Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth （diameter at breast height, total height）, natural pruning （height to fir...Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth （diameter at breast height, total height）, natural pruning （height to first dead and first live branch and branchiness） and stem and crown form of 24-year-old pedunculate oak （Quercus robur [L.]） and European ash （Fraxinus excelsior [L.]） were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha？1. Mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots and inadequate self-pruning can be controlled with trainer species, the initial stocking may be reduced significantly in oak.展开更多
Background: To increase ecosystem resilience and biodiversity, the maintenance and improvement of structural and compositional diversity of forests has become an important goal in forest management for many forest own...Background: To increase ecosystem resilience and biodiversity, the maintenance and improvement of structural and compositional diversity of forests has become an important goal in forest management for many forest owners and jurisdictions. At the same time, future harvesting intensity (HI) may increase to meet the demand for woody biomass by an increasing bioeconomy sector. Yet, the influence of HI on forest structural diversity is largely unknown. Here, we address this issue by analyzing the relationship between HI and structural diversity based on large-scale national forest inventory (NFI) data, where the latter is quantified using a previously developed Forest Structure Index and HI is expressed as wood volume removal during the period 2002-2012 for the same inventory plots. Results: Our results show a surprisingly small impact of harvesting intensity on changes in structural diversity for most of the analysed types of forests. Only intense harvesting (> 80%-90% of initial growing stock) led to a significant reduction in structural diversity. At low to moderate HI most aspects of structural diversity were positively influenced. Only the quadratic mean DBH and the volume of large trees (≥ 40 cm DBH) were substantially negatively influenced at HI > 60% and 70% of initial growing stock, respectively. Conclusions: In several forest types, HI could be increased without a reduction in overall structural diversity. Hence, structural diversity in these selectively managed forests appears to be a very resistant forest property in relation to HI. Other indicators at stand and landscape scale may be needed to adjust levels of HI that are suited to maintain forest biodiversity.展开更多
AIM： To investigate the prevalence, risk factors, and selection of the study population for cholecystolithiasis in an urban population in Germany, in relation to our own findings and to the results in the internation...AIM： To investigate the prevalence, risk factors, and selection of the study population for cholecystolithiasis in an urban population in Germany, in relation to our own findings and to the results in the international literature. METHODS： A total of 2 147 persons （1 111 females, age 42.8 ＋ 12.7 years; 1 036 males, age 42.3 ＋ 13.1 years） participating in an investigation on the prevalence of Echinococcus rnultilocularis were studied for risk factors and prevalence of gallbladder stone disease. Risk factors were assessed by means of a standardized interview and calculation of body mass index （BMI）. A diagnostic ultrasound examination of the gallbladder was performed. Data were analyzed by multiple logistic regression, using the SAS statistical software package. RESULTS： Gallbladder stones were detected in 171 study participants （8.0%, n = 2 147）. Risk factors for the development of gallbladder stone disease included age, sex, BMI, and positive family history. In a separate analysis of female study participants, pregnancy （yes/no） and number of pregnancies did not exert any influence. CONCLUSION： Findings of the present study confirm that age, female sex, BMI, and positive family history are risk factors for the development of gallbladder stone disease. Pregnancy and the number of pregnancies, however, could not be shown to be risk factors. There seem to be no differences in the respective prevalence for gallbladder stone disease in urban and rural populations.展开更多
BACKGROUND Progressive malnutrition coexists with liver diseases,particularly in patients with cirrhosis.Early diagnosis of malnutrition in patients with advanced stages of chronic liver disease and the implementation...BACKGROUND Progressive malnutrition coexists with liver diseases,particularly in patients with cirrhosis.Early diagnosis of malnutrition in patients with advanced stages of chronic liver disease and the implementation of appropriate nutritional treatment for malnourished patients should be an integral part of the therapeutic process.AIM To evaluate the nutritional status of patients with various severities of advanced liver fibrosis,using various nutritional status parameters.METHODS This study involved 118 patients with liver cirrhosis who were classified into three groups according to their Child-Pugh score.The nutritional status of the patients in each group was assessed using different methods.The average values obtained from the measurements were calculated for each research group.The influence of disease stage on the examined parameters of nutritional status