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Garnier et al. 2004.

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Garnier, E., J. Cortez, G. Billès, M.L. Navas, C. Roumet, M. Debussche, G. Laurent, A. Blanchard, D. Aubry, A. Bellmann, C. Neill, J.P. Toussaint. 2004. Plant Functional Markers Capture Ecosystem Properties During Secondary Succession. Ecology 85(9). 2630-2637.

Background

In this article, the researchers attempted to test the biomass ratio hypothesis in an abandoned vineyard using three traits, specific lead area, leaf dry matter content, and leaf nitrogen concentration. The researchers noted that a major effect which humans are having on Earth’s ecosystems involves changing land use, in this case, an agricultural use for growing grapes for wine making. Once these properties are abandoned, problems arise in terms of restoration, since the soils may have been changed in a way which may cause difficulties with restoration and succession. Traditionally, succession starts with colonial species colonizing a property which has been disturbed. The colonizing species are replaced with mid-successional species, followed by mid-climax, and finally, climax species. From here, the climax species are removed by disturbance, and the process starts over again. In the case of this vineyard, the disturbance was the removal of the previous ecosystem to make room for the components required for a vineyard. This changes the dynamic of the succession process, which could change the biomass ratio.

Methods

The study site was an abandoned vineyard in southern France in the subhumid Mediterranean climate with a soil rich in calcium and an alkaline pH. The vineyard was removed between 1962-2002. They calculated the biomass ratio at various parts of the property to account for the time range of removal. Samples were recorded in areas where herbaceous vegetation and small woody plants were found. Net primary production was calculated between May and February (growing season). Leaf characteristics were measured during the peak of the growing season (April-May). An elemental analyzer was used for these measurements. In total, 27 species were used and 54 data points were collected.

Results and Conclusions

Biomass was lowest in the first years following abandonment, which they found started to increase after seven years, but net primary productivity decreased with field age. During this time, soil carbon and nitrogen concentrations increased threefold. The explanation given is that the early, colonial species are fast growing yet small in terms of biomass. After a growing season, they died off. They were followed up by similar species. After multiple growing seasons, the dead mass from these species littered the ground, causing an increase in soil carbon and nitrogen concentrations. After enough time, seven years in this case, later successional species colonized the study site. Later successional grow much slower yet are longer lived. This would lead to a decrease in net primary production but an increase in biomass, as the species live longer. These findings are consistent with the biomass ratio hypothesis from Odum 1969. The findings from this paper resulted in the researchers suggesting that the measured characteristics being labeled as “functional markers,” as they described them as being power quantitative tools which allowed for the prediction of plant succession patterns.

A simulation model for the transient effects of climate change on forest landscapes

Prentice, IC, MT Sykes, W Cramer. 1993. A simulation model for the transient effects of climate change on forest landscapes. Ecological Modelling: 65: 51-70.

Fores are likely to show effects with the changing climate. Many early climate scientists took an optimistic view that the increase in atmospheric carbon would be taken up by trees. Recent evidence shows that this is not the case and that atmospheric carbon levels are increasing. This has lead to two conclusions. Either more carbon is being put into the atmosphere than plants, or in this case trees, can take up, or plants are not capable of using the extra carbon as biomass. This is flawed in some ways as it doesn’t take into account the increased growing season from the increased temperatures. In this article,  the researchers use a forest succession model to simulate the effects of climate change on forests and forest succession.

The researchers used the forest succession model with a resolution of 0.1 ha. This simulated a patch interaction through lightand nutrient competition. This made the forest a collection of patches. The model looked at the effects of summer and winter temperature limitations, accumulation of annual foliage net assimilation and sapwood respiration as functions of temperature, CO2 fertilization, and growing-season drought. This means that as the temperature increases, summer and winter temperatures will change but also provide a limiting factor on tree growth. Studies have indicated that as temperature increases, photosythesis rates will increase to a point. At around 80 F, the rate of photosythesis asymptotes and decreases for many temperate hardwood trees. This same curve is also seen for arctic plants with the curve shifted to the left. Trees cannot photosythesis at low temperatures as they need access to available water. Net assimilation and sapwood respiration are limited by temperature for the same reasons. Increase the temperature may not increase the assimilation of carbon but increasing the growing season would. Increasing temperatures can evaporate the soil moisture limiting available water for photosynthesis.

Structure, composition, and biomass in boreal and temperate deciduous forests approched equilibrium values between 200 and 400 years. The limiting factor to growth is available soil moisture. Increasing temperatures leads to more available water early- and late-season but a decrease in mid-season when temperatures are the highest. Although models have limitations and assumptions, they can be good prediction tools. The results of this article suggests that forests will change but eventually reach and equilibrium, yet there are factors outside of the model that can influence forest succession. A problem when talking about succession is that succession is a botanical term. The animal community must also be considered as animals can alter an ecosystem.

