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Risks And Benefits of the Use of Urine-Diverting Vermicomposting Toilet Systems Williams, Brennan 2016-04

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 	 	Photo:	Brennan	Williams	2016			Prepared	by	Brennan	Williams	University	of	British	Columbia	Department	of	Geography	April,	2016	Report	prepared	at	the	request	of	British	Columbia	Parks	in	partial	fulfilment	of	GEOG	419:	Research	in	Environmental	Geography,	for	Dr.	David	Brownstein.	 	Risks	And	Benefits	of	the	Use	of	Urine-Diverting	Vermicomposting	Toilet	Systems	 1		Risks	and	Benefits	of	the	Use	of	Urine-Diverting	Vermicomposting	Toilet	Systems		Executive	Summary:		This	work	explores	the	risks	and	benefits	associated	with	the	use	of	urine	diverting	vermicomposting	toilets	(UDVTs)	in	backcountry	areas	of	British	Columbia	Parks.	The	benefits	of	these	systems	are	well	documented,	and	include:				• reducing	the	amount	of	solid	waste	produced;	• reducing	operator	and	user	exposure	to	pathogens	and	parasites;	and,		• lessening	environmental	impacts.		The	foremost	risk	of	the	use	of	UDVTs	is	the	potential	for	the	non-native	red-wriggler	worm	(Eisenia	fetida)	to	become	invasive	if	introduced	into	these	systems.	In	order	to	mitigate	risk,	this	report	identifies	environmental	conditions	where	Eisenia	fetida	may	be	used	with	a	low	potential	of	becoming	invasive.	Furthermore,	it	identifies	measures	to	mitigate	risk	such	as	the	use	of	native	detritivores	to	facilitate	decomposition	and	makes	the	following	recommendations	to	BC	Parks:		• that	BC	Parks	continue	monitoring	Eisenia	fetida	use	where	it	has	already	commenced;		• that	moving	forward,	BC	Parks	conducts	soil	and	temperature	sampling	at	vermicomposting	sites	in	order	to	determine	whether	or	not	the	surrounding	environment	is	conducive	to	the	survival	of	Eisenia	fetida;	• that	BC	Parks	allow	for	the	use	of	Eisenia	fetida	for	vermicomposting	at	sites	where	they	are	already	present;	and,	• that	native	detritivores	(including	native	earthworms)	that	are	present	at	UDVT	sites	are	used	at	sites	where	Eisenia	Fetida	has	a	high	potential	of	becoming	invasive.			In	order	to	determine	benefits,	risks,	mitigation	measures,	and	alternatives,	this	work	relies	on	a	literature	review	in	the	form	of	a	meta-analysis	as	well	as	an	expert	interview	with	Dr.	Geoffrey	B.	Hill.	The	report	concludes	by	identifying	that	future	research	should	focus	on	structural	controls	to	limit	the	possibility	of	worms	escaping	from	UDVTs	in	order	to	reduce	invasion	potential.		 	 2	Introduction:			This	work	explores	the	risks	and	benefits	associated	with	the	use	of	urine	diverting	vermicomposting	toilets	(UDVTs)	in	backcountry	areas	of	British	Columbia	Parks.	More	specifically,	it	focuses	on	the	risks	associated	with	UDVTs	that	arise	from	the	potential	for	the	non-native	red-wriggler	earthworm	(Eisenia	fetida)	to	become	invasive	in	localized	environments	if	introduced	into	UDVTs.	While	native	invertebrates	may	be	effective	in	UDVTs,	Eisenia	fetida	are	preferred	as	native	earth	worm	species	in	British	Columbia	are	rare	and	have	become	extirpated	from	large	areas	within	the	province.	Therefore,	collecting	native	earthworm	species	for	vermicomposting	would	not	be	feasible	for	most	sites	within	British	Columbia	Parks.		Furthermore,	Eisenia	fetida	are	the	“earthworm	species	most	commonly	used	in	the	composting	industry	[as	it]	thrives	in	the	high	temperatures	that	characterize	actively	decomposing	organic	matter”	(Greiner	et	al.	350).	