M. Anne Naeth

Ecological restoration for future sustainability in a changing environment

Abstract Since its emergence in the past decades, restoration ecology has demonstrated an astounding growth as a new discipline of applied science. At the same time, this young discipline has been criticized for its retrospective goals largely based on the past, its fragmented approach, and its idealistic goals, which do not relate to the real world context. Restoration with past-focused, idealistic, and/or ad hoc goals may not work in the future because an ecosystem that is restored for the past environment is not likely to be sustainable in the changing environment of the future, simple recomposition of isolated and fragmented naturalistic patches is not likely to restore ecosystem functions, and unrealistic goals and work plans are not likely to gain public support. We advocate directing the principles and practice of ecological restoration to the future. Future- aimed restoration should acknowledge the changing and unpredictable environment of the future, assume the dynamic nature of ecological communities with multiple trajectories, and connect landscape elements for improving ecosystem functions and structures. In this paper, we discuss the predictability of restoration trajectories under changing environmental conditions, the application of ecological theories to restoration practice, the importance of interdisciplinary approaches and human interventions in ecosystem recovery, and the social context of ecological restoration.

Multi-scale impacts of crested wheatgrass invasion in mixed-grass prairie

Most of North America’s northern Great Plains have been cultivated for crop production, leaving remnants of natural mixed-grass prairie fragmented and threatened by alien plant invasions. The region’s most widespread alien perennial forage crop, crested wheatgrass (Agropyron cristatum sensu amplo), has invaded native grassland and raised concerns regarding its ecological impact. To evaluate impacts at multiple scales of organization, adjacent invaded and uninvaded mixed-grass prairie were sampled at eight widely separated locations. At the population level, native C3 mid-grasses and forbs were less abundant in invaded grasslands, while native C3 and C4 short-grass abundance was not different. At community and landscape levels, diversity was lower in invaded grasslands largely because of lower forb species richness and cover, and crested wheatgrass dominance of both cover (14% basal cover) and seedbank (404 seeds m−2). At the ecosystem level, both vegetation and litter biomass were greater in invaded grasslands, however, below ground organic matter (roots and litter), soil organic carbon, total nitrogen and phosphorus were not different. Crested wheatgrass invasion of mixed-grass prairie was associated with lower diversity within and among plant communities, and appears to simplify the composition of mixed-grass prairie landscapes. Hypotheses for crested wheatgrass dominance and persistence following invasion are suggested.

Effect of native prairie, crested wheatgrass (Agropyron cristatum (l.) Gaertn.) and Russian wildrye (Elymus junceus Fisch.) on soil chemical properties.

Crested wheatgrass and Russian wildrye are used extensively as seeded pastures in the prairie region of western Canada. Their long-term impact on soil quality was studied at 4 sites, each including plant communities of native mixed prairie rangeland and 17to 27-year-old monocultures of crested wheatgrass and Russian wildrye, in southern Alberta, Canada. Root mass and soil chemical properties were determined on the soil samples collected. Native rangeland had about 7.6 times more root mass than the seeded species from the 0to 7.5-cm depth and about equivalent mass from the 7.5to 40-cm depth. For the seeded species, root mass was significantly less between rows than within rows. Soils in the native rangeland community had significantly greater soil organic matter and lower NO3-N, chemical index, urease activity, and available phosphorus than those in the seeded pastures. Altering the plant community from native mixed prairie to either a sequence of cropping followed by an introduced grass monoculture, or directly to an introduced grass monoculture, resulted in decreased root mass and organic matter, and monosaccharide content of dry aggregates. The seeded grasses could neither return nor maintain the chemical quality of the soils in relation to that of the native rangeland.

Grazing and soil carbon along a gradient of Alberta rangelands

Abstract The regional scale response of soil carbon mass to long-term grazing exclusion was investigated in the Canadian Great Plains. Vegetation, litter, macro-organic matter and soil were sampled in paired grazed and ungrazed treatments from 9 independent locations along an environmental gradient in southern Alberta. Vegetation and litter carbon mass were greater on ungrazed treatments, but no consistent grazing effect was observed for macro-organic matter (roots, subsurface litter) or soil (fine particles < 2mm) carbon mass per equivalent soil mass. Soil carbon in mixed grass prairie was positively correlated with clay content, but no grazing effect could be detected when this subset (n = 7) was analyzed by ANCOVA. Comparison of multiple sites with a consistent sampling and reporting method revealed no general trend in the response of soil carbon to grazing. Current range management practices to maintain range types in good to poor condition appear to be consistent with maintaining the soil organic matter pool in the northern Great Plains.

Grazing intensity effects on weed populations in annual and perennial pasture systems.

