title: Functional losses in ground spider communities due to habitat structure degradation under tropical land-use change

authors: Potapov, Anton M.

subjects: Science & Technology

abstract: Deforestation and land‐use change in tropical regions result in habitat loss and extinction of species that are unable to adapt to the conditions in agricultural landscapes. If the associated loss of functional diversity is not compensated by species colonizing the converted habitats, extinctions might be followed by a reduction or loss of ecosystem functions including biological control. To date, little is known about how land‐use change in the tropics alters the functional diversity of invertebrate predators and which key environmental factors may mitigate the decline in functional diversity and predation in litter and soil communities. We applied litter sieving and heat extraction to study ground spider communities and assessed structural characteristics of vegetation and parameters of litter in rainforest and agricultural land‐use systems (jungle rubber, rubber, and oil palm monocultures) in a Southeast Asian hotspot of rainforest conversion: Sumatra, Indonesia. We found that (1) spider density, species richness, functional diversity, and community predation (energy flux to spiders) were reduced by 57–98% from rainforest to oil palm monoculture; (2) jungle rubber and rubber monoculture sustained relatively high diversity and predation in ground spiders, but small cryptic spider species strongly declined; (3) high species turnover compensated losses of some functional trait combinations, but did not compensate for the overall loss of functional diversity and predation per unit area; (4) spider diversity was related to habitat structure such as amount of litter, understory density, and understory height, while spider predation was better explained by plant diversity. Management practices that increase habitat‐structural complexity and plant diversity such as mulching, reduced weeding, and intercropping monocultures with other plants may contribute to maintaining functional diversity of and predation services provided by ground invertebrate communities in plantations.

text: Functional losses in ground spider communities due to habitat structure degradation under tropical land-use change Deforestation and land‐use change in tropical regions result in habitat loss and extinction of species that are unable to adapt to the conditions in agricultural landscapes. If the associated loss of functional diversity is not compensated by species colonizing the converted habitats, extinctions might be followed by a reduction or loss of ecosystem functions including biological control. To date, little is known about how land‐use change in the tropics alters the functional diversity of invertebrate predators and which key environmental factors may mitigate the decline in functional diversity and predation in litter and soil communities. We applied litter sieving and heat extraction to study ground spider communities and assessed structural characteristics of vegetation and parameters of litter in rainforest and agricultural land‐use systems (jungle rubber, rubber, and oil palm monocultures) in a Southeast Asian hotspot of rainforest conversion: Sumatra, Indonesia. We found that (1) spider density, species richness, functional diversity, and community predation (energy flux to spiders) were reduced by 57–98% from rainforest to oil palm monoculture; (2) jungle rubber and rubber monoculture sustained relatively high diversity and predation in ground spiders, but small cryptic spider species strongly declined; (3) high species turnover compensated losses of some functional trait combinations, but did not compensate for the overall loss of functional diversity and predation per unit area; (4) spider diversity was related to habitat structure such as amount of litter, understory density, and understory height, while spider predation was better explained by plant diversity. Management practices that increase habitat‐structural complexity and plant diversity such as mulching, reduced weeding, and intercropping monocultures with other plants may contribute to maintaining functional diversity of and predation services provided by ground invertebrate communities in plantations.

year: 2020

title: 'Not too calm'

authors: Lodge, Martin

abstract: At the time of his death in September 1999, music historian John Mansfield Thomson left a number of projects unfinished. One of these projects was an autobiography. In the course of my duties as executor of his literary estate, I subsequently discovered the beginnings of autobiographical writing on John's computer hard drive, and it was possible to include these fragments in the 2003 book John Mansfield Thomson: Notes towards a biography'.

text: 'Not too calm' At the time of his death in September 1999, music historian John Mansfield Thomson left a number of projects unfinished. One of these projects was an autobiography. In the course of my duties as executor of his literary estate, I subsequently discovered the beginnings of autobiographical writing on John's computer hard drive, and it was possible to include these fragments in the 2003 book John Mansfield Thomson: Notes towards a biography'.

