Monitoring Method for Ecological Environment Changes in Urban Plains Based on Small Mammal Surveys

Abstract

The present invention discloses a method for monitoring the changes in the ecological environment of urban plains based on the investigation of small mammals. First, after determining the pellet collection points of long-eared owls, the proportion of forest, shrub, grassland, and cultivated land coverage areas, biomass, and vascular plant species richness within the predation range area are obtained; then, based on the pellets of long-eared owls, the parameters for measuring the biodiversity index are calculated: the species richness of prey animals, the appearance frequency of prey animals in the pellets, the predation intensity of prey animals, and the biomass proportion of prey animals; finally, based on the above indicators, the comprehensive index of the ecological environment quality in the urban plain area is calculated to determine the changes in the ecological environment of the urban plain area. The use of this method solves the problem of the inability to long-term observe the biodiversity of small mammals, and provides technical support for long-term observing small mammals with good indicator functions to judge the changes in the comprehensive quality of the urban ecological environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental protection and monitoring, and specifically relates to a method for monitoring the changes of urban plain ecological environment based on the investigation of small mammals. Background Art

[0002] As the ecological corridor hub and important node between the urban mountainous area and the central urban area, the plain area of the city is distributed with a large number of farmlands and a certain number of wilderness areas, providing unique habitat types different from those of the mountainous area and the central urban area. It plays an irreplaceable role in biodiversity protection, is the main implementation area of urban ecological construction in the past decade or so, is an important node area of the urban ecological corridor, and has great potential in biodiversity restoration. In the plain area, the number and species of small mammals both dominate among mammals, and there are almost no large mammals. Therefore, small mammals are the protagonists of the ecological environment in the urban plain area.

[0003] In addition, using small mammals as indicator species to measure the changes in the urban ecological environment has many advantages. First, when the ecological environment changes, small mammals in the urban ecological environment are neither as overly sensitive as insects nor have a long time lag like large mammals; second, in the urban ecological environment, small mammals have a large number, are at a relatively high level in the food chain, and often gather in groups, which is convenient for observation and quantitative statistical analysis; third, they have limited migration ability and a narrow activity area, and can better reflect the changes in the ecological environment quality of a certain area. Therefore, selecting small mammals as the monitoring index for urban ecological environment changes can scientifically, accurately and effectively reflect the changes in the comprehensive quality of the urban ecological environment.

[0004] However, different investigation and monitoring methods for small mammals have a great impact on the monitoring results of the comprehensive quality changes of the ecological environment. By sorting out domestic and foreign reference materials, the currently commonly used investigation and monitoring methods for small mammals mainly include the transect survey method, infrared camera shooting method, Sherman trap method, Longworth trap method, cage trapping method, harp net trapping method, resident interview method, vocalization playback method, spotlight search method, echolocation call detection method and trace search method.

[0005] For example: The transect method is an investigation method that requires observing and recording the mammals and their activity traces that appear along a selected route and on both sides of the transect. Usually, the transects range from 1 to 5 kilometers. This requires the investigators to not only spend a lot of time and energy, but also the investigation can only be carried out during the day. For small mammals that are more active at night, only individual activity traces can be found, and they cannot be identified to the species level, and the number and species richness of small mammals in the area cannot be accurately estimated.

[0006] The infrared camera automatic shooting method refers to a survey method in which an observer uses an infrared induction automatic camera, hereinafter referred to as an infrared camera, to automatically record the images of animals moving within its sensing range. The infrared camera shooting method is widely used in mammal surveys. However, the infrared camera method not only has extremely high equipment procurement and maintenance costs, but also for small mammals that are active at night and move quickly, the captured images will be distorted, and clear image data cannot be obtained, resulting in the inability to identify species and the inability to obtain the species quantity and species richness in the surveyed area.

[0007] For the cage trapping method, trap method, and net trapping method, small mammals need to be captured. During the survey process, first, small mammals may die during the sampling process; second, for invasive sampling, applications need to be made to relevant departments, the procedures are cumbersome, and work cannot be carried out at any time; third, for long-term monitoring in the same area, repeated invasive sampling is required, which has a greater impact on the quantity and species of small mammals in the area and cannot accurately evaluate the regional ecological environment quality.

[0008] In addition, non-invasive sampling refers to a survey method in which, without touching or harming the mammals themselves, their shed hair, excrement, urine, food residues, or other appendages are collected. This method is suitable for long-term monitoring, but it is impossible to accurately identify the species of small mammals by collecting their shed hair, excrement, urine, food residues, or other appendages.

[0009] Through one-by-one analysis, it is found that the current traditional small mammal survey and monitoring methods at home and abroad are not applicable to the long-term monitoring of the ecological environment in urban plain areas. We need to develop a new, effective, low-cost, and scientific method as a method for urban ecological environment monitoring.

[0010] All birds of the Strigiformes order feed on animals, including small mammals, small birds, insects, earthworms, frogs, lizards, etc. Taking the long-eared owl wintering in Beijing as an example, its main foods are rodents, chiropterans, and small birds. The long-eared owl swallows its prey whole and, after digestion, spits out the indigestible fur, bones, chitin, and other debris in a ball-shaped mass, which is called a pellet. The pellets come in various shapes, such as ellipsoidal, spherical, flattened spherical, and irregular shapes, with a dark gray or grayish-white color. The surface of the freshly spit-out pellets has a film similar to saliva wrapping them. The contents of some pellets, such as bones, are exposed. Some pellets peel into a powder and disperse, while others are tightly bonded by animal hair. According to research findings, the contents of long-eared owl pellets include: bones of mammals and birds, bird feathers, animal hair, incompletely digested rats, wheat grains, plant seeds, etc. Wang Junfu's research on long-eared owls in Shanghai found that the time for long-eared owls to spit out pellets is not fixed, between 8:30 and 17:00, and the time interval for spitting out pellets is not fixed. Through statistical analysis, the number of animal skulls in a single complete pellet of long-eared owls ranges from 0 to 4, and the pellets containing 1 to 2 skulls account for 64.43%. The number of skulls separated from the pellets spit out by a single long-eared owl in a day is 1 to 3, that is, a single long-eared owl preys on 1 to 3 animals per day.

