Whole tree moisture utilization efficiency continuous monitoring system based on multi-type sensor integration
By integrating multiple types of sensors and using data fusion algorithms, the temporal and spatial problems of measuring tree water use efficiency have been solved, enabling efficient and low-cost continuous monitoring and providing stable dynamic data to support precision agriculture decision-making.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- RUBBER RES INST CHINESE ACADEMY OF TROPICAL AGRI SCI
- Filing Date
- 2025-12-07
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies for measuring tree water use efficiency suffer from insufficient temporal continuity and spatial representativeness. Traditional methods cannot achieve long-term, continuous monitoring and are subject to human error and high costs.
A multi-sensor integrated system is adopted, including a sap flow monitoring unit, a trunk radial growth monitoring unit, and an environmental monitoring unit. Combined with a multi-time series data fusion algorithm, a ratio function of tree water use to carbon sequestration is constructed through thermal diffusion method, automatic radial growth measurement instrument and temperature and humidity parameter acquisition, so as to achieve 24-hour continuous monitoring.
It enables efficient, long-term, and continuous monitoring of tree water use efficiency, reduces human and material costs, provides stable dynamic data, and supports precision agriculture decision-making.
Smart Images
Figure CN121995000A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of tree physiological monitoring and precision agriculture, and in particular to a continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors. Background Technology
[0002] Tree water use efficiency (WUE), a key physiological indicator for measuring the balance between carbon sequestration and transpiration in plants (or ecosystems), is a core indicator in forestry and agricultural water management. While existing mainstream WUE measurement methods, such as leaf gas exchange, stable isotope methods, and eddy covariance methods, can provide effective data under certain conditions, they have limitations in terms of temporal continuity, spatial representativeness, and scale transfer. Specifically, while leaf gas exchange methods can provide instantaneous WUE data, they cannot meet the needs of long-term, continuous monitoring; stable isotope methods and eddy covariance methods can provide high spatial resolution data, but when converting to individual tree WUE changes, there are scale transfer barriers, and sampling and analysis costs are high. Therefore, existing technologies suffer from two major problems: spatial limitations and temporal discrepancies. To address these issues, some scholars have attempted to calculate the dynamic patterns of whole-tree WUE based on a combination of biometric surveys and sap flow techniques, but this method can only provide dynamic data on a monthly scale, and still has significant limitations at higher temporal resolutions. This is because data obtained by biometric surveys also lacks high temporal continuity and is prone to significant human error during measurement, which may lead to misjudgments of the results.
[0003] In view of this, we propose a continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors to solve the existing problems. Summary of the Invention
[0004] The purpose of this invention is to provide a continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors, so as to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors, comprising a multi-sensor collaborative monitoring system and a multi-time-series data fusion algorithm. The multi-sensor collaborative monitoring system includes a sap flow monitoring unit, a trunk radial growth monitoring unit, and an environmental monitoring unit. The multi-time-series data fusion algorithm includes time-scale matching and a dynamic WUE model. The sap flow monitoring unit uses the thermal diffusion method to measure sap flow in the trunk. The trunk radial growth monitoring unit installs a high-precision automatic radial growth measuring instrument at breast height and continuously records changes in trunk circumference. The environmental monitoring unit simultaneously collects trunk temperature and humidity parameters. In the time-scale matching, the daily cumulative calculation of tree water use is performed and matched with daily carbon sequestration data. In the dynamic WUE model, a ratio function of tree water use to carbon sequestration is constructed.
[0006] Furthermore, the working method of the sap flow monitoring unit specifically includes: installing two probes at breast height, automatically recording the temperature difference between the two probes through a data acquisition device, calculating the trunk sap flow density according to the Granier empirical formula, and then calculating the tree's water utilization based on the trunk sapwood area.
[0007] Furthermore, after the trunk radial growth monitoring unit converts the acquired stem circumference data into diameter at breast height (DBH) data, it uses a zero-growth model to identify the structural growth and stem contraction stages, thereby identifying the daily stem growth and calculating the daily change in sapwood area.
[0008] Furthermore, the collected trunk temperature and humidity parameters were used to analyze the response of water use strategies to environmental changes.
[0009] Furthermore, the length of the dual probes is 20 mm.
