Scientifically based biodiversity management in timber concessions: contribution to conservation and sustainable use of biodiversity

During the past 25 years, forest laws in Central African countries have undergone major changes. Management plans were made mandatory: nearly 19 million hectares of timber concessions (38% of total granted concessions) were subject to a management plan in 2013 and the dynamics is currently underway. The management plan is based on a set of technical and scientific studies, including statistical surveys (management inventories) covering the whole concession and taking into account all timber species, large mammals and the main non timber forest products. These inventories allow, at concession level, to characterize ecosystems and to assess the forest conservation values, through floristic and faunal biodiversity indicators and by taking into account threats to the forest ecosystems, especially anthropogenic ones. Such management inventories are used especially for planning and forecasting harvests, while minimising environmental impacts on the forest structure and functioning, and retaining regeneration capacities of the timber species and the forest ecosystems. The knowledge gained on specific and ecosystemic biodiversity helps to define management rules to ensure the sustainability of different timber species' populations, noticeably the exploited ones. It is also used to design areas within the concessions were exploitation will not take place due to conservation interest (most biodiversity-rich areas, protection of rare or endangered species...). Such so-called “conservation series” therefore complement the protected areas network. Well-managed forest concessions can help conserve the regional forest ecosystems and maintain essential functions that they provide. However, management plans were up to now designed at the concession scale. Data acquired in forest concessions also significantly contribute to improve knowledge of the forest ecosystems and their functioning at the regional level. Using this data, the CoForChange Project (http://www.coforchange.eu) issued a map of the forest ecosystems developed in the "Sangha River Interval" region. This project suggested that those forest ecosystems could react differently to disturbance, and could need an adaptation of management methods to each ecosystem. Based on forest inventories, other initiatives are underway to map the forest types and the biomass stock at the scale of Central Africa, and might be of particular interest for policy decisions on forest ecosystems. (Texte intégral

Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change.

Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems

The Costs of Ecosystem Adaptation: Methodology and Estimates for Indian Forests

This paper presents a detailed methodology for estimating the cost of adaptation to climate change impacts on ecosystems. Up to date estimates are built-up following national investments in measures such as protected areas, with inaccurate estimates of the adaptation level needed. Here we propose a new methodology which identifies vulnerable areas due to climate impacts and the specific adaptation options feasible for these regions. An illustration of the methodology for shifts in forest ecosystems in India is presented. Advantages and future requirements for this methodology are finally discussed.Climate change, adaptation costs, forest ecosystems, India

Prioritisation for adaptation in tropical forest ecosystems : Working paper n°44

Under natural resource ecosystems shared across communities and nations, the distribution among stakeholders of risks and vulnerability to climate change is likely to be uneven on account of the nature of their stakes in the ecosystems, the degree of their dependence and the extent of degradation of the natural resources. Striving for a common adaptation strategy that safeguards the shared forest ecosystems and balances the interests of the multiple stakeholders would require a framework that encourages sharing and redistribution of ecosystem benefits and sharing of the potential climate risks and impacts on forests and stakeholders, taking into account the vulnerabilities of both ecosystems and people. This will constitute an important first step in reducing the burden of climate change on the weak and most vulnerable. Such a framework would also guide the decision making process, aid in redefining future activities especially when the risk situation changes, and help connect adaptation to sustainable national and regional development programmes through prioritisation of possible adaptation activities. This paper uses the experiences gained under the Tropical Forests and Climate Change Adaptation project of the Center for International Forest Research across three continents to propose a priority-setting process with active participation of multiple stakeholders in tropical ecosystems in developing countries perceived in their judgement to be crucial for adaptation to climate change. By attributing values to forest ecosystem goods and services for all stakeholders, prioritisation represents a common position by multiple stakeholders linking their interests and practices for a common purpose. (Résumé d'auteur

Soil carbon and nitrogen erosion in forested catchments: Implications for erosion-induced terrestrial carbon sequestration