The	research	presented	in	this	work	indicates	that	based	on	local	environmental	conditions,	there	are	sites	within	BC	Parks	where	Eisenia	fetida	may	be	used	for	vermicomposting	with	a	low	risk	of	the	species	becoming	invasive.	Furthermore,	it	indicates	that	at	sites	where	there	is	a	high	risk	of	invasion	of	Eisenia	fetida,	detritivores	from	local	soils	can	be	utilized	to	reduce	human	waste	streams.	Methods:	This	study	has	largely	been	conducted	in	the	form	of	a	meta-analysis	of	the	literature	reviewed	below.	These	sources	were	combined	in	order	to	identify	the	benefits	associated	with	UDVTs.	Furthermore,	this	allowed	for	the	determination	of	the	conditions	that	are	suitable	for	the	survival	of	Eisenia	fetida	in	order	to	identify	environments	where	there	is	a	high	degree	of	confidence	that	the	species	will	not	become	invasive	(e.g.	environments	with	soils	and	 3	temperatures	unsuitable	for	the	species).	This	research	also	incorporates	an	expert	interview	with	Dr.	Geoffrey	B	Hill,	who	is	prevalent	in	vermicomposting	literature	in	the	North	American	context	and	an	expert	on	the	subject,	in	order	to	identify	alternatives	to	the	use	of	Eisenia	fetida	in	UDVTs.	The	analysis,	findings	and	recommendations	included	in	this	draft	have	also	been	supplemented	by	internal	BC	Parks	documents	provided	by	Joanna	Hirner,	Conservation	Specialist	for	the	South	Coast	Region	of	BC	Parks.		Literature	Review:	Multiple	studies	have	been	conducted	regarding	the	benefits	of	UDVTs	over	mixed	latrine	microbial	toilets	which	do	not	divert	urine	(Hill	et	al.	2013a;	Hill	et	al.	2013b;	Hill	and	Baldwin	2012;	Hill	2013).	The	studies	identified	that	utilizing	UDVTs	reduces	the	amount	of	solid	and	liquid	waste	produced,	reduces	operator	and	user	exposure	to	pathogens	and	parasites,	and	lessens	environmental	impacts	by	limiting	leaching	into	ground	and	surface	water.	In	addition,	there	is	literature	regarding	the	environmental	impacts	of	urine	diversion,	which	has	been	proven	to	be	a	low	risk	method	for	human	waste	disposal	and	beneficial	for	local	plant	communities	as	urine	contains	the	majority	of	plant	available	nitrogen	(Bethune,	2015;	Hill	2016).	However,	very	few	studies	have	been	conducted	on	the	foremost	risk	associated	with	UDVTs	-		the	invasiveness	of	non-native	worm	species	introduced	to	them	to	facilitate	decomposition.	Addison	(2009)	reports	that	“the	widespread	invasion	of	exotic	[non-native]	earthworms	into	Canada’s	forests	could	have	global	implications”	as	earthworm	free	forests	are	“repositories	of	significant	amounts	of	carbon,	nutrients	and	biodiversity”	(61).	As	UDVTs	traditionally	rely	on	earthworms	to	facilitate	decomposition,	and	inevitably	to	function	correctly,	this	knowledge	gap	is	significant.	However,	there	is	an	abundance	of	literature	on	 4	both	native	worm	species	in	British	Columbia	and	non-native	worm	species	that	may	be	applied	in	order	to	determine	whether	or	not	the	use	of	non-native	worm	species	in	UDVTs	risks	harming	native	invertebrate	communities	(Marshall	and	Fender	1998).		Marshall	and	Fender	(1998)	develop	a	method	to	assess	the	prevalence	of	native	and	non-native	earthworm	species	at	various	sites	on	Western	Vancouver	Island.	Their	research	focuses	on	four	distinct	chronosequences	(a	set	of	forested	sites	that	share	similar	attributes	but	are	of	different	ages)	defined	by	the	age	of	trees	in	the	area:	regeneration	(7-12	years),	immature	(29-49	years),	mature	(69-89	years)	and	old	growth	(>200	years).	