[0011] By collecting the pellets of long-eared owls, processing and identifying the pellets, it is expected to conveniently obtain the number and species richness of small mammals in a region. However, in existing technologies, most of the research on long-eared owls, except for their own biological research, focuses on bionics, and no research on using them for environmental monitoring has been retrieved. Summary of the Invention

[0012] The main objective of the present invention is to design a method for monitoring the ecological environment changes in urban plain areas based on small mammals. By identifying the contents of the pellets of long-eared owls of the Strigiformes order, the number and species data of small mammals in the region can be obtained, thereby monitoring the comprehensive quality changes of the regional ecological environment. It is expected to provide technical support for the long-term observation of small mammals with good indicative effects to judge the comprehensive quality changes of the urban ecological environment. The objective of the present invention is achieved through the following technical solutions:

[0013] A method for monitoring the ecological environment changes in urban plain based on the investigation of small mammals, comprising the following steps:

[0014] Step 1: Determine the collection points of long-eared owl pellets;

[0015] Step 2: Obtain the proportion of the covered areas and biomass of forests, shrubs, grasslands, and cultivated lands within the predation range area: Taking the collection point of long-eared owl pellets as the center point and with a radius of 10 km, obtain the predation range of long-eared owls. Once a year, through remote sensing interpretation, obtain the proportion of the covered areas of forests, shrubs, grasslands, and cultivated lands within the area and the biomass of forests, shrubs, and grasslands;

[0016] Step 3: Obtain the vascular plant species richness of forests, shrubs, and grasslands within the foraging range area: In July and August of the year following the long-eared owl observation, taking the long-eared owl pellet collection point as the center point, within a range of 3 kilometers, set vegetation survey plots. The plots are 10m * 10m, including types: grassland, shrub forest, and arbor forest. There are no less than 3 plots of each type. Investigate and record the basic information within the plots, obtain the vascular plant species richness of forests, shrubs, and grasslands in the area, and conduct a re-survey of the vegetation habitat quality information of the plots every year from July to August;

[0017] Step 4: Pellet collection: From November of the current year to March of the following year, conduct pellet collection, collecting pellets once every two weeks; during the collection process, record the distribution locations and distribution quantities of long-eared owls, and at the same time do a good job in pellet measurement and numbering records;

[0018] Step 5: Pellet separation: In a petri dish, use tweezers to separate each piece of bone;

[0019] Step 6: Count the number of animals involved in the pellets: Judge the individual number of small mammals preyed upon based on the number of paired upper jaws and paired lower jaws obtained; determine the individual number of birds preyed upon by the number of undigested bird beaks or skulls or pairs of claws;

[0020] Step 7: Identify the species of small mammals preyed upon: After determining the number of animals, identify the order to which the small mammals belong by judging the bones and the positions of the incisors of each animal; and identify the species of rodents, chiropterans, and insectivores in the superorder Laurasiatheria to the species level;

[0021] Step 8: Identify the species of birds preyed upon to the order level;

[0022] Step 9: Through literature search, establish a query table for the weights of the prey of long-eared owls;

[0023] Step 10: Based on the work foundation from Step 4 to Step 9, calculate the parameters for measuring the biodiversity index: the species richness of prey animals, the occurrence frequency of prey animals in pellets, the predation intensity of prey animals, and the biomass ratio of prey animals;

[0024] Step 11: Calculate the comprehensive index of the ecological environment quality in the urban plain area:

[0025] It covers two first-level indicators: the vegetation coverage index and the biodiversity index;

[0026] The Vegetation Coverage Index has 4 secondary indicators, namely the Forest Index, Shrub Index, Grassland Index, and Cultivated Land Index; the Biodiversity Index has 4 secondary indicators, namely the Species Diversity Index of Prey Animals, the Frequency Index of Prey Animals Appearing in Pellets, the Predation Intensity Index of Predator Animals, and the Biomass Proportion Index of Prey Animals; each secondary indicator has different calculation parameters:

[0027] The calculation parameters under the secondary indicator Forest Index are: the proportion of the covered area of arbor forests, biomass, and vascular plant species richness in the area; the calculation parameters under the secondary indicator Shrub Index are: the proportion of the covered area of shrubs, biomass, and vascular plant species richness in the area; the calculation parameters under the secondary indicator Grassland Index are respectively: the proportion of the covered area of grasslands, biomass, and vascular plant species richness in the area; the calculation parameters under the secondary indicator Cultivated Land Index are: the proportion of the covered area of cultivated land in the area;

[0028] The calculation parameters under the secondary indicator Species Diversity Index of Prey Animals are: the species richness of rodents, chiropterans, laurasiatherian insectivores, and birds; the calculation parameters under the secondary indicator Frequency Index of Prey Animals Appearing in Pellets are: the frequency of rodents, chiropterans, laurasiatherian insectivores, and birds appearing in pellets; the calculation parameters under the secondary indicator Predation Intensity Index of Predator Animals are: the predation intensity of rodents, chiropterans, laurasiatherian insectivores, and birds; the calculation parameters under the secondary indicator Biomass Proportion Index of Prey Animals are: the biomass proportion of rodents, chiropterans, laurasiatherian insectivores, and birds;

[0029] The comprehensive ecological environment quality index of the urban plain area is calculated according to formula (1):

[0030]

[0031] In the formula:

[0032] UPTEI is the comprehensive ecological environment quality index of the urban plain area;

[0033] ω i is the weight of the i-th first-level indicator;

