Re-greening the Sahel? Evaluating tree cover restoration strategies in Niger

Characterization of regrowing forests is vital for understanding forest dynamics to assess the impacts on carbon stocks and to support sustainable forest management. Although remote sensing is a key tool for understanding and monitoring forest dynamics, the use of exclusively remotely sensed data to explore the effects of different variables on regrowing forests across all biomes in Brazil has rarely been investigated. Here, we analyzed how environmental and human factors affect regrowing forests. Based on Brazil's secondary forest age map, 3060 locations disturbed between 1984 and 2018 were sampled, interpreted and analyzed in different biomes. We interpreted the time since disturbance for the sampled pixels in Google Earth Engine. Elevation, slope, climatic water deficit (CWD), the total Nitrogen of soil, cation exchange capacity (CEC) of soil, surrounding tree cover, distance to roads, distance to settlements and fire frequency were analyzed in their importance for predicting aboveground biomass (AGB) and tree cover derived from global forest aboveground biomass map and tree cover map, respectively. Results show that time since disturbance interpreted from satellite time series is the most important predictor for characterizing AGB and tree cover of regrowing forests. AGB increased with increasing time since disturbance, surrounding tree cover, soil total N, slope, distance to roads, distance to settlements and decreased with larger fire frequency, CWD and CEC of soil. Tree cover increased with larger time since disturbance, soil total N, surrounding tree cover, distance to roads, distance to settlements, slope and decreased with increasing elevation and CWD. These results emphasize the importance of remotely sensing products as key opportunities to improve the characterization of forest regrowth and to reduce data gaps and uncertainties related to forest carbon sink estimation. Our results provide a better understanding of regional forest dynamics, toward developing and assessing effective forest‐related restoration and climatic mitigation strategies.

Long-term faunal responses to restoration efforts can be very different from those in the short term, but are often not quantified systematically to identify ways that maximise restoration outcomes. We report on a 9-year landscape-scale ecological experiment that tests the long-term responses of reptile populations to coarse woody debris (CWD) addition, reduced native macropod grazing, and prescribed fire. We found that reptile species richness was increased 9 years after CWD addition, as was the abundance of several common reptile species. Further, the more CWD was added to the system, the more benefits were afforded to reptiles. The positive effect of CWD depended on the surrounding vegetation structure and was greater in sites with low tree and shrub cover. Further, lower levels of macropod grazing appeared to lessen the effects of CWD addition in the long term. Our results show that restoration projects in open woodlands and scattered tree ecosystems should consider the addition of CWD as a fundamental element of their management actions. To maximise benefits of CWD addition for reptiles, we recommend a strategy of placing CWD in areas with low tree and shrub cover rather than areas with high tree and shrub cover. The addition of CWD in such areas would provide crucial shelter and foraging substrates for reptiles in a comparatively hostile portion of the landscape. Our study helps to establish guidelines for achieving long-lasting effects of ecosystem restoration for vertebrates and demonstrates the benefits of monitoring vertebrates over the long term.

The grassland/savannas in the South American Semiarid Chaco have been massively transformed into shrubland. However, the ecology of this phenomenon is little known and restoration initiatives almost non-existent. We provide information about 1) the differences in plant structure and diversity along a woody encroachment gradient, and 2) the association among plant structural and functional attributes with environmental factors. We utilized 38 sample units and obtained tree and shrub cover, herbaceous biomass, species richness and composition of grasses and woody plants and several herbaceous functional types (mainly grasses). The environmental factors were historic grazing intensity and fire frequency. Related to item 1, we found: a) shrub cover was significant and progressively greater along the woody encroachment gradient and largely exceeded the tree cover, b) the herbaceous biomass was significantly smaller, with a high woody cover (x̄=89.7%), c) the grass species richness was maximum at intermediate levels of woody cover (x̄=39.3% and 64%), d) the dissimilarity in grass species composition was maximum between very low and high levels of woody cover (x̄=15.8% and 89.7%), and e) woody species richness and composition were uniform along the woody encroachment gradient. In relation to item 2, we observed: 1) the increase in historic grazing intensity was significant and strongly associated with the reduction of fire frequency, which, in turn, was significantly associated with the increase in tree and shrub cover and the decrease in herbaceous biomass, suggesting that overgrazing reduces or eliminates the grassland fires and promotes the woody encroachment, and 2) several grass functional types were significantly associated with the historic grazing intensity and fire frequency. Our results are useful both to anticipate the grassland/savannas responses to woody encroachment processes and to plan restoration and management strategies.

