Experimental Tree Mortality Does Not Induce Marsh Transgression in a Chesapeake Bay Low-Lying Coastal Forest

Transgression into adjacent uplands is an important global response of coastal wetlands to accelerated rates of sea level rise. “Ghost forests” mark a signature characteristic of marsh transgression on the landscape, as changes in tidal inundation and salinity cause bordering upland tree mortality, increase light availability, and the emergence of tidal marsh species due to reduced competition. To investigate these mechanisms of the marsh migration process, we conducted a field experiment to simulate a natural disturbance event (e.g., storm-induced flooding) by inducing the death of established trees (coastal loblolly pine, Pinus taeda) at the marsh-upland forest ecotone. After this simulated disturbance in 2014, we monitored changes in vegetation along an elevation gradient in control and treatment areas to determine if disturbance can lead to an ecosystem shift from forested upland to wetland vegetation. Light availability initially increased in the disturbed area, leading to an increase in biodiversity of vegetation with early successional grass and shrub species. However, over the course of this 5-year experiment, there was no increase in inundation in the disturbed areas relative to the control and pine trees recolonized becoming the dominant plant cover in the disturbed study areas. Thus, in the 5 years since the disturbance, there has been no overall shift in species composition toward more hydrophytic vegetation that would be indicative of marsh transgression with the removal of trees. These findings suggest that disturbance is necessary but not sufficient alone for transgression to occur. Unless hydrological characteristics suppress tree re-growth within a period of several years following disturbance, the regenerating trees will shade and outcompete any migrating wetland vegetation species. Our results suggest that complex interactions between disturbance, biotic resistance, and slope help determine the potential for marsh transgression.

Knowledge creation in patent ecosystems: insights from Singapore

Purpose This paper aims to better understand how codified knowledge that originates in organizations contributes to the generation of idiosyncratic knowledge embedded at a more expansive level, such as that of an ecosystem. In doing so, the authors introduce the concept of patent ecosystems – conceived as configurations of codified knowledge advancements protected via patents. Design/methodology/approach Using a patent co-classification method and introducing a novel validated software, the authors map and visualize the patent ecosystem of Singapore and examine 173,597 patents published from 1995 to 2020. Findings Results reveal the prominent growth of Singapore’s patenting activities, capturing a patent ecosystem shift, from a more diverse knowledge configuration to a more specialized one. The codified knowledge mainly generated deals with pharmaceuticals and high-tech knowledge domains; further, newly emerging technologies such as blockchain are also noted. Research limitations/implications The research investigates Singapore’s context, a country in which research directions and focus areas are influenced by government interventions and leadership. Thus, future studies might examine other patent ecosystems to draw comparisons with more laissez-faire policies or ecosystems with more pronounced organic development. Originality/value The novelty of this research is the introduction of the concept of a patent ecosystem for advancing a more fine-grained understanding of the aggregated knowledge generated at the ecosystem level and its specific features, composition and development. The authors consider patents as “carriers” of different codified pieces of knowledge and patent ecosystems represent the configuration that emerges from connections of these elements. The novel approach can aid both researchers, practitioners and policymakers with future examinations in the field.

Individual and population dietary specialization decline in fin whales during a period of ecosystem shift

This study sought to estimate the effect of an anthropogenic and climate-driven change in prey availability on the degree of individual and population specialization of a large marine predator, the fin whale (Balaenoptera physalus). We examined skin biopsies from 99 fin whales sampled in the St. Lawrence Estuary (Canada) over a nine year period (1998–2006) during which environmental change was documented. We analyzed stable isotope ratios in skin and fatty acid signatures in blubber samples of whales, as well as in seven potential prey species, and diet was quantitatively assessed using Bayesian isotopic models. An abrupt change in fin whale dietary niche coincided with a decrease in biomass of their predominant prey, Arctic krill (Thysanoessa spp.). This dietary niche widening toward generalist diets occurred in nearly 60% of sampled individuals. The fin whale population, typically composed of specialists of either krill or lipid-rich pelagic fishes, shifted toward one composed either of krill specialists or true generalists feeding on various zooplankton and fish prey. This change likely reduced intraspecific competition. In the context of the current “Atlantification” of northern water masses, our findings emphasize the importance of considering individual-specific foraging tactics and not only population or group average responses when assessing population resilience or when implementing conservation measures.