[0034] n is the number of first-level indicators;

[0035] m i is the number of secondary indicators under the i-th first-level indicator;

[0036] ω ij is the weight of the j-th secondary indicator under the i-th first-level indicator;

[0037] l ij is the number of calculation parameters under the j-th secondary indicator under the i-th first-level indicator;

[0038] ω ijk is the weight of the kth calculation parameter under the jth secondary index under the ith primary index;

[0039] I ijk is the evaluation value of the kth calculation parameter under the jth secondary index under the ith primary index;

[0040] i is the primary index number;

[0041] j is the secondary index number;

[0042] k is the number of the evaluation value of the calculation parameter;

[0043] Among them, the evaluation value of the calculation parameter is calculated according to formula (2):

[0044]

[0045] In the formula:

[0046] I ijk is the evaluation value of the kth calculation parameter under the jth secondary index under the ith primary index;

[0047] X ijk is the measured value or calculated value of the kth calculation parameter under the jth secondary index under the ith primary index;

[0048] X max(ijk) is the maximum value of the kth calculation parameter under the jth secondary index under the ith primary index during the evaluation period;

[0049] X min(ijk) is the minimum value of the kth calculation parameter under the jth secondary index under the ith primary index during the evaluation period;

[0050] Step 12: Compare the changes in the ecological environment quality of different regions in the same period based on the comprehensive ecological environment quality index of the urban plain area in different regions; or compare the comprehensive ecological environment quality index of the urban plain area in the same region in different years to determine the changes in the ecological environment of the urban plain area.

[0051] Further, in Step 1, first select the points where long-eared owls are stably distributed for a long time as the alternative points for pellet collection; the points with long-term stable distribution are the locations where long-eared owls have appeared continuously for two years determined according to the bird watching record data; then conduct on-site surveys at the alternative points for long-eared owl pellet collection, and select some of the alternative points as the long-eared owl pellet collection points, requiring the distance between the two collection points to exceed 20 kilometers.

[0052] Further, in Step 2, calculate the biomass:

[0053] The biomass of the forest is calculated according to formula (3):

[0054] biofor = 4.031×ln(LAI1)+5.036 (3)

[0055] Where: LAI1 is the leaf area index of forest vegetation; biofor is the forest biomass;

[0056] The biomass of the shrub is calculated according to formula (4):

[0057] bioshrub = 4.031×ln(LAI2)+5.036 (4)

[0058] Where: bioshurb is the shrub biomass; LAI2 is the leaf area index of shrub vegetation;

[0059] The biomass of the grassland is calculated according to formula (5):

[0060] biosgrass = (420.7×RVI + 53.594) / 10000 (5)

[0061] Where: RVI is the ratio vegetation index; biosgrass is the grassland biomass;

[0062] Among them, the normalized difference vegetation index of Landsat images calculated based on GEE is as shown in formula (6):

[0063]

[0064] Where: NDVI is the normalized difference vegetation index; ρ nir is the reflectance of the near-infrared band; ρ red is the reflectance of the red light band;

[0065] The ratio vegetation index of Landsat images calculated based on GEE is as shown in formula (7):

[0066]

[0067] The calculation of the leaf area index of vegetation is carried out according to formula (8):

[0068] LAI = 5.724×NDVI - 1.536 (8)

[0069] Furthermore, in step three, the basic information recorded in the sample plot includes: vegetation type, vegetation composition, canopy density, altitude, slope, aspect, coverage, tree species, diameter at breast height, tree height, ground diameter, number of clumps, vitality; the vascular plant species richness (S-vascular plant) is the number of vascular plant species occurring in the area.

[0070] Further, in step four, before collecting the food pellets, prepare the food pellet collection tools: including plastic gloves, 95% alcohol, self-sealing bags, label paper, marker pens, a purchased video surveillance system, a field investigation record logbook, and vernier calipers.

[0071] Further, in step five, place a single food pellet in a petri dish, add 95% alcohol, and use tweezers to separate each bone.

[0072] Further, in step seven, according to the regional small mammal order retrieval table, judge the order to which each small mammal belongs based on the bones and incisor positions of each animal; establish a classification retrieval table based on the dental formula of the upper jaw teeth and by comparing the morphology of the skull in the atlas, and identify to the species level.

[0073] Further, in step eight, birds are identified to the order level based on the remaining beaks, bones, and feathers.

[0074] Further, in step ten: The species richness of the prey animals is the number of animal species appearing in the food pellets;

[0075] The calculation formula for the appearance frequency of prey animals in the food pellets is as follows:

[0076]

[0077] In the formula: F pi is the appearance frequency of the \(p_i\)th animal; NP pi is the number of food pellets containing the skulls of the \(p_i\)th animal; NP is the total number of food pellets;

[0078] The calculation formula for the predation intensity of prey animals is as follows:

[0079]

[0080] In the formula: P pi is the predation intensity of the \(p_i\)th animal; N pi is the number of individuals of the \(p_i\)th animal; N is the total number of prey animals;

[0081] The calculation formula for the biomass proportion of prey animals is as follows:

[0082]

[0083] In the formula: FB pi is the biomass proportion of the \(p_i\)th animal; N pi* is the number of individuals of the \(p_i\)th animal; B pi is the average weight of the \(p_i\)th animal; np is the number of species of prey animals.

[0084] The advantages and beneficial effects of the present invention are:

[0085] 1) The application of the method of the present invention solves the problem of the inability to long-term observe the biodiversity of small mammals, and provides technical support for long-term observation of small mammals with good indicator effects to judge the changes in the comprehensive quality of the urban ecological environment.