Source Agritrop Cirad (https://agritrop.cirad.fr/598887/)

The threatened superb parrot of south-eastern Australia exemplifies many of the challenges associated with research on wide-raging organisms which live ‘off-reserve’. Challenges include that most land is privately owned and that landscape use by such organisms does not always conform to traditional schematic and categorical landscape/fragmentation models. A multi-scale approach for embedding the detection of site-level and landscape context effects into landscape sampling design and subsequent statistical analysis is presented. The superb parrot was found scattered at varying densities throughout the agricultural landscapes of the South-West Slopes, much of which was privately owned. It responded to site-level variables and the surrounding landscape context. Overall, the superb parrot favoured lower elevation sites which were dominated by scattered, open woodlands, where Blakely’s red gum was a significant component. Mean plant productivity within 2 km, levels of woody tree cover within 3 km and (with caveats) length of roads within 3 km had a major effect on site-level response, indicating conditions in the surrounding local landscape are important to the superb parrot. This multi-scale response requires a multi-scale conservation and restoration strategy. The importance of open tree cover and amounts of Blakely’s red gum are a matter for concern, due to a general lack of tree regeneration and the particular susceptibility of Blakely’s red gum to dieback. The scattered trees in the agricultural matrix were important to the superb parrot, suggesting that it views these landscapes as a continuum of usable habitat. Strategies for restoration of larger habitat remnants should also include regeneration of trees in scattered pattern in the wider landscape, and Blakely’s red gum should be part of any strategy along with other key species such as yellow and white box. The landscape sampling approach successfully addressed the challenges of whole-landscape research. This highlights the value of ‘off-reserve’ studies across whole landscapes.

Restoring farmlands for food and nature

Forestation, including reforestation (restoring tree cover to previously forested lands) and afforestation (establishing tree cover on non‐forested lands), is a key strategy for ecological restoration and climate change mitigation. Soil microbial biomass and stoichiometry are critical indicators of the quality of ecological restoration, yet the global scale impacts of afforestation and reforestation remain poorly understood. We conducted a meta‐analysis of 1091 paired observations from 103 peer‐reviewed articles of globally distributed studies to quantify the impacts of afforestation and reforestation on soil microbial biomass and stoichiometry and to identify key influencing drivers. We found that forestation increased soil microbial biomass carbon (MBC) by 71.6%, microbial biomass nitrogen (MBN) by 80.0%, microbial biomass phosphorus (MBP) by 76.6%, and the MBN:MBP ratio by 53.3%. Preceding land use type was an important determinant of soil MBC, MBN and MBP. Afforestation of abandoned lands increased soil MBC, MBN and MBP by 28.4%, 125.5%, and 196.4%, respectively, while afforestation of farmed lands led to increases of 168.2%, 232.7% and 91.5%, respectively. Additionally, after forestation, the soil MBN:MBP ratio decreased with elevation. Synthesis and applications. We highlight the importance of considering farmed and abandoned lands in forestation programmes to enhance microbial biomass. Forestation at low elevations may increase P limitation for microorganisms. These findings are crucial for optimising forestation strategies and management, ultimately contributing to improved ecosystem‐level soil health and functioning.

Monitoring ecological restoration of riparian forest: Is the applied nucleation effective ten years after implementation in the Pampa?

This study used remote sensing and Geo-graphical Information System (GIS) to assess the status of Awoja watersheds in Ngora district of Eastern Uganda. Landsat ETM Images covering the whole of Ngora district and part of Lake Kyoga of two time periods was carried out in the period April to July 2015. This wasacquired using USGS Earth Explorer. The images were processed and enhanced with ERDAS 2014 software to aid information extraction and analysis. Land cover change analysis was performed using ENVI 5.3 software. Supervised classification method with maximum likelihood algorithm was performed to obtain land use/ cover types. Five land use/cover types were identified: open water, wetland, tree cover, agriculture and built up area. The findings indicate a fivefold increase in built up area by 154.27km2 (i.e. 375%) and open water increased by 8.7 km2 (i.e. 55.33%). Wetland, tree cover and agriculture reduced in area by -1.0km2 (i.e. 5.1%), - 48.07 km2 (i.e. 34.46%) and -114.0km2 (i.e. 51.05%), respectively. These changes mainly resulted from deforestation, wetland encroachment, poor attitude and over population. Unless, appropriate watershed restoration strategies are designed through afforestation, law enforcement on culprits, continuous sensitisation of the watershed community on the causes of degradation, the over 1,700,000 individuals whose livelihoods depend on Awojawill continue to suffer the effects of degradation. There is need to advocate for non-consumptive projects as alternative sources of income. Keywords: Remote sensing, GIS, Watersheds.