was determined using one-way analysis of variance.To investigate the relationship between the parameters determining nutritional status and the stage of disease advancement,a correlation analysis was performed.RESULTS The Child-Pugh A group had the highest mean body weight(76.42 kg),highest mean body mass index(BMI)(26.72 kg/m²),and largest mean arm circumference(27.64 cm).In the Child-Pugh B group,the mean scores of all examined variables were lower than those of the Child-Pugh A group,whereas the mean body weight and BMI of the Child-Pugh C group were higher than those of the Child-Pugh B group.There was a very strong correlation between the Child-Pugh classification and subjective global assessment score;a very strong correlation between the Child-Pugh classification and arm circumference;a strong correlation between the Child-Pugh classification and body weight,albumin concentration,fat-free mass index,muscle mass index,phase angle,and BMI;and an average correlation between Child-Pugh classification and fat mass index.Notably,these indicators deteriorated with disease progression.CONCLUSION Advanced liver fibrosis leads to the deterioration of many nutritional status parameters.The extent of malnutrition increases with the progression of liver fibrosis.The Child-Pugh score reflects the nutritional status.展开更多
Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obta...Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country-and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil and nutrient deposition.Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from10% to 53% depending on the species. Variables related to forest structure(basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species.Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etc.展开更多
Rarely,scientific developments centered around the patient as a whole arepublished.Our multidisciplinary group,headed by gastrointestinal surgeons,applied this research philosophy considering the most important aspect...Rarely,scientific developments centered around the patient as a whole arepublished.Our multidisciplinary group,headed by gastrointestinal surgeons,applied this research philosophy considering the most important aspects of thediseases“colon-and rectal cancer”in the long-term developments.Good expertcooperation/knowledge at the Comprehensive Cancer Center Ulm(CCCU)wereapplied in several phase III trials for multimodal treatments of primary tumors(MMT)and metastatic diseases(involving nearly 2000 patients and 64 centers),fortreatment individualization of MMT and of metastatic disease,for psychooncology/quality of life involving the patients’wishes,and for disease prevention.Most of the targets initially were heavily rejected/discussed in thescientific communities,but now have become standards in treatments andnational guidelines or are topics in modern translational research protocolsinvolving molecular biology for e.g.,“patient centered individualized treatment”.In this context we also describe the paths we had to tread in order to realize ournew goals,which at the end were highly beneficial for the patients from manypoints of view.This description is also important for students and youngresearchers who,with an actual view on our recent developments,might want toknow how medical progress was achieved.展开更多
Background:In bird species where offspring growth and survival rely on parents’food provisioning,parents can maximise their fitness by increasing the quantity and/or the quality of preys delivered to their offspring....Background:In bird species where offspring growth and survival rely on parents’food provisioning,parents can maximise their fitness by increasing the quantity and/or the quality of preys delivered to their offspring.Many studies have focused on inter-individual variation in feeding rate,yet this measure may not accurately reflect the total amount of food(i.e.energy)provided by parents if there is large variation in the quantity and quality of preys at each feeding.Here,we explored the relative role of individual(sex,age,body condition),breeding(hatching date,brood size)and environmental(temperature)factors on feeding rate,prey number,size and quality,and their contribution to total prey biomass delivered to the nestlings of 164 Collared Flycatcher(Ficedula albicollis)parents in 98 nests.Results:Preys delivered to the nest were mainly larvae(53.6%)and flying insects(45.6%).Feeding rate increased with brood size and age,and was higher in males than females.Mean prey number decreased,but mean prey size increased,as the season progressed and parents feeding their brood with primary larvae brought more preys per visit.Relationships between feeding rate,mean prey number and size remained when taking into account the provision-ing quality:parents brought either a large number of small prey or a small number of larger items,and the force of the trade-offs between feeding rate and mean prey number and size depended on the quality of the provisioning of the parents.Whatever the percentage of larvae among preys in the provisioning,the variance in total prey biomass was foremost explained by feeding rate(65.1%to 76.6%)compared to mean prey number(16.4%to 26%)and prey size(2.7%to 4%).Conclusions:Our study shows that variation in feeding rate,prey number,size,but not quality(i.e.percentage of lar-vae),were influenced by individual factors(sex and age)and breeding decisions(brood size and timing of breeding)and that,whatever the provisioning strategy adopted,feeding rate was the best proxy of the total biomass delivered to the nestlings.展开更多
