GB/T 43871.1-2024Technical guidelines for identification and assessment of environmental damage - Ecosystem - Part 1: Farmland ecosystem (English PDF)

3 Terms and definitions

Farmland is defined as land that can be used to grow crops, namely class 01 cultivated land of GB/T 21010, comprising paddy field, irrigated land and dry land.

A farmland ecosystem is defined as the complex in which human beings, in farmland centred on crops, use the relations between the biological and the non-biological environment and between biological populations to carry out energy conversion and material circulation through ecological structure and ecological function, and to produce material according to the needs of human society.

Damage to a farmland ecosystem is defined as the adverse change, caused by polluting the environment or destroying the ecology, of the environmental elements such as farmland soil, farmland irrigation water and the atmosphere of the farming area and of the biological elements such as the crops, together with the degradation of function and reduction of services of the farmland ecosystem those elements compose.

The farmland ecosystem service function is defined as the service to human beings rendered by the material produced by the farmland ecosystem and by the natural and man-made environment that material forms, and comprises provisioning services, supporting services, regulating services and cultural services.

4 Work procedure

The work procedure comprises the preparation of the programme, the survey and confirmation of the damage, the causal analysis, the physical quantification of the damage and the preparation of the restoration plan, the value quantification of the damage, the assessment of the effect of restoration and the preparation of the report; it is shown in Figure 1.

At the programme stage the basic situation and main features of the damage are established and, by collecting background material on the farmland soil and the crops grown in the region, the content, extent and methods of the identification and assessment are settled and the programme drawn up.

The survey stage has two parts, the exclusionary survey and the environmental damage survey. The exclusionary survey comes first and rules out cases in which the damage is caused only by climate change, natural disaster or a high background value. The damage survey that follows covers the basic condition of the farmland soil, the farmland irrigation water and the crops grown together with the types of ecosystem service, establishes the baseline level and judges the state of damage to the soil, the irrigation water, the crops and the ecosystem service functions.

At the causal analysis stage a judgement is made on the causal relation between the act of destroying the ecology or polluting the environment and the damage to the farmland ecosystem. At the physical quantification stage the assessment indicators are screened and settled, their present level is compared with the baseline level, the degree and the spatial and temporal extent of the damage are settled and the physical quantity computed; the damaged ecosystem is then rated for recoverability, and where it can be recovered the restoration target is made clear, a basic restoration plan drawn up, the interim damage computed and a compensatory restoration plan drawn up.

At the value quantification stage, for a recoverable ecosystem the resource and environmental value during the restoration period is to be included in the amount of damage besides the restoration cost, and for an unrecoverable ecosystem the amount is computed by the resource and environmental value quantification method. At the assessment stage the recovery of the ecosystem is monitored periodically and the consistency of the effect with the expected target is assessed as a whole, supplementary restoration being carried out where the target has not been reached. At the report stage the identification and assessment report and the restoration effect assessment report are prepared and a work file established as required.

6 Survey and confirmation of farmland ecosystem damage

6.1 The exclusionary survey follows NY/T 3665 and consists chiefly in a first analysis of the fact of damage and in identifying its cause; where the object is damaged only by climate change, natural disaster or a high background value, the survey stops and an investigation report is prepared, and otherwise the damage survey proceeds.

6.2.1 and 6.2.2 The indicators to be surveyed, monitored and assessed are chosen according to the type and features of the damage, with reference to Annex A. Where the damage comes from destroying the ecology, the basic information on the mode, extent and distribution of the destruction is collected, and the start and end time, the frequency and intensity and the area destroyed are surveyed, together with the evidence of the damage caused. Physical soil damage such as compaction, hardening, excavation, subsidence and artificial barrier layers is surveyed following NY/T 4155. Damage by harmful organisms requires the survey of their source, species, number, frequency of invasion, pattern and mode of occurrence and spread, and range of activity, alien species following HJ 624. Damage by over-abstraction of groundwater requires the survey of the groundwater level, the abstraction volume and the groundwater points. Damage by soil erosion requires the survey of the cause, type, duration and distribution of the erosion and the monitoring of slope, soil erosion modulus, crop cover, water and soil conservation measures, the type and area of destruction, the erosion gullies of the farmland and the production roads and gravity erosion, which may follow GB 50433, GB/T 51240 and SL 190. Damage by desertification requires the survey of crop cover, the erosion gullies of the farmland and production roads, and the area of sandy land, wind-eroded land or moving sand. Damage by salinization requires the survey of the distribution and degree or level of the salinization, the groundwater level and flow direction, the irrigation level and the several indicators of the irrigation water related to salinization. Where the damage comes from polluting the environment, the pollution source, the pollutants and the pathways are surveyed following NY/T 3665.