Conifer root discrimination against soil nitrate and the ecology of forest succession

Kronzucker, HJ, MY Siddiqi, ADM Glass. 1997. Conifer root discrimination against soil nitrate and the ecology of forest succession. Nature. 385: 59-61.

A common practice when restoring property is to plant trees which may be late-successional species. This has been noted to be problematic as many of the species do not survive. The problems associated with planting late-successional tree species are centered around the idea that there is an ecological order to succession, and when ecosystems skip stages, there soils may not yet have the composition to support later succession stages. Micro- and macronutrients, which are needed to support later succession stages, have not had the opportunity to accumulate in the soils since many of the organisms that fix nitrogen are associated with early successional stages, and the specific nitrogen compound changes from ammonium in late-successional forest soils to nitrate after disturbances. In this study, the researchers wanted to investigate the uptake of various forms of nitrogen by late-succession species, in this case white spruce.

The researchers use a radiotracer to quantify the amount of nitrate and ammonium taken up by white spruce seedlings. The trees had a much higher rate of uptake for ammonium than nitrate. This difference is though to be regulated by the protein channels in the plasma membrane. Because the protein channels limit the transport into the cell, it shows a preference for the ammonium. This is contrast to early-successional species which have an equal affinity for both nitrogen compounds. The researchers also noted that nitrate uptake was associated with nitrate exposure. Trees which had never been exposed to nitrates previously did not transport nitrates. After three days of nitrate exposure, the trees would reach their maximum nitrate uptake rate. Aspen, a pioneering tree species, does not require previous exposure to nitrates in order for it to be taken up by the tree. When the white spruce trees were exposed to both nitrates and ammonium, the trees would have an increase in ammonium uptake. This is to be expected as the tree already has structures in place to handle ammonium uptake.

This research presents an interesting look on the ecology of succession. The spruce trees are poor competitors in the early-successional stages. This may be a direct cause of the exact nitrogen compounds present in the soil while the early-successional species do not have a particular affinity for a given compound. The aspen are more opportunistic and will take advantage of any available nitrogen in the soil. It has been previously demonstrated that competition for light, water, and physical space are important for early-successional species but also access to other nutrients. Spruces become the climax species by growing slow and partitioning resources but they may not be as efficient as once thought.

Association of non-native Amur honeysuckle with other invasive plant species in eastern deciduous forests in southwestern Ohio

Culley, T, GN Cameron, SE Kolbe, AI Miller. 2016. Association of non-native Amur honeysuckle (Lonicera maackii, Caprifoliaceae) with other invasive plant species in eastern deciduous forests in southwestern Ohio. The Journal of the Torrey Botanical Society 143(4): 398-414.

Invasive species impact native communities through a variety of techniques ranging from occupation of physical space to allelopathic changes to the soil. Many studies have demonstrated that invasive species can influence successional steps and modify the habitat in ways which can facilitate or delay succession. Amur honeysuckle, a woody shrub introduced to the US from Asia, increases the diversity of non-native species through physical and chemical alterations of the habitat. In invaded areas, Amur honeysuckle alters the soil chemistry by modifying the nutrient loads. It modifies the habitat physically by crowding out other species but by also limiting light to understory species. Amur honeysuckle grows heavily along the edge of forests, causing a change in the edge effect. It prevents other trees from spreading out and expanding the forest. Forests expand in a similar fashion to post-disturbance colonization. This is called the nucleation effect, were species colonize a particular area and expand outward from the site of colonization. As the community moves outward, densities increase in the center as new species move in all directions. By adding Amur honeysuckle, the physical and chemical competition for pioneering plants can become inhibited and stall expansion.

In this study, the researchers wanted to look at the effect Amur honeysuckle had on facilitating the invasion of non-native species. To accomplish this, the researchers used plots within four study sites located in Ohio. These plots were split between those with and without Amur honeysuckle. In each of these plots, the researchers calculated species richness, abundance, proportion, and diversity of both native and non-native species. ANOVA and regression were used as their statistical approach with ANOVA being used for comparisons of obtained values and regression for identifying environmental and anthropogenic variables that explained variation.

Plots did not differ in total richness regardless of the presence of Amur honeysuckle although the presence of Amur honeysuckle was associated with an increase in richness, proportion, and diversity of non-native species. They also found that the distance to roads was an explanatory variable for predicting these values for non-native species, which would be on track with the definition that invasive species rely on anthropogenic activity for movement, regardless of intentional or accidental introduction. The researchers noted that these results are not surprising but it does open the question of management and control. There is no need to sustain populations of Amur honeysuckle in forests given the number of native alternatives like coral honeysuckle and the ability of Amur honeysuckle to facilitate the invasion of non-native species.

