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RSS2019 Vol. 41, No. 12
Display Method:
Abstract:
2019, 41(12): 1-14.
doi:10.12171/j.1000-1522.20190326
Abstract:
Forestry remote sensing has entered the stage of quantitative inversion of parameters after air-photo interpretation, satellite visual interpretation and quantitative estimation of forest volume. Under the background of strong demands of remote sensing from forestry on operational monitoring and accuracy improvement, quantitative remote sensing is gradually integrated with forestry remote sensing. It has gradually matured in talent teams, theoretical models, data sources and application methods for the quantitative studies in forestry remote sensing. This paper puts forward the concept and framework of quantitative remote sensing of forestry (QRSF), and points out the key scientific problems: (1) how to adapt remote sensing interpretation, modeling and inversion to complex forest conditions; (2) how to improve the accuracy of parameter inversion; (3) how to enrich forestry remote sensing data sources; (3) how to develop highly intelligent and automated information extraction algorithm on remote sensing data. On the basis of introducing quantitative remote sensing models and general inversion methods suitable for forestry, the application methods of hyperspectral, thermal infrared, lidar and microwave remote sensing data sources in forestry are expounded. In the future, QRSF will make breakthroughs in the unified modeling of full-band data, information fusion mechanism, physical model inversion and large-scale data fusion.
Forestry remote sensing has entered the stage of quantitative inversion of parameters after air-photo interpretation, satellite visual interpretation and quantitative estimation of forest volume. Under the background of strong demands of remote sensing from forestry on operational monitoring and accuracy improvement, quantitative remote sensing is gradually integrated with forestry remote sensing. It has gradually matured in talent teams, theoretical models, data sources and application methods for the quantitative studies in forestry remote sensing. This paper puts forward the concept and framework of quantitative remote sensing of forestry (QRSF), and points out the key scientific problems: (1) how to adapt remote sensing interpretation, modeling and inversion to complex forest conditions; (2) how to improve the accuracy of parameter inversion; (3) how to enrich forestry remote sensing data sources; (3) how to develop highly intelligent and automated information extraction algorithm on remote sensing data. On the basis of introducing quantitative remote sensing models and general inversion methods suitable for forestry, the application methods of hyperspectral, thermal infrared, lidar and microwave remote sensing data sources in forestry are expounded. In the future, QRSF will make breakthroughs in the unified modeling of full-band data, information fusion mechanism, physical model inversion and large-scale data fusion.
2019, 41(12): 15-22.
doi:10.12171/j.1000-1522.20190412
Abstract:
The low level of plantation cultivation in China is due to insufficient investment in manpower and financial resources in the field of tree breeding, and insufficient attention and implementation of breeding strategies. It leads to the difficulty of maintaining the basic breeding cycle of tree genetic improvement, and can not sustain the continuous improvement of the genetic improvement level of trees and the improvement of plantation productivity. This article comprehensively analyzed the development experience, theory and technology achievements of tree breeding at home and abroad, and put forward several issues that need to be paid attention to in the formulation and implementation of tree breeding strategies. Varieties have regionality, temporality and economic attributes. Ecological value belongs to the subsidiary benefits of planting improved varieties. It is necessary to formulate breeding objectives and breeding cycles that are scientific, specific and have certain market competitive advantages. On this basis, the construction and management of base population, selected population and breeding population of tree species should be strengthened. Scientific experimental design and analysis methods should be adopted to ensure accurate and efficient genetic testing and selection. We should continuously push on the construction of advanced-cycle breeding population, and rationally adopt techniques such as promoting flowering and fruiting, related selection or marker assisted selection to accelerate the process of mating and selection, continuously improve the genetic quality of base populations and selected populations, and even achieve the production and application of distant hybrid varieties with super-strong advantages. For the species that can reproduce asexually, physical and chemical mutagenesis and chromosome doubling can be applied at a certain stage of genetic improvement to further increase the accumulation and utilization of beneficial mutations. For the excellent varieties that have been applied to production but still have insufficient, further optimization can be carried out by molecular breeding such as genetic transformation and gene editing. Mating, genetic testing and selection are the core of the breeding cycle and the basis for further implementation of other breeding techniques, which need to be given more attention.