6.2.3 The objects of the damage survey are the farmland soil, the farmland irrigation water, the crops and the ecosystem service functions. Soil damage is surveyed from remote sensing imagery, relief and cadastral material together with field investigation, the indicators being chosen by the assessor from the real situation with reference to Annex A, and sampling, monitoring items, the settling of the analytical method and the laboratory analysis following NY/T 395. Irrigation water damage is surveyed from remote sensing imagery, hydrological and water quality material and the distribution of the water system together with field investigation, and where necessary the history of sewage irrigation is surveyed from historical material; the indicators follow GB 5084 and Annex A, and sampling, monitoring items, the settling of the analytical method and the laboratory analysis follow NY/T 396. Crop damage is surveyed following SF/Z JD0606002, the indicators following that document and Annex A, and sampling, monitoring items, the settling of the analytical method and the laboratory analysis following NY/T 398. Ecosystem service functions are surveyed by material collection, field survey, expert consultation, monitoring and sampling and laboratory testing according to the type of function damaged, so that the historical and present information on the farmland ecosystem of the assessment area is obtained and the main service functions before and during the damage are made clear; those functions chiefly comprise agricultural product supply, soil conservation, biodiversity maintenance and water conservation, biodiversity matters following the relevant national and industry standards on biodiversity observation, and genetic resources and cultural services following Annexes A and B. The restoration and pollution removal measures already carried out and their cost are also surveyed, together with the state of damage and the recoverability of any area where alternative restoration might be carried out.

6.3 Quality control requires that the survey be systematic, complete and objective and be fully recorded following GB/T 39791.2, the record being signed by the surveyor, the recorder and the witness; that the collection, preservation, transfer and analysis of soil samples meet NY/T 395, of water samples NY/T 396 and of agricultural products NY/T 398; that a list of the identification materials be made and signed by the transferring and the receiving party; and that 5 % to 10 % of the collected material be checked at random, and 5 % to 10 % of the information obtained by interview and by survey or record forms be checked at random by revisit, the damage survey being carried out again where the check reveals discrepancies.

6.4 The baseline level is confirmed in a fixed order: from comparison data unaffected by the act, taken from a similar and relatively undamaged area near the assessment area and representative in time and space; from historical data unaffected by the act, taken from figures published by government bodies before the damage or from published research, representative in time and space and obtained at a time such that no factor markedly changing the state of the farmland ecosystem intervened before the act, historical data being preferred where the time of acquisition is close to the time of the damage; from a relevant standard or threshold such as GB 5084 or GB 15618, according to the mode of use and the service function of the farmland; from an expert opinion where none of these is available, the experts being relevant to the case, generally not fewer than five and an odd number, drawn from research institutes and front-line technical staff, the majority opinion deciding where no consensus can be reached; and, where none of the above serves, by special research or simulation experiment. The baseline is expressed chiefly by the area, thickness, volume and physical and chemical indices of the farmland soil before the damage, by the quality of the irrigation water, by the yield and quality of the crops and by the state of the ecosystem service functions, the specific indicators being settled by the assessor; for an ecosystem providing chiefly provisioning services the baseline covers the yield and quality of the agricultural products, for one providing chiefly supporting and regulating services the amount of soil and fertility retained and the amount of water conserved, and for one providing chiefly cultural services the number of visitors and the level of visiting.

6.4.2 Damage is confirmed by comparing the present state of the farmland soil, the irrigation water, the atmosphere of the farming area, the crops and the features and service functions of the ecosystem with the baseline level, so that the fact and the type of damage are settled. The ecosystem may be held to be damaged where any one of the following holds: the concentration of a characteristic pollutant or a toxic and harmful substance in the soil, the irrigation water, the atmosphere or the crops exceeds the baseline and carries a potential or definite risk of harm; a physical or chemical index of those elements, pollutants and toxic and harmful substances apart, has changed adversely against the baseline; the concentration of a characteristic pollutant or toxic and harmful substance in the soil, the irrigation water or the atmosphere is enough to produce a toxic response in the crops or other organisms; the population features of the agricultural organisms, such as density, dynamics, interaction and spatial structure, the community features such as species composition, structure and dynamics, or the ecosystem features such as biodiversity have changed adversely against the baseline; the ecological service function has fallen or been lost against the baseline; or there is another circumstance causing damage to the farmland ecosystem.