[0086] During the monitoring process from November 2022 to March 2023 and from November 2023 to March 2024, a total of 876 food pellets were collected using this method. The prey identified to species level involved 2 classes, 4 orders, 10 families, 17 genera, and 20 species, and 1,734 individuals of small mammals and birds. Among them, there were 14 species of small mammals (including 5 species of Rodentia, 6 species of Chiroptera, and 3 species of Eulipotyphla), and 6 species of birds. In terms of species composition, Rodentia accounted for 86.16%; birds accounted for 7.14%; Chiroptera accounted for 3.79%; Eulipotyphla accounted for 2.91%.

[0087] 2) Compared with traditional investigation methods such as cage trapping, trapping, and net trapping, the present invention plays an important role in biodiversity protection, can reduce direct interference, maintain ecological balance, protect sensitive species, etc., and provides strong support for the long-term protection and sustainable utilization of biodiversity. Specifically, it is manifested as follows:

[0088] First, in environmental monitoring, it minimizes the interference to the ecosystem and direct interference. By avoiding direct contact with animal individuals and their habitats, it minimizes the direct impact of human activities on biodiversity. This method reduces the animal casualties that may be caused by activities such as capturing, marking, and tracking, thus protecting the population quantity and genetic diversity of species. Compared with traditional methods, since the implementation of the present invention, 1,613 small mammals have been avoided from being injured and killed due to investigation, greatly protecting the welfare of animals.

[0089] Second, the present invention increases the success rate of obtaining small mammal species by 10 species, up to 350%. Traditional investigation methods are limited by the investigation environmental conditions and terrain and cannot capture all small mammals. From 2023 to 2024, the project team used the trapping method to investigate small mammals. A total of 20 investigation plots were set up, with 100 traps in each plot. A total of 4 species of small mammals were recorded, including Rattus confucianus, Rattus norvegicus, Apodemus agrarius, and Mus musculus. While in the area where the present invention was carried out for monitoring, a total of 14 species of small mammals were recorded, covering all small mammals in the wintering season in the plain area of Beijing, making the species coverage rate of biodiversity investigation reach 100%. Compared with the investigation coverage rate of the traditional trapping method, which is only 28%, the effective acquisition rate of biodiversity data has increased by 70%.

[0090] Thirdly, some small mammals are rare and endangered species and key targets for biodiversity conservation. For example, Scaptochirus moschatus, Myotis pequinius, Myospalax fontanieri, Myotis davidii, Myotis ricketti, etc. On the one hand, they are extremely sensitive to environmental changes. On the other hand, as protected species, invasive investigations that cause damage can impose great psychological stress and stress responses on the protected species populations and can also affect the normal life and behavior of the species groups. The method adopted in the present invention can obtain effective data on the ecological environment changes in the plain area without affecting the normal behavior of animals, providing the possibility of obtaining effective data for long-term monitoring in the same area.

[0091] In summary, the present invention solves the problems existing in the current traditional methods, such as the possible harm to the investigation objects, the inability to conduct long-term continuous monitoring investigations with invasive sampling, the high cost of related equipment such as infrared cameras, the large consumption of manpower and material resources in traditional investigations, the complicated procedures for applying for investigations and the inability to conduct investigations at any time, and the inability to accurately identify the species to the species level, etc. Detailed implementation manners

[0092] Example 1:

[0093] First step: According to the natural geographical overview of the plain area in Beijing and combined with public data (data recorded by the China Bird Watching Record Center), select 10 - 20 points where long-eared owls are stably distributed for a long time (locations where long-eared owls have appeared for two consecutive years) as alternative points for pellet collection. Conduct on-site surveys at the alternative points for long-eared owl pellet collection, and select 5 points with a large number of long-eared owls as long-eared owl pellet collection points, requiring the distance between two collection points to exceed 20 kilometers.

[0094] Second step: Obtain the proportion of the covered areas and biomass of forests, shrubs, grasslands, and cultivated lands within the predation range area: Taking the long-eared owl pellet collection point as the center point and with a radius of 10 km, obtain the predation range of long-eared owls. Once a year, through remote sensing interpretation, obtain the proportion of the covered areas of forests, shrubs, grasslands, and cultivated lands within the area and the biomass of forests, shrubs, and grasslands;

[0095] The biomass of forests is calculated according to formula (3):

[0096] biofor = 4.031×ln(LAI1)+5.036 (3)

[0097] In the formula: LAI1 is the leaf area index of forest vegetation; biofor is the forest biomass;

[0098] The biomass of shrubs is calculated according to formula (4):

[0099] bioshrub = 4.031×ln(LAI2)+5.036 (4)

[0100] Where: bioshrub is the shrub biomass; LAI2 is the shrub vegetation leaf area index

[0101] The biomass of grassland is calculated according to formula (5):

[0102] biosgrass=(420.7×RVI+53.594) / 10000 (5)

[0103] Where: RVI is the ratio vegetation index; biosgrass is the grassland biomass;

[0104] The normalized vegetation index of Landsat images calculated based on GEE is as follows:

[0105]

[0106] Where: NDVI is the normalized difference vegetation index; ρ nir is the reflectivity in the near-infrared band; ρ red is the reflectivity of red light band;

[0107] The ratio vegetation index of Landsat images is calculated based on GEE as shown in formula (7):

[0108]

[0109] The vegetation leaf area index is calculated according to formula (8):

[0110] LAI=5.724×NDVI-1.536 (8)

[0111] Step 3: Obtain the species richness of vascular plants in forests, shrubs, and grasslands within the predation range: In July and August of the following year after the long-eared owl was observed, a vegetation survey plot was set up within a 3-kilometer range with the long-eared owl food pellet collection point as the center point. The plot was 10m*10m, including types: grassland, shrubs, and arbor forests. There were no less than 3 plots of each type. The basic information in the plot was investigated and recorded to obtain the species richness of vascular plants in forests, shrubs, and grasslands in the area. The vegetation habitat quality information of the plot was retested from July to August each year; the vascular plant species richness (S-vascular plant) was the number of vascular plant species appearing in the area. The arbor forest survey record table is shown in Table 1, the shrub survey record table is shown in Table 2, and the grassland survey record table is shown.

