1975～1985年,在辽宁西部前所果树农场进行红星苹果矮化中间砧试验研究。中间砧有 M 系的2,4,5,6,7,9,11、16,还有丹麦道生、保加利亚18号及甜黄魁。以山定砧嫁接苗作对照。经过10年试验,对其抗寒性、抗风、嫁接亲和力、开花株率、花序...1975～1985年,在辽宁西部前所果树农场进行红星苹果矮化中间砧试验研究。中间砧有 M 系的2,4,5,6,7,9,11、16,还有丹麦道生、保加利亚18号及甜黄魁。以山定砧嫁接苗作对照。经过10年试验,对其抗寒性、抗风、嫁接亲和力、开花株率、花序座果率,平均株产、树高、树冠体积、根系生长状况及分布、各砧穗组合的丰产相关指标进行了调查研究,并对各组合在前所果树农场自然条件及管理水平情况下的表现特点作出评价。展开更多
Inconsistencies between datasets are examined with reference to flood tidal elevations in the Tamar River estuary, Tasmania Australia. Errors in a 30-year-old commonly cited dataset have been perpetuated in subsequent...Inconsistencies between datasets are examined with reference to flood tidal elevations in the Tamar River estuary, Tasmania Australia. Errors in a 30-year-old commonly cited dataset have been perpetuated in subsequent publications and datasets, and a clarification is herein provided. Elevation of the flood tidal wave as it propagates the estuary is evident in mean tide level and mean sea level, although the analysis is compromised by the temporal differences of the datasets. As sea levels rise due to global warming, the importance of accurate on-going sea level data in any estuary will become more acute.展开更多
During the satellite pulse propagation and reception, the altimeter waveform is inevitably affected by noise. To reduce the noise level in Jason altimeter waveforms, we used singular spectrum analysis(SSA),empirical m...During the satellite pulse propagation and reception, the altimeter waveform is inevitably affected by noise. To reduce the noise level in Jason altimeter waveforms, we used singular spectrum analysis(SSA),empirical mode decomposition(EMD), and the combination of SSA and EMD to obtain the denoised waveforms. The advantages of the combined method were verified and the accuracy of the mean sea surface height(MSSH) model was improved. Comparing the denoising effect of the three methods, the results show that the signal-to-noise ratio(SNR), correlation coefficient and root-mean-square error are effectively improved by the combination of SSA and EMD. The sea surface heights(SSHs) were remeasured with a 50% threshold retracker of denoised waveforms, and the MSSH model of the Caspian Sea with a grid of 1’× 1’was established from the retracked SSHs of Jason-1/2/3. Taking the mean value of the four models as a control, it is found that the model calculated by the combined denoising method has the highest accuracy. This indicates that using the combined denoising method to reduce the noise level is beneficial to improve the accuracy of the MSSH model.展开更多
The aim of the article was to study the growth of Douglas-fir plantations in the region of the Training Experimental Forest Enterprise, Yundola （Central South Bulgaria）. The study sites were three Douglas-fir planta...The aim of the article was to study the growth of Douglas-fir plantations in the region of the Training Experimental Forest Enterprise, Yundola （Central South Bulgaria）. The study sites were three Douglas-fir plantations, ranging between 50 and 55 years of age at altitudinal range between 1,400 m and 1,600 m above sea level （masl）. The mean height, diameter at breast height, site class, stem volume as well as the mechanical resistance （H/D ratio） of Douglas-fir were measured for each plantation. The results showed that Douglas-fir had the best height growth of the studied plantations on slope facing South at altitude 1,600 masl and Douglas-fir with age 55 years old reached a mean height of 32.4 m. The average diameter at breast height of the studied plantations reaches approximately 30 cm, which shows that they are suitable for large scale wood harvesting. The average stem volume of Douglas-fir in the observed plantations up to age of 55 is within the range of 400-600 m3/ha, with an average annual volume increment from 7 m3/ha to 12 m3/ha each year. The high index of mechanical resistance （H/D ratio） indicated a risk for abiotic damages, which implicated the need for the immediate implementation of felling.展开更多
Teak(Tectona grandis L.f.)plantations are increasingly being established in tropical regions to meet a rising demand for its highly valued timber.Teak plantations have been established in the Atlantic Coastal Plain re...Teak(Tectona grandis L.f.)plantations are increasingly being established in tropical regions to meet a rising demand for its highly valued timber.Teak plantations have been established in the Atlantic Coastal Plain region of Colombia,a region climatically suitable for teak growth by having a monsoon climate with a unimodal precipitation pattern.Tree diameter at breast height(DBH,1.3 m above ground)and mean top height,periodically measured over a 17-year period in 44 permanent sampling plots of size 0.06 and 0.10 ha,were used in this study.A stochastic differential equation(SDE),along with a Bertalanffy–Richards-type height growth model,was used to model and estimate top height growth of teak plantations in Colombia.Environmental noise and height measurement errors were explicitly considered as the main uncertainty sources of mean top height growth.The best model for estimating mean top height,based on statistical performance and biological rationale,had the asymptote defined as a local parameter and the growth rate and shape specified as global parameters.This model outperformed its counterpart that had the growth rate specified as a local parameter and asymptote and shape as global parameters.The selected model also outperformed alternative approaches such as the mixed-effects model,generalized algebraic difference approach,and the dummy variable method.Estimated trajectories for the mean top height of teak in Colombia are biologically sound based on the measured height series and previous studies in Latin America.Results suggest that most of the uncertainty associated with the mean top height growth of teak plantations in Colombia was largely explained by environmental noise.The best estimated model using the SDE approach can be useful for predicting height growth and evaluating site productivity of teak plantations in Colombia and in neighbouring countries with biophysical characteristics similar to those where teak has been planted in Colombia.展开更多
文摘1975～1985年,在辽宁西部前所果树农场进行红星苹果矮化中间砧试验研究。中间砧有 M 系的2,4,5,6,7,9,11、16,还有丹麦道生、保加利亚18号及甜黄魁。以山定砧嫁接苗作对照。经过10年试验,对其抗寒性、抗风、嫁接亲和力、开花株率、花序座果率,平均株产、树高、树冠体积、根系生长状况及分布、各砧穗组合的丰产相关指标进行了调查研究,并对各组合在前所果树农场自然条件及管理水平情况下的表现特点作出评价。
文摘Inconsistencies between datasets are examined with reference to flood tidal elevations in the Tamar River estuary, Tasmania Australia. Errors in a 30-year-old commonly cited dataset have been perpetuated in subsequent publications and datasets, and a clarification is herein provided. Elevation of the flood tidal wave as it propagates the estuary is evident in mean tide level and mean sea level, although the analysis is compromised by the temporal differences of the datasets. As sea levels rise due to global warming, the importance of accurate on-going sea level data in any estuary will become more acute.
