Summary
1 The invasion of habitats by non-native plant and animal species is a global phenomenon with potentially grave consequences for ecological, economic, and social systems. Unfortunately, to date, the study of invasions has been primarily anecdotal and resistant to generalization.

2 Here, we use insights from experiments and from long-term monitoring studies of vegetation to propose a new theory in which fluctuation in resource availability is identified as the key factor controlling invasibility, the susceptibility of an environment to invasion by non-resident species. The theory is mechanistic and quantitative in nature leading to a variety of testable predictions.

3 We conclude that the elusive nature of the invasion process arises from the fact that it depends upon conditions of resource enrichment or release that have a variety of causes but which occur only intermittently and, to result in invasion, must coincide with availability of invading propagules.

https://besjournals.onlinelibrary.wiley.com/doi/epdf/10.1046/j.1365-2745.2000.00473.x

Fluctuating resources in plant communities: a general theory of invasibility

Stabilization of As, Cr, Cu, Pb and Zn in soil using amendments – A review

Contamination of soils by heavy metals is of widespread occurrence as a result of human, agricultural and industrial activities. Among heavy metals, lead is a potential pollutant that readily accumulates in soils and sediments. Although lead is not an essential element for plants, it gets easily absorbed and accumulated in different plant parts. Uptake of Pb in plants is regulated by pH, particle size and cation exchange capacity of the soils as well as by root exudation and other physico-chemical parameters. Excess Pb causes a number of toxicity symptoms in plants e.g. stunted growth, chlorosis and blackening of root system. Pb inhibits photosynthesis, upsets mineral nutrition and water balance, changes hormonal status and affects membrane structure and permeability. This review addresses various morphological, physiological and biochemical effects of Pb toxicity and also strategies adopted by plants for Pb-detoxification and developing tolerance to Pb. Mechanisms of Pb-detoxification include sequestration of Pb in the vacuole, phytochelatin synthesis and binding to glutathione and aminoacids etc. Pb tolerance is associated with the capacity of plants to restrict Pb to the cell walls, synthesis of osmolytes and activation of antioxidant defense system. Remediation of soils contaminated with Pb using phytoremediation and rhizofiltration technologies appear to have great potential for cleaning of Pb-contaminated soils.

/pdf/lead-toxicity-in-plants-3nclmzsfwp.pdf

Lead toxicity in plants

http://www.kiwiscience.com/JournalArticles/EnvironPoll2011.pdf

A review of biochars’ potential role in the remediation, revegetation and restoration of contaminated soils

No matter who we are, or where we live, our well-being depends on the way ecosystems work. Most obviously, ecosystems can provide us with material things that are essential for our daily lives, such as food, wood, wool and medicines. Although the other types of benefit we get from ecosystems are easily overlooked, they can, for example, also play an important role in regulating the environments in which we live. They can help ensure the flow of clean water and protect us from flooding or other hazards like soil erosion, land-slips and tsunamis. They can even contribute to our spiritual well-being, through their cultural or religious significance or the opportunities they provide for recreation or the enjoyment of nature.

Ecosystem Ecology: The links between biodiversity, ecosystem services and human well-being

Current approaches to the revegetation and reclamation of metalliferous mine wastes

summary
Zinc, lead and cadmium tolerance in four populations of Typha latifolia raised from seed collected from metal-contaminated and uncontaminated sites were investigated. Metal concentrations in natural plant populations showed that Zn, Pb and Cd in the leaves were maintained at low levels (Zn: 22–122, Pb: 4.7–40 and Cd: 0.2–0.8 μg g−1 d. wt), although concentrations of these metals in the associated soil-sediments (total concentrations of Zn: 86–3009, Pb: 26–18894 and Cd: 1.4–26 μg−1 d. wt) and in the roots (Zn: 46–946, Pb: 25–3628 and Cd: 1.0–17 μg g−1 d. wt) varied widely. Some differences were found between metal-contaminated and uncontaminated populations in terms of metal uptake under controlled conditions. Seedlings from metal-contaminated populations accumulated considerably more metals (up to nearly twice as much Zn and Pb and three times as much Cd) in roots than the uncontaminated population in a pot trial. In general, however, different populations of T. latifolia showed similar growth responses (the longest leaf elongation, the longest root elongation, shoot and root d. wt), metal uptake and indices of metal tolerance when seedlings were grown in the same metal treatment solutions or in the same metal-contaminated media under laboratory conditions. The data do not support the hypothesis that populations from metal-contaminated sites have evolved tolerance to Zn, Pb and Cd, but rather that T. latifolia shows constitutional tolerance.