The low level of plantation cultivation in China is due to insufficient investment in manpower and financial resources in the field of tree breeding, and insufficient attention and implementation of breeding strategies. It leads to the difficulty of maintaining the basic breeding cycle of tree genetic improvement, and can not sustain the continuous improvement of the genetic improvement level of trees and the improvement of plantation productivity. This article comprehensively analyzed the development experience, theory and technology achievements of tree breeding at home and abroad, and put forward several issues that need to be paid attention to in the formulation and implementation of tree breeding strategies. Varieties have regionality, temporality and economic attributes. Ecological value belongs to the subsidiary benefits of planting improved varieties. It is necessary to formulate breeding objectives and breeding cycles that are scientific, specific and have certain market competitive advantages. On this basis, the construction and management of base population, selected population and breeding population of tree species should be strengthened. Scientific experimental design and analysis methods should be adopted to ensure accurate and efficient genetic testing and selection. We should continuously push on the construction of advanced-cycle breeding population, and rationally adopt techniques such as promoting flowering and fruiting, related selection or marker assisted selection to accelerate the process of mating and selection, continuously improve the genetic quality of base populations and selected populations, and even achieve the production and application of distant hybrid varieties with super-strong advantages. For the species that can reproduce asexually, physical and chemical mutagenesis and chromosome doubling can be applied at a certain stage of genetic improvement to further increase the accumulation and utilization of beneficial mutations. For the excellent varieties that have been applied to production but still have insufficient, further optimization can be carried out by molecular breeding such as genetic transformation and gene editing. Mating, genetic testing and selection are the core of the breeding cycle and the basis for further implementation of other breeding techniques, which need to be given more attention.
2019, 41(12): 23-36.
doi:10.12171/j.1000-1522.20190356
Abstract:
Forest growth and yield prediction is an important field of forest management science, and modelling forest growth and yield is key to forest management decision-making. The traditional statistical growth models such as linear and nonlinear regression model, mixed-effect model, quantile regression, variable-in-error model are often applied under certain statistical assumptions, such as the data are independent, normally distributed and homoscedastic. The above requirements are usually difficult to be met for forest data with repeated observation and hierarchy. With the development of AI techniques, machine learning provides a new way for forest growth modeling, with the advantages of no requirements on data distribution, extracting deep knowledge from the data, and high accuracy. The applications in forest growth and yield are still less than other domains. We reviewed the main machine learning algorithms including classification and regression tree (CART), multivariate adaptive regression splines (MARS), bagging regression, boosted regression tree (BRT), random forest (RF), artificial neural networks (ANN),k-nearest neighbors (k-NN), and support vector machine (SVM), parameter tuning, software, advantages and challenge. We conclude that machine learning would be widely applied with great potential and its combination with traditional statistical methods would become a trend in forest growth and yield prediction.
Forest growth and yield prediction is an important field of forest management science, and modelling forest growth and yield is key to forest management decision-making. The traditional statistical growth models such as linear and nonlinear regression model, mixed-effect model, quantile regression, variable-in-error model are often applied under certain statistical assumptions, such as the data are independent, normally distributed and homoscedastic. The above requirements are usually difficult to be met for forest data with repeated observation and hierarchy. With the development of AI techniques, machine learning provides a new way for forest growth modeling, with the advantages of no requirements on data distribution, extracting deep knowledge from the data, and high accuracy. The applications in forest growth and yield are still less than other domains. We reviewed the main machine learning algorithms including classification and regression tree (CART), multivariate adaptive regression splines (MARS), bagging regression, boosted regression tree (BRT), random forest (RF), artificial neural networks (ANN),k-nearest neighbors (k-NN), and support vector machine (SVM), parameter tuning, software, advantages and challenge. We conclude that machine learning would be widely applied with great potential and its combination with traditional statistical methods would become a trend in forest growth and yield prediction.
