Wetland conservation is becoming increasingly important as wetland areas decline globally. However, no comprehensive global-scale mapping of wetland conservation priorities and targets has been published. This information is needed to extend the current protected area network and improve the conservation efficiency for wetlands. Here, we propose a cost-effective assessment model for wetland conservation by integrating wetland conservation value- and human impact-related indicators to identify global wetland conservation priorities. These priorities cover 28% of the potential global wetland distribution, and of that, only 44% is currently protected by existing protected areas. To protect more wetland conservation priorities, we propose three target-setting scenarios for protected area expansion that offer additional contributions of 9.40%, 42.40%, and 55.97%, respectively. These three global targets can be downscaled to the national level and used to update national wetland biodiversity conservation strategies and action plans under a harmonized legal and regulatory regime at different scales and jurisdictions.

Hydrological connectivity is the main non-biological driving factor of wetland ecological processes and is key to maintaining the stability and biodiversity of the whole ecosystem. Socio-economic activities have had a significant impact on the hydrological connectivity of wetlands, resulting in the loss of biodiversity and the degradation of the ecological functions of wetlands. Wetland biodiversity hotspots in Sanjiang Plain that were identified in the previous literature using the Systematic Conservation Planning (SCP) method were chosen as the research objects. The SCP method was combined with the structural hydrological connectivity index (Integral Index of Connectivity (IIC) and Probability of Connectivity (PC)) and the functional hydrological connectivity index (Morphological Spatial Pattern Analysis) to analyze the spatio-temporal changes in the hydrological connectivity of the wetland biodiversity hotspots in Sanjiang Plain. The results showed that the hydrological connectivity within the eight identified wetland biodiversity hotspots in Sanjiang Plain experienced varying degrees of decline in the period between 1995 and 2015. Structurally, the IIC values of wetlands in all of the biodiversity hotspots were more than 0.5, and the PC values were more than 0.9, but most of the hotspots showed declining trends of varying degrees from 2010 to 2015. Functionally, the average proportion of core wetlands in the hotspots has decreased by 4.82%, and the average proportion of edge wetlands has increased by 2.71% over the last 20 years. The findings on the hydrological connectivity evolution patterns can aid in the conservation and restoration of wetlands and biodiversity hotspots.

The conservation management of biodiversity hotspots is of vital significance for biological conservation. For wetlands, which are a special type of ecosystems that are based on water as their main medium, a decline in external hydrological connectivity often leads to wetland degradation inside biodiversity hotspots. In this context, the relationship between hydrological connectivity changes inside and outside hotspots is worth exploring. Based on the wetland biodiversity hotspots identified using systematic conservation planning, this study selected eight representative biodiversity hotspots with concentrated area. Integral index of connectivity, probability of connectivity (representing structural connectivity), and morphological spatial pattern analysis (representing functional connectivity) were used to analyze the hydrological connectivity changes inside various hotspots for 1995–2015. By taking the catchment area involved as the minimum basin perimeter, this study calculated the external hydrological connectivity changes of various hotspots during this period and analyzed the relationship between hydrological connectivity changes inside and outside of hotspots. The internal and external hydrological connectivity of wetland biodiversity hotspots were found to be significantly correlated. Moreover, the internal hydrological connectivity of hotspots not only declined with declining external structural connectivity, but also changed with the proportion of core wetlands, the proportion of edge wetlands, and the proportion of branch corridors. In addition, hotspots located at intersections of high-grade rivers were more significantly affected by climate change than by human activities and their hydrological connectivity increased with increasing rainfall. The internal hydrological connectivity of hotspots near low-grade rivers presented a declining trend, mainly because of human activities. This study clarified the relationship between internal and external hydrological connectivity of wetland biodiversity hotspots. Targeted internal and external control strategies are proposed, with the aim to offer references for the conservation of wetland biodiversity.

The conflict between grain production and wetland resource protection in plain wetland is prominent. Understanding the future impacts of current land use policies on wetlands is the key to rationally evaluating and adjusting these policies. Therefore, the objective of the research was to predict the potential distribution of Sanjiang plain wetland under the current land use and protection policy using remote sensing images and CA Markov models. Methodologically, Landsat TM remote sensing images of the Sanjiang Plain (2010–2020) were used to extract wetland distribution based on object-oriented methods, and the characteristics and patterns of wetland change caused by the land use and protection policies during this period were analyzed. A CA–Markov model was used to predict the potential distribution of Sanjiang Plain wetland in 2030, 2040, 2050, and 2060. Then, we summarized the advantages and disadvantages of current land use policies and put forward adjustment measures. The results indicate that during 2010 and 2020, the wetland area of Sanjiang Plain decreased by 22.34%. The conversion ratio of wetland to non-wetland type (mainly farmland) in the first half and the second half of the decade was 46.41% and 15.31%, respectively, and the decrease in wetland showed an obvious slowing trend. The spatial distribution prediction in future showed that the wetland area will continue to decline in 2030, and the decline will basically stop in 2040. Finally, the proportion of wetland area will remain at 8.68% of the total area of Sanjiang Plain, with that of some counties and cities less than 5%. It is concluded that, although the current land use policies in Sanjiang Plain can effectively slow down the wetland area shrinking and stabilize the spatial pattern, a very low proportion of wetland area in some areas will make it difficult for the wetland ecosystem to exert ecological functions and ensure regional ecological security. The wetland conservation managers should adjust the current land use policies according to relevant requirements of farmland protection policies and restore the areal proportion and spatial pattern of wetland in order to help with regional sustainable development.