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Use of phytometers for evaluating ecological restoration
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. (Landskapsekologi)
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The increase in ecological restoration can be attributed to valuation of healthyecosystems and concerns for future climate changes. Freshwaters belong among theglobally most altered ecosystems and are restored to counteract human impacts.Many Swedish streams that were channelized to facilitate timber floating have beenrestored by returning boulders and reconnecting riparian with instream habitats.Evaluation of restoration lacks reliable indicators of organism performance, possiblydue to the complexity of ecosystem responses. Phytometers, i.e. standardized plantstransplanted to different environments, are important indicators of restorationsuccess. Phytometers integrate multiple environmental factors and measureecosystem functions directly. This thesis combines a literature review with threeexperiments and focuses on phytometer use for evaluating ecological restoration. Werecommend using different phytometer species, life-forms and life-stages and longexperiments (>1 year) to obtain high resolution and generality (I). In greenhouse andfield experiments we investigated the effect of restoring channelized rivers onphytometers and abiotic variables in the riparian zone. We hypothesized thatphytometer performance varies with stream size and climate. In the greenhouse, weanalysed differences in fertility between channelized and restored reaches by growingphytometers on soils from experimental sites (II). Phytometers grew better on soilsfrom restored sites in small streams, indicating a positive effect of restoration on soil.We detected this effect already 3-7 years after restoration, suggesting a fasterrecovery than predicted. In a short-term field experiment focusing on germinationand establishment of sunflowers, seedling survival, substrate availability, and soilnutrient content in large streams were enhanced by restoration (III). Overall,phytometers performed best at high altitudes and short growing seasons. The use ofMolinia caerulea and Filipendula ulmaria as phytometers in a long-term fieldexperiment (IV) revealed a better performance at restored sites. One reason was thatsummer flow-variability was higher, particularly in medium-sized streams. Sincephytometers allocated more biomass to belowground parts at restored compared tochannelized sites, it seems important to separate above- and belowground biomass inrestoration evaluation. Restoration outcomes vary with location in the catchment.Knowing such potentially different responses could guide restorationists in where tolocate restoration to be effective or successful. We suggest that small streams reactparticularly fast to restoration. Given that the proportion of small streams is high andthat restoration success in headwaters may favour downstream reaches, werecommend restoration to begin in tributaries to larger rivers. It is not always knownwhy phytometers react the way they do. Greenhouse experiments can disentangle thecauses of phytometer responses in the field by focusing on single environmentalfactors. We demonstrate that phytometers integrate ecosystem responses torestoration by reflecting how environmental factors affect plants under fieldconditions. Further studies are needed to better understand the underlyingmechanisms.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2013. , 31 p.
Keyword [en]
Bioassay, Channelization, Ecosystem change, Ecosystem response
National Category
Ecology
Research subject
Ecological Botany
Identifiers
URN: urn:nbn:se:umu:diva-70098ISBN: 978-91-7459-623-6 (print)OAI: oai:DiVA.org:umu-70098DiVA: diva2:619503
Public defence
2013-05-31, Uminova Science Park, Tvistevägen 48, Älgsalen, Umeå universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council Formas, 215-2006-491
Available from: 2013-05-08 Created: 2013-05-03 Last updated: 2015-07-07Bibliographically approved
List of papers
1. Phytometers are underutilised for evaluating ecological restoration
Open this publication in new window or tab >>Phytometers are underutilised for evaluating ecological restoration
2013 (English)In: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 14, no 5, 369-377 p.Article in journal (Refereed) Published
Abstract [en]

Ecological restoration increases, but evaluation of restoration efforts is inadequate because reliableperformance indicators are lacking. As plants are important actors in ecological restoration, wesuggest that they be used as meters, i.e. phytometers, of restoration success. Phytometer plants aretransplanted to different conditions to integrate measures of the prevailing conditions. We analysed100 studies for the use of phytometers and especially their applicability to evaluate ecologicalrestoration. Most studies employed single species and life-stages and focused on habitat conditionsand environmental impacts. Most experiments were conducted on grasslands in wet temperate regions.Growth was the dominant response variable, in long-term studies often combined with reproductiveoutput and plant survival. Only five studies specifically evaluated ecological restoration, implying thatits potential is not yet realised. We found phytometers promising in evaluating restoration outcomesgiven that they are easy to measure, can provide rapid results, and serve as integrative indicators ofenvironmental conditions with the ability of covering many aspects of plant life and ecosystemprocesses. To evaluate restoration success with high resolution and generality, we suggest acombination of different phytometer species, life-forms and life-stages, and experimental periods >1year to reduce effects of transplantation and between-year variation and to account for time lags inecological processes and changes after restoration.

Keyword
Bioassay; Ecosystem change; Environmental disturbance; Indicator; Plants; Transplants
National Category
Natural Sciences Ecology
Research subject
Ecological Botany
Identifiers
urn:nbn:se:umu:diva-67639 (URN)10.1016/j.baae.2013.05.008 (DOI)
Funder
Formas, 215-2006-491
Available from: 2013-05-03 Created: 2013-03-25 Last updated: 2017-12-06Bibliographically approved
2. The Use of Phytometers for Evaluating Restoration Effects on Riparian Soil Fertility
Open this publication in new window or tab >>The Use of Phytometers for Evaluating Restoration Effects on Riparian Soil Fertility
2014 (English)In: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 43, no 6, 1916-1925 p.Article in journal (Refereed) Published
Abstract [en]

