Vegetation Restoration Research Articles

Spatially Explicit Evaluation of the Suitability and Quality Improvement Potential of Forest and Grassland Habitat in the Yanhe River Basin

Habitat suitability assessment for forest and grassland ecosystems is a critical component of ecological restoration and land use planning in the Loess Plateau, aiming to advance soil and water conservation and foster sustainable ecological environment development. Despite progress in vegetation restoration, systematic evaluations of habitat suitability in complex geomorphic regions like the Loess Plateau remain scarce, particularly in balancing hydrological and ecological trade-offs. The Yanhe River Basin (7725 km2), a sediment-prone tributary of the Yellow River, exemplifies the challenges of soil erosion and semi-arid climatic constraints, making it a critical case for evaluating restoration strategies. This study employed a comprehensive approach utilizing Analytic Hierarchy Process (AHP), Geographic Detector, mathematical statistics, and other methods. An evaluation indicator system and methodology were established to assess the suitability of forest and grassland habitats in the Yanhe River Basin, evaluating the suitability and quality improvement potential under the current land use conditions. The results indicate: (1) The dominant factors influencing the suitable distribution of forests include photosynthetically active radiation (PAR), soil total phosphorus content, annual precipitation, and elevation. For grasslands, the dominant factors include photosynthetically active radiation, annual average temperature, elevation, and annual precipitation. (2) In the watershed, forestland and grassland areas classified as moderately suitable or higher cover 1064.9 km2 and 4196.9 km2, accounting for 91.9% and 94.7% of their total respective areas, indicating a generally rational spatial allocation of forest and grassland ecosystems. (3) The improvable area for forests measures 366 km2 (34.4% of moderately or higher suitability zones), with most already meeting coverage thresholds. In contrast, grasslands have an improvable area of 2491.6 km2 (59.4% of moderately or higher suitability zones), where over half of the area remains below coverage thresholds corresponding to their habitat conditions. (4) Forests can adopt natural restoration-focused low-intensity interventions through strengthened closure management, while grasslands require spatially tailored measures—such as precipitation interception and enhanced stewardship—targeting suitability-based potential grades, collectively achieving overall improvement in grassland vegetation coverage. This study represents the first systematic evaluation of forest–grassland habitat suitability in the Yanhe River Basin, elucidating its spatial distribution patterns and providing critical insights for watershed-scale ecological restoration.

Converting Cropland to Forest Improves Soil Water Retention Capacity by Changing Soil Aggregate Stability and Pore-Size Distribution

The semi-arid region of North China has undergone extensive afforestation to prevent land degradation. Although afforestation was considered an effective way to improve soil water retention, the mechanism by which it affects soil hydraulic properties remained uncertain. In this study, soil water retention curve (SWRC), soil water-stable aggregates, and other soil physicochemical properties were determined in short-term abandoned cropland (AC), shrubland (SL), and woodland (WL) that had been converted from cropland for 1, 8, and 24 years, respectively. Pearson correlation analysis and partial least-squares structural equation modeling methods were used to identify the main factors affecting soil hydraulic properties. Results showed that the SWRCs of all three land uses were well-fitted by a double-exponential model. The WL and SL land uses exhibited higher soil field capacity (0.33–0.37 cm3 cm−3), wilting point (0.20–0.23 cm3 cm−3), and available water content (0.13–0.15 cm3 cm−3). Surface soil exhibits a more pronounced trend in water retention capacity changes compared to subsoil under vegetation restoration. The WL and SL land uses showed more soil macroaggregates and intra-aggregate pores at surface layers, which mainly explained the variations in hydraulic properties. The main factors influencing soil hydraulic properties were soil aggregates, matrix and structural porosity, soil organic carbon (SOC), and soil bulk density (BD). Overall, afforestation can improve soil hydraulic properties and could be an effective practice for soil and water conservation in the semi-arid region of North China.