2019, 41(12): 37-49.
doi:10.12171/j.1000-1522.20190400
Abstract:
Root is the link between plants and soil, and also the organ for plants to absorb water and nutrients. It plays a vital role in the physiological activities of plants. Poplar is widely planted in plain of North China, and the wood output accounts for almost 30% of the total wood output in China. Therefore, understanding the characteristics of poplar root is conducive to the in-depth understanding of its survival and growth mechanism, ecological adaptation strategies in various environments, so as to provide a theoretical basis for the optimization of efficient management technology of poplar plantation and the improvement of forest quality and forest yield. In this paper, based on the existing studies, the contents of poplar root morphology, distribution, dynamic characteristics, water absorption characteristics and some research methods are reviewed. Firstly, various root classification methods used in previous studies were discussed, then their shortcomings and merits and more suitable methods for poplar root classification were pointed out. Secondly, the various architecture, morphology, distribution and growth dynamics of poplar root found in existing studies were summarized, and the causes of various characteristics and their effects on the absorption efficiency of poplar root were discussed. Finally, the water absorption characteristics and mechanism of poplar root under various conditions were summarized, the deficiencies of existing research on poplar root and the future research direction were also put forward.
Root is the link between plants and soil, and also the organ for plants to absorb water and nutrients. It plays a vital role in the physiological activities of plants. Poplar is widely planted in plain of North China, and the wood output accounts for almost 30% of the total wood output in China. Therefore, understanding the characteristics of poplar root is conducive to the in-depth understanding of its survival and growth mechanism, ecological adaptation strategies in various environments, so as to provide a theoretical basis for the optimization of efficient management technology of poplar plantation and the improvement of forest quality and forest yield. In this paper, based on the existing studies, the contents of poplar root morphology, distribution, dynamic characteristics, water absorption characteristics and some research methods are reviewed. Firstly, various root classification methods used in previous studies were discussed, then their shortcomings and merits and more suitable methods for poplar root classification were pointed out. Secondly, the various architecture, morphology, distribution and growth dynamics of poplar root found in existing studies were summarized, and the causes of various characteristics and their effects on the absorption efficiency of poplar root were discussed. Finally, the water absorption characteristics and mechanism of poplar root under various conditions were summarized, the deficiencies of existing research on poplar root and the future research direction were also put forward.
2019, 41(12): 50-57.
doi:10.12171/j.1000-1522.20190325
Abstract:
China’s forestry development has entered a new stage and the ecological construction has been a main task of forestry construction. Cultivating healthy, stable, high-quality and efficient forest ecosystems has become the goal to meet the overall requirements of the construction of ecological civilization in the new era. The key to achieving this goal is to improve the structure of forests, accelerate forest growth and forward succession, improve the productivity and quality of forests by adopting scientific and rational management measures. Based on a brief review of the forest management objectives and techniques in different stages of forestry construction in China, this paper reviews the theories and techniques of forest management independently developed in China since forestry construction entered the stage of ecological construction, focusing on the technical system of “ecological harvesting and regeneration? “natural forest conservation and restoration and “structural-based forest management summarized from three aspects: theoretical basis, core technology and application practice, in order to provide a basis for precise upgrading of forest quality currently being implemented in China.
China’s forestry development has entered a new stage and the ecological construction has been a main task of forestry construction. Cultivating healthy, stable, high-quality and efficient forest ecosystems has become the goal to meet the overall requirements of the construction of ecological civilization in the new era. The key to achieving this goal is to improve the structure of forests, accelerate forest growth and forward succession, improve the productivity and quality of forests by adopting scientific and rational management measures. Based on a brief review of the forest management objectives and techniques in different stages of forestry construction in China, this paper reviews the theories and techniques of forest management independently developed in China since forestry construction entered the stage of ecological construction, focusing on the technical system of “ecological harvesting and regeneration? “natural forest conservation and restoration and “structural-based forest management summarized from three aspects: theoretical basis, core technology and application practice, in order to provide a basis for precise upgrading of forest quality currently being implemented in China.
