Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities
(1) Background: Planting density is an important factor affecting the yield of poplar per unit area. Therefore, determining the optimal height of the photosynthetic canopy layer for different planting densities is critical. (2) Methods: This study takes <i>Populus euramericana</i> ‘N3016...
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MDPI AG
2025-03-01
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| author | Taijin Zhang Xiaoting Liu Qinhui Zhang Hui Xiao Yunong Han Zhenghua Xing Fusen Wang Xiyang Zhao |
| author_facet | Taijin Zhang Xiaoting Liu Qinhui Zhang Hui Xiao Yunong Han Zhenghua Xing Fusen Wang Xiyang Zhao |
| author_sort | Taijin Zhang |
| collection | DOAJ |
| description | (1) Background: Planting density is an important factor affecting the yield of poplar per unit area. Therefore, determining the optimal height of the photosynthetic canopy layer for different planting densities is critical. (2) Methods: This study takes <i>Populus euramericana</i> ‘N3016’ × <i>Populus ussuriensis</i> as the research object. According to on the average tree height, diameter at breast height, and crown width of the stand, one standard tree was selected from each planting density for the experiment. The canopy of the standard tree was divided into five canopy layers from top to bottom, and the first-order lateral branches of each canopy layer were divided into three sites from outside to inside. The photosynthesis and leaf traits at various positions in different canopy layers were measured. (3) Results: The results revealed significant differences in photosynthetic and leaf traits at different positions of different canopy layers under different planting densities. As the canopy layer gradually declined, photosynthetic traits revealed that instantaneous photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) gradually decreased, while intercellular CO<sub>2</sub> concentration (Ci) increased. Moreover, water use efficiency (WUE) initially increased and then decreased under an 825 trees·ha<sup>−1</sup> (D3) planting density. Leaf traits revealed that as leaf length (LL) gradually decreased, leaf width (LW), leaf area (LA), and leaf water content (LWC) gradually increased. Under three planting densities, leaf traits were negatively correlated with Pn, Tr, WUE, and Gs, but positively correlated with Ci. (4) Conclusions: As the planting density decreased, the photosynthetic capacity of poplar gradually increased. With a planting density of D3, all canopy layers were able to carry out efficient photosynthesis, and all living branches within the canopy were functional. However, under the planting density of 1650 trees·ha<sup>−1</sup> (D1) and 1089 trees·ha<sup>−1</sup> (D2), canopy layers 1 to 4 could perform effective photosynthesis, while the photosynthetic capacity of canopy layer 5 was relatively weak. This study reveals the interactive effects of canopy position and stand density on leaf physiological and morphological traits, providing new insights into the photosynthetic efficiency and growth strategies of poplar under different planting densities. It also offers theoretical support for optimizing stand management and enhancing productivity. |
| format | Article |
| id | doaj-art-e2cde9be1c104c278a363894d88cdc87 |
| institution | Kabale University |
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| publishDate | 2025-03-01 |
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| series | Plants |
| spelling | doaj-art-e2cde9be1c104c278a363894d88cdc872025-08-20T03:43:26ZengMDPI AGPlants2223-77472025-03-0114689810.3390/plants14060898Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different DensitiesTaijin Zhang0Xiaoting Liu1Qinhui Zhang2Hui Xiao3Yunong Han4Zhenghua Xing5Fusen Wang6Xiyang Zhao7Jilin Provincial Key Laboratory of Tree and Grass Genetics and Breeding, College of Forestry and Grassland Science, Jilin Agricultural University, Changchun 130118, ChinaNational Key Laboratory of Forest Genetics and Breeding, Northeast Forestry University, Harbin 150040, ChinaJilin Provincial Key Laboratory of Tree and Grass Genetics and Breeding, College of Forestry and Grassland Science, Jilin Agricultural University, Changchun 130118, ChinaJilin Provincial Key Laboratory of Tree and Grass Genetics and Breeding, College of Forestry and Grassland Science, Jilin Agricultural University, Changchun 130118, ChinaJilin Provincial Key Laboratory of Tree and Grass Genetics and Breeding, College of Forestry and Grassland Science, Jilin Agricultural University, Changchun 130118, ChinaQiqihar Branch of Heilongjiang Academy of Forestry, Qiqihar City 161000, ChinaQiqihar Branch of Heilongjiang Academy of Forestry, Qiqihar City 161000, ChinaJilin Provincial Key Laboratory of Tree and Grass Genetics and Breeding, College of Forestry and Grassland Science, Jilin Agricultural University, Changchun 130118, China(1) Background: Planting density is an important factor affecting the yield of poplar per unit area. Therefore, determining the optimal height of the photosynthetic canopy layer for different planting densities is critical. (2) Methods: This study takes <i>Populus euramericana</i> ‘N3016’ × <i>Populus ussuriensis</i> as the research object. According to on the average tree height, diameter at breast height, and crown width of the stand, one standard tree was selected from each planting density for the experiment. The canopy of the standard tree was divided into five canopy layers from top to bottom, and the first-order lateral branches of each canopy layer were divided into three sites from outside to inside. The photosynthesis and leaf traits at various positions in different canopy layers were measured. (3) Results: The results revealed significant differences in photosynthetic and leaf traits at different positions of different canopy layers under different planting densities. As the canopy layer gradually declined, photosynthetic traits revealed that instantaneous photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) gradually decreased, while intercellular CO<sub>2</sub> concentration (Ci) increased. Moreover, water use efficiency (WUE) initially increased and then decreased under an 825 trees·ha<sup>−1</sup> (D3) planting density. Leaf traits revealed that as leaf length (LL) gradually decreased, leaf width (LW), leaf area (LA), and leaf water content (LWC) gradually increased. Under three planting densities, leaf traits were negatively correlated with Pn, Tr, WUE, and Gs, but positively correlated with Ci. (4) Conclusions: As the planting density decreased, the photosynthetic capacity of poplar gradually increased. With a planting density of D3, all canopy layers were able to carry out efficient photosynthesis, and all living branches within the canopy were functional. However, under the planting density of 1650 trees·ha<sup>−1</sup> (D1) and 1089 trees·ha<sup>−1</sup> (D2), canopy layers 1 to 4 could perform effective photosynthesis, while the photosynthetic capacity of canopy layer 5 was relatively weak. This study reveals the interactive effects of canopy position and stand density on leaf physiological and morphological traits, providing new insights into the photosynthetic efficiency and growth strategies of poplar under different planting densities. It also offers theoretical support for optimizing stand management and enhancing productivity.https://www.mdpi.com/2223-7747/14/6/898canopy layerleaf traitsphotosynthetic traitsplanting density<i>Populus euramericana</i> ‘N3016’ × <i>Populus ussuriensis</i> |
| spellingShingle | Taijin Zhang Xiaoting Liu Qinhui Zhang Hui Xiao Yunong Han Zhenghua Xing Fusen Wang Xiyang Zhao Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities Plants canopy layer leaf traits photosynthetic traits planting density <i>Populus euramericana</i> ‘N3016’ × <i>Populus ussuriensis</i> |
| title | Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities |
| title_full | Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities |
| title_fullStr | Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities |
| title_full_unstemmed | Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities |
| title_short | Novel Patterns of Photosynthetic Activity Within Canopies of Poplar Stands with Different Densities |
| title_sort | novel patterns of photosynthetic activity within canopies of poplar stands with different densities |
| topic | canopy layer leaf traits photosynthetic traits planting density <i>Populus euramericana</i> ‘N3016’ × <i>Populus ussuriensis</i> |
| url | https://www.mdpi.com/2223-7747/14/6/898 |
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