Analysis of Water and Sediment Changes at Different Spatial Scales and Their Attribution in the Huangfuchuan River Basin

Water–sediment evolution and attribution analysis in watersheds is one of the research focuses of hydrogeology. An in-depth investigation into the spatiotemporal variation of water and sediment at multiple spatial scales within the basin, along with a systematic assessment of the respective impacts of climate change and human activities, provides a scientific foundation for formulating effective soil and water conservation practices and integrated water resource management strategies. This research holds significant implications for the sustainable development and ecological management of the basin. In this study, the Mann–Kendall nonparametric test method, double cumulative curve method, cumulative anomaly method, and cumulative slope change rate analysis method were used to quantitatively study the effects of climate change and human activities on runoff and sediment load changes at different spatial scales in the Huangfuchuan River basin. The results show that (1) from 1966 to 2020, the annual runoff and annual sediment load discharge in the Huangfuchuan River basin showed a significant decreasing trend. Among them, the reduction in runoff and sediment in the control sub-basin of Shagedu Station in the upper reaches was more obvious than that in the whole basin. The mutation points of runoff and sediment load in the two basins were 1979 and 1998. The water–sediment relationship exhibits a power function pattern. (2) After the abrupt change, in the change period B (1980–1997), the contribution rates of climate change and human activities to runoff and sediment load reduction in the Huangfuchuan River basin were 24.12%, 75.88% and 20.05%, 79.95%, respectively. In the change period C (1998–2020), the contribution rates of the two factors to the runoff and sediment load reduction in the Huangfuchuan River basin were 18.91%, 81.09% and 15.61%, 84.39%, respectively. Among them, the influence of precipitation in the upper reaches of the Huangfuchuan River basin on the change in runoff and sediment load is higher than that of the whole basin, and the influence on the decrease of sediment load discharge is more significant before 1998. There are certain stage differences and spatial scale effects. (3) Human activities such as large-scale vegetation restoration and construction of silt dam engineering measures are the main reasons for the reduction in runoff and sediment load in the Huangfuchuan River basin and have played a greater role after 1998.

Effects of Artificial Vegetation Restoration Pattern on Soil Phosphorus Fractions in Alpine Desertification Grassland

Phosphorus (P) is essential for plant growth, but its soil availability depends on the characteristics of P fractions. However, few studies have examined soil P fractions under ecological restoration in alpine and semi-humid regions. This study investigated three restoration methods on the eastern Tibetan Plateau: planting mixed grasses (MG), planting Salix cupularis alone (SA), and planting Salix cupularis in combination with grasses (SG), restored for 14 years, with untreated sandy land (CK) as control. Through field sampling and laboratory analysis, soil P fractions and physicochemical properties were analyzed. The findings demonstrate that the three ecological restoration modes could increase total P and total organic P content and reduce inorganic P content. Ecological restoration can improve the content of soil labile P (resin-Pi, NaHCO3-Pi, and NaHCO3-Po) by activating NaOH-Pi and HCl-P, thus improving the availability of soil P and increasing the potential P (residual-P) source. Soil P fractions content positively correlated with SWC, SOC, and TN (p < 0.05) but negatively with BD and pH (p < 0.05). The experimental outcomes of this study will help to understand the P availability and its potential sources during ecological restoration while providing a scientific foundation for selecting optimal restoration strategies in alpine sandy land.

Natural Revegetation Alters Habitat Conditions, Bacterial Components, and Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Communities in Aged PAH-Polluted Soils