[0112] Table 1

[0113]

[0114]

[0115] Table 2

[0116]

[0117] Table 3

[0118]

[0119]

[0120] Step 4: Pellet collection: Prepare pellet collection tools including plastic gloves, 95% alcohol, self-sealing bags, label paper, marker pens, purchase a video surveillance system, a field investigation record logbook, and vernier calipers; from November of the current year to March of the following year, conduct pellet collection, collecting pellets every two weeks; during the collection process, record the distribution locations and quantities of long-eared owls, and at the same time do a good job in recording the collection, measurement, and numbering of pellets;

[0121] Step 5: Pellet separation: Put a single pellet into a petri dish, add 95% alcohol, and use tweezers to separate each piece of bone.

[0122] Step 6: Count the number of animals involved in the pellets: Determine the number of individuals of small mammals preyed upon based on the number of pairs of maxillae and mandibles obtained; determine the number of birds preyed upon based on the number of undigested bird beaks or skulls, or the number of pairs of claws; their skulls all include the maxilla and mandible, and each animal has a pair of maxillae and a pair of mandibles. Pair the maxillae and mandibles, and take the largest number of pairs as the number of small mammals involved in the pellets. The birds involved in the pellets all include 1 upper beak, 1 lower beak, and 1 pair of claws; take the largest number of paired quantities of upper beaks, lower beaks, and claws to determine the number of birds;

[0123] Step 7: Identify the species of small mammals. After determining the number of paired animals, in this embodiment, according to the small mammal order retrieval table in the Beijing area, judge the order to which each animal belongs based on the bones and the positions of the incisors of each animal.

[0124] Table 4

[0125]

[0126]

[0127] Identify the species of rodents, chiropterans, and laurasiatherian insectivores. Based on the dental formula of the maxillary teeth and by comparing the morphology of the skulls in the atlas as the standard, establish a classification retrieval table and identify to the species level. Take rodents as an example.

[0128] Table 5

[0129]

[0130] Step 8: Identify the bird species. The birds are identified to the order based on the remaining beaks, bones, and feathers.

[0131] Step 9: Through literature search, establish a query table for the prey weights of Asio otus as shown in Table 6.

[0132] Table 6

[0133]

[0134]

[0135] Step 10: Based on the work in Steps 5 to 10, calculate the parameters for biodiversity index determination: species richness of prey animals, occurrence frequency of prey animals in pellets, predation intensity of prey animals, and biomass proportion of prey animals.

[0136] The species richness of prey animals is the number of animal species present in the pellets.

[0137] The formula for calculating the occurrence frequency of prey animals in pellets is as follows:

[0138]

[0139] In the formula: F pi is the occurrence frequency of the pi-th animal; NP pi is the number of pellets containing the skulls of the pi-th animal; NP is the total number of pellets.

[0140] The formula for calculating the predation intensity of prey animals is as follows:

[0141]

[0142] In the formula: P pi is the predation intensity of the pi-th animal; N pi is the number of individuals of the pi-th animal; N is the total number of prey animal individuals.

[0143] The formula for calculating the biomass proportion of prey animals is as follows:

[0144]

[0145] In the formula: FB pi is the biomass proportion of the pi-th animal; N pi* is the number of individuals of the pi-th animal; B pi is the average weight of the pi-th animal; np is the number of species of prey animals.

[0146] Step Eleven: Calculate the comprehensive index of the ecological environment quality in the urban plain area: Based on the indicator system and method for the ecological environment changes in the urban plain based on small mammal surveys, calculate and obtain the comprehensive index of the ecological environment quality in the urban plain area. For the evaluation of the ecological environment quality at each point in the urban plain area, a unified indicator system is used for calculation, including two aspects: ecosystem and biodiversity.

[0147] It covers two first-level indicators: the vegetation coverage index and the biodiversity index.

[0148] The vegetation coverage index has 4 second-level indicators, namely the forest index, the shrub index, the grassland index, and the cultivated land index; the biodiversity index has 4 second-level indicators, namely the species diversity index of prey animals, the frequency index of prey animals appearing in the pellets, the predation intensity index of predator animals, and the biomass proportion index of prey animals; different calculation parameters are set under each second-level indicator:

[0149] The calculation parameters set under the second-level indicator of the forest index are: the proportion of the covered area of arbor forests, the biomass, and the vascular plant species richness in the area; the calculation parameters set under the second-level indicator of the shrub index are: the proportion of the covered area of shrubs, the biomass, and the vascular plant species richness in the area; the calculation parameters set under the second-level indicator of the grassland index are respectively: the proportion of the covered area of grasslands, the biomass, and the vascular plant species richness in the area; the calculation parameters set under the second-level indicator of the cultivated land index are: the proportion of the covered area of cultivated land in the area.

[0150] The calculation parameters set under the second-level indicator of the species diversity index of prey animals are: the species richness of rodents, bats, Eulipotyphla, and birds; the calculation parameters set under the second-level indicator of the frequency index of prey animals appearing in the pellets are: the frequency of rodents, bats, Eulipotyphla, and birds appearing in the pellets; the calculation parameters set under the second-level indicator of the predation intensity index of predator animals are: the predation intensity of rodents, bats, Eulipotyphla, and birds; the calculation parameters set under the second-level indicator of the biomass proportion index of prey animals are: the biomass proportion of rodents, bats, Eulipotyphla, and birds.

