Alien plant species: environmental risks in agricultural and agro-forest landscapes under climate change

Alien plant species have been essential for farming and agro-forestry systems and for their supply of food, fiber, tannins, resins or wood from antiquity to the present. They also contributed to supporting functions and regulating services (water, soil, biodiversity) and to the design of landscapes with high cultural and scenic value. Some of those species were intentionally introduced, others arrived accidentally, and a small proportion escaped, naturalized and became invasive in natural ecosystems—these are known as invasive alien species (IAS). Here, invasive means that these species have some significant negative impact, either by spreading from human-controlled environments (e.g. fields, gardens) to natural ecosystems, where they can cause problems to native species, or to other production systems or urban areas, impacting on agricultural, forestry activities or human health. Socio-environmental impacts associated with plant invasions have been increasingly recognized worldwide and are expected to increase considerably under changing climate or land use. Early detection tools are key to anticipate IAS and to prevent and control their impacts. In this chapter, we focus on crop and non-crop alien plant species for which there is evidence or prediction of invasive behaviour and impacts. We provide insights on their history, patterns, risks, early detection, forecasting and management under climate change. Specifically, we start by providing a general overview on the history of alien plant species in agricultural and agroforestry systems worldwide. Then, we assess patterns, risks and impacts resulting from alien plants originally cultivated and that became invasive outside cultivation areas. Afterwards, we provide several considerations for managing the spread of invasive plant species in the landscape. Finally, we discuss challenges of alien plant invasions for agricultural and agroforest systems, in the light of climate change.Joana R. Vicente was supported by POPH/FSE and FCT (Post-Doc grant SFRH/BPD/84044/2012). Ana Sofia Vaz was supported by FSE/MEC and FCT (Ph.D. grant PD/ BD/52600/2014). Ana Isabel Queiroz supported by FCT—the Portuguese Foundation for Science and Technology [UID/HIS/04209/2013 and IF/00222/2013/CP1166/CT0001]. This work received financial support from the European Union (FEDER funds POCI-01-0145-FEDER-006821) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/BIA/50027/201

Managing Trade-Offs in Coffee Agroforests

Agroforestry systems provide multiple ecosystem services and are refuges for diverse flora and fauna. Coffee is one of the main tropical agroforestry crops and of global economic importance. Over recent decades, coffee agroforestry systems have been increasingly intensified by the replacement of native shade tree diversity with one or few, often non-native, tree species. Such reduction in tree diversity might have implications for ecosystem services, such as nutrient cycling, soil fertility, pest control, and coffee production, and ultimately negative effects for the systems’ resilience to climate change. The overall aim of this thesis is to investigate the direct and indirect effects of tree diversity reduction on ecosystem services, to understand the arising management trade-offs for Coffea canephora production in the face of climate change. We therefore studied 25 agroforestry systems in Kodagu, India, across a broad rainfall and management gradient, which experience a gradual transformation of native diverse shade tree canopy to Grevillea robusta dominated shade. Climate change is expected to alter the intense monsoon rainfalls during the short, wet season by an increase in the east and a reduction in the west. The results show that the transformation towards G. robusta dominated shade has not only highly negative effects for tree diversity but also for coffee production and quality. Both coffee production and quality were lower under G. robusta dominating shade. This resulted mainly from the increased development of single-seeded fruits (pea-beans), likely a result from reduced pollination success, and higher infestation rates of the coffee berry borer, Hypothenemus hampei. This suggests that pest control and pollination services are reduced in monospecific agroforestry systems. Grevillea robusta shade reduced nutrient cycling and long-term soil fertility. In contrast to native trees, G. robusta leaf litter shedding was more dependent on the annual rainfall, which reduced litterfall in wet sites to negligible amounts. Low litter quality and reduced decomposition rates characterize G. robusta dominated agroforests, and this led to low soil fertility and a decline in soil carbon contents, particularly in wet sites. The specific characteristic of G. robusta, being a Proteaceae, reduced phosphor cycling by increasing the immobilization of the same. Although, we did not find evidence for increased nutrient limitation in C. canephora leaves under G. robusta shade, the loss of soil carbon reduces soil fertility and nutrient availability over the long-term, which will likely demand higher nutrient inputs in the future. Microclimate and soil moisture was negatively altered under G. robusta monospecific shade compared to native diverse agroforests. Low soil carbon was one of the main drivers for lower soil moisture under G. robusta, which increased nutrient leaching. This, together with higher relative air humidity, reduced coffee production in monospecific shade. While high monsoon rainfall reduced coffee production in all agroforestry types, throughfall reduction benefitted coffee plants less under G. robusta dominated shade, in which high nutrient leaching resulted in a lower final berry-set. In conclusion, we provide strong evidence that there are no trade-offs, but synergies between tree diversity, coffee production and resilience to climate change. A shade cover dominated by G. robusta affects ecosystem resilience by causing: (1) increased pest attacks likely due to a loss of complex multi-trophic interactions; (2) reduced nutrient cycling and loss of soil carbon, reducing soil fertility in the long-term; (3) reduction of soil moisture and increase of nutrient leaching likely via runoff; (4) increased relative humidity potentially due to higher transpiration of the fast-growing G. robusta. These characteristics of G. robusta dominance negatively affect coffee production and quality, and reduce the agroforestry systems’ resilience to climate change