The vegetation restoration of contaminated sites plays a critical role in ensuring the sustained stability and functional integrity of natural ecosystems. However, during the natural revegetation process, the variations in habitat conditions, bacterial community structure, and metabolic functions in aged, polluted soil are still unclear. In the present study, we investigated aged, polycyclic aromatic hydrocarbon (PAH)-polluted soils at closed, abandoned oil well sites from the Yellow River Delta. Using gene amplification and real-time qPCR methods, the abundance, taxonomy, and diversity characteristics of indigenous bacterial communities and functional bacteria carrying C12O genes in both vegetated soils and bare soils were investigated. The results show that natural revegetation significantly changes the physicochemical parameters, PAH content, and bacterial community structure of aged, PAH-polluted soils. When comparing the abundance and components of PAH-degrading bacterial communities in vegetated and bare soils, the PAH-degrading potential was revealed to be stimulated by vegetation communities. Through correlation analysis, dual stress from soil salinity and PAH contamination in bacterial communities was revealed to be mediated through alterations in the soil’s physicochemical properties by local vegetation. The network analysis revealed that bacterial communities in vegetated soils have higher network connectivity. These results elucidate the alterations in habitat conditions, bacterial components, and PAH-degrading communities following vegetation restoration, providing critical insights for optimizing ecological rehabilitation strategies in salinized and contaminated ecosystems.

Vegetation Growth Changes and Their Constraining Effects on Ecosystem Services Under Ecological Restoration in the Shendong Mining Area

Under the ecological restoration project, the vegetation in the mining area shows a significant improvement trend. Exploring the causal relationship among the implementation of ecological restoration projects in mining areas, vegetation restoration, and the improvement of ecosystem service functions is of great significance for the current green development of coal mines. Therefore, in this study, we used the kernel Normalized Vegetation Index (kNDVI) to measure how vegetation growth has changed since ecological restoration projects began. Changes in four major ecosystem service functions, including soil conservation, net primary productivity (NPP), water yield, and habitat quality, were assessed before and after the restoration projects. The relationship between kNDVI and ecosystem services was further discussed by using the constraint line method. The results show the following: (1) Under the implementation of ecological restoration projects from 1994 to 2022, the annual vegetation growth rate in the mining area has progressively risen each year at a rate of 0.0046/a. Spatially speaking, 90.44% of the mining area had a substantial upward trend, indicating clear evidence of vegetation restoration. (2) Under the scientific ecological restoration of the mining areas, the total ecosystem service index increased from 0.41 in 1994 to 0.49 in 2022. The functions of ecosystem services have been enhanced to differing extents. (3) KNDVI’s constraint effect on the four ecosystem services changed dramatically before and after the ecological restoration effort. After the ecological restoration project, kNDVI’s constraint on ecosystem services decreased. (4) After restoration, the threshold value of kNDVI for maximizing the benefits of the four ecosystem services ranges from 0.1 to 0.2, and the constraint on the total ecosystem services reaches the threshold value of 0.225. This study employs more comprehensive data to examine the intricate relationship between environmental change and service function, which is crucial for the scientific management of ecological processes and facilitates the sustainable green development of mining areas.

Vegetation Dynamics and Responses to Climate Variations and Human Activities in the Basin of the Yarlung Tsangpo, Lhasa, and Nianchu Rivers in the Tibetan Plateau

Terrestrial ecosystem vegetation are vulnerable to the joint impacts of human activities and climate change, particularly in ecologically fragile areas such as the Tibetan Plateau. Identifying vegetation cover changes and distinguishing their driving factors are crucial for ecological conservation in this region. This study utilized MODIS normalized difference vegetation index (NDVI) data from 2000 to 2019, combined with trend analysis (univariate linear regression and the Mann–Kendall test), partial correlation analysis, and residual analysis methods, to investigate the spatial and temporal dynamics of vegetation cover and its responses to climate change and human activities in the Yarlung Tsangpo River, Lhasa River, and Nianchu River Basin (YLN Basin) on the Tibetan Plateau. The results revealed significant differences in vegetation dynamics both in summer and the growing season: the average summer NDVI showed a significant decreasing trend during the study period, whereas the growing season NDVI exhibited no significant overall temporal trend, which highlighted the necessity of assessing vegetation dynamics seasonally to accurately capture their interannual complexity. Partial correlation analysis indicated that precipitation was the key limiting climatic factor for vegetation growth in this region, with its positive influence covering over 90% of the land area during summer and over 60% during the growing season. The residual analysis further indicated the dual and spatially heterogeneous roles of human activities: on the one hand, positive impacts, primarily from vegetation restoration projects, promoted NDVI increases in some areas; on the other hand, negative impacts, such as continuous grazing pressure, population growth, and associated land use changes, inhibited vegetation development in other areas. This study quantitatively assessed the combined effects of climate variability and complex human activities on the vegetation NDVI in the YLN Basin, emphasizing that the development of adaptive management and effective vegetation restoration strategies must fully consider seasonal differences, the key climatic limiting factor (water availability), and the spatial heterogeneity of human impacts to promote sustainable development in this ecologically fragile region.