[0151] The comprehensive index of the ecological environment quality in the urban plain area is calculated according to formula (1):

[0152]

[0153] In the formula:

[0154] UPTEI is the comprehensive index of the ecological environment quality in the urban plain area;

[0155] ω i is the weight of the i-th first-level indicator;

[0156] n is the number of first-level indicators;

[0157] m i is the number of second-level indicators under the i-th first-level indicator;

[0158] ω ij is the weight of the j-th second-level indicator under the i-th first-level indicator;

[0159] l ij is the number of calculation parameters under the j-th second-level indicator under the i-th first-level indicator;

[0160] ω ijk is the weight of the k-th calculation parameter under the j-th second-level indicator under the i-th first-level indicator;

[0161] I ijk is the evaluation value of the k-th calculation parameter under the j-th second-level indicator under the i-th first-level indicator;

[0162] i is the first-level indicator number;

[0163] j is the second-level indicator number;

[0164] k is the evaluation value number of the calculation parameter;

[0165] Among them, the evaluation value of the calculation parameter is calculated according to formula (2):

[0166]

[0167] In the formula:

[0168] I ijk is the evaluation value of the k-th calculation parameter under the j-th second-level indicator under the i-th first-level indicator;

[0169] X ijk is the measured value or calculated value of the k-th calculation parameter under the j-th second-level indicator under the i-th first-level indicator;

[0170] X max(ijk) is the maximum value of the k-th calculation parameter under the j-th second-level indicator under the i-th first-level indicator during the evaluation period;

[0171] X min(ijk) is the minimum value of the k-th calculation parameter under the j-th second-level indicator under the i-th first-level indicator during the evaluation period;

[0172] In this embodiment, the comprehensive index evaluation index system for the ecological environment quality of the urban plain area is as follows:

[0173] Table 7

[0174]

[0175]

[0176] In this embodiment:

[0177] The forest index is calculated according to formula (1.1):

[0178] I for = 0.50 × I sfor + 0.30 × I biofor + 0.20 × I spcifor (1.1)

[0179] Wherein:

[0180] I for is the calculated value of the forest index;

[0181] I sfor is the evaluation value of the proportion of forest cover area, and the evaluation method is calculated according to formula (2);

[0182] I biofor is the evaluation value of forest biomass, and the evaluation method is calculated according to formula (2);

[0183] I spcifor is the evaluation value of forest species richness, and the evaluation method is calculated according to formula (2);

[0184] The shrub index is calculated according to formula (1.2):

[0185] I shrub = 0.50 × I sshrub + 0.30 × I bioshrub + 0.20 × I spcihrub (1.2)

[0186] Wherein:

[0187] I shrub is the calculated value of the shrub index;

[0188] I sshrub is the evaluation value of the proportion of shrub cover area, and the evaluation method is calculated according to formula (2);

[0189] I bioshrub is the evaluation value of shrub biomass, and the evaluation method is calculated according to formula (2);

[0190] I spcihrub is the evaluation value of shrub species richness, and the evaluation method is calculated according to formula (2);

[0191] The grassland index is calculated according to formula (1.3):

[0192] I grass = 0.50 × I sgrass+0.30×I biosgrass +0.20×I spcigrass (1.3)

[0193] In the formula:

[0194] I grass is the calculated value of the grassland index;

[0195] I sgrass is the evaluation value of the proportion of grassland coverage area, and the evaluation method is calculated according to formula (2);

[0196] I biosgrass is the evaluation value of grassland biomass, and the evaluation method is calculated according to formula (2);

[0197] I spcigrass is the evaluation value of grassland species richness, and the evaluation method is calculated according to formula (2);

[0198] The evaluation value of the cultivated land index is calculated according to formula (1.4):

[0199] I cul = 1×I scul (1.4)

[0200] In the formula:

[0201] I cul is the evaluation value of the cultivated land index;

[0202] I scul is the evaluation value of the proportion of cultivated land coverage area, and the evaluation method is calculated according to formula (2);

[0203] The calculation of the species diversity index of prey animals is calculated according to formula (1.5):

[0204] I spciprey = 0.70×I spciRodentia +0.10×I spciChiroptera +0.10×I spciInsectivora +0.10×I spciAves (1.5)

[0205] In the formula:

[0206] I spciprey is the species diversity index of prey animals;

[0207] I spciRodentia is the evaluation value of the species richness of Rodentia, and the evaluation method is calculated according to formula (2);

[0208] I spciChiroptera is the evaluation value of the species richness of Chiroptera, and the evaluation method is calculated according to formula (2);

[0209] IspciInsectivora is the evaluation value of the species richness of Laurasian insectivores, and the evaluation method is calculated according to formula (2);

[0210] I spciAves is the evaluation value of the species richness of birds, and the evaluation method is calculated according to formula (2);

[0211] The calculation of the frequency index of prey animals appearing in the pellets is calculated according to formula (1.6):

[0212] I Fprey = 0.70 × I FRodentia + 0.10 × I FChiroptera + 0.10 × I FInsectivora + 0.10 × I FAves (1.6)

[0213] In the formula:

[0214] I Fprey is the species diversity index of prey animals;

[0215] I FRodentia is the evaluation value of the frequency index of rodents appearing in the pellets, and the evaluation method is calculated according to formula (2);

[0216] I FChiroptera is the evaluation value of the frequency index of bats appearing in the pellets, and the evaluation method is calculated according to formula (2);

[0217] I FInsectivora is the evaluation value of the frequency index of Laurasian insectivores appearing in the pellets, and the evaluation method is calculated according to formula (2);

[0218] I FAves is the evaluation value of the frequency index of birds appearing in the pellets, and the evaluation method is calculated according to formula (2);

[0219] The calculation of the predation intensity index of prey animals is calculated according to formula (1.7):

[0220] I predation intensity = 0.70 × I predation intensity Rodentia + 0.10 × I predation intensity Chiroptera + 0.10 × I predation intensity Insectivora + 0.10 × I predation intensity Aves (1.7)

[0221] In the formula:

[0222] I predation intensity is the predation intensity index of prey animals;