7 Causal analysis of farmland ecosystem damage

7.1.1 A causal relation between an act of destroying the ecology and damage to the farmland ecosystem may be held to exist where all of the following conditions are met together: there is a definite act of destroying the ecology; the object of the damage shows the fact of being damaged; the act and the fact of damage are correlated; the act took place before the damage to the farmland ecosystem; and the object of the damage can be shown not to be affected only by climate change, natural disaster or a high background value.

7.1.2 A causal relation between an act of polluting the environment and damage to the farmland ecosystem may be held to exist where all of the following conditions are met together: a characteristic pollutant is detected in the object of the damage at a content above the baseline; the suspected pollution source may have discharged or increased that pollutant toward the object; there is no other similar pollution source, or the effect of similar sources on the object can be excluded or neglected; the act of pollution took place before the damage; and the object can be shown not to be affected only by climate change, natural disaster or a high background value. The second condition may be examined in particular from the common origin of the pollutants, the reasonableness of the migration path and the possibility of exposure of the receptor.

7.2 Where the site has changed or partly disappeared, or where there is dispute or uncertainty, scenario reproduction or simulated investigation may be carried out by simulation experiment, theoretical analysis, multivariate statistical analysis or mathematical analysis models, expert review being added where necessary.

8 Physical quantification of the damage and preparation of the restoration plan

8.1.1 The degree of damage to the farmland ecosystem is settled as a whole from the damage to the environmental elements such as soil, irrigation water and the atmosphere of the farming area, to the ecosystem features and to the service functions. The analytic hierarchy process may be used, the assessor scoring the elements from the field survey or experts in the field being invited to score them, so that the relative size of the effect of each element is analysed and the degree of damage settled from the element weights; where an element carries several indicative indicators, the weight of each indicator may likewise be obtained by the analytic hierarchy process. On the basis of the level of the indicative indicators and of the baseline level, the degree of damage is settled by formula (1), whose legend defines the degree of damage of the indicative indicator of an environmental element, of an ecosystem feature or of a service function, its baseline level and its present level after damage.

8.1.2 The quantification of the extent of the damage covers the spatial extent and the temporal extent. From the matters to be identified, the confirmation of the damage and the quantification of its degree, together with the type and features of the ecological destruction, the migration and diffusion of the characteristic pollutant or toxic and harmful substance and the symptoms or features of the damaged object, the spatial extent is settled as a whole. Where the damage is chiefly ecological destruction, the state of the farmland ecosystem before and after the damage is settled from the features of the act together with the cadastral and land use planning, the field surveys and monitoring before and after the damage, and the remote sensing imagery and field survey data, so that the spatial extent is quantified. Where the damage is chiefly pollution, it is settled as a whole by closer monitoring and interpolation, from the duration of the pollution source, the content of the characteristic pollutant in the soil and its mode of migration and transformation, and the symptoms and duration of the crop damage. The temporal extent is settled from the duration between the occurrence of the damage and the recovery to the baseline; where the ecosystem cannot be recovered the damage is permanent, and the duration of permanent damage is generally computed as 100 years.

8.2 Recoverability is rated by literature research, expert consultation, case study and simulation experiment, so that the economic, technical and operational feasibility of restoring the damaged farmland ecosystem and its service functions to the baseline is evaluated. Where restoration measures can wholly or partly restore the system and there is no interim damage, a basic restoration plan is drawn up; where compensatory restoration is needed, the feasibility of the compensatory plan is also to be rated.