However,	given	the	numerous	biogeoclimatic	ecosystem	classifications	(BECs)	in	British	Columbia,	this	data	cannot	be	applied	to	the	whole	of	the	province	as	it	is	limited	to	40	sampling	sites	equally	divided	across	four	chronosequences.	However,	their	findings	highlight	that	native	earthworm	species	have	not	been	extirpated	from	the	whole	of	British	Columbia	and	are	mainly	confined	to	Western	Vancouver	Island.	In	addition,	few	studies	have	documented	the	collection	of	native	earthworm	species	at	sites	that	fall	outside	of	the	conditions	of	Western	Vancouver	Island,	including	sites	near	Squamish,	BC	and	Bella	Bella,	BC	(McKey-Fender	and	Fender	1982;	McKey-Fender	et	al.	1994;	Hocking	and	Reimchen	2002).	These	studies	are	helpful	to	my	research	as	they	prove	that	there	are	limited	distributions	of	native	earthworm	species	present	in	various	BECs	within	BC	that	may	be	negatively	impacted	if	non-native	species	are	added	to	UDVTs	and	are	able	to	escape	and	reproduce.	Therefore,	the	introduction	of	invasive	non-native	earthworms	not	only	poses	a	threat	to	biodiversity	as	well	as	carbon	and	nutrient	cycling,	but	also	to	native	earthworm	populations	as	a	result	of	competition	for	food	and	habitat.	 5	Many	of	the	backcountry	climates	in	BC	parks	fall	into	the	category	of	being	less	than	ideal	for	the	survivorship	of	earthworms,	and	determining	if	invasive	escapees	will	survive	climates	outside	of	the	UDVT	is	essential	to	my	findings	and	recommendations.	Addison	(2009)	presents	twelve	years	of	significant	research	on	the	distribution	of	non-native	earthworm,	focusing	on	conditions	that	are	not	optimal	for	the	survival	of	earthworms.	Complimentary	to	Addison	(2009),	Hill	and	Baldwin	(2012)	provide	evidence	that	viable	earthworm	populations	can	be	maintained	in	UDVTs	at	elevations	as	high	as	2400	meters.	However,	neither	of	these	studies	provide	clear	information	on	the	limitations	for	survival	of	earthworm	species.		There	is	an	abundance	of	literature	on	the	habitat	requirements	of	Eisenia	fetida	and	distribution	of	this	species	(Reynolds	1977;	Fender	1985;	Ferguson	2004;	Addison	2009;	Reynolds	and	Reynolds	1992).	Collectively,	these	studies	note	that	the	Eisenia	fetida	requires	substrates	high	in	organic	matter	and	pH	and	is	generally	not	found	outside	of	human	created	environments	such	as	greenhouses	(Ferguson	2004).	Addison	(2009)	notes	that	the	species	is	frost-intolerant,	but	does	not	provide	information	or	data	on	responses	to	temperature	or	conclude	which	temperatures	cause	mortality	of	Eisenia	fetida.	In	addition,	Greiner	et	al.	(2011)	provide	data	on	the	cold	tolerance	of	composting	earthworm	species	in	order	to	evaluate	invasion	potential.	However,	Holstrump	(2003)	notes	that	earthworms	can	seek	frost-free	refuge	by	burrowing	deep	into	the	group.	This	presents	a	challenge	for	my	research	as	I	must	determine	whether	Addison’s	(2009)	terminology	of	‘frost	intolerant’	indicates	that	the	species	is	incapable	of	burrowing	in	order	to	survive	frost	and	subzero	conditions.	If	the	species	is	able	to	adapt	to	subzero	air	and	soil	temperatures	in	this	manner,	it	is	indicative	that	they	may	survive	and	reproduce	outside	of	the	UDVT	regardless	of	ambient	temperatures	in	that	 6	location.	Furthermore,	none	of	these	studies	address	the	issue	of	whether	or	not	the	Eisenia	fetida	is	capable	of	surviving	outside	of	UDVTs	in	areas	with	low	elevations	that	never,	or	very	rarely	reach	sub-zero	temperatures.		