This research estimates carbon sink and allocation in above-and below-ground biomass of a 12-year-old willow coppice plantation on fl uvisol soil near the Vistula River(southern Poland).The plantation showed high C si...This research estimates carbon sink and allocation in above-and below-ground biomass of a 12-year-old willow coppice plantation on fl uvisol soil near the Vistula River(southern Poland).The plantation showed high C sink potential and sequestration rates.C sequestration by aboveground biomass was estimated at 10.8 Mg C ha^−1 a^−1.Accumulation in coarse roots was estimated at 1.5 Mg C ha^−1 a^−1 and in fi ne roots at 1.2 Mg C ha^−1 a^−1.Total C sequestered(above-ground biomass,coarse roots and fi ne roots)was estimated at 13.5 Mg C ha^−1 a^−1.These results confi rm the potential of fast-growing plantations of willow to mitigate,over a short time span,the eff ects of high CO 2 concentrations.展开更多
Improvements in the acquisition of three-dimensional(3D)information from the Airborne Laser Scanner(ALS)increase its applications for studying Earth’s surface.The use of ALS data in natural resource inventories is st...Improvements in the acquisition of three-dimensional(3D)information from the Airborne Laser Scanner(ALS)increase its applications for studying Earth’s surface.The use of ALS data in natural resource inventories is still in an experimental stage in central Europe.Here,a survey was completed in Germany,where plot-level features from LANDSAT Thematic Mapper and ALS data were applied.An automated process was developed for forest stratification using orthoimages.A genetic algorithm was applied for variable screening.Variable subsets of different sizes were employed for simultaneous predictions of structural forest attributes using the‘Random Forest’(RF)method.Performance was assessed by leave-one-out cross-validations on bootstrap resample data.Results indicate that the stratification of forest notably improved the results of predictions.The improvements were more obvious for the strata-related attributes.Accuracy was enhanced as the number of selected variables increased.However,parsimonious models are still essentially required for practical applications.The RF errors were slightly greater than those from least squares regression,as the non-parametric methods do not share the same mix of error components as regression.Through the combination of remote sensing and modelling,we conclude that our results are helpful for bridging the gap between regional earth observation and on-the-ground forest structure.展开更多
Dear Editor Roots play a key role in plant growth regulation. It is well described that the below-ground plant architecture has a significant impact on plant performance under abiotic constraints and maintains stabili...Dear Editor Roots play a key role in plant growth regulation. It is well described that the below-ground plant architecture has a significant impact on plant performance under abiotic constraints and maintains stability under increased grain load （Lynch, 2013）.展开更多
文摘Initial growing space is of critical importance to growth and quality development of individual trees. We investigated how mortality, growth （diameter at breast height, total height）, natural pruning （height to first dead and first live branch and branchiness） and stem and crown form of 24-year-old pedunculate oak （Quercus robur [L.]） and European ash （Fraxinus excelsior [L.]） were affected by initial spacing. Data were recorded from two replicate single-species Nelder wheels located in southern Germany with eight initial stocking regimes varying from 1,020 to 30,780 seedlings·ha？1. Mortality substantially decreased with increasing initial growing space but significantly differed among the two species, averaging 59% and 15% for oak and ash plots, respectively. In contrast to oak, the low self-thinning rate found in the ash plots over the investigated study period resulted in a high number of smaller intermediate or suppressed trees, eventually retarding individual tree as well as overall stand development. As a result, oak gained greater stem dimensions throughout all initial spacing regimes and the average height of ash significantly increased with initial growing space. The survival of lower crown class ashes also appeared to accelerate self-pruning dynamics. In comparison to oak, we observed less dead and live primary branches as well as a smaller number of epicormic shoots along the first 6 m of the lower stem of dominant and co-dominant ashes in all spacing regimes. Whereas stem form of both species was hardly affected by initial growing space, the percentage of brushy crowns significantly increased with initial spacing in oak and ash. Our findings suggest that initial stockings of ca. 12,000 seedlings per hectare in oak and 2,500 seedlings per hectare in ash will guarantee a sufficient number of at least 300 potential crop trees per hectare in pure oak and ash plantations at the end of the self-thinning phase, respectively. If the problem of epicormic shoots and inadequate self-pruning can be controlled with trainer species, the initial stocking may be reduced significantly in oak.