Abstract Few studies report animal grazing effects on weed populations. A study was conducted to assess weed populations in annual and perennial forage grasses grazed at various intensities by cattle over a 4-yr period. The perennial forages were Bromus inermis and Bromus riparius, and the annual forages were winter Triticosecale and a mixture of Hordeum vulgare and winter Triticosecale. With few exceptions, results from the two annual pastures could be adequately described as a group, as could the results from the two perennial pastures. The two most prevalent weed species were Capsella bursa-pastoris and Taraxacum officinale; other species encountered over the course of the study were analyzed as a group. Tillage (seedbed preparation) in the annual system supported a proliferation of annual weeds in the spring. In the perennial pasture system, a lack of tillage and spring MCPA allowed T. officinale to increase as the study progressed, especially at the highest grazing intensity. In the perennial pastures, each unit increase in grazing intensity led to 51 more C. bursa-pastoris m−2 and 4 more T. officinale m−2. At lower levels of grazing intensity, C. bursa-pastoris and other species were most abundant in the annual pastures. Weed population shifts in response to grazing pressure in the annual pasture systems were restricted because of annual tillage and MCPA. Therefore, pasture managers may subject annual pastures to heavy grazing pressure with less negative weed population consequences than perennial pastures where herbicides are not applied. Nomenclature: MCPA; Capsella bursa-pastoris (L.) Medik. CAPBP, shepherdspurse; Taraxacum officinale Weber in Wiggers TAROF, dandelion; Bromus inermis Leyss. ‘Carlton’, smooth bromegrass; Bromus riparius Rhem. ‘Paddock’, meadow bromegrass; Hordeum vulgare L. ‘AC Lacombe’, barley; × Triticosecale Wittm. ‘Pika’, winter triticale.

Initial Ecosystem Processes as Key Factors of Landscape Development—A Review

The Earths surface is the dynamic interface of climatic, biotic, and geologic systems and is often described as the Earths critical zone. Structures and processes within this zone are highly complex and heterogeneous and therefore not yet completely understood, particularly with regard to their interactions. In contrast, parts of the critical zone still in their initial development stages are expected to be less complex and heterogeneous compared to mature systems. Therefore, research approaches concentrating on this crucial initial development period of ecosystems have been recently initiated. A central hypothesis is that the initial ecosystem development phase forms the later state of ecosystems. Similarly, the behavior of mature ecosystems can only be understood if knowledge about their evolution exists. The initial development stages of geo-ecosystems are characterized by highly dynamic abiotic and biotic processes. This results in the rapid formation and alteration of structures, which in turn constitute a new framework for new processes. To disentangle the structure-process interactions, interdisciplinary and integrative research approaches in the fields of geomorphology, ecology, biology, soil science, hydrology, and environmental modeling are required. We discuss ideas that emerged from the fourth Meeting of Young Researchers in Earth Sciences (MYRES IV) held at the Brandenburg University of Technology (BTU) Cottbus in 2010 (www.myres.org), which focused on the overarching question: what are the evolutionary constraints and pathways that govern development of spatiotemporal patterns in ecosystem process and structure? This paper presents a review of the most important aspects of initial ecosystem processes as key factors of landscape development.

Coarse Woody Debris Increases Microbial Community Functional Diversity but not Enzyme Activities in Reclaimed Oil Sands Soils.

Forest floor mineral soil mix (FMM) and peat mineral soil mix (PMM) are cover soils commonly used for upland reclamation post open-pit oil sands mining in northern Alberta, Canada. Coarse woody debris (CWD) can be used to regulate soil temperature and water content, to increase organic matter content, and to create microsites for the establishment of microorganisms and vegetation in upland reclamation. We studied the effects of CWD on soil microbial community level physiological profile (CLPP) and soil enzyme activities in FMM and PMM in a reclaimed landscape in the oil sands. This experiment was conducted with a 2 (FMM vs PMM) × 2 (near CWD vs away from CWD) factorial design with 6 replications. The study plots were established with Populus tremuloides (trembling aspen) CWD placed on each plot between November 2007 and February 2008. Soil samples were collected within 5 cm from CWD and more than 100 cm away from CWD in July, August and September 2013 and 2014. Microbial biomass was greater (p<0.05) in FMM than in PMM, in July, and August 2013 and July 2014, and greater (p<0.05) near CWD than away from CWD in FMM in July and August samplings. Soil microbial CLPP differed between FMM and PMM (p<0.01) according to a principal component analysis and CWD changed microbial CLPP in FMM (p<0.05) but not in PMM. Coarse woody debris increased microbial community functional diversity (average well color development in Biolog Ecoplates) in both cover soils (p<0.05) in August and September 2014. Carbon degrading soil enzyme activities were greater in FMM than in PMM (p<0.05) regardless of distance from CWD but were not affected by CWD. Greater microbial biomass and enzyme activities in FMM than in PMM will increase organic matter decomposition and nutrient cycling, improving plant growth. Enhanced microbial community functional diversity by CWD application in upland reclamation has implications for accelerating upland reclamation after oil sands mining.