Results:	Benefits	As	UDVTs	reduce	the	amount	of	solid	and	liquid	human	waste	that	accumulates	in	holding	tanks,	they	provide	economic	benefits	to	BC	parks	(Hill	et	al.	2013a;	Hill	et	al.	2013b;	Hill	and	Baldwin	2012;	Hill	2013).	The	reduction	of	accumulated	human	waste	results	in	lower	operating	costs	that	are	associated	with	the	removal	of	human	waste	by	helicopter,	and	reduces	the	frequency	at	which	new	pits	must	be	dug	and	toilets	relocated.		Furthermore,	a	reduction	in	operator	and	user	exposure	to	pathogens	and	parasites	has	obvious	benefits	for	human	health	(Hill	et	al.	2013a;	Hill	et	al.	2013b;	Hill	and	Baldwin	2012;	Hill	2013).	It	has	been	largely	recognized	that	UDVTs	reduce	negative	environmental	impacts	by	reducing	the	amount	of	human	waste	leachate	in	surface	and	groundwater	(Hill	2016).	However,	a	reduction	in	the	amount	of	human	and	solid	waste	produced	can	also	be	associated	with	a	reduced	environmental	impact.	By	reducing	the	number	of	helicopter	flight	hours	required	for	the	operation	of	backcountry	pit	toilets,	UDVTs	lessen	greenhouse	gas	emissions	from	helicopters	–	therefore	having	a	positive	effect	on	our	climate.		Mitigating	Risk		 Eisenia	fetida	have	a	variety	of	attributes	which	make	it	ideal	for	vermicomposting	in	UDVTs.	They	withstand	handling,	tolerate	a	variety	of	moisture	contents,	thrive	at	high	densities	and	have	a	rapid	life	cycle	which	has	been	reported	to	be	50	days	from	cocoon	to	mature	adult	(Dominguez	2004).	Limitations	to	the	survival	of	Eisenia	fetida	include	propagule	 7	pressure	(a	measure	of	the	number	of	individuals	of	a	species	released	into	a	region	to	which	they	are	not	native),	soil	pH,	competition	with	other	invertebrates	and	detritivores,	soil	moisture,	and	temperature	(Greiner	et	al.	2011;	Costello	et	al.	2011;	Bohlen	et	al	2004;	Lavelle	1983).	Although	environmental	conditions	(such	as	the	pH	of	soil)	vary	a	great	deal	between	sites	in	BC	Parks,	temperature	data	is	readily	available	for	all	regions	of	the	province.	Therefore,	in	order	to	identify	sites	where	there	is	a	low	risk	of	the	species	becoming	invasive,	it	is	beneficial	to	concentrate	on	the	response	of	Eisenia	fetida	to	various	temperatures.	It	has	been	noted	that	the	species	is	largely	considered	to	have	a	low	invasion	risk	in	temperate	environments,	notably	due	to	the	intolerance	of	the	species	to	winter	temperatures	(Addison	2008;	Tiunov	et	al.	2006).	However,	Greiner	et	al.	(2011)	explain	that	“regardless	of	whether	adult	earthworms	survive	cold	temperatures,	a	species	could	regenerate	in	temperate	regions	if	its	cocoons	remain	viable	after	overwintering	and	earthworm	cocoons	tend	to	be	more	frost-tolerant	and	cold-hardy	than	adult	earthworms”	(350).			 In	order	to	analyze	the	cold	tolerance	of	Eisenia	fetida,	Greiner	et	al.	(2011)	conducted	an	experiment	where	the	species	was	subjected	to	a	room-temperature	treatment	where	the	environment	was	kept	at	18	°C	and	a	cold-temperature	treatment	where	the	environment	was	kept	at	1.5°C.	The	experiment	found	that	399	of	400	earthworms	survived	the	room-temperature	environment	after	a	period	of	seven	days.	Alternatively,	the	earthworms	kept	in	the	low-temperature	environment	reached	a	mortality	rate	of	100%	after	a	period	of	150	hours	(6.25	days).	