Defoliation symptoms on trees planted at a restoration site in Sabah, Malaysia

A study on defoliation of selected tree species was conducted at a forest restoration site located at Species Demo Plot in Luasong, Tawau Sabah. The study site is part of the INIKEA Forest Rehabilitation Project managed by Yayasan Sabah. The objective of this study was to determine the type and variation of defoliation symptoms observed on the foliage of eight to ten years old trees of Dipterocarpus conformis (KBK), Diospyros sp. (KMLM), Dryobalanops lanceolata (KPJ), Pentace laxiflora (TDH), Pentace adenophora (TDB) and Hopea ferruginea (SMKU) that were planted by line planting method. Sampling was conducted in July 2017 for a period of one week. Four replicates for each tree species was sampled. Defoliation symptoms were assessed on the crown of the trees. The mean defoliation symptom occurrence was calculated to represent each tree species. The mean defoliation symptoms among the six tree species were tested by using the Chi-square statistical analysis. Defoliation symptom occurrence across the six species of trees was categorized as herbivory, egg cases, leaf miners, leaf rollers, and galls. The highest percentage of defoliation symptom was herbivory (44.71%), followed by both egg cases and leaf miners (24.71% respectively), and only 1.18% of galls, which was the lowest. The highest mean defoliation symptom occurrence was recorded on D. lanceolata, with a mean of 4.75 occurrence, while the lowest mean defoliation symptom occurrence of 3.00 was recorded on both Diospyros sp. and H. ferruginea. Results of the Chi-square analysis indicated no significant difference (p>0.05) in the mean occurrence of defoliation symptoms across the six species of trees

The moisture response of soil heterotrophic respiration: Interaction with soil properties

Soil moisture is of primary importance for predicting the evolution of soil carbon stocks and fluxes, both because it strongly controls organic matter decomposition and because it is predicted to change at global scales in the following decades. However, the soil functions used to model the heterotrophic respiration response to moisture have limited empirical support and introduce an uncertainty of at least 4% in global soil carbon stock predictions by 2100. The necessity of improving the representation of this relationship in models has been highlighted in recent studies. Here we present a data-driven analysis of soil moisture-respiration relations based on 90 soils. With the use of linear models we show how the relationship between soil heterotrophic respiration and different measures of soil moisture is consistently affected by soil properties. The empirical models derived include main effects and moisture interaction effects of soil texture, organic carbon content and bulk density. When compared to other functions currently used in different soil biogeochemical models, we observe that our results can correct biases and reconcile differences within and between such functions. Ultimately, accurate predictions of the response of soil carbon to future climate scenarios will require the integration of soil-dependent moisture-respiration functions coupled with realistic representations of soil water dynamic

Explore before you restore: Incorporating complex systems thinking in ecosystem restoration

The global movement for ecosystem restoration has gained momentum in response to the Bonn Challenge (2010) and the UN Decade on Ecosystem Restoration (UNDER, 2021–2030). While several science-based guidelines exist to aid in achieving successful restoration outcomes, significant variation remains in the outcomes of restoration projects. Some of this disparity can be attributed to unexpected responses of ecosystem components to planned interventions.Given the complex nature of ecosystems, we propose that concepts from Complex Systems Science (CSS) that are linked to non-linearity, such as regime shifts, ecological resilience and ecological feedbacks, should be employed to help explain this variation in restoration outcomes from an ecological perspective.Our framework, Explore Before You Restore, illustrates how these concepts impact restoration outcomes by influencing degradation and recovery trajectories. Additionally, we propose incorporating CSS concepts into the typical restoration project cycle through a CSS assessment phase and suggest that the need for such assessment is explicitly included in the guidelines to improve restoration outcomes.To facilitate this inclusion and make it workable by practitioners, we describe indicators and methods available for restoration teams to answer key questions that should make up such CSS assessment. In doing so, we identify key outstanding science and policy tasks that are needed to further operationalize CSS assessment in restoration.Synthesis and applications. By illustrating how key Complex Systems Science (CSS) concepts linked to non-linear threshold behaviour can impact restoration outcomes through influencing recovery trajectories, our framework Explore Before You Restore demonstrates the need to incorporate Complex Systems thinking in ecosystem restoration. We argue that inclusion of CSS assessment into restoration project cycles, and more broadly, into international restoration guidelines, may significantly improve restoration outcomes

