Predicting natural forest regeneration: a statistical model based on inventory data     

Horst Kolo  Donna Ankerst  Thomas Knoke 《European Journal of Forest Research》2017,136(5-6):923-938

Regenerating forest stands through natural seedlings is a commonly accepted silvicultural strategy in Germany. To plan for and increase natural regeneration within a given stand, foresters must be able to estimate whether the stand in its current state can produce sufficient saplings to replace the overstory. In this paper, we present two approaches to building a model that can estimate the probability of natural regeneration occurring, based on variables that are typically readily available from forest inventories. To estimate model parameters we used the large database of the third National Forest Inventory, which covers forest stands and sites across the whole of Germany, as well as weather and soil data. We examined how these variables impact the emergence of natural regeneration, ultimately fitting a model that can predict the occurrence of natural regeneration in 72% of cases. The influence of the variables on the predicted occurrence of natural regeneration was mixed, with most stand variables contributing only minor impact and most likely influencing natural regeneration via complex interactions. The exception was vertical structure (number of stand layers), which accounted for a large proportion of the goodness-of-fit of the model. An important finding was that forest ownership structure is a key variable for the prediction of the presence of regeneration. Data from this study support the assumption that some forest owners manage their stands in a way that fosters natural regeneration.  相似文献   

Genotoxic potential of glyphosate formulations: mode-of-action investigations     

Heydens WF  Healy CE  Hotz KJ  Kier LD  Martens MA  Wilson AG  Farmer DR 《Journal of agricultural and food chemistry》2008,56(4):1517-1523

A broad array of in vitro and in vivo assays has consistently demonstrated that glyphosate and glyphosate-containing herbicide formulations (GCHF) are not genotoxic. Occasionally, however, related and contradictory data are reported, including findings of mouse liver and kidney DNA adducts and damage following intraperitoneal (ip) injection. Mode-of-action investigations were therefore undertaken to determine the significance of these contradictory data while concurrently comparing results from ip and oral exposures. Exposure by ip injection indeed produced marked hepatic and renal toxicity, but oral administration did not. The results suggest that ip injection of GCHF may induce secondary effects mediated by local toxicity rather than genotoxicity. Furthermore, these results continue to support the conclusion that glyphosate and GCHF are not genotoxic under exposure conditions that are relevant to animals and humans.  相似文献   

Multiple element concentration in the grain of spring barley (Hordeum vulgare L.) collection     

Sanjaya Gyawali  Marinus L Otte  Donna L. Jacob  Jilal Abderrazek  Ramesh Pal Singh Verma 《Journal of plant nutrition》2019,42(9):1036-1046

Multiple element analyses were carried out to investigate variation in element concentrations in barley grains of 336 genotypes. Of 13 elements analyzed, Ba ranged from 0.2 to 8.9?mg kg^?1, Ca from 186.4 to 977.5?mg kg^?1, Cu from 1.5 to 9.8?mg kg^?1, K from 353.2 to 7721.5?mg kg^?1, Mg from 1049.8 to 2024.2?mg kg^?1, Mn from 8.1 to 22.9?mg kg^?1, Na from 55.9 to 627.9?mg kg^?1, P from 2272.9 to 5428.8?mg kg^?1, S from 880.7 to 1898.0?mg kg^?1, Si from 19.1 to 663.2?mg kg^?1, and Sr from 0.35 to 2.62?mg kg^?1 in the barley grain. The least square means showed high Zn, Fe, Mg, P, and S concentration in AM-64 and AM-228 genotypes. The principal component analysis of element concentration showed four PCs explained 64.3% total variance. Strong positive correlations (p?<?0.001) of Fe-Mn, Fe-S, S-Mn, Zn-P, Zn-Mg, Mg-P, Mg-Mn, and Ca-Sr were found. The identification barley genotypes that showed high elements concentration furnish valuable genetic resources for biofortification in future.  相似文献   

Influence of canine recombinant somatotropin hormone on biomechanical and biochemical properties of the medial meniscus in stifles with altered stability     

Noone TJ  Millis DL  Korvick DL  Athanasiou K  Cook JL  Kuroki K  Buonomo F 《American journal of veterinary research》2002,63(3):419-426

