Establishment of Monitoring and Assessment Index System of Land Degradation of Farmland Ecosystems at Small-scale

Yaqi GAO, Yiyuan YANG, DI Lixiati·baoerhan, Yali ZHU

Xinjiang Academy of Forestry, Urumqi 830000, China

Land degradation is a process in which biological and economic productivity and complexity decline or lose of irrigable lands, grasslands, pastures, and forests in arid, semi-arid, dry subhumid, and extremely arid[1]. It is a much complicated and comprehensive process, affected by natural and human factors and human activities constitute a major cause[2]. Population surge is a fundamental cause of irrational human activities, because the growth of population aggravates the conflict between people and land, leading to resource shortage and even destruction.Besides,extensive economic activities also causes land degradation, for backward mode of production would result in drops of land productivity and per unit area yield. Furthermore, population change, poverty, imbalanced development,land ownership,the attitude of land users on land degradation and other economic factors should be taken into consideration as well. Additionally, the excessive application of chemical products deteriorates land degradation, for many countries provide chemical fertilizers and pesticides as subsidies for farmers[3].

Land degradation is a global issue causing economic loss of agriculture,especially serious in developing countries. In China, farmland loss from farmland degradation has reached 122.545 billion yuan,affecting Chinese agriculture. Therefore, the situation would worsen if none measures are taken[4]. The research established a monitoring and assessment index system on land degradation caused by human activities,including obtaining of assessment indices, construction and assessment of monitoring and assessment system and formulated an index system and monitoring method appropriate for land users to conduct farmland degradation monitoring by themselves, on basis of a small-scale farmland ecosystem.

Materials and Methods

Monitoring and assessment objects

The research carried out land degradation monitoring and assess-ment research based on farmland ecosystem in Xinjiang.

Assessment methods

The method of participation The research introduced the model of“from bottom to top” participation, allowing stakeholders, represented by farmers, to take part in collecting indices of land degradation monitoring and assessment and helping farmers monitor farmland degradations and trends.

KJ method It is a business tool used to collect unknown problems, fields untouched,opinions,and assumptions and group the data into groups or draw diagrams based on natural relationships. Specifically, Xinjiang invited experts in land degradation research and administrative officers and established an expert consulting group, allowing large numbers of ideas stemming from brainstorming, in order to choose land degradation pre-selected indices of farmland ecosystem.

Delphi method It is a method allowing experts to answer questionnaires in tow or more rounds. After each round, a facilitator provides an anonymous summary of the experts’ forecasts from the previous round as well as the reasons they provided for their judgments. During the process, the experts are encouraged to revise the earlier answers in light of the replies of other members.Finally,based on repetitions of many rounds, the mean scores of the final rounds determine the results.

According to farmland ecosystems in Xinjiang, the experts were invited from or out of Xinjiang in order to get opinions by filling forms in terms of selected indices, importance and weights of indices(Table 1-Table 2).It is notable that the invited experts do not contact with each other and just make judgments and fill forms relying on knowledge and experience. Then,the opinions are collected and organized to compute the concentration degree and variations of experts’views, as well as coordination degree and harmonious coefficients.

Revision on assessment index system

The concentration degree and variations of expert opinions In accordance with the form of importance degree,the number of groups with experts holding different views was sorted and then converted the importance into evaluation grades of 4,3,2 and 1,followed by evaluation and assignment.Subsequently,the concentration degree (Mj)[5]and the variations (Vj) of experts on importance were computed,as follows:

where Mjis arithmetic mean; m is the number of experts of index j; Cijrefers to evaluation grade converted from importance of index j by the ith expert;Vjrefers to variations;σjrefers to standard differences of index j by different experts.

Index revision The percentage was calculated as per concentration degree of index importance and some indices should be omitted, whose opinion concentration degree was lower than 60% or the indices with variation over 0.4.The leftover indices require further analysis and calculation.