Eisenia	fetida	cocoons	were	subjected	to	the	same	treatment,	and	it	was	found	that	their	cocoons	were	also	sensitive	to	low	temperatures	and	mortality	increased	within	the	low-temperature	environment.	However,	difficulty	counting	and	tracking	cocoons	resulted	in	a	 8	low	degree	of	certainty	regarding	the	mortality	rate	of	cocoons	within	the	1.5°C	environment.	Regardless,	it	has	been	noted	that	Eisenia	fetida	cocoons	cannot	tolerate	freezing	temperatures	whereas	other	earthworm	species	of	European	decent	are	frost	tolerant	(Holmstrup	et	al.	1990).	Although	local	environmental	conditions	may	vary	largely	between	vermicomposting	sites	in	BC	Parks,	temperature	can	be	relied	upon	as	a	factor	which	limits	the	invasion	risk	of	the	species.	Therefore,	Eisenia	fetida	can	be	utilized	at	vermicomposting	sites	where	soil	temperatures	remain	at	or	below	1.5°C	for	a	period	of	150	hours	or	longer	with	a	high	degree	of	confidence	that	they	will	not	become	invasive.	In	order	to	address	uncertainty	regarding	the	influence	of	propagule	pressure,	soil	pH,	competition	with	other	invertebrates	and	detritivores,	and	soil	moisture,	I	suggest	that	a	conservative	approach	be	taken	and	the	use	of	Eisenia	fetida	be	limited	to	sites	where	soil	temperatures	remain	below	0°C	for	a	period	of	one	week.	Furthermore,	Ferguson	(2004)	notes	that	Eisenia	fetida	require	substrates	high	in	organic	matter	such	as	manure	and	compost	as	well	as	a	soil	pH	of	6.8-7.6	to	survive.	Therefore,	the	species	may	be	used	at	sites	that	are	highly	acidic	or	alkaline,	where	there	is	a	lack	of	soil	high	in	organic	matter	(such	as	high-alpine	environments)	and	where	soil	temperatures	reach	below	0°C	for	a	period	of	a	week	or	greater	with	a	high	degree	of	confidence	that	their	invasion	potential	is	extremely	low.		Mitigating	Risk:	Alternatives	to	the	use	of	Eisenia	fetida		 Although	Eisenia	fetida	is	the	preferred	species	for	facilitating	decomposition	of	human	waste	in	urine	diverting	toilet	systems	as	they	facilitate	rapid	decomposition,	there	are	an	abundance	of	other	detritivores	that	can	effectively	serve	the	same	function	in	the	setting	of	a	UDVT.	As	recognized	by	Yang	(2006)	“detritivore	communities	influence	the	decomposition	of	detrital	resources	in	virtually	all	natural	systems”	(522).	The	definition	of	detritus	includes	 9	decomposing	plant	and	animal	parts	as	well	as	feces.	Therefore,	inputs	to	UDVTs,	including	solid	human	waste	and	toilet	paper,	can	be	considered	to	be	detrital	resources.		According	to	Hill	(2016),	toilet	paper	makes	up	the	majority	of	waste,	or	detrital	resources,	following	urine	diversion	in	UDVTS	(figure	1).			Figure	1:	Pit	at	a	UDVT	site	in	Smith	Rock	State	Park	prior	to	decomposition	Source:	Hill	(2016)	Toilet	paper	is	rich	in	available	carbon	which	has	been	demonstrated	to	encourage	the	growth	of	detritivores	(Tiunov	and	Scheu	2004).	Therefore,	they	may	be	used	to	effectively	reduce	the	solid	waste	stream	from	UDVTs.	Detritivores	are	present	in	virtually	all	soils	and	a	large	variety	of	detritivorous	species	have	been	well	documented	in	British	Columbia	whose	primary	ecosystem	function	is	to	decompose	organic	materials,	including:	Zapada	cinctipes,	Z.	haysi,	Malenka	californica,	M.	cornuta,	Capnia	sp.,	and	Lepidostoma	roafi,	Despaxia	augusta,	Harpaphe	haydeniana,	and	Brillia	retifinis	(Richardson	2001;	Cárcamo	et	al.	2001,	Cárcamo	et	al.	2000).	Therefore,	adding	soil	from	the	local	area	to	UDVTs	can	facilitate	the	decomposition	of	solid	waste	streams	in	the	context	of	the	varying	environments	of	BC	Parks.	