AimAndean montane forests are biodiversity hotspots and large carbon stores and they provide numerous ecosystem services. Following land abandonment after centuries of forest clearing for agriculture in the Andes, there is an opportunity for forest recovery. Field‐based studies show that forests do not always recover. However, large‐scale and long‐term knowledge of recovery dynamics of Andean forests remains scarce. This paper analyses tropical montane forest recovery trajectories over a 15‐year time frame at the landscape and tropical Andean scale to inform restoration planning.MethodsWe first detect “potential recovery” as areas that have experienced a forest transition between 2000 and 2005. Then, we use Landsat time series analysis of the normalized difference water index (NDWI) to classify four “realized recovery” trajectories (“ongoing”, “arrested”, “disrupted” and “no recovery”) based on a sequential pattern of 5‐yearly Z‐score anomalies for 2005–2020. We compare these results against an analysis of change in tree cover to validate against other datasets.ResultsAcross the tropical Andes, we detected a potential recovery area of 274 km2 over the period. Despite increases in tree cover, most areas of the Andes remained in early successional states (10–25% tree cover), and NDWI levelled out after 5–10 years. Of all potential forest recovery areas, 22% showed “ongoing recovery”, 61% showed either “disrupted” or “arrested recovery”, and 17% showed “no recovery”. Our method captured forest recovery dynamics in a Peruvian arrested succession context and in landscape‐scale tree‐planting efforts in Ecuador.Main conclusionsForest recovery across the Andes is mostly disrupted, arrested or unsuccessful, with consequences for biodiversity recovery and provision of ecosystem services. Low‐recovery areas identified in this study might be good candidates for active restoration interventions in this UN Decade on Restoration. Future studies could determine restoration strategies and priorities and suggest management strategies at a local planning scale across key regions in the biodiversity hotspot.

This study assessed the current status of Awoja in Ngora district of Eastern Uganda.  Remote sensing, household survey, In Pac S methodology and focus group discussions were used to acquire data from April to July, 2015.   Landsat satellite imageries from 2007 and 2013 were acquired by USGS Earth Explorer to quantify land use/cover changes.   Five land use/cover types were identified namely; (1) open water (2) wetland (3) tree cover (4) agriculture and (5) built up area.  The findings indicate a fivefold increase in built up area by 154.27Km2 and open water changed by 8.7 Km2 and a reduction in wetland area by -1.0Km2  tree cover by -48.07Km2 and agriculture area by -11.4.0Km2. The survey results indicated deforestation, wetland encroachment, poor attitude and over population as the main reasons for degradation. In Pac S methodology findings showed convergence in the perceived indicator of degraded watershed in terms of water and soil quality; vegetation type and species diversity among the lay people and technocrats. The focus group discussion findings indicated a negative trend in land use/cover change.  There is need for a concerted effort to design an appropriate restoration strategy for Awoja.   Key words: Land use/cover, remote sensing, GIS and other methods.

Semi-natural pastures have rich plant and animal communities of high conservation value which depend on extensive management. As the area of such land decreases, abandoned semi-natural grasslands have been restored to re-establish biodiversity. Restoration schemes, which include thinning of woody plants and reintroduction of grazing, are mainly designed according to the responses of well-studied groups (such as vascular plants and birds). Weevils (Curculionidae) are a very diverse phytophagous beetle family. Here, we evaluated the restoration success of pastures for weevils (Curculionidae), by comparing their species diversity in abandoned, restored, and continuously grazed semi-natural pastures on 24 sites in central Sweden. Weevils were sampled by sweep-netting. We recorded 3019 weevil individuals belonging to 104 species. There was no statistically significant difference in species numbers between the pasture management treatments. However, weevil species composition of abandoned pastures differed from those in restored and continuously managed pastures, but there was no significant difference in community composition between restored and continuously grazed pastures. The abandoned sites tended to be dominated by polyphagous species, whereas the grazed sites contained more monophagous and oligophagous species. The number of weevil species was positively related to understory vegetation height and connectivity to other semi-natural grasslands and negatively related to the cover of trees and shrubs in the pastures. We conclude that restoration of abandoned semi-natural pastures is a good approach to restore weevil communities. To maintain a species rich weevil community, pastures should be managed to be relatively open, but still have patches of tall field-layer vegetation. Restoration and conservation measures should primarily be targeted on regions and landscapes where a high proportion of semi-natural grassland still remains.