Effects of Afforestation on Soil Aggregate Stability, Carbon, and Nitrogen in Alpine Sandy Lands

Soil aggregate stability and carbon–nitrogen content are critical indicators for assessing the vegetation restoration effects. Salix cupularis plays a vital role in rehabilitating desertified alpine meadows on the eastern Qinghai–Tibet Plateau. However, research remains limited about how afforestation influences the soil aggregate stability and associated carbon and nitrogen dynamics. In this study, sandy land (0 years) served as the control, and the spatial time replacement method was used to examine changes in the soil water-stable aggregate composition, stability, organic carbon (OC) and total nitrogen (TN) contents, and density at a 0–60 cm depth after 5 and 10 years of afforestation restoration (Salix cupularis). Ecological restoration significantly enhanced the proportion of macroaggregates (>0.25 mm) in the topsoil (0–20 cm), and improved aggregate stability. After 10 years of restoration, macroaggregates increased by 45.04% and 51.32%, respectively. The average weight diameter and geometric mean diameter of the aggregates increased by 51.32% and 59.53%, respectively. Following restoration, there was a gradual increase in the OC and TN contents in the soil, with the highest increase observed in the 0–10 cm layer (266.67% and 391.67%). The OC and TN of the aggregates also displayed a similar trend. Correlation analysis results indicated a significant positive relationship between the soil OC and TN contents and density, OC content in aggregates of various diameters, and the stability of these aggregates. The Pearson’s correlation coefficient for OC in aggregates > 1 mm was the highest. Compared with 5 years, 10 years of recovery were more conducive to the formation of macroaggregates, enhancement in aggregate stability, and the accumulation of OC and TN. Therefore, vegetation restoration on the Zoige Plateau can significantly enhance the soil water-stable aggregate composition and stability and can also increase the soil and OC and TN contents and density, thereby enhancing the soil ecological quality. This study provides fundamental data and theoretical support for rehabilitating desertified grasslands on the eastern Qinghai–Tibet Plateau.

Water source of artificial plants in the northeastern margin of Tengger Desert based on hydrogen and oxygen stable isotopes

Understanding water sources and utilization strategies is essential for the water use patterns of vegetation restoration species and achieving sustainable vegetation restoration. The water use strategies of Corethrodendron scoparium and Calligonum mongolicum were studied in the afforestation area on the northeastern edge of the Tengger Desert, to provide scientific guidance for regional vegetation restoration and stand structure adjustment. We utilize hydrogen and oxygen isotope techniques and the MixSIAR model to calculate the contribution rates of these two plant species to various potential water sources from June to October. By calculating the PS index, we determined the competitive relationship of C. scoparium and C. mongolicum towards different water sources. The results showed that the soil moisture content in the 0-80 cm soil layer changed significantly due to rainfall and evaporation, but stabilized with increasing depth. Shallow soil water shows enriched stable isotope composition, while the isotope of groundwater is relatively stable, and the isotope of precipitation is more enriched than that of groundwater. The main water source of C. scoparium and C. mongolicum was soil moisture. The utilization rate of 0-40 cm soil layer was 27% (C.scoparium) and 33% (C.mongolicum), and the utilization rate of 40-80 cm soil layer was 32% (C.scoparium) and 25% (C.mongolicum). The average proportional similarity index (PS index) between the two species was 95.67%, indicating a competitive relationship with water resources. When the surface layer (0-40) soil moisture is high (July, August), both species preferentially absorb water from this layer, and the water competition is reduced. The average PS index is 89%. When the surface layer (0-40) was deficient in soil moisture (June, September and October), the water competition increased, and the PS index was 97.83%. This study emphasized the adaptation strategies of these shrubs to arid environments and found that it provided key insights for optimizing vegetation density and species composition in desert aerial seeding areas and ensuring sustainable ecological restoration in the study area.