Changes in the Gulf Stream preceded rapid warming of the Northwest Atlantic Shelf

The Northwest Atlantic Shelf provides ecological and economic benefits along the heavily populated North American coastline and beyond. In 2009-2010, abrupt warming prompted an ecosystem shift with consequences for fisheries, yet the cause of this event is unclear. Here we use satellite altimetry and in situ measurements to show that, in 2008, the Gulf Stream migrated closer to the Tail of the Grand Banks, a shift that has persisted ever since. This change reduced the westward connectivity of the Labrador Current that otherwise supplies cold, fresh, oxygen-rich waters to the shelf. Within one year after the appearance of anomalously warm and saline water at the Tail of Grand Banks, subsurface warming progressed south-westwards. Historical observations suggest a similar sequence of events may have occurred in the 1970s. Therefore, monitoring water properties at the Tail of Grand Banks may offer predictability for shelf properties and ecosystem perturbations with substantial lead time.

Resilience in Diet-quality Strategies of Mixed Native and Non-native Herbivore Communities in Semi-arid and Sub-humid Savanna Ecosystem

The global climate change processes are expected to impact African savanna ecosystems in their ecological functionality and availability of food resources for herbivores. To understand the feeding responses of large savanna herbivores placed to space-constrained and two environmentally distinct (semi-arid versus sub-humid savanna) conditions, we investigated the diet quality of five species living in a mixed community of species native and non-native for the West African savanna and compared them between the two sites as a proxy for a potential ecosystem shift due to climate change. Grazers and mixed feeders maintained diet quality in most nutrients at similar levels, while browser’s diet had lower nitrogen and fibres, specifically lignin, and more calcium in semi-arid savanna. Our findings suggest that adaptation to different ecosystems with no possibility to leave the area required changes in feeding behaviour across feeding types to maintain diet quality, especially mixed feeders escaped the competition with zebras for grasses in sub-humid savanna by switching to browse. Pure browser experienced reduced diet quality in drier environment and may potentially become susceptible to ecosystem changes. Conservation strategies should facilitate both, animals’ adequate behavioural responses together with nutritional resilience in changing savanna landscapes.

White-Sand Savannas Expand at the Core of the Amazon After Forest Wildfires

Across the tropics, climate change is increasing the frequency and severity of wildfires, exposing tropical forests to the risk of shifting into an open vegetation state. A recent satellite analysis of the Amazon basin suggests this might happen first in floodplains where forests are particularly fragile. We studied floodplain landscapes of the middle Rio Negro, covering ~ 4100 km2 at the Central Amazon region, where forest ecosystems are dominant. We used Landsat images to map 40 years of wildfire history and test the hypothesis that repeatedly burnt forests fail to regenerate and can be replaced by white-sand savanna ecosystems. In the field, using a chronosequence of ‘time after the first fire’, we assessed changes in tree species composition, herbaceous cover and topsoil properties. Here we show that when these forests are repeatedly disturbed by wildfires, their soil gradually loses clay and nutrients and becomes increasingly sandy. In synchrony, native herbaceous cover expands, forest tree species disappear and white-sand savanna tree species become dominant. This drastic ecosystem shift happened within 40 years, likely accelerated by topsoil erosion. When recurrent fires maintain floodplain forests in an open vegetation state, topsoil erosion intensifies, transforming clay-rich soils into white-sand soils that may favour savanna tree species. Our findings reveal that white-sand savannas may expand through seasonally flooded ecosystems at the core of the Amazon, facilitated by wildfires.

Seabird establishment during regional cooling drove a terrestrial ecosystem shift 5000 years ago

The coastal tussac (Poa flabellata) grasslands of the Falkland Islands are a critical seabird breeding habitat but have been drastically reduced by grazing and erosion. Meanwhile, the sensitivity of seabirds and tussac to climate change is unknown because of a lack of long-term records in the South Atlantic. Our 14,000-year multiproxy record reveals an ecosystem state shift following seabird establishment 5000 years ago, as marine-derived nutrients from guano facilitated tussac establishment, peat productivity, and increased fire. Seabird arrival coincided with regional cooling, suggesting that the Falkland Islands are a cold-climate refugium. Conservation efforts focusing on tussac restoration should include this terrestrial-marine linkage, although a warming Southern Ocean calls into question the long-term viability of the Falkland Islands as habitat for low-latitude seabirds.