[0010] Furthermore, the data acquisition frequency of the data acquisition device is 10 Hz, and the acquired data is averaged and stored every 30 minutes.
[0011] Furthermore, the daily cumulative water consumption is calculated based on the water use of the trees.
[0012] Furthermore, the sapwood area is corrected in real time using the relationship between diameter at breast height (DBH) and sapwood area, and the daily transpiration of the tree is calculated.
[0013] Furthermore, the daily increase in tree biomass and carbon sequestration were calculated using the tree species-specific biomass allometric growth equation and carbon content.
[0014] Furthermore, the high-precision automatic radial growth measuring instrument has a resolution of ≤2.5μm.
[0015] Compared with the prior art, the beneficial effects of the present invention are: Compared to traditional methods that rely on manual operation of portable photosynthesis meters, biomass surveys, or destructive sampling for isotope analysis, this invention integrates multiple types of sensors, including those for trunk sap flow, radial growth, and temperature and humidity, to achieve 24-hour continuous monitoring of multi-source physiological and ecological data. Once installed, the equipment can operate for extended periods. This significantly improves monitoring efficiency and greatly reduces manpower and material costs. Furthermore, the long-term stable data obtained through this method reflects the dynamic patterns of tree WUE (wood sap utilization), facilitating accurate analysis of tree WUE responses to environmental changes. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to the present invention. Figure 2 A scene diagram illustrating the measurement of sap flow, radial growth, and temperature in a tree trunk; Figure 3 A diagram showing the diurnal variation characteristics of sap flow in tree trunks; Figure 4 This is a diagram showing the diurnal variation characteristics of diameter at breast height. Detailed Implementation
[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example
[0018] like Figure 1 As shown, the continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors includes a multi-sensor collaborative monitoring system and a multi-time series data fusion algorithm. The multi-sensor collaborative monitoring system includes a sap flow monitoring unit, a trunk radial growth monitoring unit, and an environmental monitoring unit. The multi-time series data fusion algorithm includes time scale matching and a dynamic WUE model.
[0019] The sap flow monitoring unit uses the thermal diffusion method (TDP) to measure sap flow in the tree trunk. For example... Figure 2 As shown, a 20mm long dual probe is installed at chest height. The temperature difference between the two probes is automatically recorded by a data acquisition unit (CR1000). The data acquisition unit has a sampling frequency of 10 Hz, and the collected data is averaged and stored every 30 minutes. Figure 3 As shown, the trunk sap flow density is calculated based on the Granier empirical formula, and then the water utilization of the tree is calculated based on the trunk sapwood area.
[0020]
[0021]
[0022] In the formula: J is the trunk sap flow density, in g·m³. -2 ·s -1 ΔT is the temperature difference. max The maximum temperature difference value; As is the sapwood area, in cm². 2 Qi represents the tree's water use per 30 minutes, expressed in kg.
[0023] The daily cumulative water consumption is calculated based on the water usage of trees.
[0024]
[0025] Where Qd represents the daily water consumption of trees, in kg·day -1 .
[0026] like Figure 2 As shown, the trunk radial growth monitoring unit is equipped with a high-precision automatic radial growth measuring instrument at breast height (DBH), with a resolution ≤2.5μm, and continuously records changes in trunk circumference (C). The acquired circumference data is then converted into DBH data, as shown... Figure 4 As shown, the zero-growth model (ZG) is used to identify the structural growth and stem contraction stages, and based on this, the daily stem growth is identified and the daily change in sapwood area is calculated.
[0027] The relationship between DBH and sapwood area (As) was used to correct As in real time, and the daily transpiration of trees was calculated, as shown in Table 1.
[0028] Table 1 Daily water utilization of rubber trees Meanwhile, the daily increase in tree biomass and carbon sequestration were calculated using the specific biomass allometric growth equation for tree species (such as rubber trees) and carbon content, as shown in Table 2.
[0029] Table 2 Daily biomass increase and daily carbon sequestration of rubber trees For calculating the daily increase in tree biomass, we assume the following allometric equation for biomass based on diameter at breast height (DBH):
[0030] Among them, W Biomass Here, denoted as tree biomass, and 'a' and 'b' are species-specific parameters.
