Resilience is a key function that affects an ecosystem’s ability to recover from disturbance. Understanding the extent to which forest communities recover after a long period of disturbance without direct interventio...Resilience is a key function that affects an ecosystem’s ability to recover from disturbance. Understanding the extent to which forest communities recover after a long period of disturbance without direct intervention is important to provide context for considering ecosystem response to disturbance regimes. Species composition and structure were recorded on bottomland hardwood stands that were once inland and freshwater tidal rice fields. We sampled 17 old-field sites and 7 reference sites across three geomorphic settings. The old-field sites ranged from 30 to 120 years since agricultural abandonment. A total of 89 species were found across the old field sites and reference sample areas. Of that total, trees comprised 33 species, shrubs—5 species, and vine/herbs/forbs—51 species. Using field data, combined with stand inventory records, aerial photography (1936-2010), and high-resolution LiDAR imagery, we chronicled the evolution of the forest since the cessation of agriculture. Our findings demonstrate how Pinus taeda seeded directly after the rice fields went to fallow;and this conversion of bottomland swamp to rice to pine was a direct result of water management embankments constructed across the landscape to aid in crop irrigation. The remnant water management features may still alter flooding patterns thereby affecting development of Taxodium distichum and Nyssa aquatica in the old-fields. These results suggest, that over the 100+ years forest stands on the Santee Experimental Forest have developed to represent bottomland hardwoods characteristic of the southeastern United States coastal plain.展开更多
Individual tree health plays a vital role in maintaining a forest's ecological functions,including resources for waterfowl and other wildlife.Seasonal flooding due to altered hydrology is a major stressor on indiv...Individual tree health plays a vital role in maintaining a forest's ecological functions,including resources for waterfowl and other wildlife.Seasonal flooding due to altered hydrology is a major stressor on individual tree health in Greentree reservoirs(GTR),impounded bottomland hardwood forests especially less water tolerant species like red oaks(Quercus spp.).We evaluated the health of individual red oak species(n=6,432)in 662 plots across elevation gradients in 12 GTRs within the lower Mississippi Alluvial Valley using two tree health assessment approaches.The first approach assigns tree conditions(i.e.,stressed,moderate,low)based on overall qualitative tree attributes,while the second approach ranks stress,assigning numerical value based on the severity of four distinct qualitative tree attributes(i.e.,tip dieback,epicormics branch,bark condition,basal swell).The result indicated that the highest mean stress rank and the highest proportion of stressed tree conditions were red oak species,nuttall oak(Q.texana;18.59,0.44),willow oak(Q.phellos;18.66,0.38)and cherrybark oak(Q.pagoda;18.90,0.37).Red oak stress is positively correlated to elevation across the landscape(τ=0.10,p<0.001),but is negatively correlated to relative elevation,topographical changes,within each GTR(τ=-0.11,p<0.001).Additionally,the two health assessments are significantly associated(χ^(2)=313.78,df=2,p<0.001)and had a 13.1%misclassification rate.By utilizing the stress rank method for better classification of tree conditions to understand the adverse effect of prolonged flooding on the health of desirable red oak and other native tree species,management practices can be adjusted to improve tree health in GTRs,benefiting both wildlife and economic value.展开更多
文摘Resilience is a key function that affects an ecosystem’s ability to recover from disturbance. Understanding the extent to which forest communities recover after a long period of disturbance without direct intervention is important to provide context for considering ecosystem response to disturbance regimes. Species composition and structure were recorded on bottomland hardwood stands that were once inland and freshwater tidal rice fields. We sampled 17 old-field sites and 7 reference sites across three geomorphic settings. The old-field sites ranged from 30 to 120 years since agricultural abandonment. A total of 89 species were found across the old field sites and reference sample areas. Of that total, trees comprised 33 species, shrubs—5 species, and vine/herbs/forbs—51 species. Using field data, combined with stand inventory records, aerial photography (1936-2010), and high-resolution LiDAR imagery, we chronicled the evolution of the forest since the cessation of agriculture. Our findings demonstrate how Pinus taeda seeded directly after the rice fields went to fallow;and this conversion of bottomland swamp to rice to pine was a direct result of water management embankments constructed across the landscape to aid in crop irrigation. The remnant water management features may still alter flooding patterns thereby affecting development of Taxodium distichum and Nyssa aquatica in the old-fields. These results suggest, that over the 100+ years forest stands on the Santee Experimental Forest have developed to represent bottomland hardwoods characteristic of the southeastern United States coastal plain.
基金Five Oaks Ag Research&Education Center(DS18849)the University of Arkansas Division of Agriculture(PR02276)funding was provided by the U.S.Department of Agriculture,the National Institute of Food and Agriculture,and the McIntire-Stennis Capacity Grant(2729 YR21-25 and ARK02594).
文摘Individual tree health plays a vital role in maintaining a forest's ecological functions,including resources for waterfowl and other wildlife.Seasonal flooding due to altered hydrology is a major stressor on individual tree health in Greentree reservoirs(GTR),impounded bottomland hardwood forests especially less water tolerant species like red oaks(Quercus spp.).We evaluated the health of individual red oak species(n=6,432)in 662 plots across elevation gradients in 12 GTRs within the lower Mississippi Alluvial Valley using two tree health assessment approaches.The first approach assigns tree conditions(i.e.,stressed,moderate,low)based on overall qualitative tree attributes,while the second approach ranks stress,assigning numerical value based on the severity of four distinct qualitative tree attributes(i.e.,tip dieback,epicormics branch,bark condition,basal swell).The result indicated that the highest mean stress rank and the highest proportion of stressed tree conditions were red oak species,nuttall oak(Q.texana;18.59,0.44),willow oak(Q.phellos;18.66,0.38)and cherrybark oak(Q.pagoda;18.90,0.37).Red oak stress is positively correlated to elevation across the landscape(τ=0.10,p<0.001),but is negatively correlated to relative elevation,topographical changes,within each GTR(τ=-0.11,p<0.001).Additionally,the two health assessments are significantly associated(χ^(2)=313.78,df=2,p<0.001)and had a 13.1%misclassification rate.By utilizing the stress rank method for better classification of tree conditions to understand the adverse effect of prolonged flooding on the health of desirable red oak and other native tree species,management practices can be adjusted to improve tree health in GTRs,benefiting both wildlife and economic value.