Zinc, lead and cadmium tolerance, uptake and accumulation by Typha latifolia

Zinc, Lead and Cadmium Tolerance, Uptake and Accumulation by the Common Reed,Phragmites australis(Cav.) Trin. ex Steudel

Several studies of synthesized herbaceous plant communities have reported a positive relationship between vascular plant diversity and biomass production (Naeem et al. 1994; Tilman et al. 2001), and the European BIODEPTH experiment has been one of the most influential in this regard (Hector et al. 1999). Much, though not all, of the evidence for this relationship has come from experimental communities established from seed and harvested after only a year or two. It is not clear that such immature plant communities would be expected to provide reliable evidence of the relationship between diversity and ecosystem properties. Here we compare the relationship between diversity and biomass in BIODEPTH with that at the long-term monitoring site at Bibury in Gloucestershire, UK (Dunnett et al. 1998), a natural plant community that has much in common with BIODEPTH. The Bibury site offers a rare opportunity to address questions similar to those tackled by BIODEPTH, while avoiding some of the limitations of short-term experiments. If a positive relationship between vascular plant diversity and biomass production is an important phenomenon, one could argue that it should be detectable in natural vegetation. Previous attempts to explore the relationship between biodiversity and productivity in natural plant communities have been criticized on the grounds that both variables are frequently affected by additional (usually abiotic) variables (Lawton et al. 1998). For example, over a wide range of moderate-to-high biomass values, there is a well known negative relationship between biomass and species richness, driven by increasing competitive exclusion at higher productivity (Grime 1973; Grace 1999; Stevens et al. 2004). In experiments such as BIODEPTH, one aim is to exclude such natural sources of variation and create synthesized plant assemblages that vary only in artificially imposed levels of species richness. Of course, random environmental heterogeneity cannot be completely excluded, and Huston & McBride (2002) have shown how such heterogeneity can give rise to spurious diversity-function relationships. However, synthesized communities may also exhibit systematic variation in productivity equalling or exceeding that occurring in natural habitats, arising from the higher nitrogen availability in communities sown with N-fixing legumes. In BIODEPTH, addition of TriJolium pratense (nomenclature follows Stace 1997) increased biomass, on average, by 360 g m (Hector et al. 1999). As this increase was much larger than the effect of any other species, it is reasonable to attribute this effect to a direct result of the extra N fixed by Trifolium. The increase was also much larger than the effect of a change in diversity itself; doubling species richness increased biomass, on average, by only 80 g m-. The Bibury road verge lies on the north side of Akeman Street, originally a Roman road, in Gloucestershire, UK (National Grid reference SP 119048). The 700 m length of experimental verge was originally chosen

/pdf/biodiversity-ecosystem-function-and-plant-traits-in-mature-15gli1czm8.pdf

Biodiversity, ecosystem function and plant traits in mature and immature plant communities

summary
The effects of iron plaque on the growth of Typha latifolia L. and accumulation of copper and nickel in T. latifolia were investigated under laboratory conditions in nutrient solution cultures. Seedlings with and without iron plaque on their roots were exposed to 0.05 μg ml−1 Cu and 0.10 μg ml−1 Ni solutions for 72 d. The results showed no differences in root and shoot d. wt and leaf elongation when Cu or Ni were added to the solution and in the presence or absence of plaque. However, root length was reduced by Cu and Ni, and the reduction in root length was greater in the presence of plaque. Some Cu and Ni was adsorbed on root surfaces; roots with plaque took up more Cu, but less Ni than those without. The presence of plaque did not alter Cu uptake and translocation but increased Ni uptake and translocation. Most of the Cu and Ni taken up was retained in the roots, suggesting that the root tissue rather than the root surface or plaque is the main barrier for Cu and Ni transport. The results differ from those reported for other species.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1469-8137.1997.00758.x

Arthur J. Willis

Papers

Current approaches to the revegetation and reclamation of metalliferous mine wastes

Zinc, lead and cadmium tolerance, uptake and accumulation by Typha latifolia

Zinc, Lead and Cadmium Tolerance, Uptake and Accumulation by the Common Reed,Phragmites australis(Cav.) Trin. ex Steudel

Biodiversity, ecosystem function and plant traits in mature and immature plant communities

Copper and nickel uptake, accumulation and tolerance in Typha latifolia with and without iron plaque on the root surface