[0223] I predation intensity Rodentia is the evaluation value of the predation intensity index of rodents, and the evaluation method is calculated according to formula (2);

[0224] I predation intensity Chiroptera is the evaluation value of the predation intensity index of Chiroptera, and the evaluation method is calculated according to formula (2);

[0225] I predation intensity Insectivora is the evaluation value of the predation intensity index of Eulipotyphla, and the evaluation method is calculated according to formula (2);

[0226] I predation intensity Aves is the evaluation value of the predation intensity index of Aves, and the evaluation method is calculated according to formula (2);

[0227] The biomass proportion index of the preyed animals is calculated according to formula (1.8):

[0228] I F pre bio = 0.70 × I F pre bio Rodentia + 0.10 × I F pre bio Chiroptera + 0.10 × I F pre bio Insectivora + 0.10 × I F pre bio Aves (1.8)

[0229] In the formula:

[0230] I F pre bio is the predation intensity index of the preyed animals;

[0231] I F pre bio Rodentia is the evaluation value of the biomass proportion index of Rodentia, and the evaluation method is calculated according to formula (2);

[0232] I F pre bio Chiroptera is the evaluation value of the biomass proportion index of Chiroptera, and the evaluation method is calculated according to formula (2);

[0233] I F pre bio Insectivora is the evaluation value of the biomass proportion index of Eulipotyphla, and the evaluation method is calculated according to formula (2);

[0234] I F pre bio Aves is the evaluation value of the biomass proportion index of Aves, and the evaluation method is calculated according to formula (2);

[0235] Step Twelve: Compare the ecological environment quality changes in different regions during the same period based on the comprehensive ecological environment quality index of the urban plain areas in different regions; or compare the comprehensive ecological environment quality index of the urban plain areas in the same region in different years to determine the ecological environment changes in the urban plain areas. And in this embodiment, according to the specific value of the comprehensive ecological environment quality index of the urban plain areas, the comprehensive ecological environment quality indexes of each urban plain area are divided into 7 levels, namely 1, 2, 3, 4, 5, 6, and 7, as shown in the following table. The ecological environment quality of the urban plain areas can be classified according to specific circumstances.

[0236] Table 8

[0237]

[0238] Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred arrangement, those of ordinary skill in the art should understand that the technical solution of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for monitoring the changes in the urban plain ecological environment based on small mammal surveys, characterized in that: It includes the following steps: Step 1: Determine the pellet collection points of the long-eared owl; Step 2: Obtain the proportion of forest, shrub, grassland, and cultivated land coverage area and biomass within the predation range: Taking the long-eared owl pellet collection point as the center point and with a radius of 10 km, obtain the long-eared owl's predation range. Once a year, through remote sensing interpretation, obtain the proportion of forest, shrub, grassland, and cultivated land coverage area and the biomass of forest, shrub, and grassland within the area; Step 3: Obtain the vascular plant species richness of forest, shrub, and grassland within the predation range: In July - August of the following year after the long-eared owl observation, taking the long-eared owl pellet collection point as the center point, within a range of 3 km, set up vegetation survey plots, including types: grassland, shrub forest, and arbor forest. Investigate and record the basic information within the plots to obtain the vascular plant species richness of forest, shrub, and grassland within the area; Step 4: Pellet collection: From November of the observation year to March of the following year, conduct pellet collection, collecting pellets once every two weeks; Step 5: Pellet separation: In a petri dish, separate each bone; Step 6: Count the number of animals involved in the pellets: Determine the number of individuals of small mammals preyed upon based on the number of paired upper jaws and paired lower jaws obtained; Determine the number of individuals of birds preyed upon based on the number of undigested beaks or skulls or pairs of claws; Step 7: Identify the species of small mammals preyed upon: After determining the number of animals, identify and judge the order to which the small mammals belong; And identify the species of animals in the order Rodentia, Chiroptera, and Eulipotyphla to the species level; Step 8: Identify the species of birds preyed upon to the order level; Step 9: Through literature search, establish a query table for the weights of the prey of the long-eared owl; Step 10: Based on the work foundation from Step 4 to Step 9, calculate the parameters for measuring the biodiversity index: the species richness of prey animals, the occurrence frequency of prey animals in pellets, the predation intensity of prey animals, the biomass proportion of prey animals; Step 11: Calculate the comprehensive index of the ecological environment quality in the urban plain area: It covers two first-level indicators, namely the vegetation coverage index and the biodiversity index; The vegetation coverage index has 4 second-level indicators, namely the forest index, shrub index, grassland index, and cultivated land index; The biodiversity index has 4 second-level indicators, namely the species diversity index of prey animals, the frequency index of prey animals appearing in pellets, the predation intensity index of predator animals, and the biomass proportion index of prey animals; Different calculation parameters are set under each second-level indicator: The calculation parameters set under the second-level indicator forest index are: the proportion of the coverage area of arbor forest, biomass, and vascular plant species richness in the area; The calculation parameters set under the second-level indicator shrub index are: the proportion of the coverage area of shrub, biomass, and vascular plant species richness in the area; The calculation parameters set under the second-level indicator grassland index are respectively: the proportion of the coverage area of grassland, biomass, and vascular plant species richness in the area; The calculation parameter set under the second-level indicator cultivated land index is: the proportion of the coverage area of cultivated land in the area; The calculation parameters under the secondary index of the species diversity index of prey animals are: the species richness of rodents, chiropterans, laurasiatherian insectivores, and birds; the calculation parameters under the secondary index of the frequency index of prey animals appearing in pellets are: the frequencies of rodents, chiropterans, laurasiatherian insectivores, and birds appearing in pellets; the calculation parameters under the secondary index of the predation intensity index of predator animals are: the predation intensities of rodents, chiropterans, laurasiatherian insectivores, and birds; the calculation parameters under the secondary index of the biomass proportion index of prey animals are: the biomass proportions of rodents, chiropterans, laurasiatherian insectivores, and birds; The comprehensive index of the ecological environment quality in the urban plain area is calculated according to formula (1): Wherein: UPTEI is the comprehensive index of the ecological environment quality in the urban plain area; ω i is the weight of the i-th first-level indicator; n is the number of primary indicators; m i is the number of secondary indicators under the i-th primary indicator; ω ij is the weight of the j-th secondary indicator under the i-th primary indicator; l ij is the number of calculation parameters under the j-th secondary indicator of the i-th primary indicator; ω ijk is the weight of the k-th calculation parameter under the j-th secondary indicator under the i-th primary indicator; I ijk is the evaluation value of the k-th calculation parameter under the j-th secondary index under the i-th primary index; i is the primary indicator number; j is the secondary indicator number; k is the number of the evaluation value of the calculation parameter; Among them, the evaluation value of the calculation parameter is calculated according to formula (2): Wherein: I ijk is the evaluation value of the k-th calculation parameter under the j-th secondary index under the i-th primary index; X ijk is the measured or calculated value of the k-th calculation parameter under the j-th secondary index under the i-th primary index; X max(ijk) is the maximum value of the k-th calculation parameter under the j-th secondary indicator under the i-th primary indicator during the evaluation period; X min(ijk) is the minimum value of the k-th calculation parameter under the j-th secondary index and the i-th primary index during the evaluation period; Step 12: Compare the changes in the ecological environment quality in different regions in the same period based on the comprehensive index of the ecological environment quality in the urban plain area of different regions; or compare the comprehensive index of the ecological environment quality in the urban plain area of the same region in different years to determine the changes in the ecological environment in the urban plain area.

