In an ever-more interconnected world (social, technological and environmental), no organisation can retain a competitive position and survive disruptions as an independent entity. This article provides a review of resilience literature in its widest context and later its application at an organisational level context. The origins of the concept are reported and consequently, the various fields of research are analysed. The concept is shown to remain essentially constant regardless of its field of enquiry and has much to inform the fields of organisation theory, strategy and operations management. This article identifies a number of areas for advancing resilience research, in particular: the relationship between human and organisational resilience; understanding interfaces between organisational and infrastructural resilience.

Resilience: the concept, a literature review and future directions

Rivers are conduits for materials and energy; this, the frequent and intense disturbances that these systems experience, and their narrow, linear nature, create problems for conservation of biodiversity and ecosystem functioning in the face of increasing human influence. In most parts of the world, riparian zones are highly modified. Changes caused by alien plants — or environmental changes that facilitate shifts in dominance creating novel ecosystems — are often important agents of perturbation in these systems. Many restoration projects are underway. Objective frameworks based on an understanding of biogeographical processes at different spatial scales (reach, segment, catchment), the specific relationships between invasive plants and resilience and ecosystem functioning, and realistic endpoints are needed to guide sustainable restoration initiatives. This paper examines the biogeography and the determinants of composition and structure of riparian vegetation in temperate and subtropical regions and conceptualizes the components of resilience in these systems. We consider changes to structure and functioning caused by, or associated with, alien plant invasions, in particular those that lead to breached abiotic- or biotic thresholds. These pose challenges when formulating restoration programmes. Pervasive and escalating human-mediated changes to multiple factors and at a range of scales in riparian environments demand innovative and pragmatic approaches to restoration. The application of a new framework accommodating such complexity is demonstrated with reference to a hypothetical riparian ecosystem under three scenarios: (1) system unaffected by invasive plants; (2) system initially uninvaded, but with flood-generated incursion of alien plants and escalating invasion-driven alteration; and (3) system affected by both invasions and engineering interventions. The scheme has been used to derive a decision-making framework for restoring riparian zones in South Africa and could guide similar initiatives in other parts of the world.

/pdf/riparian-vegetation-degradation-alien-plant-invasions-and-27dko0jjke.pdf

Riparian vegetation: Degradation, alien plant invasions, and restoration prospects

Summary

1
Agricultural intensification has resulted in the reduction and fragmentation of species-rich grasslands across much of western Europe.

2
We examined the key ecological processes that limit the creation of diverse grassland communities on ex-arable land in a multi-site experiment over a wide variety of soil types and locations throughout lowland Britain.

3
The results showed it was possible to create and maintain these communities successfully under a hay-cutting and grazing management regime. Furthermore, there was a high degree of repeatability of the treatment effects across the sites.

4
Lack of seed of desirable species was the key factor limiting the assembly of diverse grassland communities. Sowing a species-rich seed mixture of ecologically adapted grassland plants was an effective means of overcoming this limitation. Community assembly by natural colonization from the seed bank and seed rain was a slow and unreliable process. However, there was no evidence to suggest that sowing a species-poor grass-dominated seed mixture made the vegetation any less susceptible to colonization by desirable species than allowing natural regeneration to take place.

5
Deep cultivation caused significant reductions in soil P and K concentrations across the sites. This had a significant beneficial effect on the establishment and persistence of sown forbs in all years. It also resulted in a significant reduction in the number of unsown weedy grasses. However, for both variables these differences were very small after 4 years.

6
Sowing a nurse crop significantly reduced the number of unsown grass species, but had no beneficial effect on the establishment of desirable species.

7
Treatments sown with the species-rich seed mixture following deep cultivation corresponded most closely to the specified target communities defined by the UK National Vegetation Classification. Natural regeneration and treatments sown with the species-poor seed mixture were much less similar to the target. The sites on circum-neutral soils achieved the greatest degree of similarity to the target. Those on calcareous and acid soils failed to achieve their targets and most closely resembled the target for neutral soils. This reflected the poor performance of the sown preferential species for these communities.