基金supported by a grant from the Ministry of Science,Research and the Arts of Baden-Württemberg(7533-10-5-78)to Jürgen Bauhussupport through the BBW For Werts Graduate Program
文摘Background: To increase ecosystem resilience and biodiversity, the maintenance and improvement of structural and compositional diversity of forests has become an important goal in forest management for many forest owners and jurisdictions. At the same time, future harvesting intensity (HI) may increase to meet the demand for woody biomass by an increasing bioeconomy sector. Yet, the influence of HI on forest structural diversity is largely unknown. Here, we address this issue by analyzing the relationship between HI and structural diversity based on large-scale national forest inventory (NFI) data, where the latter is quantified using a previously developed Forest Structure Index and HI is expressed as wood volume removal during the period 2002-2012 for the same inventory plots. Results: Our results show a surprisingly small impact of harvesting intensity on changes in structural diversity for most of the analysed types of forests. Only intense harvesting (> 80%-90% of initial growing stock) led to a significant reduction in structural diversity. At low to moderate HI most aspects of structural diversity were positively influenced. Only the quadratic mean DBH and the volume of large trees (≥ 40 cm DBH) were substantially negatively influenced at HI > 60% and 70% of initial growing stock, respectively. Conclusions: In several forest types, HI could be increased without a reduction in overall structural diversity. Hence, structural diversity in these selectively managed forests appears to be a very resistant forest property in relation to HI. Other indicators at stand and landscape scale may be needed to adjust levels of HI that are suited to maintain forest biodiversity.
文摘AIM： To investigate the prevalence, risk factors, and selection of the study population for cholecystolithiasis in an urban population in Germany, in relation to our own findings and to the results in the international literature. METHODS： A total of 2 147 persons （1 111 females, age 42.8 ＋ 12.7 years; 1 036 males, age 42.3 ＋ 13.1 years） participating in an investigation on the prevalence of Echinococcus rnultilocularis were studied for risk factors and prevalence of gallbladder stone disease. Risk factors were assessed by means of a standardized interview and calculation of body mass index （BMI）. A diagnostic ultrasound examination of the gallbladder was performed. Data were analyzed by multiple logistic regression, using the SAS statistical software package. RESULTS： Gallbladder stones were detected in 171 study participants （8.0%, n = 2 147）. Risk factors for the development of gallbladder stone disease included age, sex, BMI, and positive family history. In a separate analysis of female study participants, pregnancy （yes/no） and number of pregnancies did not exert any influence. CONCLUSION： Findings of the present study confirm that age, female sex, BMI, and positive family history are risk factors for the development of gallbladder stone disease. Pregnancy and the number of pregnancies, however, could not be shown to be risk factors. There seem to be no differences in the respective prevalence for gallbladder stone disease in urban and rural populations.