Data from: Simplification of shade tree diversity reduces nutrient cycling resilience in coffee agroforestry

1. Agroforestry systems are refuges for biodiversity and provide multiple ecosystem functions and services. Diverse multispecies shade tree canopies are increasingly replaced by monospecific shade, often dominated by non-native tree species. The loss of tree diversity and the nature of the dominating tree can have strong implications for ecosystem functions, e.g. nutrient cycling ultimately reducing crop production. 2. To understand direct and indirect impacts of shade trees on nutrient cycling and crop production, we studied coffee agroforestry systems in India along a gradient from native multispecies canopies to Grevillea robusta (Proteaceae) -dominated canopy cover. We identified 25 agroforests, across a broad rainfall and management gradient and assessed litter quantity and quality, decomposition, nutrient release, soil fertility and coffee nutrient limitations. 3. Increasing G. robusta dominance affected nutrient cycling predominantly by; (1) changing of litter phenology, (2) reducing phosphorus (P), potassium (K), magnesium (Mg), boron (B), and zinc (Zn) inputs via litterfall, decelerated litter decomposition and immobilization of P and Zn due to low quality litter, (3) reducing soil carbon (C) and micronutrients (especially sulphur (S), Mg and B). Coffee plants were deficient in several nutrients (nitrogen (N), calcium (Ca), manganese (Mn), Mg and S in organic and B in conventional management). (4) Overall G. robusta dominated agroforests were characterized by a reduction of P cycling due to low inputs, strong immobilization while decomposition and antagonistic effects on its release in litter mixtures with coffee. 4. Synthesis and applications. The conversion of shade cover in coffee agroforestry systems from diverse tree canopies to canopies dominated by Grevillea robusta (Proteaceae) reduces the inputs and cycling of several micro- and macronutrients. Soil fertility is therefore expected to decline in G. robusta dominated systems, with likely impacts on coffee production. These negative effects might increase under the longer dry periods projected by regional climate change scenarios due to the pronounced litter phenology of G. robusta. Maintaining diverse shade canopies can more effectively sustain micro- and macronutrients in a more seasonal climate

Shade tree diversity enhances coffee production and quality in agroforestry systems in the Western Ghats