Restoration of species‐rich grassland on arable land: assessing the limiting processes using a multi‐site experiment

Despite growing recognition of the conservation values of grassy biomes, our understanding of how to maintain and restore biodiverse tropical grasslands (including savannas and open-canopy grassy woodlands) remains limited. To incorporate grasslands into large-scale restoration efforts, we synthesised existing ecological knowledge of tropical grassland resilience and approaches to plant community restoration. Tropical grassland plant communities are resilient to, and often dependent on, the endogenous disturbances with which they evolved - frequent fires and native megafaunal herbivory. In stark contrast, tropical grasslands are extremely vulnerable to human-caused exogenous disturbances, particularly those that alter soils and destroy belowground biomass (e.g. tillage agriculture, surface mining); tropical grassland restoration after severe soil disturbances is expensive and rarely achieves management targets. Where grasslands have been degraded by altered disturbance regimes (e.g. fire exclusion), exotic plant invasions, or afforestation, restoration efforts can recreate vegetation structure (i.e. historical tree density and herbaceous ground cover), but species-diverse plant communities, including endemic species, are slow to recover. Complicating plant-community restoration efforts, many tropical grassland species, particularly those that invest in underground storage organs, are difficult to propagate and re-establish. To guide restoration decisions, we draw on the old-growth grassland concept, the novel ecosystem concept, and theory regarding tree cover along resource gradients in savannas to propose a conceptual framework that classifies tropical grasslands into three broad ecosystem states. These states are: (1) old-growth grasslands (i.e. ancient, biodiverse grassy ecosystems), where management should focus on the maintenance of disturbance regimes; (2) hybrid grasslands, where restoration should emphasise a return towards the old-growth state; and (3) novel ecosystems, where the magnitude of environmental change (i.e. a shift to an alternative ecosystem state) or the socioecological context preclude a return to historical conditions.

/pdf/resilience-and-restoration-of-tropical-and-subtropical-28yyrizqr2.pdf

Resilience and restoration of tropical and subtropical grasslands, savannas, and grassy woodlands.

Aim
In order to mitigate the ecological, economical and social consequences of future climate change, we must understand and quantify the response of vegetation to short-term climate anomalies. There is currently no model that quantifies vegetation resistance and resilience at a global scale while simultaneously taking climate variability into account. The goals of this study were therefore to develop a standardized indicator of short-term vegetation resilience and resistance to drought and temperature anomalies, and to improve our understanding of vegetation resistance and resilience in drought-sensitive areas by linking metrics of vegetation stability to the percentage of tree cover, non-tree vegetation and bare soil.

Location
Global.

Methods
The deviation of vegetation behaviour from expectations was quantified using anomalies in the normalized difference vegetation index (NDVI) and modelled as a function of (1) past NDVI anomalies, (2) an instantaneous drought indicator and (3) temperature anomalies. Metrics of resistance and resilience were then extracted from the model and related to the percentages of bare soil, non-tree vegetation and tree cover.

Results
Comparisons of the globally derived resilience and resistance metrics showed low resilience and low resistance to drought in semi-arid areas, low resistance to negative temperature anomalies in high-latitude areas, and low resistance to positive temperature anomalies in the Sahel and Australia. In drought-sensitive areas, resilience was highest for vegetation types with 3–20% bare soil and 5–15% tree cover.

Main conclusions
Our ARx model is the first to simultaneously derive vegetation resistance and resilience metrics at a global scale, explicitly taking into account the spatial variability of short-term climate anomalies and data reliability. Its results highlight the impact of tree cover, non-tree vegetation and bare soil on vegetation resilience.

A model quantifying global vegetation resistance and resilience to short‐term climate anomalies and their relationship with vegetation cover

Ecosystem stability and the response of ecosystems to disturbance are of crucial importance for conservation management, especially when the object is to maintain and/or to restore early-successional communities. This paper provides a selective review of ecosystem stability from a conservation perspective. Existing models of ecosystem resilience are discussed in relation to the management of successional habitats. A multivariate model for measuring stability and resilience based on Canonical Correspondence Analysis (CCA) is outlined. The criteria for the model to work are explained and the model is tested on vegetation and soil data from the Dorset Heaths. The model provides a mechanism for bringing together measurements of both structure (species composition) and function (ecosystem properties, both biotic and abiotic), to measure stability and resilience of ecosystems. The model can also be used to measure the success of management in restoring communities and to provide information to conservation policy makers and land managers.

Marrs H. Robert

Papers

Ecosystem stability and resilience: a review of their relevance for the conservation management of lowland heaths