| Dongzhaigang Mangrove Nature Reserve is the first mangrove nature reserve established in China.It is rich in mangrove plants,animals,and aquatic resources,and has a benchmark effect in the industry.Taking the Dongzhaigang Mangrove Nature Reserve as the research area and the mangrove wetland ecosystem as the research object,the paper constructs a comprehensive evaluation index system through the interpretation of remote sensing data from six periods in 1976,1985,1995,2005,2018,and 2021,combining field surveys,indoor experiments,and comprehensive evaluation,and using the framework of"ecological effectiveness-management effectiveness-socio-economic effectiveness",This paper systematically analyzes the protection effectiveness of Dongzhaigang Mangrove Nature Reserve since its establishment.The main conclusions of the paper are as follows:(1)Changes in mangrove forests in the reserve.From 1976 to 2021,the mangrove area of the Dongzhaigang Mangrove Nature Reserve increased from 1395.84 hm2 to1589.28 hm~2,with the area ratio increasing from 28.6%in 1976 to 32.6%in 2021.In1976-1985,the mangrove area in the reserve decreased by 250 hm~2.From 2005 to 2018,the area of mangrove forests in the Reserve increased by 190.08 hm2.During 1976-2021,a total of 91.77 hm~2 of mangrove wetlands in the Reserve were converted into other wetlands,and 10.71 hm~2of mangrove wetlands were converted into non wetlands;During the same period,267.71 hm~2 of other wetlands and 28.21 hm~2 of non wetlands were converted into mangrove wetlands.The sequence of transferred out areas of various types of land or wetlands:muddy beach>river>mariculture farm>other land>flood wetland/inland mudflat;The order of transferred area:muddy beach>river>other land>delta/sandbar/sand island>flood wetland/inland mudflat>paddy field.(2)Water,soil,and biological pollution in the protection area.The detection results of the water quality and soil pollution monitoring indicators in the reserve show that some exceed the standard,and the heavy metal pollution degree of plants is relatively light.The comprehensive index evaluation method of organic pollution shows that the degree of organic pollution in the seawater quality of the protected area is Grade 4,which belongs to serious pollution,mainly distributed in the Sanjiang Farm area and Tashi area;The eutrophication evaluation method shows that the overall eutrophication level of the reserve is 4 levels,belonging to a high level of eutrophication,with higher levels of eutrophication in Sanjiang Farm,Solana and Tashi areas;The single factor pollution index of heavy metals in soil ranked in the order of Cd>Zn>Cr>Cu>As>Pb.Compared with the background value of Hainan soil,Cd and Zn pollution was more serious;Among plant sampling sites,85%are lightly polluted,and 15%are heavily polluted.The pollution degree of heavy metals in the fruits of mangrove plants is ranked as Cd>Zn>As>Cu>Cr>Pb,the pollution degree of branches and trunks is Cd>Zn>Cu>As>Pb>Cr,the pollution degree of leaves is Cd>Zn>As>Cu>Cr>Pb,and the pollution degree of flowers is Cd>Zn>Cu>As>Pb>Cr.Compared with the plant background value,the enrichment degree of Cd and Zn is relatively large,belonging to a relatively serious level.(3)Changes in the landscape pattern of the reserve.From the perspective of landscape pattern type index,from 1976 to 2021,the number of patches in salt water marshes,muddy beaches,construction land,ditches,agricultural ponds/ponds,flood wetlands/inland mudflat and freshwater aquaculture farms increased slightly,while the NP value of mariculture farms and other land uses increased by 149 and 57/ha respectively in the past 45 years,while the number of paddy fields decreased by 39/ha;From the perspective of changes in the landscape pattern index of mangroves,the NP value of mangroves in Dongzhai Port increased and decreased frequently from 1976 to2021,but overall,there was an increasing trend.During 2005-2018,the maximum increase in NP value was 74 per hectare;Among the protection effects of mangrove plants,the change range of mangrove area from 1976 to 2021 decreased first and then increased,indicating that the protection effect was good,and the probability of human interference during this period was continuously decreasing.(4)Protection of mangrove plants in the reserve.In terms of mangrove plant species and endangered protected plants,the number of mangrove plants in the region increased from 28 species in 17 families in 1995 to 35 species in 19 families in 2021.However,the decline in mangrove plant species and population size caused by human interference and coastal development is difficult to reverse;In 2006,there were only 10plants of the typical endangered plant"Red Elephant Plum"in the whole reserve and all of them were artificially transplanted.By 2022,there were nearly 1000 plants.The increase of mangrove species and the endangered status of individual species are slowing down,indicating that the research area has achieved good results in protecting endangered mangrove plants.(5)Achievements in the management and control of protected areas.The Dongzhaigang Mangrove National Nature Reserve has a full score for the evaluation of six indicators:staffing,institutional setup,vocational training,system construction,educational level,and publicity work,indicating that these four aspects of work have met the requirements of effective management.The evaluation of the four indicators of maintenance and use,facility types,patrol work,and funding management is relatively low,indicating that there is considerable room for improvement in these four areas of work,especially patrol work and funding,which need to be further improved.(6)Socio economic results.The contribution rate of community residents’fishing methods,fishing income,fishing months,fishing volume,protection attitude,as well as the scale of freshwater aquaculture farms,the number of permanent residents,the number of secondary schools,and the distance from villages to mangroves are all greater than 10.They are highly dependent on mangroves,and human destructive behavior is the main influencing factor for mangrove damage.The occupational structure,income sources,and protection awareness of residents in surrounding communities have important impacts on the change of mangrove area in the study area.From 1976 to 2021,the income source and occupational structure of residents shifted from agriculture and fishery to migrant work.The reduction of residents’cultivation activities and the action of returning ponds to forests directly promoted the increase of mangrove area in the protected area;The government and various departments implementing mangrove protection policies and related industrial policies,investing a large amount of protection publicity funds,and timely updating publicity means can positively guide residents to attach importance to mangrove protection and enhance their awareness of protection.(7)Comprehensive protection effectiveness.The comprehensive effectiveness evaluation based on the"ecology management socio-economic"framework shows that the comprehensive protection effectiveness index of the protected area is at the"good"level.However,the eutrophication index of water quality in the protected area is relatively high and the score of organic pollution is relatively low,respectively,being 0and 1.73,indicating that the phenomenon of water pollution in the area still exists;There is a low level of funding satisfaction,daily management/patrol frequency,and publicity and education frequency in the reserve,indicating that mangrove management needs to be further strengthened;In terms of tourist behavior and awareness,the scores of tourism frequency and dissuasion intention were 0.54 and 0.15,respectively,indicating that the harm caused by tourism still exists;Soil heavy metals,plant heavy metals,changes in species of protected plants and endangered species,changes in mangrove area,fragmentation index,and wetland conservation awareness scores are relatively high,which have a relatively small impact on mangrove conservation effectiveness.The conservation effectiveness index for area increase and decrease,size of endangered species groups,number of patches,and institutional integrity is greater than 7,indicating that these aspects of conservation effectiveness are good. |
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