This	has	been	witnessed	by	Hill	(2016)	in	Smith	Rock	State	Park,	where	local	soil	from	a	streambed	was	added	 10	to	a	UDVT.	After	4	months	of	processing	under	a	plastic	sheet,	and	with	the	addition	of	water	for	moisture,	decomposition	had	occurred	to	the	point	that	tree	root	growth	was	visible	throughout	the	solid	waste	(figure	2).			Figure	2:	Waste	after	4	months	of	decomposition	with	detritivores	at	Smith	Rock	State	Park	Source:	Hill	(2016)	As	detritivores	are	present	throughout,	and	native	to,	British	Columbia’s	soils,	they	can	easily	be	added	to	UDVTs	with	no	risk	of	them	becoming	invasive.	Therefore,	at	sites	where	temperature	and	soil	conditions	may	allow	for	Eisenia	fetida	to	become	invasive,	such	as	sites	which	do	not	reach	temperatures	below	0°C	for	a	period	of	greater	than	a	week	or	that	have	a	pH	of	6.8-7.6,	native	detritivores	may	be	used	to	facilitate	the	decomposition	process	in	order	to	reduce	the	amount	of	waste	produced	by	UDVTs.	This	would	result	in	the	same	benefits	as	the	use	of	Eisenia	fetida	in	these	systems,	including	a	reduction	of	the	amount	of	waste	produced,	a	reduction	in	operator	and	user	exposure	to	pathogens	and	parasites	and	a	reduced	environmental	impact.	 11	However,	it	is	worth	noting	that	detritivores	are	less	abundant	in	alpine	environments	that	are	dominated	by	glacial	ice,	snow,	ice-rock	interfaces	and	rock	surfaces	and	fissures	(Nagy	2009).	Therefore,	the	use	of	native	detritivores	at	alpine	locations	may	be	challenging.	Conversely,	locations	dominated	by	these	features	most	frequently	occur	at	altitudes	that	reach	sub-zero	temperatures	for	long	periods	of	time	during	the	winters	of	British	Columbia.	Therefore,	instead	of	native	detritivores,	Eisenia	fetida	can	be	introduced	to	alpine	UDVTs	in	order	facilitate	decomposition	with	a	high	degree	of	certainty	that	they	will	not	become	invasive.	Recommendations:			 Currently,	BC	Parks	has	retained	a	third	party	consulting	firm	to	conduct	monitoring	at	sites	where	Eisenia	fetida	have	been	introduced	to	UDVTs.	This	method	for	monitoring	relies	on	periodically	checking	these	sites	to	determine	whether	or	not	Eisenia	fetida	have	spread	outside	of	the	UDVTs.	Due	to	it’s	nature,	this	type	of	monitoring	is	both	time	consuming	and	expensive.	As	the	habitat	attributes	required	for	the	survival	of	Eisenia	fetida	are	well	documented,	I	recommend	that	BC	Parks	continue	monitoring	at	sites	where	it	has	already	commenced.	However,	I	recommend	that	moving	forward,	BC	Parks	conduct	soil	and	temperature	sampling	at	vermicomposting	sites	in	order	to	determine	whether	or	not	the	surrounding	environment	is	conducive	to	the	survival	of	Eisenia	fetida.	For	example,	if	pH	levels	fall	well	outside	the	range	of	6.8-7	and	temperatures	reached	0°C	for	a	period	of	greater	than	a	week	during	the	year,	it	could	be	concluded	with	a	reasonable	amount	of	certainty	that	any	escapees	from	the	UDVT	would	not	survive.		 12		 Furthermore,	I	recommend	that	native	detritivores	(including	native	earthworms	if	present)	are	used	at	sites	where	Eisenia	Fetida	has	the	potential	to	become	invasive.	This	can	be	accomplished	by	simply	gathering	wet	mucky	soil	from	the	site,	or	a	nearby	stream	bed,	and	adding	it	to	the	UDVT.			 Finally,	at	sites	where	populations	of	Eisenia	fetida	have	already	been	established,	I	recommend	that	BC	Parks	allow	for	the	use	of	the	species	for	vermicomposting	as	they	are	already	present	in	the	area,	and	their	introduction	to	the	UDVT	is	unlikely	to	result	in	further	harm	to	the	local	environment.		