Fine root dynamics in lodgepole pine and white spruce stands along productivity gradients in reclaimed oil sands sites.

Abstract Open‐pit mining activities in the oil sands region of Alberta, Canada, create disturbed lands that, by law, must be reclaimed to a land capability equivalent to that existed before the disturbance. Re‐establishment of forest cover will be affected by the production and turnover rate of fine roots. However, the relationship between fine root dynamics and tree growth has not been studied in reclaimed oil sands sites. Fine root properties (root length density, mean surface area, total root biomass, and rates of root production, turnover, and decomposition) were assessed from May to October 2011 and 2012 using sequential coring and ingrowth core methods in lodgepole pine (Pinus contorta Dougl.) and white spruce (Picea glauca (Moench.) Voss) stands. The pine and spruce stands were planted on peat mineral soil mix placed over tailings sand and overburden substrates, respectively, in reclaimed oil sands sites in Alberta. We selected stands that form a productivity gradient (low, medium, and high productivities) of each tree species based on differences in tree height and diameter at breast height (DBH) increments. In lodgepole pine stands, fine root length density and fine root production, and turnover rates were in the order of high > medium > low productivity sites and were positively correlated with tree height and DBH and negatively correlated with soil salinity (P < 0.05). In white spruce stands, fine root surface area was the only parameter that increased along the productivity gradient and was negatively correlated with soil compaction. In conclusion, fine root dynamics along the stand productivity gradients were closely linked to stand productivity and were affected by limiting soil properties related to the specific substrate used for reconstructing the reclaimed soil. Understanding the impact of soil properties on fine root dynamics and overall stand productivity will help improve land reclamation outcomes.

Establishment of a native bunch grass and an invasive perennial on disturbed land using straw-amended soil

Native grasslands around the word face increased threats from non-native species. Fescue prairie in North America, in good rangeland condition, is dominated by the perennial bunch grass, Festuca hallii, whereas disturbances are often colonized by Poa pratensis, an introduced perennial rhizomatous grass which is competitive in nitrogen rich soils. F. hallii thrives in typical low nitrogen grassland soils and recovers poorly once disturbed. Disturbance to soil caused by well site construction may decrease organic carbon and potassium, and increase nitrogen, phosphorus, pH and electrical conductivity, creating conditions conducive to invasion by P. pratensis. This research tested the hypothesis that F. hallii would tolerate nitrogen depleted soil, through addition of carbon as a straw amendment to newly reclaimed well sites, better than P. pratensis. Our second hypothesis was that F. hallii is negatively affected by disturbed soil and P. pratensis is not. We treated three sites with three straw amendment rates, seeded monocultures of F. hallii and P. pratensis, and monitored establishment over three years. F. hallii biomass, root biomass, leaf length and cover increased in response to straw treatments, whereas P. pratensis showed little response. F. hallii was positively affected by prior-year soil water, and current-year ammonium and potassium. P. pratensis was positively affected by current-year soil water, potassium and nitrate. P. pratensis responded positively to higher pH and electrical conductivity found in disturbed soil and F. hallii responded poorly. The positive relationship of P. pratensis to pH above 7 could explain why it can invade reclaimed disturbed grassland; whereas the negative reaction of F. hallii might explain its failure to recover. We concluded the addition of straw as a soil amendment is a possible solution to poor establishment of F. hallii.

Natural Recovery of Rough Fescue (Festuca hallii (Vasey) Piper) Grassland After Disturbance by Pipeline Construction in Central Alberta, Canada

ABSTRACT: Many attempts to restore grasslands after pipeline construction, including soil manipulation such as topsoil stripping and replacement, and revegetation methods such as seeding native species or non-native cover species, have been unsuccessful. Recent pipeline techniques have used minimum disturbance and revegetation via natural recovery. The goal of this research was to evaluate natural recovery in rough fescue (Festuca hallii (Vasey) Piper) grassland in central Alberta, Canada. Plant species cover was evaluated, comparing pipeline right-of-way disturbances to undisturbed controls. Pipeline construction methods were assessed to determine which would be most successful in returning native grassland species. Pipelines with the most intense disturbances were dominated by wheatgrasses, with abundant bare ground and sparse moss and lichen cover; whereas those with the least intense disturbances had cover similar to native grassland. Results confirmed the importance of minimum disturbance in grasslands. Retaining grassland sod through plow-in pipeline construction and keeping disturbance as narrow as possible is critical to successful recovery. Rough fescue appears to recover better with plow-in pipeline construction than with seeding, most likely from intact sod. Therefore, narrow trenching with plow-in techniques is recommended for grasslands.