The cost of mitigation strategies for agricultural adaptation to global change

Land recovery and the improvement of lands affected by desertification for agricultural use, is achieved when a sustained recovery of agricultural productivity over time is obtained. In the areas affected by desertification and drought, it is common that the ecosystems do not have enough funding for water management and irrigation. This situation leads to an inadequate assessment of the environmental goods and services in arid zones. As a result we have a misuse of these dry lands. Many countries are implementing policies and making investments and efforts to mitigate arid land degradation and desertification through the National Action Programs (NAP). However, for the long term planning of mitigation and adaptation strategies, it is necessary to know the cost of recovery and land improvement in certain areas in order to forecast the budgets. This is the main objective of this paper in order to combat desertification and drought in central northern Chile. We have calculated a recovery cost per hectare by region and for each of the agriculture, livestock and forestry (ALF) promotion agencies. The results indicate that the cost of land reclamation in the northern regions is much higher than in the southern regions of this studied area. The cost is especially high for Region II, where investment per hectare is almost to 3000 US$ per hectare. At the other extreme is the Region VII, in the south of the studied area where the investment required per hectare barely reaches 500 US$. The contribution of the promotion agencies to the total cost also varied among regions and agencies. We discuss the results within a context of recovery cost per hectare depending on the different environmental characteristics and agricultural development of each of the studied regions.     

Timid spider uses odor and visual cues to actively select protected nesting sites near ants

Associations in which a more vulnerable species gains protection by seeking out the company of a pugnacious “protector” species capable of deterring predators are documented among mixed-species groups from various taxa, but experimental studies are rare. We consider an unusual arthropod-based example in which the associate species, Phintella piantensis, is a jumping spider (Salticidae) that associates with the territorial weaver ant Oecophylla smaragdina, which in turn is a potential predator of Phintella. However, the predator we consider in this mixed-species association is Scytodes sp., a spitting spider (Scytodae) that often targets salticids as prey. Scytodes adopts a strategy of building its web over salticid nests and then preying on resident salticids when they leave or return to their nests. Our experiments show that, on the basis of olfactory cues, Scytodes is deterred from the vicinity of O. smaragdina. Phintella builds dense ant-proof nests to minimize the risk of being killed by Oecophylla, and we show that olfactory as well as visual cues of ants elicit nest building by Phintella. We propose that Phintella actively chooses to situate nests in the vicinity of weaver ants as defense against a specific ant-averse predator that singles out salticids as preferred prey.     

Energy efficiency and conservation for individual Americans

Americans make up only 4% of the world population, yet currently consume 25% of the world’s fossil fuels. The U.S. imports 63% of its oil and it is predicted that by 2020 the U.S. will be importing 95% of its oil resources. Over the past century, ample and affordable supplies of fossil fuels have powered the growth and prosperity of the economies of the US and other countries. Within this century, world oil supplies will decline while demand is projected to continue to increase, suggesting that we will have to transition to different fuels or become much more energy efficient or both. Looking ahead to the near decades, estimates are that consumers will have to reduce their energy use by at least 50%. This reduction will be necessary in large part due the decline in the availability of conventional oil and gas, but also because the U.S. population will continue to grow in number. Although government action is important, individuals too often discount their ability to make significant contributions to solving such major problems. This investigation identifies how informed and concerned individuals can collectively conserve fossil energy. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. An erratum to this article can be found at     

Understanding deforestation in the southern Yucatán: insights from a sub-regional, multi-temporal analysis

The southern Yucatán has been identified as a deforestation hot spot. Land-change studies document the extent of forest loss at a regional scale, and case studies provide insights into the drivers of deforestation at the household level. Those studies have paid minimal attention to sub-regional analysis, especially to discrete land-management units above the household level. This analysis of upland forest change addresses the range of variation in deforestation among 96 ejidos (communal lands) and the Calakmul Biosphere Reserve, the two dominant land-tenure and land-management units in the region. Satellite imagery, census, and land-tenure data are used to establish the extent and location of deforestation patterns, and multivariate techniques are employed to identify biophysical and socioeconomic variables that explain such patterns. Results show that, for the 1984–1993 period, deforestation in the southern Yucatán was not as prevalent as implied by its hot spot designation. Three clusters of deforestation are identified. A logistic regression analysis establishes that size of forest holdings, population growth, and location in the precipitation gradient correlate with ejidos that experienced higher deforestation rates than the rest of the land-tenure units. For the 1993–2000 period, conservation programs and changes in the economic context of this “hollow frontier” contributed to reduce deforestation rates and extent. This analysis illustrates the spatio-temporal heterogeneity of much tropical forest change and caution that it should bring to simple formulations of modeling this change and prescribing policies to control it.     

Numerical model to assess the impact of the strategies to mitigate desertification

Desertification is considered a global environmental problem with political and socioeconomic implications. Desertification, exacerbated by climate change, is the largest environmental problem in Chile affecting almost two third of the national territory. This study takes place in a latitudinal gradient of the north-central Chilean drylands, where desertification is a threat to agriculture, livestock and forestry (ALF). In the context of the United Nations Convention to Combat Desertification (UNCCD) and the implementation of the Chilean National Action Programme (NAP), the country is conducting policies and investing in mitigation strategies to combat land degradation and desertification. The main objective of this paper is the development of an integrative methodological approach using real data of the territorial and socioeconomic indicators. With the proposed methodology we assess the impact of the mitigation and land degradation strategies supported by the ALF promotion agencies in the fight against desertification, projecting different scenarios of change. The data were collected in 2008 in Santiago, Chile. The results of the Principal Component Analysis (PCA) suggest that technical irrigation and the improvement of grasslands and pastures play an important role in the fight against desertification. The results of the model projections are consistent, suggesting that the efforts of the ALF promotion agencies have a positive impact in fighting desertification. Inaction of ALF mitigation strategies would increase desertification. This methodological approach, performed with real data, is a contribution for the development of integrative assessments, for replication and for forthcoming discussions.