in gaps over 800 m2 and balsam fir in those under 200 m2. Transition models showed that the greater longevity of yellow birch than balsam fir ensured its maintenance as a dominant. Dominant species coexistence thus results from divergent use of available resources through time and space. Forest management should maintain variability in harvest timing and size because the use of one gap size or a single rotation age will lead to an imbalance in species proportion relative to natural stands.
MODELING MATERIALS WITH A STRETCHING THRESHOLD
Authors: FARINA A. , FASANO A. , FUSI L. , RAJAGOPAL K. R. 
Published: November 2007

We examine the dynamics of materials characterized by the presence of a deformation threshold beyond which no deformation is possible. The class of bodies that we are interested in studying are described by an implicit constitutive relationship between the Cauchy stress and the deformation gradient. A specific one-dimensional dynamical problem is studied, showing that the mathematical model takes the form of a hyperbolic free boundary problem in which the free boundary conditions can be of two different types, selected according to whether the stress is continuous at the interface (separating the deformable region from the fully strained region), or whether it is discontinuous. Both situations have been analyzed. Sample numerical computations are carried out using data that are relevant to biological materials. A comparison with the problem obtained from a limiting procedure for a constitutive model with a piecewise linear elastic response is performed, showing a very interesting feature, namely that the limit does not lead to the solution of the model with a threshold. This is however not surprising as the latter exhibits dissipative behavior.
Histone deacetylase inhibitor suberoylanilide hydroxamic acid induces apoptosis through both mitochondrial and Fas (Cd95) signaling in head and neck squamous carcinoma cells
Authors: Gillenwater Ann M. , Zhong Meiling , Lotan Reuben 
Published: November 2007

Abstract
Alterations in histone acetylation status have been implicated in carcinogenesis. Histone deacetylase inhibitors, such as suberoylanilide hydroxamic acid (SAHA), can potentially reactivate aberrantly silenced genes by restoring histone acetylation and allowing gene transcription. However, the mechanisms underlying the effects of SAHA on cell growth, differentiation, and death remain unclear. In this study, we assessed the activity of SAHA in modulating cell growth and apoptosis in head and neck squamous cell carcinoma (HNSCC) cells compared with premalignant leukoplakia and normal oral cells. SAHA induced growth inhibition, cell cycle changes, and apoptosis in HNSCC cell lines but had limited effects on premalignant and normal cells. Although SAHA triggered the mitochondrial pathway of apoptosis, including cytochrome c release, caspase-3 and caspase-9 activation, and poly(ADP-ribose) polymerase cleavage in HNSCC cells, specific inhibition of caspase-9 only partially blocked the induction of apoptosis induction. SAHA also activated the extrinsic apoptosis pathway, including increased Fas and Fas ligand (FasL) expression, activation of caspase-8, and cleavage of Bid. Interfering with Fas signaling blocked apoptosis induction and blunted growth inhibition by SAHA. Our results show for the first time that SAHA induces apoptosis in HNSCC cells through activation of the Fas/FasL death pathway in addition to the intrinsic mitochondrial pathway although having comparatively little activity against precancerous and normal oral cells with intrinsic Fas and FasL expression. [Mol Cancer Ther 2007;6(11):2967–75]
MFTZ-1, an actinomycetes subspecies–derived antitumor macrolide, functions as a novel topoisomerase II poison
Authors: Xie Cheng-Ying , Zhu Hong , Lin Li-Ping , Miao Ze-Hong , Geng Mei-Yu , Cai Yu-Jun , Chen Yi , Zhao Hua-Jun , Luo Hai-Bin , Zhang Xiong-Wen , Fan Li-Ming , Shen Yue-Mao , Ding Jian 
Published: November 2007

Abstract
14-Ethyl-2,5,11-trimethyl-4,13,19,20-tetraoxa-tricyclo[14.2.1.17,10]eicosane-3,12-dione (MFTZ-1), a new macrolide compound isolated from Streptomyces sp. Is9131, displayed wide cytotoxicity in human tumor cell lines with an average IC50 of 0.905 μmol/L. Notably, MFTZ-1 showed significant cytotoxicity in the three multidrug resistance cell lines with an average resistance factor of 2.08. The in vivo experiments showed that MFTZ-1 had inhibitory effects on the human ovarian carcinoma HO-8910 cell line xenotransplanted in nude mice. Further studies showed that MFTZ-1 induced DNA double-strand breaks and triggered mitochondria-dependent apoptosis in human leukemia HL-60 cells. Using a yeast genetic system, we found that topoisomerase (Topo) II rather than Topo I was the primary cellular target of MFTZ-1. Most importantly, MFTZ-1 functions as a novel nonintercalative Topo II poison via binding to ATPase of Topo II, characterized by its strong inhibition on the decatenation and relaxation of Topo II. The capacity of MFTZ-1 to stabilize Topo II–DNA covalent complexes was comparable with that of the classic Topo II poison, etoposide. Moreover, using a Topo II catalytic inhibitor aclarubicin and Topo II–deficient HL-60/MX2 cells, we further showed that MFTZ-1–triggered DNA double-strand breaks and apoptosis occurred in a Topo II–dependent manner. Together, the well-defined Topo II–poisoning function and the potent antitumor activity, with the appreciable anti–multidrug resistance action in particular, promises MFTZ-1 as a novel potential Topo II–targeted agent, which merits further research and development. [Mol Cancer Ther 2007;6(11):3059–70]
Extended treatment with physiologic concentrations of dietary phytochemicals results in altered gene expression, reduced growth, and apoptosis of cancer cells
Authors: Moiseeva Elena P. , Almeida Gabriela M. , Jones George D.D. , Manson Margaret M. 
Published: November 2007