The Effects of Long-Term Land Use Changes on Bacterial Community Structure and Soil Physicochemical Properties in the Northeast Mollisol Region of China

Soil microorganisms are essential for maintaining the function and health of agricultural ecosystems. However, the responses of microbial communities to long-term changes in land use have been insufficiently explored. Hence, based on a 15 years of field experiments in the northeast Mollisol region of China, we applied the Illumina high-throughput sequencing technology to study the effects of different land use types, including conventional tillage (CT), bare land (BL), no tillage (NT), natural vegetation restoration (NVR), and afforestation (AF), on bacterial communities along the soil profile (0–5 cm, 5–10 cm, 10–20 cm, and 20–30 cm) and co-occurrence networks and identified their relationships with soil physicochemical properties. The findings indicated that the land use type as well as soil depth affected the diversity and structure of bacterial communities significantly. There was no marked difference in the diversity of bacterial communities between CT and NT at different soil depths, except for a depth of 20–30 cm. In NT, NVR, and AF, the relative abundance of Actinomycetota and Firmicutes was higher than that in CT. Conversely, CT showed a remarkably higher abundance of Proteobacteria and Acidobacteriota than BL, NT, NVR, and AF. Compared with CT and BL, increased stability and complexity of the community co-occurrence networks was identified for NT, NVR, and AF. Additionally, the diversity and composition of bacterial communities were correlated with the soil’s total nitrogen (TN), pH as well as total organic carbon (TOC). Our study revealed the potential mechanism by which long-term land use changes affected the distribution of soil bacterial communities, which was of high importance for sustainable development of agriculture and optimal management of land resources.

Long-term coordinated morphological and hydrological traits of desert mosses in an arid temperate desert.

The adaptive plasticity of xerophytic vegetation in response to hydrological fluctuations serves as a critical determinant of ecosystem stability in arid regions. However, it is still unclear how mosses respond to long-term changes in water availability. We investigated Bryum argenteum Hedw., Didymodon vinealis (Brid.) Zander, and Syntrichia caninervis Mitt., which have sequentially colonized an arid revegetated area of the Tengger Desert (Northern China). The study focused on altered aboveground morphological, physiological and hydrological traits at different periods of restoration (35y, 41y and 66y) of artificial sand-fixing vegetation. B. argenteum had the smallest shoot size, biomass, Fv/ Fm, NSC content and the highest population density. In contrast, D. vinealis and S. caninervis exhibited larger shoot size, greater biomass, higher Fv/ Fm and NSC content but lower population densities. Moreover, for B. argenteum and D. vinealis, there was a trade-off between water absorption and retention. B. argenteum had the slowest water absorption and lowest dehydration rate, whereas D. vinealis exhibited greater water absorption and a faster dehydration rate. S. caninervis, however, had both high water absorption and a slow dehydration rate, which may have been facilitated by its awns. Our findings revealed that the succession of moss species in a restored desert followed three sequential adaptive trajectory shifts: from species with small shoot sizes, prioritizing high-density colonization and conservative hydrological functions (low water absorption and strong water retention capacities), to those with larger shoot sizes, prioritizing low-density colonization and competitive hydrological functions (high water absorption and rapid dehydration), and finally to species with even larger shoot sizes, featuring morphological innovations (awns) that have excellent water holding capacity (awn-mediated absorption-retention synergy). This study demonstrated that moss species can progressively optimize their adaptive strategies under prolonged ecological restoration.