OBJECTIVE: To determine biomechanical and biochemical properties of the medial meniscus in a semi-stable stifle model and in clinical patients and to determine the effect of canine recombinant somatotropin hormone (STH) on those properties. ANIMALS: 22 healthy adult dogs and 12 dogs with meniscal damage secondary to cranial cruciate ligament (CCL) rupture. PROCEDURE: The CCL was transected in 15 dogs, and stifles were immediately stabilized. Implants releasing 4 mg of STH/d were placed in 7 dogs, and 8 received sham implants. Seven dogs were used as untreated controls. Force plate analysis was performed before surgery and 2, 5, and 10 weeks after surgery. After 10 weeks, dogs were euthanatized, and menisci from surgical and contralateral stifles were harvested. The torn caudal horn of the medial meniscus in dogs with CCL rupture comprised the clinical group. Creep indentation determined aggregate modulus (HA), Poisson's ratio (v), permeability (k), and percentage recovery (%R). Water content (%W), collagen content (C), sulfated glycosaminoglycan (sGAG) content, and collagen type-I (cI) and -II (cII) immunoreactivity were also determined. RESULTS: Surgical and clinical groups had lower HA, k, %R, C, sGAG, cI, and clI and higher %W than the non-surgical group. Surgical stifles with greater weight bearing had stiffer menisci than those bearing less weight. Collagen content was higher in the surgical group receiving STH than the surgical group without STH. CONCLUSIONS AND CLINICAL RELEVANCE: Acute stabilization and moderate weight bearing of the CCLdeficient stifle appear to protect stiffness of the medial meniscus. Normal appearing menisci from CCL-deficient stifles can have alterations in biomechanical and biochemical properties, which may contribute to meniscal failure.  相似文献   

Explaining unexplained diarrhea and associating risks and infections     

Denno DM  Klein EJ  Young VB  Fox JG  Wang D  Tarr PI 《Animal health research reviews / Conference of Research Workers in Animal Diseases》2007,8(1):69-80

Gastrointestinal illnesses are common afflictions. However, knowledge of their etiology is often lacking. Moreover, most cases of infections with reportable enteric pathogens (Campylobacter jejuni, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, Cryptosporidia and Giardia) have sporadic modes of acquisition, yet control measures are often biased towards mitigation of risks discerned by outbreak analysis. To determine the etiology of unexplained diarrhea it is important to study populations that can be matched to appropriate controls and to couple thorough classic microbiologic evaluation on receipt of specimens with archiving and outgrowth capabilities. Research evaluations should address the potential roles of a broad panel of candidate bacterial pathogens including diarrheagenic E. coli, Listeria monocytogenes, Helicobacters and jejuni Campylobacters, and also apply novel massively parallel sequencing and nucleic acid detection technologies that allow the detection of viral pathogens. To fill voids in our knowledge regarding sources of known enteric pathogens it will be critical to extend case-control studies to assess risk factors and exposures to patients with non-epidemic illnesses and to appropriate controls. By filling these gaps in our knowledge it should be possible to formulate rational prevention mechanisms for human gastrointestinal illnesses.  相似文献   

Managing invasive plants on public conservation forestlands: Application of a bio-economic model   总被引：1，自引：0，他引：1  

Donna J. Lee  Damian C. Adams  C.S. Kim   《Forest Policy and Economics》2009,11(4):237-243

Public conservation forestlands protect natural resources, provide wildlife habitat, and service a multi-billion dollar recreation industry. Invasive upland plants (IPs) threaten to dramatically reduce the flow of goods and services from these lands. In the late 1990s, a Florida (USA) state program began combating IPs on public conservation lands. By 2007, the program had controlled roughly 1/3 of the 1.5 million IP-infested acres, primarily due to a surge in expenditures that began in 2001 and peaked in 2005. This study evaluates the effectiveness and efficiency of the program by simulating the costs and benefits of IP control through 2016 under five feasible policy alternatives: (I) Do nothing, (II) Maintenance control, (III) 2001–2004 level (of program spending), (IV) 2005 level, and (V) Maximum net present value. To evaluate the policies, we construct a bio-economic model that is parameterized using observations of IP coverage and data from 11 state regions. Given the uncertain nature of IP spread, we simulate the policies' economic impacts under two plausible spread rates. Simulation results indicate that the program's recent efforts are highly effective – generating up to $865.1 million in present value net benefits through 2016 – but less efficient than more costly, front-loaded spending that can generate up to 4.37 times more net benefits.  相似文献   

Considering Food and Society by William Whit     

Donna Maurer  Mia Moore Barker  Jacqueline M. Newman  William C. Whit 《Agriculture and Human Values》1998,15(1):85-89