2019, 41(12): 58-68.
doi:10.12171/j.1000-1522.20190434
Abstract:
ObjectiveFor evaluating the self-thinning theory, selecting the optimum fitting method that can truly describe self-thinning dynamics is a hot topic and a difficult task.
MethodIn this study, we compared different approaches for fitting self-thinning equations, including three traditional methods, i.e., hand-fitting method, interval method and relative density (RD) method; three regression methods, i.e., ordinary least squares regression (OLS) method, reduced major axis regression (RMA) method and quantile regression (QR) method; and three frontier model methods, i.e., corrected OLS (COLS) method, deterministic frontier function (DFF) method and stochastic frontier function (SFF) method. The data from 553 sample plots of even-aged Chinese fir (
Cunninghamia lanceolata) plantations in Fujian Province, eastern China was employed.
ResultThe results indicated that hand-fitting method was easy but subjective. The coefficients estimated by interval method can be influenced significantly by interval length, and the estimated slope tended to be flatter than the real slope. The RD method can avoid influence of independent-density mortality, but the result would be affected by the predetermined theoretical constant for the slope. The maximum size-density lines fitted by the OLS, RMA and COLS methods tended to inaccurately match the actual boundaries of data points, and differed from the stand self-thinning upper boundary line. The maximum size-density line fitted by QR method can be close to the stand self-thinning upper boundary line when the quantile value approached 100%. The maximum size-density line fitted by linear programming approach was more suitable than the line fitted by quadratic programming approach. However, statistical inference was very difficult with the DFF and QR methods. SFF method was relatively objective, however, the fitted maximum size-density line can truly describe self-thinning process only when variance of stochastic error terms was small enough and close to zero.
ConclusionFinally, the optimum self-thinning equation for Chinese fir plantations in Fujian Provence is determined as ln(QMD) = 7.795 0.620ln(
N), which can provide a reference for developing efficient measures of stand density control.
2019, 41(12): 69-76.
doi:10.12171/j.1000-1522.20190440
Abstract:
ObjectivesBiomass estimation is critical for carbon stock assessment under global climate change. Taibai Mountain is the main peak in the Qinling Mountains. The forest biomass distribution in Taibai Mountain would provide basis for the dynamics of forest carbon sequestration during the vegetation restoration in the Qinling Mountain.
MethodWe analyzed the differences of above-ground biomass in different habitats, sampling scales and DBH classes. The significance of difference was determined by ANOVA based on the field measurements of environmental factors and trees with DBH 1 cm in two 1.5 ha permanent plots in the primary and secondary
Q. alienavar.
acuteserrataforests.
ResultThe results showed that the average above-ground biomass of the primary and secondary forest plots were 279.50 and 217.81 t/ha, respectively. Significant differences were found in above-ground biomass in different habitats. In the primary forest, the above-ground biomass was larger in the habitat with low total nitrogen, while the above-ground biomass in the secondary forest was larger in habitat with lower available phosphorus. Moreover, the above-ground biomass was larger in the habitat with a higher degree of concavity in the primary forest. At the same sampling scale, the above-ground biomass in the primary forest was larger than in the secondary forest. No significant difference in the above-ground biomass was found at different sampling scales in each forest. However, in the primary forest, the average above-ground biomass showed an unimodal trend along the increase of DBH class. And the above-ground biomass was the largest at the DBH class. The above-ground biomass increased along the increase of the DBH class in the secondary forest. The above-ground biomass in the primary forest was higher than that in the secondary forest at the ~ DBH classes, while smaller than that in the secondary forest at the DBH class.
ConclusionTherefore, disturbance, habitat heterogeneity and DBH class can affect the above-ground biomass allocation in
Q. alienavar.
acuteserrataforests.
2019, 41(12): 77-87.
doi:10.12171/j.1000-1522.20190324
Abstract:
ObjectiveExtinction coefficient (
k) is an important indicator to simulate the light transmission in the crown. By comparing the different methods to obtain
k, this paper aims to select the optimal method to estimate the dynamical PAR in the crown of
Larix olgensistrees.