Intensification of multispecies coffee agroforests reduces shade tree diversity with implications for tropical biodiversity. We investigated how tree biodiversity and its effects on coffee production and quality changes along a gradient of intensification (from diverse multispecies to Grevillea robusta dominated shade) across 25 Coffea canephora agroforests in Kodagu, India. Intensification causes a marked reduction in tree biodiversity (Shannon's diversity: 2.74 to 0.29). Reduced tree diversity negatively affected both coffee production and quality (in terms of bean size), and increased incidences of pest attack, the coffee berry borer (Hypothenemus hampei). These results were consistent across a broad rainfall gradient (1060 mm yr−1 to 4370 mm yr−1) and management systems (conventional vs. organic farming and irrigation). Our results reveal important co-benefits of multispecies agroforestry systems for biodiversity conservation and coffee production. Nonetheless, intensification provides farmers with new livelihood options and income sources. To maintain high diversity agroforests, these opportunity costs need to be accounted for in developing realistic market strategies for biodiversity conservation

Shade tree diversity enhances coffee production and quality in agroforestry systems in the Western Ghats

Intensification of multispecies coffee agroforests reduces shade tree diversity with implications for tropical biodiversity. We investigated how tree biodiversity and its effects on coffee production and quality changes along a gradient of intensification (from diverse multispecies to Grevillea robusta dominated shade) across 25 Coffea canephora agroforests in Kodagu, India. Intensification causes a marked reduction in tree biodiversity (Shannon's diversity: 2.74 to 0.29). Reduced tree diversity negatively affected both coffee production and quality (in terms of bean size), and increased incidences of pest attack, the coffee berry borer (Hypothenemus hampei). These results were consistent across a broad rainfall gradient (1060 mm yr−1 to 4370 mm yr−1) and management systems (conventional vs. organic farming and irrigation). Our results reveal important co-benefits of multispecies agroforestry systems for biodiversity conservation and coffee production. Nonetheless, intensification provides farmers with new livelihood options and income sources. To maintain high diversity agroforests, these opportunity costs need to be accounted for in developing realistic market strategies for biodiversity conservation

soil characteristics

Characteristics of the soil; First column is an identifier, second column is the plantation number and third column is the plot replicate in the plantation. Fourth column is the density of the soil, columns five to eight are the soil contents of gravel, clay, silt and sand, ninth column is the soil pH, tenth column is the cation exchange capacity, eleventh and twelveth columns are the total soil carbon and mineral N concentrations in the soil, columns thirteen to last are the plant available concentrations of P, K, Ca, Mg, S, Fe, Mn, Zn, and B. The data has been collected in December 2014

plantation characteristics

Characteristics of plantations; First column is an identifier, second column is the plantation number and third column is the plot replicate in the plantation. Fourth and fifth columns are the latitude and longitude of the plot site, sixth column is the management type, seventh column is the annual rainfall, eight and ninth columns are the age and altitude of the plantation, tenth and eleventh columns are the coffee age and coffee plants per hectare, the last column is the slope. The data has been collected in February-May 2013

Shade tree and coffee litter mass and nutrients inputs

Litter fall and nutrient inputs; First column is an identifier, second column is the plantation number and third column is the plot replicate in the plantation. Fourth,fifth, sixth and seventh columns are the yearly inputs per hectare of total litter, coffee leaf litter, shade tree leaf litter (excluding Grevillea robusta leaf litter) and Grevillea robusta leaf litter. The columns eight to eighteen are the yearly nutrient inputs per hectare through coffee litter, the columns nineteen to twenty nine are the yearly nutrient inputs per hectare through shade tree leaf litter. The data has been collected in between June 2013 to December 2014

Shade tree characteristics

Characteristics of shade trees; First column is an identifier, second column is the plantation number and third column is the plot replicate in the plantation. Fourth column is the number of trees per hectare, fifth and sixth columns are the stand basal area and mean basal area of the trees, seventh column is the percentage of Grevillea robusta trees per plot, column eight is the Shannon's diversity index per plot, ninth column is the canopy cover at coffee harvest (December). The data has been collected in February 2013 to December 2014

units and description

description and units of data in csv file