year: 2005

title: Maori land in Hauraki

authors: Hart, Philip

abstract: Imagining the Hauraki Peninsula to contain payable goldfields and knowing that land to the south of Thames had great agricultural potential, Pakeha were determined to acquire it, and were frustrated by what was considered to be ‘Maori intransigence’. For their part, Maori landowners were justifiably concerned about losing their land, and hindered and delayed opening it to settlement for as long as possible. A major difficulty for officials seeking to acquire land was how to determine boundaries between different blocks and how to identify the true owners when there were rival claims put forward by hapu and individuals. Land purchase agents used a variety of means to get blocks through the land court and then to individualize the title, notably the controversial ‘raihana’ policy, which benefited some landowners at the expense of others. The expensive legal process involved often forced those who had proved their ownership to sell land to pay for their success, a success which resulted in grantees treating the land as their personal property rather than tribal property. Some Pakeha as well as many Maori protested at the unfair process; even James Mackay, the most effective practitioner of raihana, came to lament his success and its consequences for the younger generation of Maori (he blamed the system, not himself). When far too late, it was urged that land should have been leased rather than sold and that proceeds from sales should not have been squandered.
Instead of having commissions of enquiry, as some suggested, the land court system meant that judges determined ownership on the evidence presented to them, even though some owners were not present nor had their interests represented. Sometimes the evidence was false, as was admitted by some witnesses when their perjury was exposed. And in the case of the Ohinemuri district, for which the records survive, when the land was sold to the Crown some Maori received too much money, some too little, and some missed out altogether. The struggles to open Ohinemuri to miners and settlers is examined in detail, revealing that some rangatira expected economic gain and that Te Hira’s party, who opposed the opening, were undermined by some of Te Hira’s followers: being ‘Hauhau’, they refused to take money from the Crown but instead took raihana, meaning goods which were charged against their land in a way they did not understand. Nor did anyone fully understand the system apart from Mackay, whose policy was eventually repudiated by the politicians who had encouraged it previously. Not all land was lost, but because the government did not assist landowners with advice and finance until well into the twentieth century what land that was retained could not be developed adequately.

text: Maori land in Hauraki Imagining the Hauraki Peninsula to contain payable goldfields and knowing that land to the south of Thames had great agricultural potential, Pakeha were determined to acquire it, and were frustrated by what was considered to be ‘Maori intransigence’. For their part, Maori landowners were justifiably concerned about losing their land, and hindered and delayed opening it to settlement for as long as possible. A major difficulty for officials seeking to acquire land was how to determine boundaries between different blocks and how to identify the true owners when there were rival claims put forward by hapu and individuals. Land purchase agents used a variety of means to get blocks through the land court and then to individualize the title, notably the controversial ‘raihana’ policy, which benefited some landowners at the expense of others. The expensive legal process involved often forced those who had proved their ownership to sell land to pay for their success, a success which resulted in grantees treating the land as their personal property rather than tribal property. Some Pakeha as well as many Maori protested at the unfair process; even James Mackay, the most effective practitioner of raihana, came to lament his success and its consequences for the younger generation of Maori (he blamed the system, not himself). When far too late, it was urged that land should have been leased rather than sold and that proceeds from sales should not have been squandered.
Instead of having commissions of enquiry, as some suggested, the land court system meant that judges determined ownership on the evidence presented to them, even though some owners were not present nor had their interests represented. Sometimes the evidence was false, as was admitted by some witnesses when their perjury was exposed. And in the case of the Ohinemuri district, for which the records survive, when the land was sold to the Crown some Maori received too much money, some too little, and some missed out altogether. The struggles to open Ohinemuri to miners and settlers is examined in detail, revealing that some rangatira expected economic gain and that Te Hira’s party, who opposed the opening, were undermined by some of Te Hira’s followers: being ‘Hauhau’, they refused to take money from the Crown but instead took raihana, meaning goods which were charged against their land in a way they did not understand. Nor did anyone fully understand the system apart from Mackay, whose policy was eventually repudiated by the politicians who had encouraged it previously. Not all land was lost, but because the government did not assist landowners with advice and finance until well into the twentieth century what land that was retained could not be developed adequately.

year: 2016