Method(1) The PAR data was divided into fitting data and validation data with a ratio of 3:1 and the
kpredicting model was developed; (2) artificially setting
kwith different gradients and using fitting data to estimate crown PAR then selecting the optimal
kvalue; (3) Based on the average leaf inclination data, we calculated
kwith the average leaf inclination formula. The test data was used as an independent sample to conduct an independent test on the PAR estimated by the above three methods. By comparing the above three method’s estimation effect on PAR in the crown, we selected the optimal
kto estimate dynamical PAR with meteorological data.
ResultAccording to the measured PAR data, there was a big difference in the crown’s rotation pseudowhorls
k, which ranged from 0.1 to 1.5, and showed an obvious exponential or power function relationship with RDINC. Meanwhile, solar altitude angle (
S
a), max cumulative leaf area (MCLA), needle area density (NAD), and crown surface area (CS) also had significant effects on
kvertical variation. Therefore, considering the exponential function as basic model, the
kpredicting model was established with RDINC, Sa, MCLA, NAD, and CS as independent variables, and the fitting result indicated that the
kmodel performed well (
R
2= 0.736, RMSE = 0.124). PAR was best estimated when
kwas 0.32. The difference of
kvalues in each pseudowhorl calculated by the average leaf inclination distribution formula was not obvious, which ranged from 0.3 to 0.7. The perform of the above three methods on PAR estimation was tested and the results showed that the Method I performed the best (mean error ME = 2.88, mean absolute error: MAE = 117.4, precision estimation:
P= 91.53%), Method II was better (ME = 2.88, MAE = 217.5,
P= 88.12%), Method III was the worst (Method III-1 ME = 121.4, MAE = 210.1,
P= 55.85%; Method III-2 ME = 226.4, MAE = 259.0,
P= 42.93%).
Conclusion
kwas not a constant value in the case of different trees, different pseudowhorls and different Sa. In this study, the
kmodel was established which fully took Sa, CLA and RDINC into account. The PAR for
Larix olgensistrees was well estimated based on the
kmodel. The results will provide a scientific basis for simulating the net photosynthetic rate of live crown with different position for planted
Larix olgensistrees.
Abstract:
The landscape pattern, which could exert critical impacts on the carbon and water distribution and their coupling in the ecosystem, is the product of integrated actions of ecological processes on a time-spaced scale.
ObjectiveThe objective of this study is to explore the interaction law between landscape pattern and water use efficiency at multiple scales, and to provide a theoretical basis for studies of the coupling relationship between landscape pattern and ecological process, and regional ecological planning.
MethodWe used the Biome-BGC model optimized by the PEST model to simulate water use efficiency (WUE) of Qianyanzhou forest ecosystem from 2000 to 2014, and analyzed the correlations between landscape pattern index (LPI) and WUE, landscape pattern and total primary productivity (GPP), and their trends.
ResultThe results showed that: (1) the landscape fragmentation index (NP and PD) and WUE had a significantly negative correlation in the buffer range of 10?0, while there was a significantly positive correlation between AREA-MN and WUE in this range; (2) The landscape shape index (SHAPE and FRAC) was significantly positive correlated with WUE in the range of 50?00; (3) The positive correlation between landscape polymerization index (PLADJ and AI) and WUE was significant in the range of 10?0; (4) Both landscape diversity and uniformity index (SIDI and SIEI) showed a significantly negative correlation with WUE when the buffer was between 10 to 20, while a significantly positive correlation in the buffer range of 70?00; (5) The correlation between landscape pattern index and water use efficiency showed a conspicuous scale effect; (6) The change law of the correlation between GPP and LPI was consistent with the correlation between WUE and LPI.
ConclusionThis indicates that the coupling of landscape pattern and ecological process is affected by the scale effect. We suggest that the scale effect should be fully considered into regional ecological planning so that the coupling effect of landscape pattern and ecological process could be maximized.
2019, 41(12): 96-107.
doi:10.12171/j.1000-1522.20190433
Abstract:
ObjectiveForest-based bioenergy “forestry-oil integration industry (hereinafter referred to as the “forestry-oil integration industry) is main consisted by biomass energy enterprises, which combines feedstock forest cultivation with series product production, such as biodiesel products. This paper aims to optimize the development pattern, and promote the development of industry.