Abstract
Dietary phytochemicals exhibit chemopreventive potential in vivo through persistent low-dose exposures, whereas mechanistic in vitro studies with these agents generally use a high-dose single treatment. Because the latter approach is not representative of an in vivo steady state, we investigated antitumor activity of curcumin, 3,3′-diindolylmethane (DIM), epigallocatechin gallate (EGCG), genistein, or indole-3-carbinol (I3C) in breast cancer MDA-MB-231 cells, exposed in long-term culture to low concentrations, achievable in vivo. Curcumin and EGCG increased cell doubling time. Curcumin, EGCG, and I3C inhibited clonogenic growth by 55% to 60% and induced 1.5- to 2-fold higher levels of the basal caspase-3/7 activity. No changes in expression of cell cycle–related proteins or survivin were found; however, I3C reduced epidermal growth factor receptor expression, contributing to apoptosis. Because some phytochemicals are shown to inhibit DNA and histone modification, modulation of expression by the agents in a set of genes (cadherin-11, p21Cip1, urokinase-type plasminogen activator, and interleukin-6) was compared with changes induced by inhibitors of DNA methylation or histone deacetylation. The phytochemicals modified protein and/or RNA expression of these genes, with EGCG eliciting the least and DIM the most changes in gene expression. DIM and curcumin decreased cadherin-11 and increased urokinase-type plasminogen activator levels correlated with increased cell motility. Curcumin, DIM, EGCG, and genistein reduced cell sensitivity to radiation-induced DNA damage without affecting DNA repair. This model has revealed that apoptosis and not arrest is likely to be responsible for growth inhibition. It also implicated new molecular targets and activities of the agents under conditions relevant to human exposure. [Mol Cancer Ther 2007;6(11):3071–9]
Synergistic activity of the histone deacetylase inhibitor suberoylanilide hydroxamic acid and the bisphosphonate zoledronic acid against prostate cancer cells in vitro
Authors: Sonnemann Jürgen , Bumbul Beata , Beck James F. 
Published: November 2007

Abstract
Bisphosphonates are widely used agents for the treatment of malignant bone disease. They inhibit osteoclast-mediated bone resorption and can have direct effects on cancer cells. In this study, we investigated whether the anticancer activity of the third-generation bisphosphonate zoledronic acid (ZOL) could be enhanced by combination with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA). We found that ZOL and SAHA cooperated to induce cell death in the prostate cancer cell lines LNCaP and PC-3. The effect was synergistic, as evidenced by combination index isobologram analysis. ZOL and SAHA synergized to induce dissipation of the mitochondrial transmembrane potential, to activate caspase-3, and to trigger DNA fragmentation, showing that the combination of ZOL and SAHA resulted in the initiation of apoptosis. Because ZOL acts by inhibiting the mevalonate pathway, thereby preventing protein prenylation, we explored whether the mevalonate pathway was also the target of the cooperative action of ZOL and SAHA. We found that geranylgeraniol, but not farnesol, significantly reduced ZOL/SAHA-induced cell death, indicating that the synergistic action of the agents was due to the inhibition of geranylgeranylation. Consistently, a direct inhibitor of geranylgeranylation, GGTI-298, synergized with SAHA to induce cell death, whereas an inhibitor of farnesylation, FTI-277, had no effect. In addition, SAHA synergized with mevastatin, an inhibitor of the proximal enzyme in the mevalonate pathway. These in vitro findings provide a rationale for an in vivo exploration into the potential of combining SAHA and ZOL, or other inhibitors of the mevalonate pathway, as an effective strategy for anticancer therapy. [Mol Cancer Ther 2007;6(11):2976–84]
Baicalein induces cancer cell death and proliferation retardation by the inhibition of CDC2 kinase and survivin associated with opposite role of p38 mitogen-activated protein kinase and AKT
Authors: Chao Jui-I , Su Wen-Chi , Liu Huei-Fang 
Published: November 2007

Abstract
The bioactive flavonoid baicalein has been shown to have in vitro growth-inhibitory activity in human cancer cells, although the mechanism of action is poorly understood. Baicalein (40–80 μmol/L for 24 h) more effectively induced cytotoxicity compared with other flavonoids (baicalin, catechin, genistein, quercetin, and rutin) in bladder cancer cells. Baicalein induced cell proliferation inhibition and apoptosis. The levels of cyclin B1 and phospho-CDC2 (Thr161) were reduced, whereas the G2-M phases were elevated by baicalein. Treatment of CDC2 kinase or CDC25 phosphatase inhibitors augments the baicalein-induced cytotoxicity. A variety of human bladder cancer cell lines expressed survivin proteins, which were located on the mitotic phases and regulated mitotic progression. Baicalein markedly reduced survivin protein expression. Transfection of a survivin small interfering RNA diminished the level of survivin proteins and increased the baicalein-mediated cell death. Overexpression of survivin enhanced cell proliferation and resisted the baicalein-induced cytotoxicity. Interestingly, baicalein induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and AKT. SB203580, a specific p38 MAPK inhibitor, attenuated proliferation inhibition and restored the protein levels of phospho-CDC2 (Thr161) and survivin in the baicalein-exposed cells; conversely, blockade of AKT activation enhanced cytotoxicity and the reduction of phospho-CDC2 (Thr161) and survivin proteins. As a whole, these findings provide that the opposite role of p38 MAPK and AKT regulates CDC2 kinase and survivin and the inhibition of CDC2-survivin pathway by baicalein contributes to apoptosis and proliferation retardation in cancer cells. [Mol Cancer Ther 2007;6(11):3039–48]