Kendall’s coefficient of concordance (rw) Kendall’s W is used for assessing agreement among raters.The data normalization is as follows:Original data are converted into grades from the same expert, which is called ordering. Because the same expert has the same grades on indices, the same grade exists at converting, when the means are computed based on the ranks[6]. The calculation of Kendall’s coefficient of concordance is as follows[7]:The coefficient is detected with SPSS as per Kendall method, supposing the opinions of experts on index importance are correlated or stochastic. The alternative hypothesis is that experts have come to an agreement on index importance,with correlation of 0.05 and confidence interval of 95%. If the opinions given by experts are similar, the detection can be stopped, or next round will follow.

Calculation of index weight When the experts reach agreement, weight of index is normalized,as follows:

where Dwjrefers to weight of the jthindex; Cijrefers to weight of the jthindex of the ithexpert.It is notable that an index can be omitted if Dwjof the jthindex is lower.

Table 1 The form on importance degree of land degradation monitoring and assessment indices of farmland ecosystem under influence of human activities in Xinjiang

Table 2 The form on weight of land degradation monitoring and assessment indices of farmland ecosystem under influence of human activities in Xinjiang

Results and Analysis

Monitoring on farmland degradation and establishment of pre-selected index collection

According to land degradation index recommended by farmers and experts, concepts and fields relevant to land degradation evaluation are determined, logical structure and relationship of land degradation types are analyzed, and information of land degradation research, evaluation index are collected.On basis of accessibility and independence of evaluation indices,the factors relevant to land degradation are selected to group a pre-index collection by qualitative analysis.

Table 3 The distributions of importance degree and variations of pre-selected indices of land degradation of farmland ecosystem by consulting experts

Table 4 The distributions of importance degree and variations of indices of land degradation of farmland ecosystem by consulting experts

Revision and improvements of evaluation index system

According to pre-index collection,31 consulting forms were issued, of which 25 forms were collected, indicating the collection rate of 80.6%.Specifically,the valid forms totaled 24,representing 96% . The impor tance and variation degrees of land degradation pre-indices of farmland ecosystem under influence of human activities were computed by consulting experts(Table 3).

The indices were revised in accordance with the principle that indices with importance degree below 60% or variation degree over 0.4 should be omitted(Table 4).

The coefficient of concordance

Based on detection of original assumption by Kendall’s method, it can be concluded that

Establishment of farmland degradation monitoring and evaluation index system in Xinjiang

According to evaluation on land degradation of farmland ecosystem under influence of human driving forces, farmland degradation monitoring and evaluation index system include farming system, measures,mulch residuals, fertilizer pollutions,pesticide pollution, irrigation method,salt content of soils,engineering measures of discharging alkali, agricultural protection forests and poverty, with weights of 0.130, 0.109, 0.098, 0.097,0.086, 0.101, 0.105, 0.104, 0.114 and 0.083,respectively.

Conclusions and Discussions

Farmland degradation concerns sustainable development, stabilization of farmer’s income, and national crop safety.It is notable that human activity,especially for irrational activity, is a major cause of farmland degradation.In China, rural land contract operation is widely applied,and household contract management dominates in rural areas, with the contract term of 30 years, so that such contract relationship of lands is protected by national laws[8].Therefore,only when land management households take initiative to keep a watchful eye on land degradation could land quality and ecosystem of farmland be resolved and agricultural sustainable development be achieved.

At present, more researches are available on land quality and sustainable use in agricultural production, but less attention is paid to monitoring and assessment on farmland ecosystem land degradation. Still, land degradations of watershed ecosystems at home and abroad have been explored and some measures are proposed. For example, Shu conducted research on causes of land degradation in Xinjiang and proposed countermeasures[9]. Luo et al. investigated environment of land degradation in the middle and upper reaches of the Yangtze River and the controls on the degradation of grasslands,saline-alkali soil,mining lands,southern subtropical hills and desertification control[10].

The research,based on first-hand information, standardized related data and proposed monitoring and assessment system of farmland degradation driven by human activities, from the perspective of small-scale land degradation monitoring.The indices of the system are accessible,and convenient for operation, which is suitable for land managers self-monitoring, reducing irrational farming activities, improving farmland productivity and preventing farmland degradation.The assessment on land degradation by the method allows comparisons in terms of different regions and time phases and normalizes farmland ecosystem monitoring, providing scientific references for monitoring and warning research, and establishment of dynamic monitoring, database, management information system, and monitoring research network of land degradation.

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