Explore before you restore: Incorporating complex systems thinking in ecosystem restoration

Abstract The global movement for ecosystem restoration has gained momentum in response to the Bonn Challenge (2010) and the UN Decade on Ecosystem Restoration (UNDER, 2021–2030). While several science‐based guidelines exist to aid in achieving successful restoration outcomes, significant variation remains in the outcomes of restoration projects. Some of this disparity can be attributed to unexpected responses of ecosystem components to planned interventions. Given the complex nature of ecosystems, we propose that concepts from Complex Systems Science (CSS) that are linked to non‐linearity, such as regime shifts, ecological resilience and ecological feedbacks, should be employed to help explain this variation in restoration outcomes from an ecological perspective. Our framework, Explore Before You Restore, illustrates how these concepts impact restoration outcomes by influencing degradation and recovery trajectories. Additionally, we propose incorporating CSS concepts into the typical restoration project cycle through a CSS assessment phase and suggest that the need for such assessment is explicitly included in the guidelines to improve restoration outcomes. To facilitate this inclusion and make it workable by practitioners, we describe indicators and methods available for restoration teams to answer key questions that should make up such CSS assessment. In doing so, we identify key outstanding science and policy tasks that are needed to further operationalize CSS assessment in restoration. Synthesis and applications. By illustrating how key Complex Systems Science (CSS) concepts linked to non‐linear threshold behaviour can impact restoration outcomes through influencing recovery trajectories, our framework Explore Before You Restore demonstrates the need to incorporate Complex Systems thinking in ecosystem restoration. We argue that inclusion of CSS assessment into restoration project cycles, and more broadly, into international restoration guidelines, may significantly improve restoration outcomes. </jats:p

Soil rehabilitation following tractor logging: early results on amendments and tilling in a second rotation Acacia mangium plantation in Sabah, Malaysia

Timber extraction with crawler tractors in humid tropical forests causes degradation of soil physical properties and decreases plant growth. We tested rehabilitation of tracks in a second rotation Acacia mangium plantation in Sabah, Malaysia, by tilling with additions of NPK-fertilizer, ash and organic material to a depth of 15–20 cm. Two years after planting total basal area of A. mangium seedlings was 62% higher outside tracks compared to unimproved tracks, while on NPK-fertilized tracks performance was 700% higher compared to unimproved tracks. Corresponding figures for average height were 40 and 80%. After 8 days with little rain track topsoil experienced water shortage with all studied soil improvements. For ‘non-tracked’ areas wilting-point (-1500 kPa) was not reached during 17 days of dry weather, and more meso-pores were present. Consequently, depending on rainfall after planting the effect of soil rehabilitation on tree performance may be less positive than shown here, because dry periods of 2 weeks length are common in the humid tropics. Bulk density on plots outside tracks in this second-generation plantation was 60% higher than have been reported in similar first generation plantations. It is discussed that this might be a warning that repeated logging and fire may have a detrimental effect on soil physical properties

Carbon sequestration in tropical forests and water: a critical look at the basis for commonly used generalizations

Tree planting in the tropics is conducted for a number of reasons including carbon sequestration, but often competes with increasingly scarce water resources. The basics of forest and water relations are frequently said to be well understood but there is a pressing need to better understand and predict the hydrological effects of land-use and climate change in the complex and dynamic landscapes of the tropics. This will remain elusive without the empirical data required to feed hydrological process models. It is argued that the current state of knowledge is confused by too broad a use of the terms 'forest' and '(af)forestation', as well as by a bias towards using data generated mostly outside the tropics and for nondegraded soil conditions. Definitions of forest, afforestation and reforestation as used in the climate change community and their application by land and water managers need to be reconciled. © 2009 Blackwell Publishing Ltd