8.3.1 The restoration target is in principle the baseline level. Where the growing conditions are severely damaged and the baseline is hard to reach, or where restoration to it is not economically, technically or operationally feasible, the content of the target pollutant in the restored soil is to be brought to or below the screening value laid down in GB 15618, and the quality and productivity are to be not lower than the reclamation quality control standard of TD/T 1036 for agricultural land of the corresponding region and type; the part that cannot be restored to the baseline may be dealt with by a suitable alternative restoration plan or quantified in value by an environmental value assessment method. The assessment indicators of the basic and compensatory restoration plans are chosen according to the service function: farmland area, product yield and quality for a chiefly provisioning system; farmland area, soil and fertility retention and water conservation for a chiefly supporting and regulating system; the number of visitors and the level of visiting for a chiefly cultural system; and, where the act was one of pollution, the soil environmental quality indices and the pollutant concentration in the crops as well.

8.3.1 (continued) The restoration technique is screened in four steps. The restoration mode is settled from the features of the act, following GB/T 16453.1 and NY/T 3499. The technique is then screened by reference to similar cases and to the features, degree and extent of the damage and the nature of the ecosystem, following GB/T 16453.1, GB/T 30600, GB/T 39792.1 and GB 50288, or by expert scoring with an indicator system and weights so that the candidate techniques are ranked and one or more proposed. The technique is then verified for feasibility by a field trial on a farmland ecosystem with conditions similar to the assessment area, or directly on a small plot inside it; where the technique has already been successfully applied in the field on a similar system, experts may be assembled to review the case data and reports instead of a field trial. Finally the technique is confirmed from the verification result, having regard to cost and feasibility. Once the extent, target, mode and technique are settled, the concrete methods of basic and compensatory restoration are fixed and a detailed restoration plan prepared.

8.3.2 and 8.3.3 Where the duration from the occurrence of the damage to the recovery to the baseline is longer than one year, the interim damage is to be computed and both a basic and a compensatory restoration plan drawn up; where it is one year or less, only a basic plan is needed. The interim damage is generally quantified by equivalence analysis, and the scale of the compensatory restoration computed from it; the indicator chosen for the quantification is generally the one with the longest damage and recovery time among those expressing the extent or the degree of the damage, the computation following GB/T 39791.1. For a chiefly provisioning system, where the farmland was already in agricultural use before the damage and no products can be grown or raised while the basic plan is carried out, the interim damage is computed at the market price of the products during the restoration period; where it was not in use before the damage and no use is planned during the restoration, resource equivalency analysis applies. For a chiefly supporting and regulating system, resource equivalency analysis and service equivalency analysis are preferred; for a chiefly cultural system, value equivalency analysis. The principles and methods of the compensatory plan follow GB/T 39791.1, its scale depending on the size of the interim damage, and the indicators expressing the level of compensatory restoration are settled according to its type, with reference to the part of 8.3.1 on the restoration target.

9 Value quantification of farmland ecosystem damage

9.1 The general rules are that the cost of removing the pollution incurred after the act, so as to lessen or remove the harm to the farmland ecosystem, is taken at the cost actually incurred, the necessity and reasonableness of which is to be judged; that recoverable damage is computed by the restoration cost method; and that unrecoverable damage may be computed by the market value method, the replacement cost method, the travel cost method or the willingness to pay method, so that the resource and environmental value of the farmland ecosystem is quantified.

9.2.1 The restoration cost comprises direct and indirect costs. The direct costs cover the main equipment, materials and works of the restoration project, and the indirect costs cover monitoring of the works, project supervision, environmental supervision, quality control, safety protection and the prevention of secondary pollution or damage. The method of computing the cost is chosen in the following order of priority: statistics of actual expenditure, a detailed cost breakdown, contractor quotation, reference to a guideline or handbook, and comparison with cases, following GB/T 39791.1 and GB/T 39792.1. The costs and expenses are taken from the actual survey data of the place where the plan is carried out. Where natural restoration, plant restoration or field management restoration is used, the cost is estimated from the actual expenditure and by the market value method.

9.2.2 The resource and environmental value of the farmland ecosystem is quantified as follows. For a chiefly provisioning system, the loss of the provisioning function is quantified by the market value method, the computation following NY/T 1263 or SF/Z JD0601001. Where supporting and regulating services existed before the damage, the technical parameters needed are obtained by material collection, interview, questionnaire, expert consultation, monitoring and sampling and laboratory testing, the physical and value quantities being obtained following B.1 and B.2 of Annex B and the computation following NY/T 1263. Where cultural services were provided before the damage, parameters such as the number of leisure and tourism visits are obtained by survey and the loss of the cultural function quantified by the travel cost method, the computation following B.3 of Annex B. For agricultural genetic species resources the computation follows HJ 627. The resource and environmental value of the farmland ecosystem is computed by formula (2), whose legend defines the value of the damage, the type of service function damaged, the service function value of the damaged farmland, the discount or compound interest rate, any given year within the assessment period, the assessment base year, the starting year of the damage and the final year of the damage; the summation signs of the formula are lost in the extracted text and the formula is not reproduced here.