MethodBased on the survey of related companies, investigation of feedstock plantations, calculation of carbon emissions on soapberry biodiesel by lifecycle assessment, estimating on profits of feedstock forests cultivation and product production, etc., this paper analyzes the current situation of “forestry-oil integration industry in China, and the economic benefits of different cultivation patterns and different industry chains.
Result(1) The industry had basically formed a certain scale of feedstock forests base, and most companies had already created a series of biodiesel production processes and products with independent intellectual property. (2) The amount of CO
2sequestration of feedstock forest reached 25.38 t while producing 1 t of biodiesel; the CO
2eqemissions of lifecycle was 19.41 t, which had decreased by 621.77% compared with petroleum diesel. (3) Most feedstock forests were cultivated by seeding pattern with extensive management, late fruit stage, low yield and high cost; taking 20 years as the project lifecycle, the fruit selling price was 4 RMB/kg (year 2017), the seeding cultivation pattern would loss about 1 687.68 RMB/(ha·yr), and the high scion & head-changing pattern would have an average annual profit of 419.57 RMB/(ha·yr); if the clone’s cultivation mode was formed, the costs would be recovered in the 10th year, and the annual profit was 2 675.55 RMB/(ha·yr), which could greatly improve the economic benefit; If the fruits selling price was 9 RMB/kg (year 2019), the costs would be recovered in the 5th year, and the annual profit was 20 675 RMB/(ha·yr). (4) The average profit was 18.65 RMB when using 1 t of soapberry dried fruit to produce biodiesel, and the average profit of saponin products was 6 573.3 RMB; if poly-generation products production line was formed, it could be estimated that the total income would increase to 55.66 million RMB.
Conclusion“Clones plantation culture pattern + poly-generation industry chain pattern was the ideal pattern for development of the industry, which would promote comprehensive benefits. In addition, in view of industrial supporting policies, four suggestions were proposed, i.e., enjoying inclusive financial subsidy policy, enjoying National Seed Industry and improved variety preferential policies, enjoying fiscal and tax preferential policies and requiring the proportion of biodiesel in petroleum diesel.
Abstract:
ObjectiveBy quantitative study of the effects of forest fire disturbance on soil organic carbon and its components in forest ecosystems, this paper aims to reveal the changing law of forest fire disturbance on soil organic carbon and components of forest ecosystem, with a view to providing scientific reference for the study of carbon cycle and carbon process of forest soil.
MethodTaking the subtropical fir forest of Guangdong Province as the research object, the effects of different forest fire disturbance intensity on soil organic carbon density, organic carbon component content and fine root biomass were measured quantitatively on the level of forest ecosystem by means of adjacent sample land comparison method and field investigation sampling and laboratory test analysis, to investigate the influencing mechanism of forest fire disturbance on soil organic carbon density, soil organic carbon component content and fine root biomass.
ResultForest fire disturbance had an effect on soil organic carbon density, soil organic carbon component content and fine root biomass in Chinese fir forest, and the changing trend of soil organic carbon density and soil organic carbon component content was the control > mild forest fire disturbance > moderate forest fire disturbance > severe forest fire disturbance. There was no significant difference in the effect of mild forest fire disturbance on soil organic carbon density (
P> 0.05), while moderate and severe forest fire disturbance significantly reduced soil organic carbon density (
P< 0.05). The biomass of soil in Chinese fir forest was lower than that in the same place, the trend of change was severe forest fire disturbance > moderate forest fire disturbance, mild forest fire disturbance only significantly reduced the fine root biomass (
P< 0.05) of soil surface, while moderate and severe forest fire disturbance significantly reduced soil surface and shallow fine root biomass (
P< 0.05). The soil fine root biomass of Chinese fir forest was lower than that in different forest fire interference intensity, the changing trend was severe forest fire disturbance > moderate forest fire disturbance > mild forest fire disturbance, and mild forest fire disturbance only significantly reduced the fine root biomass (
P< 0.05) of soil surface. Moderate and severe forest fire disturbance significantly reduced soil surface and shallow fine root biomass (
P< 0.05).