文摘BACKGROUND Progressive malnutrition coexists with liver diseases,particularly in patients with cirrhosis.Early diagnosis of malnutrition in patients with advanced stages of chronic liver disease and the implementation of appropriate nutritional treatment for malnourished patients should be an integral part of the therapeutic process.AIM To evaluate the nutritional status of patients with various severities of advanced liver fibrosis,using various nutritional status parameters.METHODS This study involved 118 patients with liver cirrhosis who were classified into three groups according to their Child-Pugh score.The nutritional status of the patients in each group was assessed using different methods.The average values obtained from the measurements were calculated for each research group.The influence of disease stage on the examined parameters of nutritional status was determined using one-way analysis of variance.To investigate the relationship between the parameters determining nutritional status and the stage of disease advancement,a correlation analysis was performed.RESULTS The Child-Pugh A group had the highest mean body weight(76.42 kg),highest mean body mass index(BMI)(26.72 kg/m²),and largest mean arm circumference(27.64 cm).In the Child-Pugh B group,the mean scores of all examined variables were lower than those of the Child-Pugh A group,whereas the mean body weight and BMI of the Child-Pugh C group were higher than those of the Child-Pugh B group.There was a very strong correlation between the Child-Pugh classification and subjective global assessment score;a very strong correlation between the Child-Pugh classification and arm circumference;a strong correlation between the Child-Pugh classification and body weight,albumin concentration,fat-free mass index,muscle mass index,phase angle,and BMI;and an average correlation between Child-Pugh classification and fat mass index.Notably,these indicators deteriorated with disease progression.CONCLUSION Advanced liver fibrosis leads to the deterioration of many nutritional status parameters.The extent of malnutrition increases with the progression of liver fibrosis.The Child-Pugh score reflects the nutritional status.
基金funded by the SIMWOOD project(Grant Agreement No.613762)of the EU H2020 Programmefacilitated by the Alter For project(Grant Agreement No.676754)+3 种基金the VERIFY project(Grant Agreement No.776810)Co-funding was received from the topsector Agri&Food under No.AF-EU-15002The Dutch National Forest Inventory is funded by the Ministry of Economic AffairsThe regional forest inventory in Piemonte was produced with the support of EU structural funds
文摘Background: Over the last decades, many forest simulators have been developed for the forests of individual European countries. The underlying growth models are usually based on national datasets of varying size, obtained from National Forest Inventories or from long-term research plots. Many of these models include country-and location-specific predictors, such as site quality indices that may aggregate climate, soil properties and topography effects. Consequently, it is not sensible to compare such models among countries, and it is often impossible to apply models outside the region or country they were developed for. However, there is a clear need for more generically applicable but still locally accurate and climate sensitive simulators at the European scale, which requires the development of models that are applicable across the European continent. The purpose of this study is to develop tree diameter increment models that are applicable at the European scale, but still locally accurate. We compiled and used a dataset of diameter increment observations of over 2.3 million trees from 10 National Forest Inventories in Europe and a set of 99 potential explanatory variables covering forest structure, weather, climate, soil and nutrient deposition.Results: Diameter increment models are presented for 20 species/species groups. Selection of explanatory variables was done using a combination of forward and backward selection methods. The explained variance ranged from10% to 53% depending on the species. Variables related to forest structure(basal area of the stand and relative size of the tree) contributed most to the explained variance, but environmental variables were important to account for spatial patterns. The type of environmental variables included differed greatly among species.Conclusions: The presented diameter increment models are the first of their kind that are applicable at the European scale. This is an important step towards the development of a new generation of forest development simulators that can be applied at the European scale, but that are sensitive to variations in growing conditions and applicable to a wider range of management systems than before. This allows European scale but detailed analyses concerning topics like CO2 sequestration, wood mobilisation, long term impact of management, etc.
文摘Rarely,scientific developments centered around the patient as a whole arepublished.Our multidisciplinary group,headed by gastrointestinal surgeons,applied this research philosophy considering the most important aspects of thediseases“colon-and rectal cancer”in the long-term developments.Good expertcooperation/knowledge at the Comprehensive Cancer Center Ulm(CCCU)wereapplied in several phase III trials for multimodal treatments of primary tumors(MMT)and metastatic diseases(involving nearly 2000 patients and 64 centers),fortreatment individualization of MMT and of metastatic disease,for psychooncology/quality of life involving the patients’wishes,and for disease prevention.Most of the targets initially were heavily rejected/discussed in thescientific communities,but now have become standards in treatments andnational guidelines or are topics in modern translational research protocolsinvolving molecular biology for e.g.,“patient centered individualized treatment”.In this context we also describe the paths we had to tread in order to realize ournew goals,which at the end were highly beneficial for the patients from manypoints of view.This description is also important for students and youngresearchers who,with an actual view on our recent developments,might want toknow how medical progress was achieved.