  相似文献   

Relationship between efficacy of mating disruption and gypsy moth density     

Ksenia S. Onufrieva  Andrea D. Hickman  Donna S. Leonard  Patrick C. Tobin 《国际虫害防治杂志》2019,65(1):44-52

Mating disruption tactics involve the deployment of pheromones to interfere with mate finding behaviors in insect populations. This management strategy is the dominant one used against expanding gypsy moth populations in the United States, and historically it has been assumed to be most effective against low-density populations. Operationally, mating disruption is used in areas where the season-long trap catch is <30 males/trap, however the maximum population density at which mating disruption is effective remains unknown. We analysed historical gypsy moth mating disruption treatment data from 2000 to 2010, and used this information to guide the mating disruption field studies conducted from 2012 to 2015 against artificially-created populations of various densities, from 0 to 116 males/trap/day. We observed that mating disruption tactics at a dose of 15 g AI/ha were effective against gypsy moth populations with a season-long trap catch of at least 115 males/trap. This research highlights the utility of mating disruption in higher gypsy moth densities than what is currently recommended in management programs.  相似文献   

Growth rates of rainbow smelt in Lake Champlain: effects of density and diet     

Donna L. Parrish  Lars G. Rudstam  Patrick J. Sullivan 《Ecology of Freshwater Fish》2011,20(4):503-512

Stritzel Thomson JL, Parrish DL, Parker‐Stetter SL, Rudstam LG, Sullivan PJ. Growth rates of rainbow smelt in Lake Champlain: effects of density and diet. Ecology of Freshwater Fish 2010. © 2010 John Wiley & Sons A/S Abstract – We estimated the densities of rainbow smelt (Osmerus mordax) using hydroacoustics and obtained specimens for diet analysis and groundtruthed acoustics data from mid‐water trawl sampling in four areas of Lake Champlain, USA–Canada. Densities of rainbow smelt cohorts alternated during the 2‐year study; age‐0 rainbow smelt were very abundant in 2001 (up to 6 fish per m²) and age‐1 and older were abundant (up to 1.2 fish per m²) in 2002. Growth rates and densities varied among areas and years. We used model selection on eight area–year‐specific variables to investigate biologically plausible predictors of rainbow smelt growth rates. The best supported model of growth rates of age‐0 smelt indicated a negative relationship with age‐0 density, likely associated with intraspecific competition for zooplankton. The next best‐fit model had age‐1 density as a predictor of age‐0 growth. The best supported models (N = 4) of growth rates of age‐1 fish indicated a positive relationship with availability of age‐0 smelt and resulting levels of cannibalism. Other plausible models were contained variants of these parameters. Cannibalistic rainbow smelt consumed younger conspecifics that were up to 53% of their length. Prediction of population dynamics for rainbow smelt requires an understanding of the relationship between density and growth as age‐0 fish outgrow their main predators (adult smelt) by autumn in years with fast growth rates, but not in years with slow growth rates.  相似文献   

Expression of follistatin is associated with egg formation in the oviduct of laying hens     

Sanjeev Wasti  Nirvay Sah  Donna L. Kuehu  Yong S. Kim  Rajesh Jha  Birendra Mishra 《Animal Science Journal》2020,91(1)

The objective of this study was to examine the expression profiles of follistatin (FST) and its associated molecules (MSTN, INHA, INHBB, INHBA, ACVR2A, and ACVR2B) in the oviduct of laying hens at 3 hr and 20 hr post‐ovulation (p.o., n = 5; 35 weeks old), molting (n = 5; 60 weeks old), and non‐laying (n = 4; 35–60 weeks old) hens and also to localize the FST by using immunohistochemistry assay. Expression of FST was significantly higher (p < .05), and MSTN was lower in the uterus of laying hens around 15–20 hr p.o. (during eggshell formation), however, their expressions in the magnum remain unchanged across different physiological stages of hens. FST was mainly expressed in the luminal and glandular epithelium of the uterine tissues, and their expression intensity was highest in laying hens during the eggshell mineralization. There was a relatively increased expression of INHA in the magnum of laying hens around 3 hr p.o. as compared to non‐laying and molting hens. At the same time (3 hr p.o.), there was a significant (p < .05) decrease in the expression of the INHBB, ACVR2A, and ACV2B. These results indicate that follistatin may regulate the differentiation of uterine luminal and glandular epithelium during eggshell biomineralization.  相似文献