Effects of Vegetation Restoration on Rill Erosion on the Chinese Loess Plateau

ABSTRACTAccurately describing rill erosion is important for building physical process models of soil erosion. Vegetation restoration may lead to differences in soil properties and root characteristics, and thus likely affects the rill erosion process to flowing water erosion, reflected by rill erodibility (Kr) and critical shear stress (τc). However, few studies have been conducted to evaluate this effect of vegetation restoration on the Loess Plateau of China. The present work chose eight typical herbaceous plants, commonly appearing at diverse vegetation succession periods on the Chinese Loess Plateau, for discovering how soil properties and root characteristics affect rill erosion. In total, we collected 240 undisturbed soil samples for overland flow scouring within the hydraulic flume in the presence of six shear stresses (range, 5.94–18.58 Pa). According to our findings, Kr and τc were 0.015–0.411 s m−1 and 0.050–6.059 Pa among eight typical grasslands. Cultivated grasslands have high Kr and low τc; the Kr was 5–25 times greater than that of other grasslands, and τc was 89%–98% less than that of other grasslands. Plants with tap root systems exhibited a 5‐fold increase in Kr value and a 50% reduction in τc compared to those with fibrous root systems. The Kr and τc were affected by the root‐soil complex, with interaction effects of root and soil being 54% and 50%, respectively. The Kr decreased with increasing bulk density (BD), soil cohesion, soil organic matter, and soil aggregate as power functions and decreased with increasing root surface area density (RSAD) and root length density as exponential functions. The τc increased with specific root length (SRL) and BD as power functions. Those above‐mentioned soil properties and root characteristics indicated that Kr was dominantly affected by cohesion and RSAD, and τc was affected by BD and SRL. Kr was simulated through soil cohesion (Coh) and RSAD, and τc was simulated by soil BD and SRL as power functions. Our constructed model achieved satisfactory performance.

Effects of vegetation restoration on soil microbial necromass carbon and organic carbon in grazed and degraded sandy land.

Effects of vegetation restoration on soil microbial necromass carbon and organic carbon in grazed and degraded sandy land.

Identifying cumulative transition effects of large-scale vegetation restoration on climate and hydrology via a dynamically separating framework

Identifying cumulative transition effects of large-scale vegetation restoration on climate and hydrology via a dynamically separating framework

Global Change Modulates Microbial Carbon Use Efficiency: Mechanisms and Impacts on Soil Organic Carbon Dynamics.

Microbial carbon use efficiency (CUE) is a key parameter of initial microbial utilization of organic matter in soil. The responses of CUE to global change factors (GCFs) remain unclear due to their multiple effects and interactions. Here, this study generalized 385 observations obtained using various methods, including 13C-/14C-labeled substrates, 18O-labeled water, stoichiometric modeling, and others. The effects of climate change (drought, precipitation, warming), fertilization (nitrogen addition, phosphorus addition, potassium addition, and nitrogen fertilization combined with phosphorus and potassium), land use conversion, and natural restoration, were evaluated along with their 16 associated GCFs on CUE. CUE was insensitive to climate change factors and most fertilization practices, maintaining a mean value of 0.36 under global change scenarios. Farmland conversion to forest and vegetation restoration decreased CUE by 11% and 17%, respectively. Grassland restoration increased CUE by 41%, indicating that grasslands have high potential for soil carbon accrual. Nitrogen fertilization combined with phosphorus and potassium increased CUE by 18% because the combined application of nutrients allows plants to produce organic matter sources with high-quality and decreases nutrient limitations for microorganisms. Increase in soil pH induced by GCFs leads to higher CUE. The CUE was decoupled from soil organic carbon content under several global change scenarios (e.g., warming, fertilization), suggesting that this relationship is not universally consistent across GCFs. This study provides a new perspective on the responses of CUE to GCFs and deepens our understanding of the global change effects on microbial physiology with consequences for soil carbon cycling.