The ecological restoration of streams in Sweden has become increasingly important to counteract effects of past timber floating. In this study, we focused on the effect on riparian soil properties after returning coarse sediment (cobbles and boulders) to the channel and reconnecting riparian with instream habitats. Restoration increases habitat availability for riparian plants, but its effects on soil quality are unknown. We also analyzed whether the restoration effect differs with variation in climate and stream size. We used standardized plant species to measure the performance of a grass (Phleum pratense L.) and a forb (Centaurea cyanus L.) in soils sampled in the riparian zones of channelized and restored streams and rivers. Furthermore, we analyzed the mass fractions of carbon (C) and nitrogen (N) along with the proportions of the stable isotopes C-13 and N-15 in the soil, as well as its grain size composition. We found a positive effect of restoration on biomass of phytometers grown in riparian soils from small streams, indicating that restoration enhanced the soil properties favoring plant performance. We suggest that changed flooding with more frequent but less severe floods and slower flows, enhancing retention, could explain the observed patterns. This positive effect suggests that it may be advantageous to initiate restoration efforts in small streams, which make up the highest proportion of the stream network in a catchment. Restoration responses in headwater streams may then be transmitted downstream to facilitate recovery of restored larger rivers. If the larger rivers were restored first, a slower reaction would be expected.

National Category
Ecology
Identifiers
urn:nbn:se:umu:diva-98585 (URN)10.2134/jeq2014.05.0197 (DOI)000345096000010 ()
Available from: 2015-01-26 Created: 2015-01-23 Last updated: 2017-12-05Bibliographically approved
3. Restoration effects on germination and survival of plants in the riparian zone: a phytometer study
Open this publication in new window or tab >>Restoration effects on germination and survival of plants in the riparian zone: a phytometer study
2015 (English)In: Plant Ecology, ISSN 1385-0237, E-ISSN 1573-5052, Vol. 216, no 3, 465-477 p.Article in journal (Refereed) Published
Abstract [en]

Many streams that were channelized to facilitate timber floating in northern Sweden, have in recent years been restored by returning coarse sediment (cobbles and boulders) to the channel and reconnecting riparian with instream habitats. We asked if such restoration measures affect germination and survival of plants in the riparian zone, and if such potential effects depend on location in the catchment. We used a paired site approach, comparing the performance of Helianthus annuus (sunflower) phytometers (seeds and seedlings) in the riparian zone in channelized versus restored river reaches along climate and stream size gradients in the Vindel River catchment in northern Sweden. Phytometer survival, substrate availability, and soil nutrient content in large streams were enhanced by restoration, but overall, phytometer performance was negatively related to the length of the growing season, i.e. phytometers grew best at high altitudes and short growing seasons. This result may have been caused by less competition from the shorter and sparser neighbouring vegetation at these sites or to more frequent flooding events, enhancing retention of organic matter. Soil nutrient levels were lowest close to the coast and in large streams, probably due to deposition of mineral sediment. The higher availability of riparian habitat at restored than at channelized sites suggests that plant species richness and abundance may potentially increase after restoration. Seedling transplantation seems to be a preferable revegetation measure, because phytometer seedlings established better than seeds and survival was significantly higher at restored sites. The good plant performance at sites with short growing seasons and high altitudes suggests that, with limited resources, restoration measures should first be located to such sites.

Keyword
Habitat availability, Helianthus annuus, Plant performance, Relative growth rate, Soil, Sunflower, rvival, Sweden
National Category
Botany
Identifiers
urn:nbn:se:umu:diva-101385 (URN)10.1007/s11258-015-0450-3 (DOI)000349975000010 ()
Note

Originally published in manuscript form with title "Restoration effects on germination and establishment of plants in the riparian zone: a phytometer study"

Available from: 2015-07-07 Created: 2015-03-30 Last updated: 2017-12-04Bibliographically approved
4. A long-term phytometer study to evaluate stream restoration along climate and discharge gradients
Open this publication in new window or tab >>A long-term phytometer study to evaluate stream restoration along climate and discharge gradients
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Simplified channel morphology caused by the channelization of rivers to facilitatetimber floating resulted in a less variable flow regime with faster flows in the mainchannel. Restoration measures aiming to counteract these impacts, such as the returnof boulders to the channel and the reconnection of the riparian zone with instreamhabitats, are expected to create a higher, more natural hydrological variability andenhance riparian site quality. In this study, we analysed the number and duration offlooding events at channelized and restored river reaches with an indirect methodusing diurnal temperature oscillation. In a long-term field experiment, we evaluatedthe effect of flooding regime on riparian plant performance by measuring survival andbiomass increment of two transplanted phytometer species, a grass (Molinia caerulea)and a forb (Filipendula ulmaria). We found that flow variability was significantlyhigher at restored compared to channelized sites in medium-sized and large streams,particularly during summer months. Phytometer performance was better at restoredsites and positively correlated with summer flooding, indicating that a more variableflow after restoration improved site conditions for phytometer growth. This may notonly result from the higher heterogeneity in channel morphology caused by thereturned boulders, but can probably also be attributed to a lower flow velocity atrestored sites. Flood variables were more often correlated with other abiotic variablesat restored than at channelized sites, which points to an increased land-waterconnectivity as a result of restoration.

Keyword
bioassay; channelization; environmental disturbance; Filipendula ulmaria;
National Category
Ecology
Research subject
Ecological Botany
Identifiers
urn:nbn:se:umu:diva-67643 (URN)
Funder
Formas, 215-2006-491
Available from: 2013-05-03 Created: 2013-03-25 Last updated: 2013-05-06Bibliographically approved

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