Contrasting impacts of a native and an invasive exotic shrub on flood-plain succession

Bellingham, PJ, DA Peltzer, LR Walker. 2005. Contrasting impacts of a native and an invasive exotic shrub on flood-plain succession. Journal of Vegetative Science 16:135-142.

Succession looks at ecosystems changes but focuses primarily on the native plant community present. With an increase in commercial trade, many species are being introduced to ecosystems in which they did not evolve. This can be problematic as they change interactions in the ecosystem. They may cause an ecosystem to become unstable and change to an ecosystem which may have not been present. They can also facilitate the colonization of other invasive species. This facilitation can be above-ground through aggressive growth or colonization of free space or below-ground through the introduction of allelopathic effects or increased resource competition.

In this article, the researchers were exploring how a native N-fixing shrub and a non-native, non-N-fixing shrub would alter the ecosystems N:P ratio following a flood. This would make the research into primary succession since the seed bank and existing soils would have been altered due to the flood.

They measured the soil and plant N and P concentrations, light levels, plant community, and above-ground biomass of the native and non-native shrub when they were in four successional stages. The four stages are open (pre-colonization), young (following colonization), vigorous (rapid growing stage), and mature (flowering individuals). The open stage served as a control for soil conditions directly following disturbance.

The researchers found that the native shrub, although occurring at lower densities, dominated the above-ground biomass by the vigorous stage and that the soil N levels increased with increasing biomass. The introduction of the non-native shrub did not change the soil N level. The non-native shrub biomass was associated with an increase in soil P levels. During the young stage, the dominate species present were non-native but this changed by the mature stage. As the native shrub biomass increased, non-native species richness decreased.

It is thought that the non-native shrub may have facilitated the soil for an initial colonization of invasive species but altered it enough that those species could not sustain in the changed N:P ratios allowing for the dominance of native species in the mature phase of succession. Although the non-native shrub may have supported a dominance of native species, it may cause other ecosystem changes not measured in this study. If another disturbance occurs and does not change over the soils, it may allow for the subsequent colonization of non-native species. The introduction of an artificial disturbance leading to secondary succession could easily show this as a disturbance causing primary succession should produce similar results to this study.

Mechanisms of primary succession following deglaciation at Glacier Bay, Alaska

Chapin III, FS, LR Walker, CL Fastie, LC Sharman. 1994. Mechanisms of primary succession following deglaciation at Glacier Bay, Alaska. Ecological Monographs 64(2): 149-175.

Primary succession is the process in which the vegetation colonizes new soils which have been completely removed of vegetation and the seed bank. This differs from secondary succession where the vegetation is removed but the seed bank still persists in the soil. Primary succession is usually associated with glacial retreats or lava flows. During this time, resources in the soil may be limited due to sterilization or removal of soils containing microbes which can facilitate colonization. In this article, the researchers were looking at the how nitrogen-fixing colonizers facilitate establishment of late-successional species and other effects which they may have with succession.

Soil before succession were limited in N and P for pioneering plants. As early-successional species colonized, P became the limiting resource. When early-successional species were present, mid- and late-successional species had a harder time dealing with the competition of the smaller, faster growing plants. This is thought to have been from the early-successional species limiting seed success. Spruce species did grow rapidly with early- and mid-successional species but growth slowed when reaching the spruce stage (late-succession). The higher N and P requirements of the larger spruce trees may have limited the growth in late-succession. Another problem for larger spruce trees are the increase below ground competition.

The authors did a great job of addressing competition at and below the soil surface. Light competition did play a factor in mid-successional species displacing early-successional species but they also did it through allelopathic effects and physical competition below ground. Although the allelopathic effects assisted the mid-successional species, spruces are better competitors below ground.

It was demonstrated that early- and mid-successional species did produce a facilitative effect on mid- and late-successional species through additional organic matter and the addition of N to the soil. One thing that would be interesting to see is the changes in the soil composition after succession. This study focused on primary succession meaning that the soils may have changed slightly since being void of vegetation. New mineral deposits from glaciation combined with additional organic material from the colonizing early-successional vegetation and leaf fall from the mid-successional vegetation may have altered the top layers of soil which plants will use during their early stages of growth. Although the effects may be minimal, it would play a large role in establishment new species and seedling success as well as species on the forest floor.

Forest succession and terrestrial–aquatic biodiversity in small forested watersheds: a review of principles, relationships and implications for management

Brooks, RT, KH Nislow, WH Lowe, MK WIlson, DI King. 2012. Forest succession and terrestrial–aquatic biodiversity in small forested watersheds: a review of principles, relationships and implications for management. Forestry 85(3): 315-328.