10 Assessment of the effect of farmland ecosystem restoration and preparation of the report

10.1 After the restoration plan has been carried out, the recovery of the farmland ecosystem is followed periodically and the consistency of the effect with the expected target assessed as a whole; where the target has not been reached, supplementary restoration is to be continued or the ecological and environmental loss quantified. The assessment comprises preliminary preparation, assessment of the restoration process and assessment of the completion of the restoration target.

10.2 Preliminary preparation comprises material collection, interview and site reconnaissance. The material collected covers the damage survey report, the monitoring data, the identification and assessment report, the restoration plan, the implementation scheme, the monitoring data during construction, the supervision report, the completion report and the tending records. The interviews are held with the departments and persons responsible and with those who took part in the survey, the identification and assessment, the preparation of the plan, the construction and the supervision, so that the whole process is understood. The site reconnaissance establishes the progress of recovery of the soil, the irrigation water quality, the crops and the service functions, and is recorded by photographs, video and text.

10.3 The assessment of the restoration process comprises a summary of the process and an analysis of the process monitoring data. From the material, the interviews and the reconnaissance, and against the restoration plan, the consistency of each measure with the plan is analysed by comparison; where the construction did not cover the content of the plan, supplementary restoration is to be carried out. The measures against secondary pollution from the waste, waste water and waste gas produced during construction are analysed, together with the possibility, type, area and control measures of secondary pollution and damage to the soil, the irrigation water and the service functions. From the monitoring data obtained, the way the responsible units carried out monitoring according to the plan and the relevant standards is analysed; where the data are not sufficient, supplementary monitoring is to be carried out meeting the requirements of the process monitoring, which follow the part of 6.2.3 on the survey of the objects of damage; where they are sufficient, the completion of the restoration target is first analysed as 10.4.3 requires.

10.4 The assessment of the completion of the target begins with a conceptual model. From the material, the interviews, the reconnaissance, the summary of the process and the analysis of the monitoring data, a conceptual model of the state before and after restoration is built in text and diagrams, so as to give a basis for the survey and monitoring plan of the assessment stage; the model chiefly covers the general situation of the restoration, the natural conditions that affect the environmental or ecological restoration, and the change of the target indicators over time. A survey and monitoring plan for the assessment stage is then drawn up from the conceptual model and the restoration target, making clear the content, area, indicators, methods, frequency and timing. The survey and monitoring are carried out after the completion of the restoration works; where the mode is artificial restoration or artificially assisted natural restoration, the restored area is assessed and the secondary damage that may arise in the surrounding area is surveyed and evaluated, and where the mode is natural restoration only the restored area is assessed; the indicators are chosen from Annex A according to the target set in the plan, and the methods follow the part of 6.2.3 on the survey of the objects of damage. From the features of the works and the monitoring data, the data obtained are analysed as needed and the completion of the indicators judged: where the target has been reached, restoration may stop and the assessment end; where it has not, supplementary restoration is to be continued or the ecological and environmental loss quantified; and where only part of the area falls short, supplementary restoration or loss quantification applies to that part.

11 The identification and assessment institution prepares, according to the requirements of the entrusting party and the relevant laws and regulations, either a judicial appraisal opinion or an identification and assessment report. The judicial appraisal opinion follows the document format required by the notice of the Ministry of Justice on the issue of judicial appraisal document formats, and the format and content of the identification and assessment report follow GB/T 39791.1. After the restoration effect assessment is completed, a restoration effect assessment report is prepared, whose content chiefly comprises the project background, the assessment work programme covering the target, basis, content and standards, extent, technical route and methods, the assessment of the restoration process covering the process summary and the analysis of the process monitoring data, the assessment of the completion of the target covering the conceptual model, the survey and monitoring and the analysis of completion, the conclusions and the attachments.