Suggestions	for	Future	Research:		 This	research	focuses	largely	on	the	environmental	conditions	required	for	the	survival	of	non-native	earthworm	species	in	order	to	determine	their	potential	to	become	invasive.	I	suggest	that	any	future	research	on	the	topic	of	the	use	of	Eisenia	fetida	in	UDVTs	should	focus	on	structural	controls	to	limit	the	number	of	escapees	from	the	system.	If	structural	controls	are	economically	feasible	and	practical	to	install	at	vermicomposting	sites	throughout	BC	Parks,	and	can	be	proven	to	be	effective	at	ensuring	there	are	no	escapees,	BC	Parks	will	be	able	to	forego	expensive	monitoring	at	these	sites	and	implement	vermicomposting	with	an	even	lower	invasion	potential.	Hill	(2016)	notes	that	various	pit	designs	in	UDVTs	already	exist,	including	open	pit,	pits	lined	with	pressure	treated	timber,	plastic	bags	and	concrete	boxes.	Each	of	these	designs	has	advantages	and	disadvantages,	with	some	being	more	secure	than	others.	However,	the	construction	of	more	secure	pits	(such	as	concrete	pits)	may	not	be	feasible	in	remote	areas	of	BC	Parks.			 	 13	References:	 Addison,	J.	A.	"Distribution	and	Impacts	of	Invasive	Earthworms	in	Canadian	Forest	Ecosystems."	Biological	Invasions	11.1	(2009):	59-79.			Bethune,	David.	A	Novel	Urine	Evaporation	and	Collection	System	for	Dry	Toilets.	Thesis.	University	of	Calgary.	Department	of	Engineering,	2015:	1-118.			Bohlen,	Patrick	J.,	Groffman,	Peter	M.,	Fahey,	Timothy	J.,	Fisk,	Melany	C.,	Suarez,	Esteban.,	Pelletier,	Derek	M.,	and	Fahey,	Robert	T.	"Ecosystem	Consequences	of	Exotic	Earthworm	Invasion	of	North	Temperate	Forests."	Ecosystems	7.1	(2004):	1-12.			Cárcamo,	H.	A.,	Prescott,	C.E.,	Chanway,	C.P.,	and	Abe,	T.A.	"Do	soil	fauna	increase	rates	of	litter	breakdown	and	nitrogen	release	in	forests	of	British	Columbia,	Canada?"	Canadian	Journal	of	Forest	Research	31.7	(2001):	1195-1204.		Cárcamo,	H.	A.,	Abe,	T.A.,	Prescott,	C.E.,	Holl,	F.B.,	and	Chanway,	C.P.	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McKay-Fender,	D.,	and	Fender,	W.M.	“The	identity	of	Plutellus	perrieri	Benham	1892	and	its	distribution	in	relation	to	glacial	refugia.”	Megadrilogica	4.1	(1982):	81-86.		Nagy,	L.,	and	Grabherr,	G.	The	Biology	of	Alpine	Habitats.	Oxford;	New	York;	Oxford	University	Press,	2009.			Reynolds	J.W.,	and	Reynolds	K.W.	“Earthworms	on	the	North	Shore	of	the	Saint	Laurent	(Quebec).”	Megadrilogica	4	(1992):	145-161.		Reynolds,	J.W.	The	earthworms	(Lumbricidae	and	Sparganphilidae)	of	Ontario.	Toronto:	Royal	Ontario	Museum,	1977.			 15	Richardson,	John	S.	"Life	Cycle	Phenology	of	Common	Detritivores	from	a	Temperate	Rainforest	Stream."	Hydrobiologia	455.1	(2001):	87-95.			Tiunov,	Alexei	V.,	and	Scheu,	Stefan.	"Carbon	Availability	Controls	the	Growth	of	Detritivores	(Lumbricidae)	and	their	Effect	on	Nitrogen	Mineralization."	Oecologia	138.1	(2004):	83-90.			Tiunov,	Alexei	V.,	Hale,	Cindy	M.,	Holdsworth,	Andrew	R.,	and	Vsevolodova-Perel,	Tamara	S.	"Invasion	Patterns	of	Lumbricidae	into	the	Previously	Earthworm-Free	Areas	of	Northeastern	Europe	and	the	Western	Great	Lakes	Region	of	North	America."	Biological	Invasions	8.6	(2006):	1223-1234.		Yang,	Louie	H.	"Interactions	between	a	Detrital	Resource	Pulse	and	a	Detritivore	Community.”	Oecologia	147.3	(2006):	522-532.		


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