Spatiotemporal changes and response to vegetation restoration of comprehensive ecological risk: Quantification using the external risk source-structure-function framework

Spatiotemporal changes and response to vegetation restoration of comprehensive ecological risk: Quantification using the external risk source-structure-function framework

Effects of plant carbon inputs and soil microbe on soil organic carbon accumulation in different tropical vegetation restoration strategies

Effects of plant carbon inputs and soil microbe on soil organic carbon accumulation in different tropical vegetation restoration strategies

Response Pattern of Rainfall to the Efficiency and Threshold of Soil Water Recharge in Different Slopes

Rational and effective utilization of rainfall is crucial to vegetation restoration and ecological reconstruction for engineering slopes. However, plant and vegetated concrete considerably affect soil water distribution and rainfall replenishment, which is rarely accounted for in current studies. To this end, the effects of plant and vegetated concrete on spatiotemporal distribution and soil water recharge were explored. First, four field model slopes were constructed to monitor soil water content. The spatiotemporal variations and distribution characteristics of soil water under different restoration modes were analyzed. The indicators including amount, efficiency, and threshold of soil water recharge in ecological slopes were assessed. At last, the effects of plant and vegetated concrete on the spatiotemporal distribution and recharge characteristics of soil water were discussed. Results showed that ecological restoration alters spatiotemporal distribution characteristics and reduces soil water content of engineering slopes. During rainfall process, ecological restoration extends the lag time but increases amount and efficiency of rainfall replenishment. Comparably, ecological shrub slope gains the highest lag time and rainfall threshold. Cynodon dactylon is superior to Magnolia multiflora in raising rainfall replenishment capacity. Additionally, vegetated concrete enhances rainfall replenishment efficiency by altering soil properties and interacting with plants. This study deepened the understanding of hydrological effects of ecological restoration on slopes and provided a theoretical basis for ensuring sustainable slope management.

Vegetation Restoration Outpaces Climate Change in Driving Evapotranspiration in the Wuding River Basin

Vegetation Restoration Outpaces Climate Change in Driving Evapotranspiration in the Wuding River Basin

Comparable Riparian Tree Cover in Historical Grasslands and Current Croplands of the Eastern Great Plains, with Model Expansion to the Entire Great Plains, U.S.A.

One question about historical grassland ecosystems in the Great Plains region of central North America is the percentage of tree cover overall and near major rivers, compared to current tree cover. Here, I assessed tree cover in reconstructions of historical grasslands in the eastern Great Plains, isolating tree cover adjacent to major rivers, and then compared historical land cover to current (year 2019) land cover. As an extension to supply information for the entire Great Plains region, I modeled historical cover. For the 28 million ha extent of the eastern Great Plains, historical land cover was 86% grasslands and 14% trees, but 57% grasslands and 43% trees within 100 m of rivers. Tree cover near rivers ranged from 5.4% to 90% for 15 large river watersheds, indicating that any amount of tree cover could occur near rivers at landscape scales. Currently, the overall extent was 3.6% herbaceous vegetation and 6.6% forested, with 82% crops and pasture and 8% development. Within 100 m of rivers, crop and pasture decreased to 44% of cover, resulting in 14% herbaceous cover and 38% forested cover. Current tree cover ranged from 6.2% to 66% near rivers in 15 watersheds, which was relatively comparable to historical tree cover (ratios of 0.6 to 1.5). Results generally were similar for combined tree and shrub cover modeled for the entire Great Plains. Variability, even at landscape scales of large watersheds, was the normal condition for tree cover in grasslands and riparian ecosystems of the Great Plains. In answer to the question about tree cover in historical grassland ecosystems in the eastern Great Plains, tree cover typically was about three-fold greater near rivers than tree cover throughout grasslands. Combined tree and shrub cover near rivers was more than two-fold greater than tree and shrub cover throughout the Great Plains. Riparian forest restoration, as a management practice to reduce streambank erosion, overall has been effective, as indicated by current tree cover (38% near rivers in the eastern Great Plains) comparable to historical tree cover (43% near rivers in the eastern Great Plains), albeit as measured at coarse landscape scales with dynamics in vegetation and river locations. As a next step, restoration of grassland vegetation and non-riparian wetlands likely will help reestablish infiltrative watersheds, augmenting riparian forest restoration.