Succession is the process of changing in the species composition of an ecosystem over time. When observing succession, consideration should also be taken on the surrounding communities. In this review article, the authors performed a literature review demonstrating that succession in riparian forests caused a change in the diversity of surrounding watersheds. They also outlined the impacts of management of riparian habitats on watershed biodiversity.

The location of the forest impacts the stream and changes water quality. This is also a two-way street. A forest located near the headwater causes a impact on the stream but a forest further down the watershed is effected by the processes occurring upstream. Once the forests move through succession, the tree and understory composition change. This changes the type of leaves dropped into the water. Dissolved organic matter released from the leaf into the water changes. There are also numerous other changes which occur. All of this causes impacts on the biodiversity within the water but also causes changes to the terrestrial and amphibious organisms that live in and around the water.

Literature does show gaps in the information concerning creation and maintenance of riparian forests. One trend the authors did find was that creation of riparian forests did not cause any negative effects of aquatic diversity. Many articles in the literature have demonstrated that creating riparian habitat, which the authors referred to as ESFH for early-succession forest habitat, had a positive change on increasing biodiversity while building new food webs connections and reinforcing existing connections. In order to maintain the food web structure, maintenance in the form of periodic disturbance needs to be applied. The authors suggested that the disturbances could be either natural or human influenced and should take into consideration historic disturbance regimes.

The authors outlined key areas where information and data is missing. One question which stood out was novel management strategies. This would involve management in areas where local ordinances or funding limitations can make management difficult. Many of the other questions centered around studying diversity changes and recruitment of species into the riparian habitat and how that might impact the in-stream diversity.

Factors Influencing Succession: Lessons from Large, Infrequent Natural Disturbances

Turner, MG, WL Baker, CJ Peterson, RK Peet. 1998. Factors Influencing Succession: Lessons from Large, Infrequent Natural Disturbances. Ecosystems 1:511-523.

 

Disturbances are a common way for energy and biomass locked in an ecosystem to be released. The amount of energy released is dependant on several disturbance factors; frequency, size, and intesity. Succession and disturbances have been studied heavily, although before this study, many of the factors were not looked at heavily due to the infrequency of natural disturbances. Human-induced disturbances are easy to study in that they are conditions can be measured prior to the disturbance. In this article, the autors aimed to find factors which influence succession after natural disturbances.

Through the article, the authors highlighted several points. One point is that successional variability can be linked with intesity, size, and frequency. This demostrates that not all disturbances in the same ecosystem will result in the same successional outcome. After a disturbance, colonization has been observed to happen in pockets. The authors refered to this as a nucleation process. From these pockets, species will begin to spread from these points. This is thought to be a residual from the disturbance. Seed dispursal is relatively short given the size of some species. A high intensity disturbance can cause a local extripation of those seeds. This would create an edge effect around the disturbance with species capable of distant dispursal colonizing the interior of the disturbance. This is relative to the intesity of the disturbance. With a low intensity, the parent species may not be affected and therefore, have a greater change of seed dispursal due to the reduced competition from those who were removed by the disturbance.

Size is also a major factor with disturbances. With a total removal of species in a given area, the space will be open to colonization. Abiotic factors will contribute to what has access to the space, and the survival rate of propagules. Much of this is ecosystem dependant. In an ecosystem where wind is a major form of seed dispursal, the pressure is much higher on seeds since there will be a high colonization rate when compared to an area where few species rely on wind. The same can also be said for species reliant on water or animals for seed transport and germination. If the disturnance is small is scale, there may be no change to the animal community or the physical structure of the ecosystem. A large disturbance may prevent animals from crossing or limit water movement through the ecosystem. If a species relies on animals for seed scarification or water f0r dormancy signalling, there can be excess stress placed on the seed for germination.

Temporally, there are many problems which may exist. Many disturbances happen at regular times of the year. If a disturbance schedule were to change, it may alter the successional community. A late season fire may not cause problems for early flowering forbs and cool season grasses as their seeds may have dispursed far enough away to not be affected by the fire but late flowering forbs and warm season grasses may suffer from a higher rate of seed mortality. A flood can cause the reverse in that it would help to dispurse the seeds present.

It is also noted that these factors do not exist in isolation. By combining factors, models can be used to predict successional aspects on an ecosystem, with some limitations. Any combination of the factors can cause a shift in the post-disturbance successional community. While a model may account for this, it may be too complex to be of any practical use in real time. The authors did note a future direction for studies. These included answering questions regarding spacial and temporal recovery patterns, covergent and divergent communities, and factors which control these. Many of these questions have been studied since this paper was published, but there is still room for improvement as disturbances are changing. Deforestation and urbanization are changing the intesity, size, and frequency of disturbances. Another question the authors did not mention is the impact of anthropogenic change in an ecosystem. Humans have suppressed or alter disturbances, which is a disturbance in itself. This should be accounted for when considering disturbances.