Because of illegal logging, habitat fragmentation, and high value timber Andean montane forest Cedrela species (such as Cedrela angustifolia), is endangered in Central and South America. Studying the effects of climate change and tree cover loss on the distribution of C. angustifolia will help us to understand the climatic and ecological sensitivity of this species and suggest conservation and restoration strategies. Using ecological niche modeling with two algorithms (maximum entropy (MaxEnt) and Random Forest) under the ecological niche conservatism approach, we generated 16,920 models with different combinations of variables and parameters. We identified suitable areas for C. angustifolia trees under present and future climate scenarios (2040, 2070, and 2100 with SSP 3-7.0 and SSP 5-8.5), tree cover loss, and variables linked to soil and topography. Our results demonstrated 10 environmental variables with high percentage contributions and permutation importance; for example, precipitation seasonality exhibited the highest contribution to the current and future distribution of Cedrela angustifolia. The potential present distribution was estimated as 13,080 km2with tree cover loss and 16,148.5 km2without tree cover loss. From 2040 to 2100 the species distribution will decrease (from 22.16% to 36.88% with tree cover loss variation). The results indicated that Bolivia displayed higher habitat suitability than Ecuador, Peru, and Argentina. Finally, we recommend developing conservation management strategies that consider both protected and unprotected areas as well as the impact of land-use changes to improve the persistence of C. angustifolia in the future.

Patches of second-growth forest are biodiversity islands with critical importance in agricultural landscapes, providing ecosystem services that support human livelihoods and promote biodiversity, no matter the size. Natural regeneration presents an opportunity for forest landscape restoration (FLR) at low cost. However, this is not always the chosen strategy for the smallholder farmers that control about 80% of farms worldwide and are the primary decision-makers for large land areas with restoration potential. Understanding the perceptions of farmers on restoration strategies can increase our capacity to implement restoration projects. We surveyed 64 Panamanian land managers in Los Santos province, where 53% of farmers are smallholders, to better understand how they perceive restoration strategies (reforestation, regeneration, and assisted natural regeneration) and their preferences. Participants were most confident defining reforestation, associating it with tree planting. Farmers associated natural regeneration with independently growing vegetation, and assisted natural regeneration with human intervention and tree planting. Farmers were polarized in their preference for land clearing, with 36% preferring it as a first option and 42% preferring it as a last option. Over half of participants ranked letting vegetation grow and tree planting among their first and second options. High percentages of tree cover were associated with low preference for land clearing. Large farm size was associated with higher preference for natural regeneration. Expanding natural regeneration requires clearly defining and standardizing this practice. Understanding farmers’ preferences and knowledge of restoration practices will allow the best FLR strategies to be implemented in each specific case to achieve desired restoration goals.KeywordsCattleCommunity-based researchForest landscape restoration (FLR)ParticipatoryReforestationRegenerationTree planting

Tropical deforestation is mainly driven by agricultural expansion, land grabbing, illegal logging, urbanization, cattle ranching as well as mining. However, extraction of minerals and its impacts in high biodiversity regions are still poorly known, particularly in Colombia, a tropical megadiverse hotspot. Here, using high-resolution datasets of forest cover changes and detailed geospatial mining data for Colombia, we show a growing contribution of legal mining to national deforestation: 3.4% over the 2001–2018 period, with a peak at 5.6% in 2017. During this period, around 121 819 ha have been deforested inside legal mining concessions, and an estimation of over 400 000 ha deforested by both legal and illegal. Gold and coal are the most important legally-mined materials in Colombia associated to deforestation, particularly in the recent years with 511% and 257% tree cover loss increases respectively (average over 2016–2018 compared to 2001–2015 average of mined material deforestation average). Three Colombian departments summed out ∼70% of the national deforestation occurring in legal concessions: in 2018, up to 23% of deforestation in Antioquia was taking place in legal mines (gold producer). Finally, we found that only 1% (respectively, 3%) of the concessions contribute to 60% (>90%) of the legal mining-related deforestation, mainly driven by large clearings to agriculture. Environmental law enforcement, monitoring activities and engaging the mining industry in effective forest conservation and landscape restoration strategies are urgently needed in Colombia for preserving biodiversity and ecosystem services.