基金We acknowledge the National Natural Science Foundation of China(grant number 41974013)for financial support.
文摘During the satellite pulse propagation and reception, the altimeter waveform is inevitably affected by noise. To reduce the noise level in Jason altimeter waveforms, we used singular spectrum analysis(SSA),empirical mode decomposition(EMD), and the combination of SSA and EMD to obtain the denoised waveforms. The advantages of the combined method were verified and the accuracy of the mean sea surface height(MSSH) model was improved. Comparing the denoising effect of the three methods, the results show that the signal-to-noise ratio(SNR), correlation coefficient and root-mean-square error are effectively improved by the combination of SSA and EMD. The sea surface heights(SSHs) were remeasured with a 50% threshold retracker of denoised waveforms, and the MSSH model of the Caspian Sea with a grid of 1’× 1’was established from the retracked SSHs of Jason-1/2/3. Taking the mean value of the four models as a control, it is found that the model calculated by the combined denoising method has the highest accuracy. This indicates that using the combined denoising method to reduce the noise level is beneficial to improve the accuracy of the MSSH model.
文摘The aim of the article was to study the growth of Douglas-fir plantations in the region of the Training Experimental Forest Enterprise, Yundola （Central South Bulgaria）. The study sites were three Douglas-fir plantations, ranging between 50 and 55 years of age at altitudinal range between 1,400 m and 1,600 m above sea level （masl）. The mean height, diameter at breast height, site class, stem volume as well as the mechanical resistance （H/D ratio） of Douglas-fir were measured for each plantation. The results showed that Douglas-fir had the best height growth of the studied plantations on slope facing South at altitude 1,600 masl and Douglas-fir with age 55 years old reached a mean height of 32.4 m. The average diameter at breast height of the studied plantations reaches approximately 30 cm, which shows that they are suitable for large scale wood harvesting. The average stem volume of Douglas-fir in the observed plantations up to age of 55 is within the range of 400-600 m3/ha, with an average annual volume increment from 7 m3/ha to 12 m3/ha each year. The high index of mechanical resistance （H/D ratio） indicated a risk for abiotic damages, which implicated the need for the immediate implementation of felling.
基金The sabbatic and travel expenses of the lead author for the 2019 Southern Mensurationists meeting in AshevilleNorth CarolinaSeptember 15–17,were funded by the National University of Colombia。
文摘Teak(Tectona grandis L.f.)plantations are increasingly being established in tropical regions to meet a rising demand for its highly valued timber.Teak plantations have been established in the Atlantic Coastal Plain region of Colombia,a region climatically suitable for teak growth by having a monsoon climate with a unimodal precipitation pattern.Tree diameter at breast height(DBH,1.3 m above ground)and mean top height,periodically measured over a 17-year period in 44 permanent sampling plots of size 0.06 and 0.10 ha,were used in this study.A stochastic differential equation(SDE),along with a Bertalanffy–Richards-type height growth model,was used to model and estimate top height growth of teak plantations in Colombia.Environmental noise and height measurement errors were explicitly considered as the main uncertainty sources of mean top height growth.The best model for estimating mean top height,based on statistical performance and biological rationale,had the asymptote defined as a local parameter and the growth rate and shape specified as global parameters.This model outperformed its counterpart that had the growth rate specified as a local parameter and asymptote and shape as global parameters.The selected model also outperformed alternative approaches such as the mixed-effects model,generalized algebraic difference approach,and the dummy variable method.Estimated trajectories for the mean top height of teak in Colombia are biologically sound based on the measured height series and previous studies in Latin America.Results suggest that most of the uncertainty associated with the mean top height growth of teak plantations in Colombia was largely explained by environmental noise.The best estimated model using the SDE approach can be useful for predicting height growth and evaluating site productivity of teak plantations in Colombia and in neighbouring countries with biophysical characteristics similar to those where teak has been planted in Colombia.