ConclusionThe results show that forest fire disturbance reduces soil organic carbon density and decreases gradually with the increase of soil profile depth. The content of soil labile organic carbon is decreasing with the increase of forest fire disturbance intensity and the decrease of soil profile after different forest fire interference intensities. By analyzing the distribution pattern and influencing mechanism of soil carbon density after forest fire disturbance, this paper provides a reference for the management of ecosystem carbon sink after forest fire disturbance and the quantitative evaluation of the influence of forest fire disturbance on the carbon bank of forest ecosystem.
2019, 41(12): 119-127.
doi:10.12171/j.1000-1522.20190058
Abstract:
ObjectiveThe aim is to examine the impact of a snow event in the early growing season on photosynthetically physiological status of a typical shrub, and to understand photosynthetically physiological mechanism to acclimate to the snow stress.
MethodWe monitored the variations in chlorophyll fluorescence and calculated energy partitioning parameters continuously in situ by a multi-channel monitoring fluorometry during a snow event which covered a period of prior- and post-snowing days, in relation to environmental factors.
ResultActual photosynthetic quantum yield (
Φ
PSII) was lowest on snow day. The daytime mean value of
Φ
PSIIon snow day was 40% and 33% lower than that of prior and post snow. Regulatory energy dissipation (
Φ
NPQ) and non-photochemical quenching (NPQ) were highest on snow day, with daytime mean value of
Φ
NPQbeing 95% and 48% higher than that of prior and post snow, respectively. The daytime mean value of NPQ on snow day was 94% and 76% higher than that of prior and post snow. Maximal quantum yield of PSII photochemistry (
F
v/
F
m) was 0.69 on snow day, smaller than that of prior snow, and smaller than stress line of 0.73.
F
v/
F
mrecovered back within 3? days. There were opposite response trends at PAR threshold of 900 μmol/（m
2·s）and at air temperature of 10 ? indicating different controlling environmental factors around the thresholds. Water availability was always one of the most common limitations during the stress recovery.
ConclusionThere was a stress for
Artemisia ordosicaduring the snow event. The stress was mainly induced by the synergy of low temperature and high radiation.
A. ordosicaacclimated to the stress by mechanism of increasing ratio of regulatory thermal energy dissipation of energy partitioning in PSII reaction center. The 3? days were needed for
A. ordosicato recover from the snow stress. The recovery period could be shortened by condition of low radiation, moderate high temperature and high moisture.
Abstract:
ObjectiveThis paper explores the influence mechanism of landscape complexity and stand factors on cytospora canker of poplar caused by
Cytospora chrysospermaacross two different field soil conditions, to provide theoretical basis for rational allocation of landscape patterns to control cytospora canker effectively, and to further develop sustainable poplar (
Populusspp.) plantations.
MethodWe spent 2 years (2018?019) collecting cytospora canker data across two different soil physical and chemical properties in Xinjiang Uygur Autonomous Region of wester China: one in Karamay City and another in Manasi County. Using general linear mixed effect models (GLMMs) with the random effect of year to analyze how the landscape complexity and stand factors influence cytospora canker at landscape scale.
ResultResults showed that the cytospora canker of
Populus nigraand
P. albavar.
pyramidalisboth had significantly positive relationships with tree density, as well as the Shannon diversity index of pests. Compared with
P. albavar.
pyramidalis,
P. nigrahad a significant relationship with the height of first live branch. The cytospora canker of the two tree species was both correlated negatively with the proportion of non-poplar hosts, as well as elevation. The cytospora canker had a significant correlation with physical and chemical properties of soil, in the same landscape structure, the disease incidence in Karamay City was higher than that in Manasi County. Under the same soil conditions, the incidence of cytospora canker in simple landscape was higher than that in complex landscape.