文摘Background:In bird species where offspring growth and survival rely on parents’food provisioning,parents can maximise their fitness by increasing the quantity and/or the quality of preys delivered to their offspring.Many studies have focused on inter-individual variation in feeding rate,yet this measure may not accurately reflect the total amount of food(i.e.energy)provided by parents if there is large variation in the quantity and quality of preys at each feeding.Here,we explored the relative role of individual(sex,age,body condition),breeding(hatching date,brood size)and environmental(temperature)factors on feeding rate,prey number,size and quality,and their contribution to total prey biomass delivered to the nestlings of 164 Collared Flycatcher(Ficedula albicollis)parents in 98 nests.Results:Preys delivered to the nest were mainly larvae(53.6%)and flying insects(45.6%).Feeding rate increased with brood size and age,and was higher in males than females.Mean prey number decreased,but mean prey size increased,as the season progressed and parents feeding their brood with primary larvae brought more preys per visit.Relationships between feeding rate,mean prey number and size remained when taking into account the provision-ing quality:parents brought either a large number of small prey or a small number of larger items,and the force of the trade-offs between feeding rate and mean prey number and size depended on the quality of the provisioning of the parents.Whatever the percentage of larvae among preys in the provisioning,the variance in total prey biomass was foremost explained by feeding rate(65.1%to 76.6%)compared to mean prey number(16.4%to 26%)and prey size(2.7%to 4%).Conclusions:Our study shows that variation in feeding rate,prey number,size,but not quality(i.e.percentage of lar-vae),were influenced by individual factors(sex and age)and breeding decisions(brood size and timing of breeding)and that,whatever the provisioning strategy adopted,feeding rate was the best proxy of the total biomass delivered to the nestlings.
基金The National Centre for Research and Development,Poland(Project No.PBS2/A8/26/2014).
文摘This research estimates carbon sink and allocation in above-and below-ground biomass of a 12-year-old willow coppice plantation on fl uvisol soil near the Vistula River(southern Poland).The plantation showed high C sink potential and sequestration rates.C sequestration by aboveground biomass was estimated at 10.8 Mg C ha^−1 a^−1.Accumulation in coarse roots was estimated at 1.5 Mg C ha^−1 a^−1 and in fi ne roots at 1.2 Mg C ha^−1 a^−1.Total C sequestered(above-ground biomass,coarse roots and fi ne roots)was estimated at 13.5 Mg C ha^−1 a^−1.These results confi rm the potential of fast-growing plantations of willow to mitigate,over a short time span,the eff ects of high CO 2 concentrations.
文摘Improvements in the acquisition of three-dimensional(3D)information from the Airborne Laser Scanner(ALS)increase its applications for studying Earth’s surface.The use of ALS data in natural resource inventories is still in an experimental stage in central Europe.Here,a survey was completed in Germany,where plot-level features from LANDSAT Thematic Mapper and ALS data were applied.An automated process was developed for forest stratification using orthoimages.A genetic algorithm was applied for variable screening.Variable subsets of different sizes were employed for simultaneous predictions of structural forest attributes using the‘Random Forest’(RF)method.Performance was assessed by leave-one-out cross-validations on bootstrap resample data.Results indicate that the stratification of forest notably improved the results of predictions.The improvements were more obvious for the strata-related attributes.Accuracy was enhanced as the number of selected variables increased.However,parsimonious models are still essentially required for practical applications.The RF errors were slightly greater than those from least squares regression,as the non-parametric methods do not share the same mix of error components as regression.Through the combination of remote sensing and modelling,we conclude that our results are helpful for bridging the gap between regional earth observation and on-the-ground forest structure.
文摘Dear Editor Roots play a key role in plant growth regulation. It is well described that the below-ground plant architecture has a significant impact on plant performance under abiotic constraints and maintains stability under increased grain load （Lynch, 2013）.