2. The monitoring method for urban plain ecological environment changes based on small mammal surveys according to claim 1, characterized in that: In Step 1, select the points where long-eared owls are stably distributed for a long time as the alternative points for pellet collection; the points where long-eared owls are stably distributed for a long time are the locations where long-eared owls appear continuously for two years determined according to the bird watching record data; Then, conduct on-site surveys at the alternative points for long-eared owl pellet collection, and select some of the alternative points as the long-eared owl pellet collection points, requiring the distance between the two collection points to exceed 20 kilometers.

3. The monitoring method for urban plain ecological environment changes based on small mammal surveys according to claim 1, characterized in that: In Step 2, biomass calculation: The biomass of forests is calculated according to formula (3): biofor = 4.031×ln(LAI1)+5.036 (3) Wherein: LAI1 is the leaf area index of forest vegetation; biofor is the forest biomass; The biomass of shrubs is calculated according to formula (4): bioshrub = 4.031×ln(LAI2)+5.036 (4) Wherein: bioshurb is the shrub biomass; LAI2 is the leaf area index of shrub vegetation; The biomass of grasslands is calculated according to formula (5): biosgrass = (420.7×RVI + 53.594) / 10000 (5) Wherein: RVI is the ratio vegetation index; biosgrass is the grassland biomass; Among them, the normalized vegetation index of Landsat images calculated based on GEE is as shown in formula (6): Where: NDVI is the Normalized Difference Vegetation Index; ρ nir is the reflectance in the near-infrared band; ρ red is the reflectance in the red band; The ratio vegetation index of Landsat images calculated based on GEE is as shown in formula (7): The calculation of the leaf area index of vegetation is calculated according to formula (8): LAI = 5.724×NDVI - 1.536 (8).

4. The method for monitoring the changes in the urban plain ecological environment based on the investigation of small mammals according to claim 1, characterized in that: In Step 3, the basic information recorded in the quadrat includes: vegetation type, vegetation composition, canopy density, altitude, slope, aspect, coverage, tree species, diameter at breast height, tree height, ground diameter, number of clumps, vitality; the species richness of vascular plants uses the number of vascular plant species appearing in the area.

5. The method for monitoring the changes in the urban plain ecological environment based on the investigation of small mammals according to claim 1, wherein: In Step 4, before collecting the pellets, prepare the pellet collection tools: including plastic gloves, 95% alcohol, self-sealing bags, label paper, marker pens, a purchased video surveillance system, a field investigation record logbook, and vernier calipers.

6. The monitoring method for urban plain ecological environment changes based on small mammal surveys according to claim 1, wherein: In Step 5, place a single pellet in a petri dish, add 95% alcohol, and use forceps to separate each bone.

7. The monitoring method for urban plain ecological environment changes based on small mammal surveys according to claim 1, characterized in that: In Step 7, according to the regional small mammal order retrieval table, determine the order to which each small mammal belongs based on the bones and incisor positions of each animal; establish a classification retrieval table based on the dental formula of the upper jaw teeth and by comparing the morphology of the skull in the atlas, and identify to the species level.

8. The monitoring method for urban plain ecological environment changes based on small mammal surveys according to claim 1, characterized in that: In Step 8, identify birds to the order level based on the remaining beaks, bones, and feathers.

9. The method for monitoring the changes in the urban plain ecological environment based on small mammal surveys according to claim 1, wherein: In Step 10: The species richness of the prey animals is the number of animal species present in the pellets; The formula for calculating the frequency of occurrence of prey animals in the pellets is as follows: Where: F pi is the occurrence frequency of the \(i\)th animal; NP pi is the number of pellets containing the skulls of the \(i\)th animal; NP is the total number of pellets; The formula for calculating the predation intensity of prey animals is as follows: Where: P pi is the predation intensity of the \(i\)-th species of animal; N pi is the number of individuals of the \(i\)-th species of animal; N is the total number of individuals of the prey animals; The formula for calculating the biomass proportion of prey animals is as follows: where: FB pi is the biomass proportion of the $i$-th animal; N pi* is the number of individuals of the $i$-th animal; B pi is the average weight of the $i$-th animal; np is the number of species of prey animals.

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