ConclusionOverall, our study shows that the occurrence of cytospora canker on poplar can be reduced via management of habitats and enhanced tree resistance at landscape scale, and provides valuable contributions to landscape research and for managing outbreaks of insects and pathogens. In afforestation planning, the potential impact of the surrounding landscape structure on insects and pathogens should be considered. The effects of landscape features on cytospora canker of poplar can be monitored on a large scale and over long periods of time using land cover data to improve economic and environmental benefits.
2019, 41(12): 139-152.
doi:10.12171/j.1000-1522.20190307
Abstract:
ObjectiveEcological corridor is an important component of cultural heritage corridor, and vegetation restoration is the core of ecological corridor construction. Vegetation restoration in cultural heritage corridors should not only meet the requirements of ecological restoration, but also meet higher demands, e.g., inheriting historical features and presenting characteristic landscapes. Scenic forest is an artificial or natural community with ornamental, recreational and tourism function under the premise of ecological stability, which has high ecological, aesthetic and tourism value, and can realize the balanced development of natural ecological and cultural landscape in the cultural heritage corridor. Therefore, the study of scenic forest construction strategies in cultural heritage corridors is very important and urgent.
MethodThis study took the “Special Planning of Scenic Forest in the Ancient Great Wall Cultural Heritage Corridor of Datong City as an example, and explored the strategy of constructing scenic forest in the heritage corridor. The specific methods were as follows: first, according to laws and regulations, the buffer zones of heritage protection were decided. Outside the buffer zone, after collecting and analyzing the digital information, the scopes of afforestation were determined. Then the afforestation classes were resolved according to the specific conditions of the land. Next, according to the specific situation of the corridor, the vegetation landscape control and afforestation intensity control were formulated. Finally, the selection of varieties, vegetation community construction and planting method design were determined based on the local native plant community.
ResultThis research breaks through the traditional afforestation method and guides the construction of cultural heritage corridors along the length of the ancient Great Wall in Datong City with a length of about 250 km and a surface area of nearly 186 km
2.
ConclusionThe successful implementation of this case fully proves the effectiveness of the above-mentioned scenic forest construction strategy in the heritage corridor.
Abstract:
ObjectivePut species diversity protection as the goal, bird habitat construction as the breakthrough point, recommend methods and strategies were put forward for promoting country park landscape quality.
MethodAfter the survey of bird species being conducted in Longquan Lake area, some target species of birds were selected. Through the study and analysis of the ecological habits of the target species, the need for habitat was clarified. Vertical and horizontal space of bird habitat suitability index system was constructed, including water type, habitat area, water bank form, waterfront buffer zone, plant coverage, terror distance,water depth and plant height. These indices were analyzed and summarized to draw a scientific and rational country park landscape plan.
ResultA total of 23 target species of birds were identified and their habitats were about 20.3 hectares, including 11.4 hectares of water area habitats and 8.9 hectares of land area habitats. Water area habitats had six zones: the surface area of water in each zone was between 2.6 and 5.8 hectares. The coverage of aquatic plants was between 30% and 65%. The flush distance was 50 meters; the average water depth was between 0.8 and 2.5 meters. The average height of aquatic plants was 0.3 and 1.8 meters. Land habitat also had six zones: arbor coverage of the waterfront buffer area in each zone was between 10% and 16%, shrub coverage was between 35% and 44% and herb coverage was between 40% and 55%.The average plant height was 8.6 to 22.5 meters. Herb ranged from 12 to 31 species; the flush distance was 50 meters too.
Conclusion(1) The index system of bird habitat suitability was constructed and the construction strategy was proposed, which could provide theoretical support and practical guidance for the planning and design of country parks. (2) Country parks should have different sizes, rich functions, winding natural slope revetment and a certain depth of water space; plant landscape should not only meet birds requirements for water area, near-shore buffer zone, vegetation coverage, community composition and height, but also enhance the richness of ground cover. Park roads and sites should adopt a strategy of near-natural materials and low bird disturbance. (3) During the planning and design of country parks, attention should be paid not only to the demand of birds for habitat and the relationship between different species of birds, but also to meet the needs of human leisure and recreation, so as to realize the harmonious coexistence of man and birds.