Lateral movement of organic matter (OM) due to erosion is now considered an important flux term in terrestrial carbon (C) and nitrogen (N) budgets, yet most published studies on the role of erosion focus on agricultural or grassland ecosystems. To date, little information is available on the rate and nature of OM eroded from forest ecosystems. We present annual sediment composition and yield, for water years 2005-2011, from eight catchments in the southern part of the Sierra Nevada, California. Sediment was compared to soil at three different landform positions from the source slopes to determine if there is selective transport of organic matter or different mineral particle size classes. Sediment export varied from 0.4 to 177 kg ha-1, while export of C in sediment was between 0.025 and 4.2 kg C ha-1 and export of N in sediment was between 0.001 and 0.04 kg N ha-1. Sediment yield and composition showed high interannual variation. In our study catchments, erosion laterally mobilized OM-rich litter material and topsoil, some of which enters streams owing to the catchment topography where steep slopes border stream channels. Annual lateral sediment export was positively and strongly correlated with stream discharge, while C and N concentrations were both negatively correlated with stream discharge; hence, C: N ratios were not strongly correlated to sediment yield. Our results suggest that stream discharge, more than sediment source, is a primary factor controlling the magnitude of C and N export from upland forest catchments. The OM-rich nature of eroded sediment raises important questions about the fate of the eroded OM. If a large fraction of the soil organic matter (SOM) eroded from forest ecosystems is lost during transport or after deposition, the contribution of forest ecosystems to the erosion-induced C sink is likely to be small (compared to croplands and grasslands)

Resilience of New Zealand indigenous forest fragments to impacts of livestock and pest mammals

A number of factors have combined to diminish ecosystem integrity in New Zealand indigenous lowland forest fragments surrounded by intensively grazed pasture. Livestock grazing, mammalian pests, adventive weeds and altered nutrient input regimes are important drivers compounding the changes in fragment structure and function due to historical deforestation and fragmentation. We used qualitative systems modelling and empirical data from Beilschmiedia tawa dominated lowland forest fragments in the Waikato Region to explore the relevance of two common resilience paradigms – engineering resilience and ecological resilience – for addressing the conservation management of forest fragments into the future. Grazing by livestock and foraging/predation by introduced mammalian pests both have direct detrimental impacts on key structural and functional attributes of forest fragments. Release from these perturbations through fencing and pest control leads to partial or full recovery of some key indicators (i.e. increased indigenous plant regeneration and cover, increased invertebrate populations and litter mass, decreased soil fertility and increased nesting success) relative to levels seen in larger forest systems over a range of timescales. These changes indicate that forest fragments do show resilience consistent with adopting an engineering resilience paradigm for conservation management, in the landscape context studied. The relevance of the ecological resilience paradigm in these ecosystems is obscured by limited data. We characterise forest fragment dynamics in terms of changes in indigenous species occupancy and functional dominance, and present a conceptual model for the management of forest fragment ecosystems

Local forest structure variability increases resilience to wildfire in dry western U.S. coniferous forests.

A 'resilient' forest endures disturbance and is likely to persist. Resilience to wildfire may arise from feedback between fire behaviour and forest structure in dry forest systems. Frequent fire creates fine-scale variability in forest structure, which may then interrupt fuel continuity and prevent future fires from killing overstorey trees. Testing the generality and scale of this phenomenon is challenging for vast, long-lived forest ecosystems. We quantify forest structural variability and fire severity across >30 years and >1000 wildfires in California's Sierra Nevada. We find that greater variability in forest structure increases resilience by reducing rates of fire-induced tree mortality and that the scale of this effect is local, manifesting at the smallest spatial extent of forest structure tested (90 × 90 m). Resilience of these forests is likely compromised by structural homogenisation from a century of fire suppression, but could be restored with management that increases forest structural variability

The effects of intense fire on headwater streams of the Colville National Forest, WA

Thesis (M.S.) University of Alaska Fairbanks, 2006Forest fires play an important role in shaping ecosystems, and there has been growing concern on the effects of high intensity fires on forest and aquatic ecosystems. Headwater streams are highly connected to riparian and surrounding terrestrial systems, and to downstream aquatic systems, partly through prey and organic matter transfers via aquatic invertebrate drift and emergence. Because of their small size, headwater streams may experience the greatest initial impact from forest fire, but may also return to pre-fire conditions quicker than larger streams. In this study, headwater streams from replicated burned and control watersheds were sampled in the two years following an intense forest fire in northeastern Washington. Benthic, drift and emergence samples of aquatic invertebrates were taken and analyzed for differences in density, biomass and community composition between watershed types. There was significantly higher density of invertebrates in burned sites, but no difference in biomass except in invertebrate emergence which was greater at burned sites. There was lower diversity in the burned watersheds, and the invertebrate community was dominated by chironomids. These changes in invertebrate density and community composition could influence the food resources available to aquatic and riparian consumers