[0031]
[0032] Where ΔBiomass represents the daily accumulated biomass; ΔDBH represents the daily cumulative increase in radius. In this embodiment, rubber trees are used as an example, with values of a and b being 0.136 and 2.437, respectively.
[0033] Calculation of daily carbon sequestration by trees:
[0034] This embodiment uses the rubber tree as an example, whose average carbon content is 48%, therefore C content It is 0.48.
[0035] The environmental monitoring unit simultaneously collects tree trunk temperature and humidity parameters, which are used to analyze the response of water use strategies to environmental changes.
[0036] In the time-scale matching, the daily cumulative calculation of tree water use is performed and matched with the daily carbon sequestration data; in the dynamic WUE model, the ratio function of tree water use to carbon sequestration is constructed, taking rubber trees as an example, as shown in Table 3.
[0037] Table 3. Water use efficiency (WUE) of rubber trees
[0038] In the formula, ΔC is the daily carbon sequestration of trees, and Qd is the daily cumulative water consumption.
[0039] In summary, the whole-tree WUE dynamic calculation method, which integrates multi-source physiological and ecological data at high temporal resolution, addresses the two core problems of spatial limitations and temporal discretization in traditional techniques. By integrating dynamic data on trunk sap flow and radial growth at high temporal resolution to construct a whole-tree WUE calculation model, a high-precision dynamic assessment of the whole-tree level WUE can be achieved. Simultaneously, users can use this method to analyze the tree's adaptation mechanisms to environmental changes, providing technical support for water management decisions in smart forestry.
[0040] The above specific embodiments are merely several preferred embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.
Claims
1. A continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors, characterized in that: The system includes a multi-sensor collaborative monitoring system and a multi-time-series data fusion algorithm. The multi-sensor collaborative monitoring system comprises a sap flow monitoring unit, a trunk radial growth monitoring unit, and an environmental monitoring unit. The multi-time-series data fusion algorithm includes time-scale matching and a dynamic WUE model. The sap flow monitoring unit uses the thermal diffusion method to measure sap flow in the trunk. The trunk radial growth monitoring unit installs a high-precision automatic radial growth measuring instrument at breast height and continuously records changes in trunk circumference. The environmental monitoring unit simultaneously collects trunk temperature and humidity parameters. In the time-scale matching, the daily cumulative calculation of tree water use is performed and matched with daily carbon sequestration data. In the dynamic WUE model, a ratio function of tree water use to carbon sequestration is constructed.
2. The continuous monitoring system for whole-tree water use efficiency based on multi-type sensor integration according to claim 1, characterized in that, The working method of the sap flow monitoring unit includes: installing two probes at breast height, automatically recording the temperature difference between the two probes through a data acquisition device, calculating the sap flow density of the trunk according to the Granier empirical formula, and then calculating the water utilization of the tree based on the area of the sapwood of the trunk.
3. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 1, characterized in that: After the trunk radial growth monitoring unit converts the acquired stem circumference data into diameter at breast height (DBH) data, it uses a zero-growth model to identify the structural growth and stem contraction stages. Based on this, it identifies the daily stem growth and calculates the daily change in sapwood area.
4. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 1, characterized in that: The collected tree trunk temperature and humidity parameters are used to analyze the response of water use strategies to environmental changes.
5. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 2, characterized in that: The length of the dual probes is 20mm.
6. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 2, characterized in that: The data acquisition frequency of the data acquisition device is 10 Hz, and the acquired data is averaged and stored every 30 minutes.
7. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 2, characterized in that: The daily cumulative water consumption is calculated based on the water usage of trees.
8. The continuous monitoring system for whole-tree water use efficiency based on multi-type sensor integration according to claim 3, characterized in that: The sapwood area is corrected in real time by using the relationship between diameter at breast height (DBH) and sapwood area, and the daily transpiration of trees is calculated.
9. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 3, characterized in that: The daily increase in tree biomass and carbon sequestration were calculated using the allometric growth equation for tree species and carbon content.
10. The continuous monitoring system for whole-tree water use efficiency based on the integration of multiple types of sensors according to claim 1, characterized in that: The high-precision automatic radial growth measuring instrument has a resolution of ≤2.5μm.