Urbanization intensifies tree sap flux but divergently for different tree species groups in China

Author(s):  
Lei Ouyang ◽  
Jie Du ◽  
Zhenzhen Zhang ◽  
Ping Zhao ◽  
Liwei Zhu ◽  
...  
Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1158
Author(s):  
M. Rebeca Quiñonez-Piñón ◽  
Caterina Valeo

The authors have developed a scaling approach to aggregate tree sap flux with reduced error propagation in modeled estimates of actual transpiration () of three boreal species. The approach covers three scales: tree point, single tree trunk, and plot scale. Throughout the development of this approach the error propagated from one scale to the next was reduced by analyzing the main sources of error and exploring how some field and lab techniques, and mathematical modeling can potentially reduce the error on measured or estimated parameters. Field measurements of tree sap flux at the tree point scale are used to obtain canopy transpiration estimates at the plot scale in combination with allometric correlations of sapwood depth (measured microscopically and scaled to plots), sapwood area, and leaf area index. We compared the final estimates to actual evapotranspiration and actual transpiration calculated with the Penman–Monteith equation, and the modified Penman–Monteith equation, respectively, at the plot scale. The scaled canopy transpiration represented a significant fraction of the forest evapotranspiration, which was always greater than 70%. To understand climate change impacts in forested areas, more accurate actual transpiration estimates are necessary. We suggest our model as a suitable approach to obtain reliable estimates in forested areas with low tree diversity.


2007 ◽  
Vol 112 (G3) ◽  
pp. n/a-n/a ◽  
Author(s):  
K. R. Hultine ◽  
S. E. Bush ◽  
A. G. West ◽  
J. R. Ehleringer

2005 ◽  
Vol 53 (4) ◽  
pp. 337 ◽  
Author(s):  
Nicholas Goodwin ◽  
Russell Turner ◽  
Ray Merton

Mapping the spatial distribution of individual species is an important ecological and forestry issue that requires continued research to coincide with advances in remote-sensing technologies. In this study, we investigated the application of high spatial resolution (80 cm) Compact Airborne Spectrographic Imager 2 (CASI-2) data for mapping both spectrally complex species and species groups (subgenus grouping) in an Australian eucalypt forest. The relationships between spectral reflectance curves of individual tree species and identified statistical differences among species were analysed with ANOVA. Supervised maximum likelihood classifications were then performed to assess tree species separability in CASI-2 imagery. Results indicated that turpentine (Syncarpia glomulifera Smith), mesic vegetation (primarily rainforest species), and an amalgamated group of eucalypts could be readily distinguished. The discrimination of S. glomulifera was particularly robust, with consistently high classification accuracies. Eucalypt classification as a broader species group, rather than individual species, greatly improved classification performance. However, separating sunlit and shaded aspects of tree crowns did not increase classification accuracy.


Ecohydrology ◽  
2016 ◽  
Vol 10 (1) ◽  
pp. e1797 ◽  
Author(s):  
G. G. T. Chandrathilake ◽  
Nobuaki Tanaka ◽  
Naoto Kamata

Author(s):  
Kristian Skau Bjerreskov ◽  
Thomas Nord-Larsen ◽  
Rasmus Fensholt

Mapping forest extent and forest cover classification are important for the assessment of forest resources in socio-economic as well as ecological terms. Novel developments in the availability of remotely sensed data, computational resources, and advances in areas of statistical learning have enabled fusion of multi-sensor data, often yielding superior classification results. Most former studies of nemoral forests fusing multi-sensor and multi-temporal data have been limited in spatial extent and typically to a simple classification of landscapes into major land cover classes. We hypothesize that multi-temporal, multi-censor data will have a specific strength in further classification of nemoral forest landscapes owing to the distinct seasonal patterns of the phenology of broadleaves. This study aimed to classify the Danish landscape into forest/non-forest and further into forest types (broadleaved/coniferous) and species groups, using a cloud-based approach based on multi-temporal Sentinel 1 and 2 data and machine learning (random forest) trained with National Forest Inventory (NFI) data. Mapping of non-forest and forest resulted in producer accuracies of 99% and 90 %, respectively. The mapping of forest types (broadleaf and conifer) within the forested area resulted in producer accuracies of 95% for conifer and 96% for broadleaf forest. Tree species groups were classified with producer accuracies ranging 34-74%. Species groups with coniferous species were the least confused whereas the broadleaf groups, especially Oak, had higher error rates. The results are applied in Danish National accounting of greenhouse gas emissions from forests, resource assessment and assessment of forest biodiversity potentials.


Forests ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 757 ◽  
Author(s):  
Ruyi Zhou ◽  
Dasheng Wu ◽  
Luming Fang ◽  
Aijun Xu ◽  
Xiongwei Lou

Traditional field surveys are expensive, time-consuming, laborious, and difficult to perform, especially in mountainous and dense forests, which imposes a burden on forest management personnel and researchers. This study focuses on predicting forest growing stock, one of the most significant parameters of a forest resource assessment. First, three schemes were designed—Scheme 1, based on the study samples with mixed tree species; Scheme 2, based on the study samples divided into dominant tree species groups; and Scheme 3, based on the study samples divided by dominant tree species groups—the evaluation factors are fitted by least-squares equations, and the non-significant fitted-factors are removed. Second, an overall evaluation indicator system with 17 factors was established. Third, remote sensing images of Landsat Thematic Mapper, digital elevation model, and the inventory for forest management planning and design were integrated in the same database. Lastly, a backpropagation neural network based on the Levenberg–Marquardt algorithm was used to predict the forest growing stock. The results showed that the group estimation precision exceeded 90%, which is the highest standard of total sampling precision of inventory for forest management planning and design in China. The prediction results for distinguishing dominant tree species were better than for mixed dominant tree species. The results also showed that the performance metrics for prediction could be improved by least-squares equation fitting and significance filtering of the evaluation factors.


Ecohydrology ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. e1979 ◽  
Author(s):  
Zhenzhen Zhang ◽  
Ping Zhao ◽  
Xiuhua Zhao ◽  
Juan Zhou ◽  
Peiqiang Zhao ◽  
...  

2019 ◽  
Vol 117 (5) ◽  
pp. 435-442
Author(s):  
Benjamin O Knapp ◽  
Samantha E Anderson ◽  
Patrick J Curtin ◽  
Casey Ghilardi ◽  
Robert G Rives

Abstract Securing oak regeneration is a common management challenge in the central and eastern United States. We quantified the abundance of tree species groups in clearcuts in mid-Missouri more than 30 years following harvest to determine differences in species dominance based on aspect (exposed, protected, or ridge sites). Each tree was classified as “dominant” or “suppressed” based on its relative contribution to cumulative stand stocking, following concepts of the tree–area relation. Although maples or understory species were the most abundant across all sites, oaks and hickories contributed to more than 60 percent of the dominant stems on the exposed sites. In contrast, oaks and hickories made up less than 25 percent of the dominant stems on protected and ridge sites. Results indicate that clearcutting reset the successional trajectory, from a transition to maple dominance to maintaining oak–hickory dominance, on exposed sites but not on ridge or protected sites.


Trees ◽  
2005 ◽  
Vol 19 (6) ◽  
pp. 628-637 ◽  
Author(s):  
Dirk Hölscher ◽  
Oliver Koch ◽  
Sandra Korn ◽  
Ch. Leuschner

2019 ◽  
Vol 43 (11) ◽  
pp. 988-998
Author(s):  
Zhen-Zhen ZHANG ◽  
Ke-Jia YANG ◽  
Yu-Lu GU ◽  
Ping ZHAO ◽  
Lei OUYANG ◽  
...  

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